Medical devices, namely, access catheters for providing controlled fluid access to the body; medical instruments in the nature of a sliding valve and hub system for connection and disconnection of suction to an aspiration catheter; medical instruments in the nature of a valve and hub system for achieving hemostasis during removal of an occlusion or thrombus; medical instruments in the nature of a hemostasis valve for decreasing the risk of thromboembolism; medical instruments for decreasing the risk of thromboembolism in the nature of a hemostasis valve that is actuated by a slider mechanism to open or close valve