Current and Calcium Responses to Local Activation of Axonal NMDA Receptors in Developing Cerebellar Molecular Layer Interneurons

In developing cerebellar molecular layer interneurons (MLIs), NMDA increases spontaneous GABA release. This effect had been attributed to either direct activation of presynaptic NMDA receptors (preNMDARs) or an indirect pathway involving activation of somato-dendritic NMDARs followed by passive spread of somatic depolarization along the axon and activation of axonal voltage dependent Ca2+ channels (VDCCs). Using Ca2+ imaging and electrophysiology, we searched for preNMDARs by uncaging NMDAR agonists either broadly throughout the whole field or locally at specific axonal locations. Releasing either NMDA or glutamate in the presence of NBQX using short laser pulses elicited current transients that were highly sensitive to the location of the spot and restricted to a small number of varicosities. The signal was abolished in the presence of high Mg2+ or by the addition of APV. Similar paradigms yielded restricted Ca2+ transients in interneurons loaded with a Ca2+ indicator. We found that the synaptic effects of NMDA were not inhibited by blocking VDCCs but were impaired in the presence of the ryanodine receptor antagonist dantrolene. Furthermore, in voltage clamped cells, bath applied NMDA triggers Ca2+ elevations and induces neurotransmitter release in the axonal compartment. Our results suggest the existence of preNMDARs in developing MLIs and propose their involvement in the NMDA-evoked increase in GABA release by triggering a Ca2+-induced Ca2+ release process mediated by presynaptic Ca2+ stores. Such a mechanism is likely to exert a crucial role in various forms of Ca2+-mediated synaptic plasticity

Synthesis of 5-Hydroxyectoine from Ectoine: Crystal Structure of the Non-Heme Iron(II) and 2-Oxoglutarate-Dependent Dioxygenase EctD

As a response to high osmolality, many microorganisms synthesize various types of compatible solutes. These organic osmolytes aid in offsetting the detrimental effects of low water activity on cell physiology. One of these compatible solutes is ectoine. A sub-group of the ectoine producer's enzymatically convert this tetrahydropyrimidine into a hydroxylated derivative, 5-hydroxyectoine. This compound also functions as an effective osmostress protectant and compatible solute but it possesses properties that differ in several aspects from those of ectoine. The enzyme responsible for ectoine hydroxylation (EctD) is a member of the non-heme iron(II)-containing and 2-oxoglutarate-dependent dioxygenases (EC 1.14.11). These enzymes couple the decarboxylation of 2-oxoglutarate with the formation of a high-energy ferryl-oxo intermediate to catalyze the oxidation of the bound organic substrate. We report here the crystal structure of the ectoine hydroxylase EctD from the moderate halophile Virgibacillus salexigens in complex with Fe3+ at a resolution of 1.85 Å. Like other non-heme iron(II) and 2-oxoglutarate dependent dioxygenases, the core of the EctD structure consists of a double-stranded β-helix forming the main portion of the active-site of the enzyme. The positioning of the iron ligand in the active-site of EctD is mediated by an evolutionarily conserved 2-His-1-carboxylate iron-binding motif. The side chains of the three residues forming this iron-binding site protrude into a deep cavity in the EctD structure that also harbours the 2-oxoglutarate co-substrate-binding site. Database searches revealed a widespread occurrence of EctD-type proteins in members of the Bacteria but only in a single representative of the Archaea, the marine crenarchaeon Nitrosopumilus maritimus. The EctD crystal structure reported here can serve as a template to guide further biochemical and structural studies of this biotechnologically interesting enzyme family

Ionic liquids at electrified interfaces

Until recently, “room-temperature” (<100–150 °C) liquid-state electrochemistry was mostly electrochemistry of diluted electrolytes(1)–(4) where dissolved salt ions were surrounded by a considerable amount of solvent molecules. Highly concentrated liquid electrolytes were mostly considered in the narrow (albeit important) niche of high-temperature electrochemistry of molten inorganic salts(5-9) and in the even narrower niche of “first-generation” room temperature ionic liquids, RTILs (such as chloro-aluminates and alkylammonium nitrates).(10-14) The situation has changed dramatically in the 2000s after the discovery of new moisture- and temperature-stable RTILs.(15, 16) These days, the “later generation” RTILs attracted wide attention within the electrochemical community.(17-31) Indeed, RTILs, as a class of compounds, possess a unique combination of properties (high charge density, electrochemical stability, low/negligible volatility, tunable polarity, etc.) that make them very attractive substances from fundamental and application points of view.(32-38) Most importantly, they can mix with each other in “cocktails” of one’s choice to acquire the desired properties (e.g., wider temperature range of the liquid phase(39, 40)) and can serve as almost “universal” solvents.(37, 41, 42) It is worth noting here one of the advantages of RTILs as compared to their high-temperature molten salt (HTMS)(43) “sister-systems”.(44) In RTILs the dissolved molecules are not imbedded in a harsh high temperature environment which could be destructive for many classes of fragile (organic) molecules

Social exclusion of older persons: a scoping review and conceptual framework

As a concept, social exclusion has considerable potential to explain and respond to disadvantage in later life. However, in the context of ageing populations, the construct remains ambiguous. A disjointed evidence-base, spread across disparate disciplines, compounds the challenge of developing a coherent understanding of exclusion in older age. This article addresses this research deficit by presenting the findings of a two-stage scoping review encompassing seven separate reviews of the international literature pertaining to old-age social exclusion. Stage one involved a review of conceptual frameworks on old-age exclusion, identifying conceptual understandings and key domains of later-life exclusion. Stage two involved scoping reviews on each domain (six in all). Stage one identified six conceptual frameworks on old-age exclusion and six common domains across these frameworks: neighbourhood and community; services, amenities and mobility; social relations; material and financial resources; socio-cultural aspects; and civic participation. International literature concentrated on the first four domains, but indicated a general lack of research knowledge and of theoretical development. Drawing on all seven scoping reviews and a knowledge synthesis, the article presents a new definition and conceptual framework relating to old-age exclusion

The plasma membrane calcium-ATPase as a major mechanism for intracellular calcium regulation in neurones from the rat superior cervical ganglion

Patch-clamp recording combined with indo-1 measurement of free intracellular calcium concentration ([Ca2+]i) was used to determine the homeostatic systems involved in the maintenance of resting [Ca2+]i and in the clearance of Ca2+ transients following activation of voltage-gated Ca2+ channels in neurones cultured from rat superior cervical ganglion (SCG). The Ca2+ binding ratio was estimated to be ∼500 at 100 nM, decreasing to ∼250 at [Ca2+]i≈ 1 μM, and to involve at least two buffering systems with different affinities for Ca2+. Removal of extracellular Ca2+ led to a decrease in [Ca2+]i that was mimicked by the addition of La3+, and was more pronounced after inhibition of the endoplasmic reticulum Ca2+ uptake system (SERCA). Inhibition of the plasma membrane Ca2+ pump (PMCA) by extracellular alkalinisation (pH 9) or intracellular carboxyeosin both increased resting [Ca2+]i and prolonged the recovery of Ca2+ transients at peak [Ca2+]i≤ 500 nM. For [Ca2+]i loads > 500 nM, recovery showed an additional plateau phase that was abolished in m-chlorophenylhydrazone (CCCP) or on omitting intracellular Na+. Inhibition of the plasma membrane Na+ -Ca2+ exchanger (NCX) and of SERCA had a small but significant additional effect on the rate of decay of these larger Ca2+ transients. In conclusion, resting [Ca2+]i is maintained by passive Ca2+ influx and regulated by a large Ca2+ buffering system, Ca2+ extrusion via a PMCA and Ca2+ transport from the intracellular stores. PMCA is also the principal Ca2+ extrusion system at low Ca2+ loads, with additional participation of the NCX and intracellular organelles at high [Ca2+]i

Cifoplastia no tratamento da fratura vertebral por insuficiência: avaliação funcional prospectiva Cifoplastia en el tratamiento de la fractura vertebral por insuficiencia: evaluación funcional prospectiva Kyphoplasty in the treatment of vertebral compression fracture: prospective functional evaluation

OBJETIVO: Avaliar o resultado funcional e o grau de satisfação do tratamento cirúrgico utilizando cifoplastia em pacientes com fratura vertebral por insuficiência localizada na coluna tóraco-lombar. MÉTODOS: Foi realizado um estudo prospectivo em pacientes adultos, com diagnóstico de fratura vertebral por insuficiência com evolução superior a oito semanas, apresentando dor no local da fratura e edema ósseo evidente ao exame de RM. A avaliação funcional foi realizada através do Oswestry Disability Index 2.0 e da Escala Visual Analógica de Dor no pré- e pós-operatório. A satisfação pessoal com o tratamento foi quantificada pela escala de Johnson. RESULTADOS: Houve melhora significativa da dor com uma queda média de 6.4 pontos na Escala Visual Analógica de Dor ao final de doze meses de seguimento em comparação ao período pré-operatório (p < 00,5). A avaliação funcional mostrou 88% de resultados excelentes ou bons, sendo que sete pacientes (41%) apresentaram excelentes resultados e oito pacientes (47%) tiveram resultados bons. Dois pacientes (12%) mantiveram sua avaliação funcional inalterada. Quanto à graduação subjetiva de satisfação, 82% declararam-se satisfeitos sendo que 59% estavam completamente satisfeitos e 23% satisfeitos com mínimas restrições. Três pacientes (18%) declararam-se insatisfeitos com o resultado do procedimento. CONCLUSÃO: A cifoplastia mostrou-se efetiva em melhorar a função e liberar a dor em pacientes com fratura vertebral por insuficiência. A ocorrência de uma complicação grave (IAM) chama atenção para a necessidade de suporte hospitalar adequado durante a realização do procedimento.<br>OBJETIVO: Evaluar el resultado funcional y el grado de satisfacción del tratamiento quirúrgico mediante cifoplastia en pacientes con fractura vertebral debido a la insuficiencia situada en la columna toracolumbar. MÉTODOS: Se realizó un estudio prospectivo en pacientes adultos, con diagnóstico de fractura vertebral por insuficiencia, con tiempo de evolución de más de ocho semanas, con dolor en el sitio de la fractura y edema óseo evidente por resonancia magnética. La evaluación funcional se realizó mediante el Índice de Incapacidad de Oswestry 2.0 y la Escala Analógica Visual del Dolor antes y después de la operación. La satisfacción personal con el tratamiento fue medida por la escala de Johnson. RESULTADOS: Una mejora significativa en el dolor con una caída promedio de 6,4 puntos en la escala visual analógica del dolor al final de doce meses de seguimiento, en comparación con el período preoperatorio (p <0,05). La evaluación funcional mostró 88% de resultados excelentes o buenos, con 07 pacientes (41%) que tuvieron resultados excelentes y 08 pacientes (47%) buenos resultados. Dos pacientes (12%) se mantuvieron sin cambios la evaluación funcional. En cuanto al grado subjetivo de satisfacción, 82% dijeron que estaban satisfechos y 59% se mostraron satisfechos por completo, y el 23% satisfechos con restricciones mínimas. Tres pacientes (18%) informaron estar insatisfechos con el resultado del procedimiento. CONCLUSIÓN: La cifoplastia ha demostrado ser eficaz en la mejora de la función y la liberación del dolor en pacientes con fractura vertebral por insuficiencia. La aparición de una complicación grave (Infarto Agudo del Miocardio llama la atención sobre la necesidad de atención hospitalaria adecuada durante el procedimiento.<br>OBJECTIVE: To evaluate the functional outcome and degree of satisfaction of surgical treatment using kyphoplasty in patients with vertebral compression fractures located in the thoracolumbar spine. METHODS: Prospective study in which adult patients diagnosed with vertebral compression fracture with a course over eight weeks, with pain at the fracture site and bone edema evident by MRI imaging were identified and evaluated for the study. The functional evaluation was performed through the Oswestry Disability Index 2.0 and Visual Analogue Scale of Pain pre- and postoperatively. The personal satisfaction with treatment was measured by the scale of Johnson. RESULTS: A significant improvement in pain with an average fall of 6.4 points in the Visual Analogue Scale of Pain at the end of twelve months of follow-up compared to preoperatively (p < 00.5). The functional evaluation showed 88% excellent or good results, with seven patients (41%) with excellent results and eight patients (47%) with good results. Two patients (12%) maintained their functional assessment unchanged. As to the subjective degree of satisfaction, 82% said they were satisfied, and of those, 59% were completely satisfied and 23% satisfied with minimal restrictions. Three patients (18%) reported being dissatisfied with the outcome of the procedure. CONCLUSION: Kyphoplasty has proven effective in improving the function and relieving the pain in patients with vertebral compression fracture. The occurrence of a serious complication (AMI) calls attention to the need for proper hospital care during the procedure