Intracellular pH Modulates Taste Receptor Cell Volume and the Phasic Part of the Chorda Tympani Response to Acids

The relationship between cell volume and the neural response to acidic stimuli was investigated by simultaneous measurements of intracellular pH (pHi) and cell volume in polarized fungiform taste receptor cells (TRCs) using 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF) in vitro and by rat chorda tympani (CT) nerve recordings in vivo. CT responses to HCl and CO2 were recorded in the presence of 1 M mannitol and specific probes for filamentous (F) actin (phalloidin) and monomeric (G) actin (cytochalasin B) under lingual voltage clamp. Acidic stimuli reversibly decrease TRC pHi and cell volume. In isolated TRCs F-actin and G-actin were labeled with rhodamine phalloidin and bovine pancreatic deoxyribonuclease-1 conjugated with Alexa Fluor 488, respectively. A decrease in pHi shifted the equilibrium from F-actin to G-actin. Treatment with phalloidin or cytochalasin B attenuated the magnitude of the pHi-induced decrease in TRC volume. The phasic part of the CT response to HCl or CO2 was significantly decreased by preshrinking TRCs with hypertonic mannitol and lingual application of 1.2 mM phalloidin or 20 μM cytochalasin B with no effect on the tonic part of the CT response. In TRCs first treated with cytochalasin B, the decrease in the magnitude of the phasic response to acidic stimuli was reversed by phalloidin treatment. The pHi-induced decrease in TRC volume induced a flufenamic acid–sensitive nonselective basolateral cation conductance. Channel activity was enhanced at positive lingual clamp voltages. Lingual application of flufenamic acid decreased the magnitude of the phasic part of the CT response to HCl and CO2. Flufenamic acid and hypertonic mannitol were additive in inhibiting the phasic response. We conclude that a decrease in pHi induces TRC shrinkage through its effect on the actin cytoskeleton and activates a flufenamic acid–sensitive basolateral cation conductance that is involved in eliciting the phasic part of the CT response to acidic stimuli

Effect of topical microporous polysaccharide hemospheres on the duration and amount of fluid drainage following mastectomy: a prospective randomized clinical trial

Abstract Background Seroma formation is the most common complication after mastectomy and places patients at risk of associated morbidities. Microporous polysaccharide hemospheres (MPH) consists of hydrophilic, plant based, polysaccharide particles and is currently used as an absorbable hemostatic agent. An animal model evaluating MPH and seroma formation after mastectomy with axillary lymph node dissection showed a significant decrease in seroma volume. Study aim was to evaluate topical MPH on the risk of post-mastectomy seroma formation as measured by total drain output and total drain days. Methods Prospective randomized single-blinded clinical trial of patients undergoing mastectomy for the treatment of breast cancer. MPH was applied to the surgical site in the study group and no application in the control group. Results Fifty patients were enrolled; eight were excluded due to missing data. Forty-two patients were evaluated, control (n = 21) vs. MPH (n = 21). No difference was identified between the two groups regarding demographics, tumor stage, total drain days, total drain output, number of clinic visits, or complication rates. On a subset analysis, body mass index (BMI) greater than 30 was identified as an independent risk factor for high drain output. Post hoc analyses of MPH controlling for BMI also revealed no statistical difference. Conclusions Unlike the data presented in an animal model, no difference was demonstrated in the duration and quantity of serosanguinous drainage related to the use of MPH in patients undergoing mastectomy for the treatment of breast cancer. BMI greater than 30 was identified as an independent risk factor for high drain output and this risk was not affected by MPH use. NCT03647930, retrospectively registered 08/2018

Stimulus-driven and strategic neural responses to fearful and happy facial expressions in humans

The human amygdala responds selectively to consciously and unconsciously perceived facial expressions, particularly those that convey potential threat such as fear and anger. In many social situations, multiple faces with varying expressions confront observers yet little is known about the neural mechanisms involved in encoding several faces simultaneously. Here we used event-related fMRI to measure neural activity in pre-defined regions of interest as participants searched multi-face arrays for a designated target expression (fearful or happy). We conducted separate analyses to examine activations associated with each of the four multi-face arrays independent of target expression (stimulus-driven effects), and activations arising from the search for each of the target expressions, independent of the display type (strategic effects). Comparisons across display types, reflecting stimulus-driven influences on visual search, revealed activity in the amygdala and superior temporal sulcus (STS). By contrast, strategic demands of the task did not modulate activity in either the amygdala or STS. These results imply an interactive threat-detection system involving several neural regions. Crucially, activity in the amygdala increased significantly when participants correctly detected the target expression, compared with trials in which the identical target was missed, suggesting that the amygdala has a limited capacity for extracting affective facial expressions