Evaluating Osteoarthritis Management Programs: outcome domain recommendations from the OARSI Joint Effort Initiative.

OBJECTIVE: To develop sets of core and optional recommended domains for describing and evaluating Osteoarthritis Management Programs (OAMPs), with a focus on hip and knee Osteoarthritis (OA). DESIGN: We conducted a 3-round modified Delphi survey involving an international group of researchers, health professionals, health administrators and people with OA. In Round 1, participants ranked the importance of 75 outcome and descriptive domains in five categories: patient impacts, implementation outcomes, and characteristics of the OAMP and its participants and clinicians. Domains ranked as "important" or "essential" by ≥80% of participants were retained, and participants could suggest additional domains. In Round 2, participants rated their level of agreement that each domain was essential for evaluating OAMPs: 0 = strongly disagree to 10 = strongly agree. A domain was retained if ≥80% rated it ≥6. In Round 3, participants rated remaining domains using same scale as in Round 2; a domain was recommended as "core" if ≥80% of participants rated it ≥9 and as "optional" if ≥80% rated it ≥7. RESULTS: A total of 178 individuals from 26 countries participated; 85 completed all survey rounds. Only one domain, "ability to participate in daily activities", met criteria for a core domain; 25 domains met criteria for an optional recommendation: 8 Patient Impacts, 5 Implementation Outcomes, 5 Participant Characteristics, 3 OAMP Characteristics and 4 Clinician Characteristics. CONCLUSION: The ability of patients with OA to participate in daily activities should be evaluated in all OAMPs. Teams evaluating OAMPs should consider including domains from the optional recommended set, with representation from all five categories and based on stakeholder priorities in their local context.

Photonic crystal resonators for inverse-designed multi-dimensional optical interconnects.

We experimentally demonstrate a 400 Gbit/s optical communication link utilizing wavelength-division multiplexing and mode-division multiplexing for a total of 40 channels. This link utilizes a novel, to the best of our knowledge, 400 GHz frequency comb source based on a chip-scale photonic crystal resonator. Silicon-on-insulator photonic inverse-designed 4 × 4 mode-division multiplexer structures enable a fourfold increase in data capacity. We show less than -10 dBm of optical receiver power for error-free data transmission in 34 out of a total of 40 channels using a PRBS31 pattern.

Observation of rotational coherence in an excited state of CO.

The vacuum ultraviolet (VUV) radiation is generated in the strong-field-ionized CO molecules through 2+1 resonance excitation with two-color femtosecond laser pulses. When scanning the relative delay between two pump pulses, the rotational-resolved VUV radiations show periodic oscillations lasting as long as 500 ps. Fourier analysis reveals that these oscillations correspond to rotational beat frequencies of the A2Πi state of CO+, which is the result of multi-channel interference during the resonant excitation process. High resolution of Fourier transform spectra up to 0.067cm-1 allows us to obtain the fine energy levels of the A2Πi state. The theoretical calculation is in good agreement with the experimental observation. This work reveals the rotational coherence of the ionic excited state and shows the prospect of rotational coherence spectroscopy in measuring fine structures of molecular ions.

Development of a core capability framework for qualified health professionals to optimise care for people with osteoarthritis: an OARSI initiative.

OBJECTIVE: Develop a generic trans-disciplinary, skills-based capability framework for health professionals providing care for people with OA. DESIGN: e-Delphi survey. An international inter-professional Delphi Panel (researchers; clinicians; consumer representatives) considered a draft framework (adapted from elsewhere) of 131 specific capabilities mapped to 14 broader capability areas across four domains (A: person-centred approaches; B: assessment, investigation and diagnosis; C: management, interventions and prevention; D: service and professional development). Over three rounds, the Panel rated their agreement (Likert or numerical rating scales) on whether each specific capability in Domains B and C was essential (core) for all health professionals when providing care for all people with OA. Those achieving consensus (≥80% of Panel) rating of ≥ seven out of ten (Round 3) were retained. Generic domains (A and D) were included in the final framework and amended based on Panel comments. RESULTS: 173 people from 31 countries, spanning 18 disciplines and including 26 consumer representatives, participated. The final framework comprised 70 specific capabilities across 13 broad areas i) communication; ii) person-centred care; iii) history-taking; iv) physical assessment; v) investigations and diagnosis; vi) interventions and care planning; vii) prevention and lifestyle interventions; viii) self-management and behaviour change; ix) rehabilitative interventions; x) pharmacotherapy; xi) surgical interventions; xii) referrals and collaborative working; and xiii) evidence-based practice and service development). CONCLUSION: Experts agree that health professionals require an array of skills in person-centred approaches; assessment, investigation and diagnosis; management, interventions and prevention; and service and professional development to provide optimal care for people with OA.

[Therapeutic effects of pars plana vitrectomy combined with internal limiting membrane peeling on high myopic foveoschisis].

Objective: To observe the clinical efficacy of vitrectomy combined with foveal-sparing circular internal limiting membrane peeling with the central fovea reserved in patients with high myopic foveoschisis. Methods: Case-control study. A total of 72 patients (86 eyes) with foveoschisis due to high myopia who underwent vitrectomy combined with internal limiting membrane peeling in Lishui Municipal Central Hospital of Zhejiang Province from June 2016 to May 2017 were enrolled, including 18 males (18 eyes) and 54 females (68 eyes), aged (50.5±8.9) years. The patients were randomly divided into the observation group (34 cases, 43 eyes) and the control group (38 cases, 43 eyes) using a random number table and random number residual grouping method. Vitrectomy was performed in all patients. In the control group, the limiting membrane in the macular area was removed during surgery. In the observation group, the foveal annular internal limiting membrane was preserved during surgery. In severe cases, cataract extraction was performed. Results: In the observation group, the mean central foveal thickness (CFT) on optical coherence tomography was (723.49±130.95) µm preoperatively and decreased to (286.33±210.73) µm postoperatively, and the difference had statistical significance (t=17.059, P=0.000). In 39 eyes with complete or partial healing of the foveal split, the best corrected visual acuity (BCVA) was (0.99±0.40) logMAR before the treatment and increased to 0.68±0.24 after the treatment, and the difference had statistical significance (t=7.585, P=0.000). In the control group, the mean CFT was (726.98±140.62) µm and (297.88±241.56.) µm before and after the treatment, respectively, and the difference had statistical significance (t=16.271, P=0.000). In 38 eyes with complete or partial healing of the foveal split, the BCVA increased from preoperative 1.04±0.47 to postoperative 0.69±0.21, and the difference had statistical significance (t=6.707, P=0.00). With the follow-up time as the efficacy determination time, there was no significant difference in BCVA (t=0.22, P=0.983) and CFT (t=0.236, P=0.814) between the observation group and the control group (P>0.05); there was significant difference in the incidence rate of macular holes (P=0.026). There was no statistically significant difference in the rate of complete macular morphology healing between the two groups (P=0.816). Conclusion: Vitrectomy combined with foveal-sparing circular internal limiting membrane peeling can effectively treat high myopic macular holes and reduce the formation of postoperative macular holes. (Chin J Ophthalmol, 2020, 56: 928-932).

Chinese military medical teams in the Ebola outbreak of Sierra Leone.

The 2014-2015 Ebola virus disease (EVD) epidemic in West Africa was the largest in history. The three most affected countries, Guinea, Liberia and Sierra Leone, have faced enormous challenges in controlling transmission and providing clinical care for patients with EVD. The Chinese government, in response to the requests of the WHO and the governments of the affected countries, responded rapidly by deploying Chinese military medical teams (CMMTs) to the areas struck by the deadly epidemic. A total of three CMMTs, comprising 115 military medical professionals, were rotationally deployed to Freetown, Sierra Leone to assist with infection prevention and control, clinical care and health promotion and training. Between 1 October 2014 and 22 March 2015, the CMMTs in Sierra Leone admitted and treated a total of 773 suspected and 285 confirmed EVD cases. Among the 285 confirmed cases, 146 (51.2%) patients survived after treatment. In addition, the CMMTs maintained the record of zero infections among healthcare workers and zero cross-infections between quarantined patients. In this manuscript, we aim to give an overview of the mission, and share our best practices experience on predeployment preparedness, EVD holding and treatment centre building and EVD case management.

Superradiance for Atoms Trapped along a Photonic Crystal Waveguide.

We report observations of superradiance for atoms trapped in the near field of a photonic crystal waveguide (PCW). By fabricating the PCW with a band edge near the D(1) transition of atomic cesium, strong interaction is achieved between trapped atoms and guided-mode photons. Following short-pulse excitation, we record the decay of guided-mode emission and find a superradiant emission rate scaling as Γ̅(SR)∝N̅Γ(1D) for average atom number 0.19≲N̅≲2.6 atoms, where Γ(1D)/Γ'=1.0±0.1 is the peak single-atom radiative decay rate into the PCW guided mode, and Γ' is the radiative decay rate into all the other channels. These advances provide new tools for investigations of photon-mediated atom-atom interactions in the many-body regime.

Retraction Note: LncRNA UCA1 affects osteoblast proliferation and differentiation by regulating BMP-2 expression.

The article "LncRNA UCA1 affects osteoblast proliferation and differentiation by regulating BMP-2 expression", by R.-F. Zhang, J.-W. Liu, S.-P. Yu, D. Sun, X.-H. Wang, J.-S. Fu, Z. Xie, published in Eur Rev Med Pharmacol Sci 2019; 23 (16): 6774-6782-DOI: 10.26355/eurrev_201908_18715-PMID: 31486475 has been retracted by the authors for the following reasons: - The data presented in the manuscript require further validation, which may affect the results. After careful consideration, we have decided to withdraw it to ensure its reliability and reproducibility. All authors concur with this decision. This article has been retracted. The Publisher apologizes for any inconvenience this may cause. https://www.europeanreview.org/article/18715.

Ion homeostasis and apoptosis.

Alterations in the transmembrane gradients of several physiological ions may influence programmed cell death. In particular, recent data suggest that increases in intracellular calcium may either promote or inhibit apoptosis, depending on the level, timing and location, whereas loss of intracellular potassium promotes apoptosis.

Significance of TRPS1 in the development and clinicopathologic of hepatocellular carcinoma.

OBJECTIVE: The purpose of this paper was to explore roles and significance of transcriptional repressor GATA binding 1 (TRPS1) in the process of hepatocellular carcinoma (HCC) and clinicopathological parameters of HCC patients, respectively. PATIENTS AND METHODS: The expression of TRPS1 was detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) and Western blot. Chi-square test was used to investigate the association between TRPS1 and clinicopathological parameters of HCC patients. SiRNA was designed to suppress the expression of TRPS1. Moreover, transwell assay and cell cycle analysis were adopted to determine the invasion ability and proliferation ability of HCC cells. RESULTS: It was demonstrated that TRPS1 was abnormally over-expressed in HCC tissues and cells, and was closely associated with the vascular invasion, tumor size, and TNM stage of HCC patients. Besides, the results indicated that the inhibition of TRPS1 in HCC cells could impede the cell invasion ability and proliferation ability. CONCLUSIONS: TRPS1 plays a key role in the development of HCC and is closely associated with the clinicopathological parameters of HCC patients. Hence, it is proposed that TRPS1 may serve as a novel prognostic marker and a potential therapeutic target for HCC treatment.

NMDA receptor-mediated K+ efflux and neuronal apoptosis.

Neuronal death induced by activating N-methyl-D-aspartate (NMDA) receptors has been linked to Ca2+ and Na+ influx through associated channels. Whole-cell recording from cultured mouse cortical neurons revealed a NMDA-evoked outward current, INMDA-K, carried by K+ efflux at membrane potentials positive to -86 millivolts. Cortical neurons exposed to NMDA in medium containing reduced Na+ and Ca2+ (as found in ischemic brain tissue) lost substantial intracellular K+ and underwent apoptosis. Both K+ loss and apoptosis were attenuated by increasing extracellular K+, even when voltage-gated Ca2+ channels were blocked. Thus NMDA receptor-mediated K+ efflux may contribute to neuronal apoptosis after brain ischemia.

Mediation of neuronal apoptosis by enhancement of outward potassium current.

Apoptosis of mouse neocortical neurons induced by serum deprivation or by staurosporine was associated with an early enhancement of delayed rectifier (IK) current and loss of total intracellular K+. This IK augmentation was not seen in neurons undergoing excitotoxic necrosis or in older neurons resistant to staurosporine-induced apoptosis. Attenuating outward K+ current with tetraethylammonium or elevated extracellular K+, but not blockers of Ca2+, Cl-, or other K+ channels, reduced apoptosis, even if associated increases in intracellular Ca2+ concentration were prevented. Furthermore, exposure to the K+ ionophore valinomycin or the K+-channel opener cromakalim induced apoptosis. Enhanced K+ efflux may mediate certain forms of neuronal apoptosis.

LncRNA UCA1 affects osteoblast proliferation and differentiation by regulating BMP-2 expression.

OBJECTIVE: The aim of this study was to detect the expression of long non-coding ribonucleic acid (lncRNA) urothelial carcinoma associated 1 (UCA1) in the plasma of patients with osteoporosis (OST), and to investigate its influences on the proliferation and differentiation of osteoblasts and its mechanism. PATIENTS AND METHODS: Plasma samples were collected from 52 OST patients treated in our hospital and 30 healthy subjects receiving a physical examination, respectively. The expression level of lncRNA UCA1 in OST patients and healthy subjects were detected via Reverse Transcription-Polymerase Chain Reaction (RT-PCR). Furthermore, osteoblast MC3T3-E1 cell lines with a stable knockout of UCA1 in mice were constructed using small-interfering RNA (siRNA). The influence of UCA1 knockout on the proliferation of osteoblasts was detected using cell counting kit-8 (CCK-8) assay. Meanwhile, the proportion of EdU-positive cells in osteoblasts of the control group and UCA1 knockout group was detected using EdU staining. Moreover, the messenger RNA (mRNA) levels of differentiation-related genes, including Runt-related transcription factor 2 (Runx2), Collagen1α1, osteoclast (OC), osteoprotegerin (OPG), osteopontin (OPN) and Osterix (OSX), were detected via RT-PCR. The protein expression level of Runx2 was detected via Western blotting. In addition, osteoblasts were cultured with a bone-derived medium for 14 d. Then, the differentiation status was detected via alizarin red staining and alkaline phosphatase staining. Finally, the expression of bone morphogenetic protein-2 (BMP-2)/(Smad1/5/8) signaling pathway was analyzed using Western blotting. RESULTS: The expression of plasma lncRNA UCA1 was significantly increased in OST patients (p<0.05). Cell experiments revealed that UCA1 siRNA intervention could significantly promote the proliferation and differentiation of osteoblast MC3T3-E1 cell lines. In addition, Western blotting showed that the pro-apoptotic effect of UCA1 might be mediated by the BMP-2/(Smad1/5/8) signaling pathway in osteoblasts. CONCLUSIONS: Inhibiting lncRNA UCA1 can promote the proliferation and differentiation of osteoblasts by activating the BMP-2/(Smad1/5/8) signaling pathway in osteoblasts. Therefore, UCA1 is expected to be a new therapeutic target for OST.

Erythropoietin attenuates intracerebral hemorrhage by diminishing matrix metalloproteinases and maintaining blood-brain barrier integrity in mice.

The protective mechanism of recombinant human erythropoietin (rhEPO) on blood-brain barrier (BBB) after brain injury is associated with the attenuation of neuro-inflammation. We hypothesize that rhEPO treatment after intracerebral hemorrhage (ICH) modulates matrix metalloproteinase (MMP) activity, maintains BBB integrity, and reduces BBB breakdown-associated inflammation. Adult male 129S2/sv mice were subjected to autologous whole blood-induced ICH. rhEPO or saline was administered intraperitoneally immediately after surgery and for 3 more days until day of sacrifice. BBB permeability was measured by Evans blue leakage, and edema was assessed by brain water content. Immunofluorescence and Western blotting were performed to detect expression of tight junction marker occludin, type IV collagen, MMPs, tissue inhibitor of metalloproteinase (TIMP), and glial fibrillary acidic protein, rhEPO prevented Evans blue leakage, reduced brain edema, and preserved expression of occludin and collagen IV. rhEPO treatment decreased MMP-2 expression, increased TIMP-2 expression, and reduced the number of reactive astrocytes in the brain compared to saline control. We conclude that rhEPO reduces MMP activity, BBB disruption, and the glial cell inflammatory reaction 3 days after ICH. Our study provides additional evidence for the mechanism of rhEPO's neurovascular protective effects and a potential clinical application in the treatment of ICH.

Age-related neural degeneration in nuclear-factor kappaB p50 knockout mice.

Nuclear factor-kappaB is a transcription factor that regulates a variety of genes involved not only with immune and inflammatory responses, but also in cell survival. Nuclear-factor kappaB in the CNS is an area of current research interest; however, its role in age-related neural degeneration is obscure. The present study examines developmental degeneration changes in wild type and nuclear factor-kappaB p50 subunit knockout mice (p50-/-) using various morphological methodologies. P50-/- mice appeared normal at birth. At 6 and 10 months old, the body weight of p50-/- mice was significantly less than that of wild type mice and they started to die from aging. Consistently, terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end-labeling positive cells in the cortex were significantly more in p50-/- mice than that in wild type mice, and neuronal cells in the cortex, hippocampus and caudate nucleus-putamen decreased in p50-/- mice. Fewer myelinated axons of the optic nerve were found in p50-/- mice than in wild type mice at 6 months. In p50-/- mice, morphological examinations showed: 1) aging and degenerative changes in the cortex and hippocampus including increased lipofuscin granules in neural cytoplasm, 2) abnormal capillaries, 3) dark and watery alterations and organelle accumulations, 4) apoptotic glia cells, and 5) terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end-labeling and caspase-3 positive neurons. These results suggest that nuclear-factor kappaB may play an important role in neurovascular development, cell survival, and the aging process in the CNS. This new evidence linking nuclear-factor kappaB to myelination and aging may be of considerable importance for several areas of basic and clinical neuroscience.

Modulation and genetic identification of the M channel.

Potassium channels constitute a superfamily of the most diversified ion channels, acting in delicate and accurate ways to control or modify many physiological and pathological functions including membrane excitability, transmitter release, cell proliferation and cell degeneration. The M-type channel is a unique ligand-regulated and voltage-gated K(+) channel showing distinct physiological and pharmacological characteristics. This review will cover some important progress in the study of M channel modulation, particularly focusing on membrane transduction mechanisms. The K(+) channel genes corresponding to the M channel have been identified and will be reviewed in detail. It has been a long journey since the discovery of M current in 1980 to our present understanding of the mysterious mechanisms for M channel modulation; a journey which exemplifies tremendous achievements in ion channel research and exciting discoveries of elaborate modulatory systems linked to these channels. While substantial evidence has accumulated, challenging questions remain to be answered.

Selective activation of group II mGluRs with LY354740 does not prevent neuronal excitotoxicity.

Recent reports have suggested a role for group II metabotropic glutamate receptors (mGluRs) in the attenuation of excitotoxicity. Here we examined the effects of the recently available group II agonist (+)-2-Aminobicyclo[3.1.0]hexane-2-6-dicarboxylic acid (LY354740) on N-methyl-D-aspartate (NMDA)-induced excitotoxic neuronal death, as well as on hypoxic-ischemic neuronal death both in vitro and in vivo. At concentrations shown to be selective for group II mGluRs expressed in cell lines (0.1-100 nM), LY354740 did not attenuate NMDA-mediated neuronal death in vitro or in vivo. Furthermore, LY354740 did not attenuate oxygen-glucose deprivation-induced neuronal death in vitro or ischemic infarction after transient middle cerebral artery occlusion in rats. In addition, the neuroprotective effect of another group II agonist, (S)-4-carboxy-3-phenylglycine (4C3HPG), which has shown injury attenuating effects both in vitro and in vivo, was not blocked by the group II antagonists (2 S)-alpha-ethylglutamic acid (EGLU), (RS)-alpha-methyl-4-sulphonophenylglycine (MSPG), or the group III antagonist (S)-alpha-methyl-3-carboxyphenylalanine (MCPA), suggesting that this neuroprotection may be mediated by other effects such as upon group I mGluRs.

Role of K(+) efflux in apoptosis induced by AMPA and kainate in mouse cortical neurons.

Activation of ionotropic glutamate receptors can induce neuronal apoptosis in vitro and in vivo. We showed previously that activation of the N-methyl-D-aspartic acid (NMDA) subtype of glutamate receptors in a low Ca(2+) and low Na(+) condition induced apoptotic neuronal death, and that the K(+) efflux via NMDA receptor channels was likely a key event in NMDA-induced apoptosis. Since non-NMDA receptors, alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA) and kainate receptors, are also permeable to K(+), we tested the hypothesis that stimulating K(+) efflux via non-NMDA receptor channels could induce apoptosis in cultured cortical neurons. Using a Ca(2+)-free and Na(+)-free external solution, application of kainate revealed outward membrane currents carried by K(+) efflux. In a low Ca(2+)/low Na(+) medium, a 5-h exposure to 50-500 microM AMPA in the presence of the NMDA receptor antagonist MK801 induced dose-dependent neuronal death 24 h after the onset of the insult, accompanied by intracellular K(+) reduction and caspase-3 activation. The AMPA-induced cell death was attenuated by the caspase inhibitor Z-Val-Ala-Asp(OMe)-fluoromethyl ketone (Z-VAD-FMK) and by the protein synthesis inhibitor cycloheximide. Reducing K(+) efflux by raising extracellular K(+) concentration from 5 to 25 mM attenuated AMPA-triggered cell death, the Ca(2+) channel antagonist nifedipine showed no effect on the AMPA toxicity. Kainate induced similar neuronal death sensitive to attenuation by Z-VAD-FMK or elevated extracellular K(+).We suggest that the non-NMDA receptor-mediated K(+) efflux may participate in apoptotic process and that blocking excessive K(+) efflux mediated by NMDA and non-NMDA receptors may selectively prevent neuronal apoptosis under certain pathological conditions.

Nitric oxide reduces Ca(2+) and Zn(2+) influx through voltage-gated Ca(2+) channels and reduces Zn(2+) neurotoxicity.

The translocation of synaptic Zn(2+) from nerve terminals into selectively vulnerable neurons may contribute to the death of these neurons after global ischemia. We hypothesized that cellular Zn(2+) overload might be lethal for reasons similar to cellular Ca(2+) overload and tested the hypothesis that Zn(2+) neurotoxicity might be mediated by the activation of nitric oxide synthase. Although Zn(2+) (30-300microM) altered nitric oxide synthase activity in cerebellar extracts in solution, it did not affect nitric oxide synthase activity in cultured murine neocortical neurons. Cultured neurons exposed to 300-500microM Zn(2+) for 5min under depolarizing conditions developed widespread degeneration over the next 24h that was unaffected by the concurrent addition of the nitric oxide synthase inhibitor N(G)-nitro-L-arginine. Furthermore, Zn(2+) neurotoxicity was attenuated when nitric oxide synthase activity in the cultures was induced by exposure to cytokines, exogenous nitric oxide was added or nitric oxide production was pharmacologically enhanced. The unexpected protective effect of nitric oxide against Zn(2+) toxicity may be explained, at least in part, by reduction of toxic Zn(2+) entry. Exposure to nitric oxide donors reduced Ba(2+) current through high-voltage activated calcium channels, as well as K(+)-stimulated neuronal uptake of 45Ca(2+) or 65Zn(2+). The oxidizing agents thimerosal and 2,2'-dithiodipyridine also reduced K(+)-stimulated cellular 45Ca(2+) uptake, while akylation of thiols by pretreatment with N-ethylmaleimide blocked the reduction of 45Ca(2+) uptake by a nitric oxide donor.The results suggest that Zn(2+)-induced neuronal death is not mediated by the activation of nitric oxide synthase; rather, available nitric oxide may attenuate Zn(2+) neurotoxicity by reducing Zn(2+) entry through voltage-gated Ca(2+) channels, perhaps by oxidizing key thiol groups.

Non-quantal acetylcholine release at mouse neuromuscular junction: effects of elevated quantal release and aconitine.

The rate of non-quantal acetylcholine (ACh) release was estimated at the mouse neuromuscular junction by observing the effect of (+)-tubocurarine on endplate membrane potential or current in preparations pretreated with an irreversible anti-acetylcholinesterase (anti-AChE). Voltage clamping was an effective method for measuring non-quantal release. Non-quantal release was markedly inhibited by 10 microM aconitine. Non-quantal release was not significantly increased by 10 microM dihyroouabain (DHO). (It has been reported that ouabain increases the leak). Non-quantal release was roughly doubled following exposure to hypertonic solution or to elevated K(+)-solution. This is in accord with the hypothesis that the leak is by way of ACh transporters incorporated into the terminal membrane following exocytosis, but other interpretations remain to be tested.