The purpose of this study was to compare extraction sites augmented with bovine bone mineral (BBM) with and without resorbable membrane coverage. BBM particles were grafted in fresh human extraction sockets of 23 patients; in 12 of these patients, a guided tissue regeneration (GTR) membrane was applied. After 9 months ...

Periodontitis is a major chronic inflammatory disorder that can lead to the destruction of the periodontal tissues and, ultimately, tooth loss. To date, flap debridement and/or flap curettage and periodontal regenerative therapy with membranes and bone grafting materials have been employed with distinct levels of clinical success. Current resorbable and ...

Based on the principles of biomimetic mineralization, biocomposite nanofibrous membranes were fabricated by the growth of CaP crystals on electrospun gelatin nanofibers to mimic both the physical architecture and chemical composition of natural bone ECM. Plenty more CaP crystals formed on the nanofibrous membrane containing Ca(2+) ion precursors, in which ...

High-energy synchrotron X-ray diffraction is used to study in situ elastic strains in hydroxyapatite (HAP) for bovine femur cortical bone subjected to uniaxial compressive loading. Loadunload tests at room temperature (27°C) and body temperature (37°C) show that the load transfer to the stiff nano-size HAP platelets from the surrounding compliant ...

Asymmetrically porous polycaprolactone (PCL)/Pluronic F127 guided bone regeneration (GBR) membranes were fabricated. The top surface of the membrane had nanosize pores (∼10 nm) which can effectively prevent invasion by fibrous connective tissue but permeate nutrients, whereas the bottom surface had microsize pores (∼200 μm) which can enhance the adhesiveness with ...

Poly(dioxanone) (PDO) is colorless, crystalline, a biodegradable synthetic polymers that is used for biomedical applications, such as surgical sutures, cardiovascular applications, orthopedics, and plastic surgery. Recently, bone morphogenetic protein-2 (BMP-2) is widely used for bone tissue engineering. For the first time we report here on the in vitro performance of ...

Bioactive ceramic materials like tricalcium phosphate (TCP) have been emerging as viable material alternatives to the current therapies of bone scaffolding to target fracture healing and osteoporosis. Both material and architectural characteristics play a critical role in the osteoconductive capacity and strength of bone scaffolds. Thus, the objective of this ...

Temporal bones are valuable resources to study ear diseases. Although there are several methods for removing temporal bones from cadavers, such methods are not usually described in enough details in experimental research papers. OBJECTIVES: To describe a simple and rapid method for ear canal and tympanic membrane removal, and to ...

PURPOSE: Bone drilling causes an increase in bone temperature, and a temperature above 47°C is critical because it causes thermal bone necrosis. Thermal osteonecrosis is common with the drill diameter of ≥4.5 mm without cooling. The aim of this study was to determine the increase of bone temperature during drilling using ...

Periodontal regeneration is defined as regeneration of the tooth-supporting tissues including cementum, periodontal ligament, and alveolar bone. Guided tissue regeneration (GTR) has been demonstrated to be an effective technique to achieve periodontal regeneration. In the GTR procedures, various kinds of membranes play important roles. Chitosan, a deacetylated derivative of chitin, ...

Purpose: The principle of guided tissue and bone regeneration has long been established for treating bone and periodontal defects. In addition to nonabsorbable barriers, various collagens have become accepted as membrane materials for separating the graft from soft tissue. However, collagen membranes differ significantly in their barrier function and biocompatibility. ...

Antibiotic-loaded bone cement is widely used to treat musculoskeletal infections. Here we tested whether the curing temperature affected pore size of the cement and antibiotic release. Bone cement containing vancomycin was cured at 3 temperatures (50, 25 and 0°C). The solidified vancomycin-loaded cement was stored for 1-week at 25 and ...

Synaptic vesicles have a high sterol content, but the importance of vesicular sterols during vesicle recycling is unclear. We used the Drosophila temperature-sensitive dynamin mutant, shibire-ts1, to block endocytosis of recycling synaptic vesicles and to trap them reversibly at the plasma membrane where they were accessible to sterol extraction. Depletion ...

In this work, the toxic influence of metallic ions (Na+, Cu2+, Al3+) on the serum albumin were studied by fluorescence, resonance light scattering (RLS), synchronous fluorescence, UV-vis absorption and circular dichroism (CD) spectroscopy. The experimental results indicated that ion electric charge is not the main factor affecting the structure of ...

Two models have been proposed for endophilin function in synaptic vesicle (SV) endocytosis. The scaffolding model proposes that endophilin's SH3 domain recruits essential endocytic proteins, whereas the membrane-bending model proposes that the BAR domain induces positively curved membranes. We show that mutations disrupting the scaffolding function do not impair endocytosis, ...

Neurotransmitter release is achieved through the fusion of synaptic vesicles with the neuronal plasma membrane (exocytosis). Vesicles are then retrieved from the plasma membrane (endocytosis). It was hypothesized more than 3 decades ago that endosomes participate in vesicle recycling, constituting a slow endocytosis pathway required especially after prolonged stimulation. This ...

The Drosophila larval neuromuscular junction (NMJ) shares many structural and functional similarities to synapses in other animals, including humans. These include the basic feature of synaptic transmission as well as the molecular mechanisms regulating the synaptic vesicle cycle. Because of its large size, easy accessibility, and the well-characterized genetics, the ...

Neurotransmitter release relies on the fusion of synaptic vesicles with the plasma membrane of synaptic boutons, which is followed by the recycling of vesicle components and formation of new vesicles. It is not yet clear whether upon fusion the vesicles persist as multimolecular patches in the plasma membrane, or whether ...

The inhibitory neurotransmitter gamma-amino butyric acid (GABA) is synthesized by two isoforms of the enzyme glutamic acid decarboxylase (GAD): GAD65 and GAD67. Whereas GAD67 is constitutively active and produces >90% of GABA in the central nervous system, GAD65 is transiently activated and augments GABA levels for rapid modulation of inhibitory ...

The Na-K-2Cl cotransporter (NKCC2) mediates NaCl absorption by the thick ascending limb of Henle's loop (THAL). Exocytosis and endocytosis regulates surface expression of most transporters. However, little is known about the mechanism of NKCC2 trafficking in the absence of stimulating hormones and whether this mechanism contributes to regulation of steady-state ...

Chemical neurotransmission between neurons is a major point for modulation of neuronal activity. The neuronal synapse is the site of continuous cycles of rapid vesicle fusion (exocytosis) followed by their retrieval (endocytosis). Ongoing research efforts are largely focused on synaptic proteins involved in membrane fusion-and-fission, but it is now becoming ...

Synaptic vesicles need to be mobile to reach their release sites during synaptic activity. We investigated vesicle mobility throughout the synaptic vesicle cycle using both conventional and subdiffraction-resolution stimulated emission depletion fluorescence microscopy. Vesicle tracking revealed that recently endocytosed synaptic vesicles are highly mobile for a substantial time period after ...

Endophilin A1 is a BAR (Bin/amphiphysin/Rvs) protein abundant in neural synapses that senses and induces membrane curvature, contributing to neck formation in presynaptic endocytic vesicles. To investigate its role in membrane remodeling, we used cryoelectron microscopy to characterize structural changes induced in lipid vesicles by exposure to endophilin. The vesicles ...

Changes in postsynaptic membrane composition underlie many forms of learning-related synaptic plasticity in the brain. At excitatory glutamatergic synapses, fusion of intracellular vesicles at or near the postsynaptic plasma membrane is critical for dendritic spine morphology, retrograde synaptic signaling, and long-term synaptic plasticity. Whereas the molecular machinery for exocytosis in ...

Imbalances in brain cholesterol homeostasis have been observed in several neurodegenerative diseases. In Niemann-Pick Type C (NPC) disease, mutations in NPC1 or NPC2 lead to endosomal cholesterol accumulation, neuronal dysfunction and death. Cholesterol in synaptic plasma membranes influences membrane fluidity, curvature, and protein function, and its depletion may adversely affect ...

Biochemical studies have suggested that certain synaptic proteins associate with lipid rafts to perform key functions within the synapse. However, variability in biochemical preparations raises questions as to which synaptic proteins actually associate with lipid rafts. In the present study, we use both electron microscopy and biochemistry to investigate AMPA ...

We report that cholesterol depletion with methyl-beta-cyclodextrin (MbetaCD) acutely applied to rat brain synaptosomes is accompanied by an immediate increase in transporter-mediated glutamate release and decrease in exocytotic release. To clarify the possible mechanisms underlying these phenomena, we investigated the influence of MbetaCD on synaptic vesicle acidification and exo/endocytotic process ...

Short-term synaptic plasticity undergoes important age-dependent changes that have crucial implications during the development of the nervous system. Paired-pulse facilitation is a form of short-term synaptic plasticity by which the response to the second of two temporally-paired stimuli is larger and more reliable than the response to the first stimulus. ...

Studies demonstrate that cholesterol plays a critical role in the regulation of neurotransmitter release and that secretory vesicle swelling is a requirement for the regulated expulsion of intravesicular contents during cell secretion. In view of this, the involvement of cholesterol in synaptic vesicle swelling was hypothesized and tested in the ...

Synaptic vesicles recycle repeatedly in order to maintain synaptic transmission. We have previously proposed that upon exocytosis the vesicle components persist as clusters, which would be endocytosed as whole units. It has also been proposed that the vesicle components diffuse into the plasma membrane and are then randomly gathered into ...

The synaptic vesicle is currently the most well-characterized cellular organelle. During neurotransmitter release it undergoes multiple cycles of exo- and endocytosis. Despite this the vesicle manages to retain its protein and lipid composition. How does this happen? Here we provide a brief overview of the molecular architecture of the synaptic ...

Recent evidence suggests that the Ca(2+)-sensors synaptotagmin-1 and Doc2b deform synaptic membranes during synaptic vesicle exocytosis. We discuss how local curvature generated by these and other proteins may stimulate membrane fusion and discuss the potential implications of these findings for other cellular fusion events.

Cargo transport by microtubule-based motors is essential for cell organisation and function. The Bicaudal-D (BicD) protein participates in the transport of a subset of cargoes by the minus-end-directed motor dynein, although the full extent of its functions is unclear. In this study, we report that in Drosophila zygotic BicD function ...

The presynaptic terminal contains a complex network of filaments whose precise organization and functions are not yet understood. The cryoelectron tomography experiments reported in this study indicate that these structures play a prominent role in synaptic vesicle release. Docked synaptic vesicles did not make membrane to membrane contact with the ...

Secretory vesicle swelling is central to cell secretion, but the underlying mechanism of vesicle swelling, particularly synaptic vesicles, is not completely understood. The G(alphai3)-PLA2-mediated involvement of water channel AQP-1 in the regulation of secretory vesicle swelling in exocrine pancreas and the G(alphao)-mediated AQP-6 involvement in synaptic vesicle swelling in neurons ...

Prion diseases are disorders of protein conformation in which PrPC, the normal cellular conformer, is converted to an abnormal, protease-resistant conformer rPrPSc. Approximately 80% of rPrPSc accumulates in neuronal plasma membranes where it changes their physical properties and profoundly affects membrane functions. In this review we explain how rPrPSc is ...

Synaptic transmission depends on neurotransmitter pools stored within vesicles that undergo regulated exocytosis. In the brain, the vesicular monoamine transporter-2 (VMAT(2)) is responsible for the loading of dopamine (DA) and other monoamines into synaptic vesicles. Prior to storage within vesicles, DA synthesis occurs at the synaptic terminal in a two-step ...

Sodium-chloride coupled neurotransmitter transporters achieve reuptake of their physiological substrate by exploiting the pre-existing sodium-gradient across the cellular membrane. This terminates the action of previously released substrate in the synaptic cleft. However, a change of the transmembrane ionic gradients or specific binding of some psychostimulant drugs to these proteins, like ...

The size of a synaptic vesicle (SV) is generally thought to be determined by the amount of lipid and membrane protein it contains. Once formed, it is thought to remain constant in size. Using fluorescence correlation spectroscopy and cryogenic electron microscopy, we show that glutamatergic vesicles reversibly increase their size ...

The maintenance of ion gradients across plasma membranes is a prerequisite for the establishment of cellular membrane potentials, electrical signalling, and metabolite transport. At active synapses, pre- and postsynaptic ion gradients are constantly challenged and used for signalling purposes. Perisynaptic glia, mainly represented by fine processes of astrocytes which get ...

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The GTPase dynamin is essential for CME (clathrin-mediated endocytosis), but its exact function and mechanism of action have been controversial. Here, we review findings that have led to the current models for dynamin function, either as a mechanochemical enzyme driving membrane fission or as a regulatory GTPase monitoring rate-limiting steps ...

To enable fusion between biological membranes, t-SNAREs and v-SNARE present in opposing bilayers, interact and assemble in a circular configuration forming ring-complexes, which establish continuity between the opposing membranes, in presence of calcium ions. The size of a t-/v-SNARE ring complex is dictated by the curvature of the opposing membrane. ...

Exocytosis and endocytosis of synaptic vesicles are tightly coordinated to maintain a steady supply of new vesicles during periods of extended neuronal stimulation. Yao et al. (2009) now report that a synaptic vesicle membrane protein named Flower promotes endocytosis at neuromuscular junctions in the fruit fly Drosophila.

Glutamate release and synaptic vesicle heterotypic/homotypic fusion were characterized in brain synaptosomes of rats exposed to hypergravity (10 G, 1h). Stimulated vesicular exocytosis determined as KCl-evoked fluorescence spike of pH-sensitive dye acridine orange (AO) was decreased twice in synaptosomes under hypergravity conditions as compared to control. Sets of measurements demonstrated ...

Vesicle recycling is vital for maintaining membrane homeostasis and neurotransmitter release. Multiple pathways for retrieving vesicles fused to the plasma membrane have been reported in neuroendocrine cells. Dynasore, a dynamin GTPase inhibitor, has been shown to specifically inhibit endocytosis and vesicle recycling in nerve terminals. To characterize its effects in ...

The fusion of synaptic vesicles with the pre-synaptic plasma membrane mediates the secretion of neurotransmitters at nerve terminals. This pathway is regulated by an array of protein-protein interactions. Of central importance are the soluble NSF (N-ethylmaleimide-sensitive factor) attachment protein receptor (SNARE) proteins syntaxin 1 and SNAP25, which are associated with ...

In the absence of efficient diagnostic and therapeutic tools, Alzheimer's disease (AD) is a major public health concern due to longer life expectancy in the Western countries. Although the precise cause of AD is still unknown, soluble beta-amyloid (Abeta) oligomers are considered the proximate effectors of the synaptic injury and ...

We combined electron microscopy (EM), synaptic vesicle staining by fluorescent marker FM1-43, photoconversion of the dye into an electron dense product, and electrical recordings of synaptic responses to study the distribution of reserve and recycling vesicles and its dependence on stimulation in Drosophila motor boutons. We showed that, at rest, ...

The surface expression and localization of AMPA receptors (AMPARs) at dendritic spines are tightly controlled to regulate synaptic transmission. Here we show that de novo exocytosis of the GluR2 AMPAR subunit occurs at the dendritic shaft and that new AMPARs diffuse into spines by lateral diffusion in the membrane. However, ...