Magneto-optical diffractive deep neural network.

We propose a magneto-optical diffractive deep neural network (MO-D2NN). We simulated several MO-D2NNs, each of which consists of five hidden layers made of a magnetic material that contains 100 × 100 magnetic domains with a domain width of 1 µm and an interlayer distance of 0.7 mm. The networks demonstrate a classification accuracy of > 90% for the MNIST dataset when light intensity is used as the classification measure. Moreover, an accuracy of > 80% is obtained even for a small Faraday rotation angle of π/100 rad when the angle of polarization is used as the classification measure. The MO-D2NN allows the hidden layers to be rewritten, which is not possible with previous implementations of D2NNs.

Low Molecular Weight Supramolecular Hydrogels for Sustained and Localized In Vivo Drug Delivery.

Supramolecular hydrogels are emerging as next-generation alternatives to synthetic polymers for drug delivery applications. Self-assembling peptides are a promising class of supramolecular gelator for in vivo drug delivery that have been slow to be adopted despite advantages in biocompatibility due to the relatively high cost of producing synthetic peptide hydrogels compared to synthetic polymer gels. Herein we describe the development and use of inexpensive low molecular weight cationic derivatives of phenylalanine (Phe) as injectable hydrogels for in vivo delivery of an anti-inflammatory drug, diclofenac, for pain mitigation in a mouse model. N-Fluorenylmethoxycarbonyl phenylalanine (Fmoc-Phe) derivatives were modified at the carboxylic acid with diaminopropane (DAP) to provide Fmoc-Phe-DAP molecules that spontaneously and rapidly self-assemble in aqueous solutions upon addition of physiologically relevant sodium chloride concentrations to give hydrogels. When self-assembly occurs in the presence of diclofenac, the drug molecule is efficiently encapsulated within the hydrogel network. These hydrogels exhibit robust shear-thinning behavior, mechanical stability, and drug release profiles to enable application as injectable hydrogels for in vivo drug delivery. Delivery of diclofenac in vivo was demonstrated by a localized injection of an Fmoc-F5-Phe-DAP/diclofenac hydrogel into the ankle joint of mice with induced ankle injury and associated inflammation-induced pain. Remediation of pain in the ankle joint was observed immediately after initial injection and was sustained for a period of nearly two weeks while diclofenac controls remediated pain for less than one day. This data demonstrates the promise of these supramolecular hydrogels as inexpensive next-generation materials for sustained and localized drug delivery in vivo.

Presence of caffeine reversibly interferes with efficacy of acupuncture-induced analgesia.

Acupuncture is an alternative treatment for wide spectrum chronic pain. However, its validity remains controversial due to the disputed efficacy assessed in various clinical studies. Moreover, variability amongst individuals complicates the predictability of outcome, which impedes the integration of acupuncture into mainstream pain management programs. In light of our previous finding that the analgesic effect of acupuncture is mediated by adenosine A1 receptor activation at the acupuncture point, we here report that in acute and chronic animal pain models, oral intake of caffeine, a potent adenosine receptor antagonist, interferes with acupuncture analgesia, even at a low dose. Local administration of caffeine at the acupuncture point was sufficient to eliminate the analgesic effect, dismissing the systemic action of caffeine. Such interference was reversible, as caffeine withdrawal fully restored the efficacy of acupuncture by the next day, and long-term exposure to caffeine did not alter A1 receptor expression at the acupuncture point. Combined, these data indicate that a trace amount of caffeine can reversibly block the analgesic effects of acupuncture, and controlling caffeine consumption during acupuncture may improve pain management outcomes.

Neuronal transgene expression in dominant-negative SNARE mice.

Experimental advances in the study of neuroglia signaling have been greatly accelerated by the generation of transgenic mouse models. In particular, an elegant manipulation that interferes with astrocyte vesicular release of gliotransmitters via overexpression of a dominant-negative domain of vesicular SNARE (dnSNARE) has led to documented astrocytic involvement in processes that were traditionally considered strictly neuronal, including the sleep-wake cycle, LTP, cognition, cortical slow waves, depression, and pain. A key premise leading to these conclusions was that expression of the dnSNARE was specific to astrocytes. Inconsistent with this premise, we report here widespread expression of the dnSNARE transgene in cortical neurons. We further demonstrate that the activity of cortical neurons is reversibly suppressed in dnSNARE mice. These findings highlight the need for independent validation of astrocytic functions identified in dnSNARE mice and thus question critical evidence that astrocytes contribute to neurotransmission through SNARE-dependent vesicular release of gliotransmitters.

Ammonia triggers neuronal disinhibition and seizures by impairing astrocyte potassium buffering.

Ammonia is a ubiquitous waste product of protein metabolism that can accumulate in numerous metabolic disorders, causing neurological dysfunction ranging from cognitive impairment to tremor, ataxia, seizures, coma and death. The brain is especially vulnerable to ammonia as it readily crosses the blood-brain barrier in its gaseous form, NH3, and rapidly saturates its principal removal pathway located in astrocytes. Thus, we wanted to determine how astrocytes contribute to the initial deterioration of neurological functions characteristic of hyperammonemia in vivo. Using a combination of two-photon imaging and electrophysiology in awake head-restrained mice, we show that ammonia rapidly compromises astrocyte potassium buffering, increasing extracellular potassium concentration and overactivating the Na(+)-K(+)-2Cl(-) cotransporter isoform 1 (NKCC1) in neurons. The consequent depolarization of the neuronal GABA reversal potential (EGABA) selectively impairs cortical inhibitory networks. Genetic deletion of NKCC1 or inhibition of it with the clinically used diuretic bumetanide potently suppresses ammonia-induced neurological dysfunction. We did not observe astrocyte swelling or brain edema in the acute phase, calling into question current concepts regarding the neurotoxic effects of ammonia. Instead, our findings identify failure of potassium buffering in astrocytes as a crucial mechanism in ammonia neurotoxicity and demonstrate the therapeutic potential of blocking this pathway by inhibiting NKCC1.

Fibroblast cytoskeletal remodeling induced by tissue stretch involves ATP signaling.

Fibroblasts in whole areolar connective tissue respond to static stretching of the tissue by expanding and remodeling their cytoskeleton within minutes both ex vivo and in vivo. This study tested the hypothesis that the mechanism of fibroblast expansion in response to tissue stretch involves extracellular ATP signaling. In response to tissue stretch ex vivo, ATP levels in the bath solution increased significantly, and this increase was sustained for 20 min, returning to baseline at 60 min. No increase in ATP was observed in tissue incubated without stretch or tissue stretched in the presence of the Rho kinase inhibitor Y27632. The increase in fibroblast cross sectional area in response to tissue stretch was blocked by both suramin (a purinergic receptor blocker) and apyrase (an enzyme that selectively degrades extracellular ATP). Furthermore, connexin channel blockers (octanol and carbenoxolone), but not VRAC (fluoxetine) or pannexin (probenecid) channel blockers, inhibited fibroblast expansion. Together, these results support a mechanism in which extracellular ATP signaling via connexin hemichannels mediate the active change in fibroblast shape that occurs in response to a static increase in tissue length.

Traditional acupuncture triggers a local increase in adenosine in human subjects.

UNLABELLED: Acupuncture is a form of Eastern medicine that has been practiced for centuries. Despite its long history and worldwide application, the biological mechanisms of acupuncture in relieving pain have been poorly defined. Recent studies in mice, however, demonstrate that acupuncture triggers increases in interstitial adenosine, which reduces the severity of chronic pain through adenosine A1 receptors, suggesting that adenosine-mediated antinociception contributes to the clinical benefits of acupuncture. We asked here whether acupuncture in human subjects is also linked to a local increase in interstitial adenosine concentration. We collected microdialysis samples of interstitial fluid before, during, and after delivering 30 minutes of conventional acupuncture in the Zusanli point in human subjects. The interstitial adenosine concentration increased significantly during acupuncture and remained elevated for 30 minutes after the acupuncture. Acupuncture-mediated adenosine release was not observed if acupuncture was not delivered in the Zusanli point or if the acupuncture needle was inserted, but not rotated. This study strengthens the role of adenosine in acupuncture-mediated antinociception by directly providing such evidence in humans. PERSPECTIVE: This article presents further evidence of the role of adenosine in acupuncture-mediated antinociception by demonstrating that local adenosine concentrations increase in the acupoint in human subjects receiving traditional acupuncture.

Astrocytes modulate neural network activity by Ca²+-dependent uptake of extracellular K+.

Astrocytes are electrically nonexcitable cells that display increases in cytosolic calcium ion (Ca²+) in response to various neurotransmitters and neuromodulators. However, the physiological role of astrocytic Ca²+ signaling remains controversial. We show here that astrocytic Ca²+ signaling ex vivo and in vivo stimulated the Na+,K+-ATPase (Na+- and K+-dependent adenosine triphosphatase), leading to a transient decrease in the extracellular potassium ion (K+) concentration. This in turn led to neuronal hyperpolarization and suppressed baseline excitatory synaptic activity, detected as a reduced frequency of excitatory postsynaptic currents. Synaptic failures decreased in parallel, leading to an increase in synaptic fidelity. The net result was that astrocytes, through active uptake of K+, improved the signal-to-noise ratio of synaptic transmission. Active control of the extracellular K+ concentration thus provides astrocytes with a simple yet powerful mechanism to rapidly modulate network activity.

Extracellular Ca²âº acts as a mediator of communication from neurons to glia.

Defining the pathways through which neurons and astrocytes communicate may contribute to the elucidation of higher central nervous system functions. We investigated the possibility that decreases in extracellular calcium ion concentration ([Ca(2+)](e)) that occur during synaptic transmission might mediate signaling from neurons to glia. Using noninvasive photolysis of the photolabile Ca(2+) buffer diazo-2 {N-[2-[2-[2-[bis(carboxymethyl)amino]-5-(diazoacetyl)phenoxy]ethoxy]-4-methylphenyl]-N-(carboxymethyl)-, tetrapotassium salt} to reduce [Ca(2+)](e) or caged glutamate to simulate glutamatergic transmission, we found that a local decline in extracellular Ca(2+) triggered astrocytic adenosine triphosphate (ATP) release and astrocytic Ca(2+) signaling. In turn, activation of purinergic P2Y1 receptors on a subset of inhibitory interneurons initiated the generation of action potentials by these interneurons, thereby enhancing synaptic inhibition. Thus, astrocytic ATP release evoked by an activity-associated decrease in [Ca(2+)](e) may provide a negative feedback mechanism that potentiates inhibitory transmission in response to local hyperexcitability.

Cultured astrocytes do not release adenosine during hypoxic conditions.

Recent reports based on a chemiluminescent enzymatic assay for detection of adenosine conclude that cultured astrocytes release adenosine during mildly hypoxic conditions. If so, astrocytes may suppress neural activity in early stages of hypoxia. The aim of this study was to reevaluate the observation using high-performance liquid chromatography (HPLC). The HPLC analysis showed that exposure to 20 or 120 minutes of mild hypoxia failed to increase release of adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), and adenosine from cultured astrocytes. Similar results were obtained using a chemiluminescent enzymatic assay. Moreover, since the chemiluminescent enzymatic assay relies on hydrogen peroxide generation, release of free-radical scavengers from hypoxic cells can interfere with the assay. Accordingly, adenosine added to samples collected from hypoxic cultures could not be detected using the chemiluminescent enzymatic assay. Furthermore, addition of free-radical scavengers sharply reduced the sensitivity of adenosine detection. Conversely, use of a single-step assay inflated measured values due to the inability of the assay to distinguish adenosine and its metabolite inosine. These results show that cultured astrocytes do not release adenosine during mild hypoxia, an observation consistent with their high resistance to hypoxia.

Critical role of aquaporin-4 (AQP4) in astrocytic Ca2+ signaling events elicited by cerebral edema.

Aquaporin-4 (AQP4) is a primary influx route for water during brain edema formation. Here, we provide evidence that brain swelling triggers Ca(2+) signaling in astrocytes and that deletion of the Aqp4 gene markedly interferes with these events. Using in vivo two-photon imaging, we show that hypoosmotic stress (20% reduction in osmolarity) initiates astrocytic Ca(2+) spikes and that deletion of Aqp4 reduces these signals. The Ca(2+) signals are partly dependent on activation of P2 purinergic receptors, which was judged from the effects of appropriate antagonists applied to cortical slices. Supporting the involvement of purinergic signaling, osmotic stress was found to induce ATP release from cultured astrocytes in an AQP4-dependent manner. Our results suggest that AQP4 not only serves as an influx route for water but also is critical for initiating downstream signaling events that may affect and potentially exacerbate the pathological outcome in clinical conditions associated with brain edema.

Adenosine A1 receptors mediate local anti-nociceptive effects of acupuncture.

Acupuncture is an invasive procedure commonly used to relieve pain. Acupuncture is practiced worldwide, despite difficulties in reconciling its principles with evidence-based medicine. We found that adenosine, a neuromodulator with anti-nociceptive properties, was released during acupuncture in mice and that its anti-nociceptive actions required adenosine A1 receptor expression. Direct injection of an adenosine A1 receptor agonist replicated the analgesic effect of acupuncture. Inhibition of enzymes involved in adenosine degradation potentiated the acupuncture-elicited increase in adenosine, as well as its anti-nociceptive effect. These observations indicate that adenosine mediates the effects of acupuncture and that interfering with adenosine metabolism may prolong the clinical benefit of acupuncture.

2D networks of rhombic-shaped fused dehydrobenzo[12]annulenes: structural variations under concentration control.

A series of alkyl- and alkoxy-substituted rhombic-shaped bisDBA derivatives 1a-d, 2a, and 2b were synthesized for the purpose of the formation of porous networks at the 1,2,4-trichlorobenzene (TCB)/graphite interface. Depending on the alkyl-chain length and the solute concentration, bisDBAs exhibit five network structures, three porous structures (porous A, B, and C), and two nonporous structures (nonporous D and E), which are attributed to their rhombic core shape and the position of the substituents. BisDBAs 1a and 1b with the shorter alkyl chains favorably form a porous structure, whereas bisDBAs 1c and 1d with the longer alkyl chains are prone to form nonporous structures. However, upon dilution, nonporous structures are typically transformed into porous ones, a trend that can be understood by the effect of surface coverage, molecular density, and intermolecular interactions on the system's enthalpy. Furthermore, porous structures are stabilized by the coadsorption of solvent molecules. The most intriguing porous structure, the Kagome pattern, was formed for all compounds at least to some extent, and the size of its triangular and hexagonal pores could be tuned by the alkyl-chain length. The present study proves that the concentration control is a powerful and general tool for the construction of porous networks at the liquid-solid interface.

P2Y1 receptor signaling enhances neuroprotection by astrocytes against oxidative stress via IL-6 release in hippocampal cultures.

Cell survival is a critical issue in the onset and progression of neurodegenerative diseases and following pathological events including ischemia and traumatic brain injury. Oxidative stress is the main cause of cell damage in such pathological conditions. Here, we report that adenosine 5'-triphosphate (ATP) protects hippocampal astrocytes from hydrogen peroxide (H(2)O(2))-evoked oxidative injury in astrocyte monocultures. The effect of ATP was prevented by a selective antagonist of or siRNAs against P2Y(1)R. Interestingly, in astrocyte-neuron cocultures, ATP also produced neuroprotective effects against H(2)O(2)-evoked neuronal cell death, whereas ATP did not produce any neuroprotective effects in monocultures. The ATP-induced neuroprotection in cocultures was completely inhibited by silencing of astrocytic P2Y(1)R expression, indicating that ATP acts on astrocytes and enhances their neuroprotective functions by activating P2Y(1)R. Furthermore, this neuroprotective effect was mimicked by applying conditioned medium from astrocytes that had been stimulated by ATP, implying an involvement of diffusible factors from astrocytes. We found that, in both purified astrocyte cultures and astrocyte-neuronal cocultures, ATP and the P2Y(1)R agonist 2-methylthioadenosine 5' diphosphate (2MeSADP) induced the release of interleukin-6 (IL-6), but this did not occur in neuron monocultures. Moreover, exogenous IL-6 produced a neuroprotective effect, and the neuroprotection induced by P2Y(1)R-stimulated astrocytes was prevented in the presence of an anti-IL-6 antibody. Taken together, these results suggest that P2Y(1)R-stimulated astrocytes protect against neuronal damage induced by oxidative stress, and that IL-6 is a crucial signaling molecule released from astrocytes. Thus, activation of P2Y(1)R in astrocytes may rescue neurons from secondary cell death under pathological conditions.

Donors and acceptors based on triangular dehydrobenzo[12]annulenes: formation of a triple-layered rosette structure by a charge-transfer complex.

We present here the results of studies of the synthesis and properties of donors and acceptors based on triangular dehydrobenzo[12]annulene ([12]DBA) system as a pi core. These studies were aimed at controlling the supramolecular crystal structure. Toward this end, the tricyano[12]DBA 2 and dodecafluoro[12]DBA ( 3) were synthesized as acceptors (A) and the tris(dialkylamino)[12]DBAs 4a-d as donors (D), and their electronic properties were determined by electronic absorption spectroscopy and electrochemical measurements. The main focus, though, was the formation of supramolecular structures in crystals. These compounds form distinct packing patterns as a result of the different intermolecular interactions. Tricyano[12]DBA 2 forms a two-dimensional (2D) sheet structure via hydrogen-bonding interactions, whereas a tilted-stack structure was found for 3 because of the lack of significant intermolecular interactions. Tris(dibutylamino)[12]DBA 4b exhibits a ladder-type 2D structure, probably because of van der Waals interactions between the butyl groups. The most significant finding is that charge-transfer interactions between donor 4a and acceptor 3 combined with their triangular molecular shapes and lateral CH...F hydrogen bonding result in the formation of a 2D rosette structure consisting of two different trimeric (DAD- and ADA-type) sandwich structures with 1:2 and 2:1 A/D ratios, respectively.

Synthesis of dehydrobenzo[18]annulene derivatives and formation of self-assembled monolayers: implications of core size on alkyl chain interdigitation.

The synthesis of a series of dodecadehydrotribenzo[18]annulene ([18]DBA) derivatives is reported, together with their steady-state absorption and fluorescence properties. The main focus, though, is on the self-assembly of these compounds at the liquid-solid interface as investigated with scanning tunneling microscopy (STM), highlighting the effect of alkyl chain orientation and alkyl chain length on the molecular ordering. Owing to the large triangular pi-electron system of the [18]DBAs, two different types of alkyl chain orientation are observed. The observed changes in the monolayer networks upon elongation of the alkyl chains are attributed to the increased van der Waals interactions between molecules and substrate. The effect of the core size on the alkyl chain orientation and, as a result, the monolayer structure is discussed in relation to the results obtained previously for triangularly-shaped dehydrobenzo [12]annulene ([12]DBA) derivatives and triphenylene derivatives. A guideline for substituent spacing allowing control of molecular alignment for large planar pi-electron systems utilizing directional alkyl chain interdigitation is also discussed.