Magnetically guided virus stamping for the targeted infection of single cells or groups of cells

To understand and control complex tissues, the ability to genetically manipulate single cells is required. However, current delivery methods for the genetic engineering of single cells, including viral transduction, suffer from limitations that restrict their application. Here we present a protocol that describes a versatile technique that can be used for the targeted viral infection of single cells or small groups of cells in any tissue that is optically accessible. First, cells of interest are selected using optical microscopy. Second, a micropipette—loaded with magnetic nanoparticles to which viral particles are bound—is brought into proximity of the cell of interest, and a magnetic field is applied to guide the viral nanoparticles into cellular contact, leading to transduction. The protocol, exemplified here by stamping cultured neurons with adeno-associated viruses (AAVs), is completed in a few minutes and allows stable transgene expression within a few days, at success rates that approach 80%. We outline how this strategy is applied to single-cell infection in complex tissues, and is feasible both in organoids and in vivo

Magnetically guided virus stamping for the targeted infection of single cells or groups of cells

To understand and control complex tissues, the ability to genetically manipulate single cells is required. However, current delivery methods for the genetic engineering of single cells, including viral transduction, suffer from limitations that restrict their application. Here we present a protocol that describes a versatile technique that can be used for the targeted viral infection of single cells or small groups of cells in any tissue that is optically accessible. First, cells of interest are selected using optical microscopy. Second, a micropipette—loaded with magnetic nanoparticles to which viral particles are bound—is brought into proximity of the cell of interest, and a magnetic field is applied to guide the viral nanoparticles into cellular contact, leading to transduction. The protocol, exemplified here by stamping cultured neurons with adeno-associated viruses (AAVs), is completed in a few minutes and allows stable transgene expression within a few days, at success rates that approach 80%. We outline how this strategy is applied to single-cell infection in complex tissues, and is feasible both in organoids and in vivo

Type-specific dendritic integration in mouse retinal ganglion cells

Neural computation relies on the integration of synaptic inputs across a neuron’s dendritic arbour. However, it is far from understood how different cell types tune this process to establish cell-type specific computations. Here, using two-photon imaging of dendritic Ca2+ signals, electrical recordings of somatic voltage and biophysical modelling, we demonstrate that four morphologically distinct types of mouse retinal ganglion cells with overlapping excitatory synaptic input (transient Off alpha, transient Off mini, sustained Off, and F-mini Off) exhibit type-specific dendritic integration profiles: in contrast to the other types, dendrites of transient Off alpha cells were spatially independent, with little receptive field overlap. The temporal correlation of dendritic signals varied also extensively, with the highest and lowest correlation in transient Off mini and transient Off alpha cells, respectively. We show that differences between cell types can likely be explained by differences in backpropagation efficiency, arising from the specific combinations of dendritic morphology and ion channel densities

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

Geology of the Amm gold mine, Cadillac township, Quebec.

The property of Amm Gold Mines Limited comprises a group of seven claims in Cadillac Township, Abitibi County, Quebec. The group occupies a position near the north-south centreline of Cadillac Township between the Noranda-Valdor high-way and the Noranda-Valdor branch of the Canadian National Railways. The claims are numbered A-584, A-585 and A-5882l to A-58825 inclusive, and have a combined area or about 370 acres. The property 1s bounded on the east and north by Pandora Cadillac, on the west by Pandora Cadillac, Wood Cadillac, Routhier Cadillac and Benard Cadillac, while the railway right-of-way passes within 150 feet of the most southerly point of the property. The transmission lines of the Northern Quebec Power Co. pass through the central part of the property. [...