Technique for repetitive recording from fetal respiratory neurons

We developed a new method for repetitive recording of medullary neurons in fetal sheep in situ. The technique involves chronically fixing the fetal head to the flank of the ewe by way of a Teflon plate that has a removable window. This window allows direct access of a recording electrode to the floor of the fourth ventricle of the fetus. In four of six fetuses, repetitive recordings lasting 3-4 h were possible for up to 6 days. By operating on younger fetuses and with care, this time span could be extended. This novel method should be useful in the future for extracellular and intracellular recordings of neurons in the developing fetus without disturbing the fetal state and for the study of putative neurotransmitters during development with iontophoretic techniques.

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GABA- and Glycine-Mediated Fall of Intracellular pH in Rat Medullary Neurons In Situ

Journal of Neurophysiology ◽

10.1152/jn.1997.77.4.1844 ◽

1997 ◽

Vol 77 (4) ◽

pp. 1844-1852 ◽

Cited By ~ 25

Author(s):

Mark Lückermann ◽

Stefan Trapp ◽

Klaus Ballanyi

Keyword(s):

Intracellular Ph ◽

Reversal Potential ◽

Membrane Conductance ◽

Respiratory Neurons ◽

Intracellular Acidosis ◽

Bath Application ◽

Brain Stem Slices ◽

Medullary Neurons

Lückermann, Mark, Stefan Trapp, and Klaus Ballanyi. GABA- and glycine-mediated fall of intracellular pH in rat medullary neurons in situ. J. Neurophysiol. 77: 1844–1852, 1997. In the region of the ventral respiratory group in brain stem slices from neonatal rats, intracellular pH (pHi) and membrane currents ( I m) or potentials were measured in neurons dialyzed with the pH-sensitive dye 2′,7′-bis-carboxyethyl-5(6)-carboxyfluorescein. Currents and increases in membrane conductance ( g m) during bath application of 0.1 or 1 mM γ-aminobutyric acid (GABA) were accompanied by a delayed mean fall of pHi by 0.17 and 0.25 pH units, respectively, from a pHi baseline of 7.33. These effects were reversibly suppressed by 50–100 μM bicuculline. Similar effects on I m, g m, and pHi were revealed on administration of 0.1 or 1 mM glycine. These responses were abolished by 10–100 μM strychnine. Dialysis of the cells with 15–30 μM carbonic anhydrase led to an acceleration of the kinetics and a potentiation of the GABA-induced pHi decrease. GABA- and glycine-evoked pHi decreases were very similar during recordings with either high- or low-Cl− patch electrodes, although the reversal potential of the accompanying currents differed by ∼60 mV. The GABA-induced pHi decrease, but not the accompanying I m and g m responses, was suppressed in CO2/HCO− 3-free, N-2-hydroxy-ethylpiperazine- N′-2-ethane sulphonic acid pH-buffered solution. Depolarization from −60 to +30 mV resulted in a sustained fall of pHi by maximally 0.5 pH units. In this situation, the GABA-induced fall of pHi turned into an intracellular alkalosis of 0.09–0.15 pH units. The results confirm and extend previous findings obtained in vivo that GABA- or glycine-induced intracellular acidosis of respiratory neurons is due to efflux of HCO− 3 via the receptor-coupled Cl− channel.

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Synthetic Studies Towards Spirocyclic Imine Marine Toxins Using N-Acyl Iminium Ions as Dienophiles in Diels–Alder Reactions

Synlett ◽

10.1055/s-0039-1691593 ◽

2020 ◽

Vol 31 (07) ◽

pp. 657-671

Author(s):

Jared L. Freeman ◽

Freda F. Li ◽

Daniel P. Furkert ◽

Margaret A. Brimble

Keyword(s):

Biological Activities ◽

Diels Alder ◽

Direct Access ◽

Marine Toxins ◽

Chemical Structures ◽

Marine Toxin ◽

Iminium Ions ◽

Iminium Ion ◽

Novel Method

Cyclic imine marine toxins have attracted considerable attention from the synthetic community in the past two decades due to their unique chemical structures and clinically relevant biological activities. This review presents recent efforts of our group in the development of various strategies to efficiently construct the common spirocyclic imine fragments of the cyclic imine toxins. In particular, the use of α,β-unsaturated N-acyl iminium ion dienophiles in Diels–Alder reactions are highlighted, whereby direct access to spirocyclic imine motifs was obtained and important mechanistic details were discovered. Alternative approaches to spirocyclic imine systems involving hydroamination of amino alkynes are also summarized. One such approach led to serendipitous access to N-vinyl amide products, while our most recently reported approach involving an intermolecular Diels–Alder/cross-coupling sequence using novel 2-bromo-1,3-butadienes to access 5,6-spirocyclic imines is also discussed. Additionally, the development of a novel method to construct another challenging motif present in the portimines is also introduced.1 Introduction2 Strategies towards the Spirocyclic Imine Fragment of Cyclic Imine Toxins2.1 Diels–Alder Cycloadditions of α,β-Unsaturated N-Acyl Iminium Dienophiles2.2 Early Studies Using in situ-Generated Iminium Ion Dienophiles2.3 Use of More Stable Iminium Ion Dienophiles for Diels–Alder Reactions2.4 Other Notable Strategies towards Spirocyclic Imines2.5 Recent Efforts towards the 5,6-Spirocyclic Imine Marine Toxin Portimine A2.6 Construction of Another Challenging Motif of Portimine A3 Conclusion and Future Perspectives

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Development of a novel method for the in-situ dechlorination of immovable iron elements: optimization of Cl− extraction yield through experimental design

Scientific Reports ◽

10.1038/s41598-021-90006-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Marco Veneranda ◽

Nagore Prieto-Taboada ◽

Jose Antonio Carrero ◽

Ilaria Costantini ◽

Aitor Larrañaga ◽

...

Keyword(s):

Experimental Design ◽

Optimization Design ◽

Degradation Process ◽

Extraction Yield ◽

Alkaline Solutions ◽

Iron Core ◽

Total Consumption ◽

Iron Leaching ◽

Novel Method

AbstractThe conservation of iron objects exposed to marine aerosol is threatened by the formation of akaganeite, a highly unstable Cl-bearing corrosion phase. As akaganeite formation is responsible of the exfoliation of the rust layer, chlorides trigger a cyclic alteration phenomenon that often ends with the total consumption of the iron core. To prevent this degradation process, movable iron elements (e.g. archaeometallurgical artefacts) are generally immersed in alkaline dechlorination baths. Aiming to transfer this successful method to the treatment of immovable iron objects, we propose the in-situ application of alkaline solutions through the use of highly absorbent wraps. As first step of this novel research line, the present work defines the best desalination solution to be used and optimizes its extraction yield. After literature review, a screening experimental design was performed to understand the single and synergic effects of common additives used for NaOH baths. Once the most effective variables were selected, an optimization design was carried out to determine the optimal conditions to be set during treatment. According to the experimental work here presented, the use of 0.7 M NaOH solutions applied at high temperatures (above 50 °C) is recommended. Indeed, these conditions enhance chloride extraction and iron leaching inhibition, while promoting corrosion stabilization.

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Using Sentinel-2 Images to Estimate Topography, Tidal-Stage Lags and Exposure Periods over Large Intertidal Areas

Remote Sensing ◽

10.3390/rs13020320 ◽

2021 ◽

Vol 13 (2) ◽

pp. 320

Author(s):

José P. Granadeiro ◽

João Belo ◽

Mohamed Henriques ◽

João Catalão ◽

Teresa Catry

Keyword(s):

Large Scale ◽

Exposure Period ◽

Intertidal Area ◽

Digital Elevation ◽

Geographical Bias ◽

Novel Method ◽

Tidal Stage ◽

Sentinel 2

Intertidal areas provide key ecosystem services but are declining worldwide. Digital elevation models (DEMs) are important tools to monitor the evolution of such areas. In this study, we aim at (i) estimating the intertidal topography based on an established pixel-wise algorithm, from Sentinel-2 MultiSpectral Instrument scenes, (ii) implementing a set of procedures to improve the quality of such estimation, and (iii) estimating the exposure period of the intertidal area of the Bijagós Archipelago, Guinea-Bissau. We first propose a four-parameter logistic regression to estimate intertidal topography. Afterwards, we develop a novel method to estimate tide-stage lags in the area covered by a Sentinel-2 scene to correct for geographical bias in topographic estimation resulting from differences in water height within each image. Our method searches for the minimum differences in height estimates obtained from rising and ebbing tides separately, enabling the estimation of cotidal lines. Tidal-stage differences estimated closely matched those published by official authorities. We re-estimated pixel heights from which we produced a model of intertidal exposure period. We obtained a high correlation between predicted and in-situ measurements of exposure period. We highlight the importance of remote sensing to deliver large-scale intertidal DEM and tide-stage data, with relevance for coastal safety, ecology and biodiversity conservation.

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A novel method for in situ stabilization of calcium arsenic residues via yukonite formation

The Science of The Total Environment ◽

10.1016/j.scitotenv.2022.153090 ◽

2022 ◽

pp. 153090

Author(s):

Yumeng Wang ◽

Shaofeng Wang ◽

Yu Song ◽

Peiwen Zhang ◽

Xu Ma ◽

...

Keyword(s):

In Situ Stabilization ◽

Novel Method

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High Shear in Situ Exfoliation of 2D Gallium Oxide Sheets from Centrifugally Derived Thin Films of Liquid Gallium

10.26434/chemrxiv.14571573 ◽

2021 ◽

Author(s):

Kasturi Vimalanathan ◽

Timotheos Palmer ◽

Zoe Gardner ◽

Irene Ling ◽

Soraya Rahpeima ◽

...

Keyword(s):

Gallium Oxide ◽

High Mass ◽

Liquid Gallium ◽

The Novel ◽

Continuous Flow Condition ◽

Novel Method ◽

Hydrogen Evolution Reactions ◽

Insulating Properties ◽

Microfluidics Platform

Herein, we have explored the use of a microfluidics platform for the exfoliation and oxidation of liquid gallium into ultrathin sheets of gallium oxide under continuous flow condition. The novel method developed here takes advantage of the high mass transfer in liquids and has the potential for creating high yielding thin sheets of oxidised gallium with insulating properties as well as acts as an active catalyst in hydrogen evolution reactions. This highlights the potential utility of the sheets as an alternative to the expensive and scarce noble metal based electrocatalysts

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Nutrient and hormone levels in Douglas-fir corrosion cavities, megagametophytes, and embryos during embryony

Canadian Journal of Forest Research ◽

10.1139/x05-173 ◽

2005 ◽

Vol 35 (10) ◽

pp. 2447-2456 ◽

Cited By ~ 18

Author(s):

John G Carman ◽

Gordon Reese ◽

Rodney J Fuller ◽

Timnit Ghermay ◽

Roger Timmis

Keyword(s):

Pseudotsuga Menziesii ◽

Dry Mass ◽

Douglas Fir ◽

Chemical Analyses ◽

Dynamic Changes ◽

Hormone Levels ◽

Corrosion Cavity ◽

Novel Method ◽

Indole 3 Acetic Acid

Gymnospermous embryos are nourished by fluids secreted from the megagametophyte. During early embryony, these fluids occupy the newly formed corrosion cavity. We describe a novel method for extracting corrosion cavity fluid and provide chemical analyses based on extractions from approximately 120 000 Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) megagametophytes. Levels of potassium, phosphorus, calcium, zinc, and iron were higher in corrosion cavity fluid than in whole tissue, but levels of sulphur and manganese were lower. Levels of cyclitols, sucrose equivalents, erythrose, and arabinose were many-fold higher in corrosion cavity fluid than in whole tissues. Ala, Ser, Arg, Glx, and NH3 exceeded 80 mmol/kg dry mass in corrosion cavity fluid. These levels were about 100-fold higher than those found in whole tissues. During early embryony, hormone levels in corrosion cavity fluid were higher than levels observed in whole megagametophytes by 120-fold for indole-3-acetic acid, 53-fold for abscisic acid, and 8- to 10-fold for cytokinins. Nutrient and hormone levels tended to be much higher in the corrosion cavity fluid than would have been predicted based on whole-tissue analyses. Dynamic changes in nutrient and hormone levels occurred over time in the corrosion cavity, and these changes may normalize embryony in situ.

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Tone-dependent responses to endothelin in the isolated perfused fetal sheep pulmonary circulation in situ

Journal of Applied Physiology ◽

10.1152/jappl.1991.70.3.1228 ◽

1991 ◽

Vol 70 (3) ◽

pp. 1228-1234 ◽

Cited By ~ 65

Author(s):

S. Cassin ◽

V. Kristova ◽

T. Davis ◽

P. Kadowitz ◽

G. Gause

Keyword(s):

Pulmonary Circulation ◽

Vena Cava ◽

Fetal Lung ◽

Left Pulmonary Artery ◽

Pulmonary Vasculature ◽

Fetal Sheep ◽

Vascular Responses ◽

Arterial Perfusion ◽

Ovine Fetal

Pulmonary vascular responses to endothelin (ET-1), a peptide derived from endothelial cells in culture, were investigated in the ovine fetus delivered by cesarean section from chloralose-anesthetized ewes with intact umbilical circulation. Circulation to the lower left lobe of the fetal lung was isolated in situ and perfused at constant flow with blood withdrawn from the inferior vena cava. Injection of graded doses of ET-1 into the left pulmonary artery decreased pulmonary arterial perfusion pressure in a dose-related manner. At doses of 100, 300, and 1,000 ng, pulmonary vascular resistance per kilogram body weight (PVR/kg) was decreased 30, 40, and 42%, respectively. However, when fetuses were ventilated with 100% oxygen, 100- and 300-ng doses of ET-1 decreased PVR/kg by 5 and 9%, respectively. In contrast, injection of 1,000 ng of ET-1 resulted in a reversal of the response, and PVR/kg was increased by 70%. Ventilation of the right lung alone resulted in a similar reversal of the vasodilator response to 1,000 ng of ET-1, and a 138% increase in PVR/kg was recorded. These studies demonstrate for the first time that ET-1 has vasodilator activity in the normally high-tone ovine fetal pulmonary circulation. In addition, these results show that ET-1 has vasoconstrictor activity in the newly ventilated low-tone pulmonary vasculature. The present data indicate the pulmonary vascular responses to ET-1 are tone dependent in the ovine fetal pulmonary circulation.

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Poly(catecholamine) Coating and Biofunctionalization of CsPbBr3 Microcrystals

10.26434/chemrxiv.14049710.v2 ◽

2021 ◽

Author(s):

Sangyeon Cho ◽

Seok-Hyun Yun

Keyword(s):

Lipid Bilayers ◽

Environmental Stability ◽

Live Cells ◽

Functional Coatings ◽

Common Strategy ◽

Novel Method ◽

Halide Perovskites ◽

The Stability ◽

New Applications

Lead halide perovskites (LHP) microcrystals are promising materials for various optoelectronic applications. Surface coating on particles is a common strategy to improve their functionality and environmental stability, but LHP is not amenable to most coating chemistries because of its intrinsic weakness against polar solvents. Here, we describe a novel method of synthesizing LHP microcrystals in a super-saturated polar solvent using sonochemistry and applying various functional coatings on individual microcrystals in situ. We synthesize cesium lead bromine perovskite (CsPbBr3) microparticles capped with organic poly-norepinephrine (pNE) layers. The catechol group of pNE coordinates to bromine-deficient lead atoms, forming a defect-passivating and diffusion-blocking shell. The pNE layer enhances the stability of CsPbBr3 in water by 2,000-folds, enabling bright luminescence and lasing from single microcrystals in water. Furthermore, the pNE shell permits biofunctionalization with proteins, small molecules, and lipid bilayers. Luminescence from CsPbBr3 microcrystals is sustained in water over 1 hour and observed in live cells. The functionalization method may enable new applications of LHP particles in water-rich environments.

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