Visualizing partial solvation at the air-water interface.

Despite significant research, the mechanistic nuances of unusual reactivity at the air-water interface, especially in microdroplets, remain elusive. The likely contributors include electric fields and partial solvation at the interface. To reveal these intricacies, we measure the frequency shift of a well-defined azide vibrational probe at the air-water interface, while independently controlling the surface charge density by introducing surfactants.

Effects of in utero exposure to fluoxetine on the gastrointestinal tract of rat offspring.

Perinatal exposure to selective serotonin reuptake inhibitors (SSRIs) has been shown to disrupt the development of serotonergic signaling pathways in the brain and enteric nervous system. Serotonin (5-hydroxytryptamine; 5-HT) signaling is critical for gastrointestinal homeostasis; changes in 5-HT expression and regulation have been associated with gastrointestinal diseases of motility and inflammation. We tested the hypothesis that perinatal exposure to the SSRI fluoxetine can influence the development of the gastrointestinal tract in exposed offspring.

Jet-Cooled Phosphorescence Excitation Spectrum of the T(n,π*) ← S Transition of 4-Pyran-4-one.

The 4-pyran-4-one (4PN) molecule is a cyclic conjugated enone with spectroscopically accessible singlet and triplet (n,π*)excited states. Vibronic spectra of 4PN provide a stringent test of electronic-structure calculations, through comparison of predicted vs measured vibrational frequencies in the excited state. We report here the T(n,π*) ← S phosphorescence excitation spectrum of 4PN, recorded under the cooling conditions of a supersonic free-jet expansion.

Nitric Oxide Is Essential for Generating the Minute Rhythm Contraction Pattern in the Small Intestine, Likely via ICC-DMP.

Nitrergic nerves have been proposed to play a critical role in the orchestration of peristaltic activities throughout the gastrointestinal tract. In the present study, we investigated the role of nitric oxide, using spatiotemporal mapping, in peristaltic activity of the whole mouse intestine. We identified a propulsive motor pattern in the form of propagating myogenic contractions, that are clustered by the enteric nervous system into a minute rhythm that is dependent on nitric oxide.

First performance report of QIAreach™ Anti-SARS-CoV-2 Total Test, an innovative nanoparticle fluorescence digital detection platform.

In 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a global pandemic. Disease diagnosis, appropriate clinical management and infection control are all important factors in controlling the spread of SARS-CoV-2. The QIAreach™ Anti-SARS-CoV-2 Total Test (Anti-CoV2) is a rapid, qualitative serological test, using proprietary nanoparticle fluorescence technology to detect total antibody (IgA, IgM, and IgG) against SARS-CoV-2.

Modulation of contractions in the small intestine indicate desynchronization via supercritical Andronov-Hopf bifurcation.

The small intestine is covered by a network of coupled oscillators, the interstitial cells of Cajal (ICC). These oscillators synchronize to generate rhythmic phase waves of contraction. At points of low coupling, oscillations desynchronise, frequency steps occur and every few waves terminates as a dislocation.

The cyclic motor patterns in the human colon.

Background: High-resolution colonic manometry gives an unprecedented window into motor patterns of the human colon. Our objective was to characterize motor activities throughout the entire colon that possessed persistent rhythmicity and spanning at least 5 cm.

Methods: High-resolution colonic manometry using an 84-channel water-perfused catheter was performed in 19 healthy volunteers.

On the nature of high-amplitude propagating pressure waves in the human colon.

Characterization of high-amplitude propagating pressure waves (HAPWs or HAPCs) plays a key role in diagnosis of colon dysmotility using any type of colonic manometry. With the introduction of high-resolution manometry, more insight is gained into this most prominent propulsive motor pattern. Here, we use a water-perfused catheter with 84 sensors with intervals between measuring points of 1 cm throughout the colon, for 6-8 h, in 19 healthy subjects.

Associations Between Colonic Motor Patterns and Autonomic Nervous System Activity Assessed by High-Resolution Manometry and Concurrent Heart Rate Variability.

Abnormal colonic motility may be associated with dysfunction of the autonomic nervous system (ANS). Our aim was to evaluate if associations between colonic motor patterns and autonomic neural activity could be demonstrated by assessing changes in heart rate variability (HRV) in healthy volunteers. A total of 145 colonic motor patterns were assessed in 11 healthy volunteers by High-Resolution Colonic Manometry (HRCM) using an 84-channel water-perfused catheter.

A myogenic motor pattern in mice lacking myenteric interstitial cells of Cajal explained by a second coupled oscillator network.

The interstitial cells of Cajal associated with the myenteric plexus (ICC-MP) are a network of coupled oscillators in the small intestine that generate rhythmic electrical phase waves leading to corresponding waves of contraction, yet rhythmic action potentials and intercellular calcium waves have been recorded from c-kit-mutant mice that lack the ICC-MP, suggesting that there may be a second pacemaker network. The gap junction blocker carbenoxolone induced a "pinstripe" motor pattern consisting of rhythmic "stripes" of contraction that appeared simultaneously across the intestine with a period of ~4 s. The infinite velocity of these stripes suggested they were generated by a coupled oscillator network, which we call X.

Cell-specific effects of nitric oxide on the efficiency and frequency of long distance contractions in murine colon.

Background: Nitric oxide (NO) mediates inhibitory neurotransmission and is a critical component of neuronal programs that generate propulsive contractions. NO acts via its receptor NO-sensitive guanylyl cyclase (NO-GC) which is expressed in smooth muscle cells (SMC) and interstitial cells of Cajal (ICC). Organ bath studies with colonic rings from NO-GC knockout mice (GCKO) have indicated NO-GC to modulate spontaneous contractions.

Noradrenaline inhibits neurogenic propulsive motor patterns but not neurogenic segmenting haustral progression in the rabbit colon.

Background: Excessive sympathetic inhibition may be a cause of colon motor dysfunction. Our aim was to better understand the mechanisms of sympathetic inhibition on colonic motor patterns using the rabbit colon, hypothesizing that noradrenaline selectively inhibits propulsive motor patterns.

Methods: Changes in motor patterns of the rabbit colon were studied ex vivo using noradrenaline and adrenoceptor antagonists and analyzed using spatiotemporal diameter maps.

Characterization of Simultaneous Pressure Waves as Biomarkers for Colonic Motility Assessed by High-Resolution Colonic Manometry.

Simultaneous pressure waves (SPWs) in manometry recordings of the human colon have been associated with gas expulsion. Our hypothesis was that the SPW might be a critical component of most colonic motor functions, and hence might act as a biomarker for healthy colon motility. To that end, we performed high-resolution colonic manometry (HRCM), for the first time using an 84-sensor (1 cm spaced) water-perfused catheter, in 17 healthy volunteers.

Abnormal absorptive colonic motor activity in germ-free mice is rectified by butyrate, an effect possibly mediated by mucosal serotonin.

The role of short-chain fatty acids (SCFAs) in the control of colonic motility is controversial. Germ-free (GF) mice are unable to produce these metabolites and serve as a model to study how their absence affects colonic motility. GF transit is slower than controls, and colonization of these mice improves transit and serotonin [5-hydroxytryptamine (5-HT)] levels.

Heterogeneity of calcium clock functions in dormant, dysrhythmically and rhythmically firing single pacemaker cells isolated from SA node.

Current understanding of how cardiac pacemaker cells operate is based mainly on studies in isolated single sinoatrial node cells (SANC), specifically those that rhythmically fire action potentials similar to the in vivo behavior of the intact sinoatrial node. However, only a small fraction of SANC exhibit rhythmic firing after isolation. Other SANC behaviors have not been studied.

Phase waves and trigger waves: emergent properties of oscillating and excitable networks in the gut.

The gut is enmeshed by a number of cellular networks, but there is only a limited understanding of how these networks generate the complex patterns of activity that drive gut contractile functions. Here we review two fundamental types of cell behaviour, excitable and oscillating, and the patterns that networks of such cells generate, trigger waves and phase waves, respectively. We use both the language of biophysics and the theory of nonlinear dynamics to define these behaviours and understand how they generate patterns.

Slow wave contraction frequency plateaux in the small intestine are composed of discrete waves of interval increase associated with dislocations.

New Findings: What is the central question of this study? What is the nature of slow wave-driven contraction frequency gradients in the small intestine? What is the main finding and its importance? Frequency plateaux are composed of discrete waves of increased interval, each wave associated with a contraction dislocation. Smooth frequency gradients are generated by localized neural modulation of wave frequency, leading to functionally important wave turbulence. Both patterns are emergent properties of a network of coupled oscillators, the interstitial cells of Cajal.

Computer algorithms for automated detection and analysis of local Ca2+ releases in spontaneously beating cardiac pacemaker cells.

Local Ca2+ Releases (LCRs) are crucial events involved in cardiac pacemaker cell function. However, specific algorithms for automatic LCR detection and analysis have not been developed in live, spontaneously beating pacemaker cells. In the present study we measured LCRs using a high-speed 2D-camera in spontaneously contracting sinoatrial (SA) node cells isolated from rabbit and guinea pig and developed a new algorithm capable of detecting and analyzing the LCRs spatially in two-dimensions, and in time.

The phase response and state space of slow wave contractions in the small intestine.

What is the central question of this study? What are the dynamical rules governing interstitial cell of Cajal (ICC)-generated slow wave contractions in the small intestine, as reflected in their phase response curve and state space? What is the main finding and its importance? The phase response curve has a region of phase advance surrounding a phase delay peak. This pattern is important in generating a stable synchrony within the ICC network and is related to the state space of the ICC; in particular, the phase delay peak corresponds to the unstable equilibrium point that threads the ICC's limit cycle. Interstitial cells of Cajal (ICCs) generate electrical oscillations in the gut.

Network properties of interstitial cells of Cajal affect intestinal pacemaker activity and motor patterns, according to a mathematical model of weakly coupled oscillators.

What is the central question of this study? What are the effects of interstitial cells of Cajal (ICC) network perturbations on intestinal pacemaker activity and motor patterns? What is the main finding and its importance? Two-dimensional modelling of the ICC pacemaker activity according to a phase model of weakly coupled oscillators showed that network properties (coupling strength between oscillators, frequency gradient and frequency noise) strongly influence pacemaker network activity and subsequent motor patterns. The model explains motor patterns observed in physiological conditions and provides predictions and testable hypotheses for effects of ICC loss and frequency modulation on the motor patterns. Interstitial cells of Cajal (ICC) are the pacemaker cells of gut motility and are associated with motility disorders.

Abnormal cannabidiol attenuates experimental colitis in mice, promotes wound healing and inhibits neutrophil recruitment.

Background: Non-psychotropic atypical cannabinoids have therapeutic potential in a variety of inflammatory conditions including those of the gastrointestinal tract. Here we examined the effects of the atypical cannabinoid abnormal cannabidiol (Abn-CBD) on wound healing, inflammatory cell recruitment and colitis in mice.

Methods: Colitis was induced in CD1 mice by a single intrarectal administration of trinitrobenzene sulfonic acid (TNBS, 4 mg/100 μl in 30 % ethanol) and Abn-CBD and/or the antagonists O-1918 (Abd-CBD), AM251 (CB1 receptor) and AM630 (CB2 receptor), were administered intraperitoneally (all 5 mg/kg, twice daily for 3 days).

Spatial Noise in Coupling Strength and Natural Frequency within a Pacemaker Network; Consequences for Development of Intestinal Motor Patterns According to a Weakly Coupled Phase Oscillator Model.

Pacemaker activities generated by networks of interstitial cells of Cajal (ICC), in conjunction with the enteric nervous system, orchestrate most motor patterns in the gastrointestinal tract. It was our objective to understand the role of network features of ICC associated with the myenteric plexus (ICC-MP) in the shaping of motor patterns of the small intestine. To that end, a model of weakly coupled oscillators (oscillators influence each other's phase but not amplitude) was created with most parameters derived from experimental data.