阅读说明：本技术 具有固定钳钩的闭合装置 (Closure device with fixed jaw hook ) 是由 保罗·史密斯 马修·R·贾格尔斯基 纳伦·素昂 凯文·J·麦克尔威 肖恩·赖安 亚厉克斯· 于 2017-05-08 设计创作，主要内容包括：一种装置包括收纳管,其从近端纵向延伸至远端且包括延伸通过其的通道。所述收纳管被可释放地联接至所述装置的近侧部分。所述装置还包括第一臂,其被刚性固定至所述收纳管的所述远端以从其向远侧延伸。此外,所述装置包括第二臂,其近端被可滑动地接收在所述收纳管内,以使得所述第二臂可在打开形态和闭合形态之间移动,在所述打开形态中,所述第二臂远离所述第一臂侧向移动,且所述第二臂的远端向远侧移动经过所述第一臂的所述远端,且在所述闭合形态中,所述第二臂向所述第一臂移动,且所述第二臂的所述远端朝向所述第一臂的所述远端向近侧移动。(A device includes a receiving tube extending longitudinally from a proximal end to a distal end and including a channel extending therethrough. The receiving tube is releasably coupled to a proximal portion of the device. The device also includes a first arm rigidly secured to the distal end of the receiving tube to extend distally therefrom. Further, the device includes a second arm having a proximal end slidably received within the receiving tube such that the second arm is movable between an open configuration in which the second arm is moved laterally away from the first arm and a distal end of the second arm is moved distally past the distal end of the first arm, and a closed configuration in which the second arm is moved toward the first arm and the distal end of the second arm is moved proximally toward the distal end of the first arm.)

1. A device for treating tissue, comprising:

a receiving tube extending longitudinally from a proximal end to a distal end and including a channel extending therethrough, the receiving tube being releasably coupled to a proximal portion of the device;

a flexible member extending between a distal end releasably coupled to the receiving tube and a proximal end, the proximal end remaining outside the living body in an operative configuration allowing user contact of the device;

a first arm rigidly coupled to the receiving tube and extending from a first arm proximal end at the distal end of the receiving tube to a first arm distal end; and

a second arm extending from a second arm proximal end to a second arm distal end, the second arm proximal end being slidably received within the receiving tube such that the second arm is movable between an open configuration in which the second arm is laterally moved away from the first arm and the second arm distal end is moved distally past the first arm distal end, and a closed configuration in which the second arm is moved toward the first arm and the second arm distal end is proximally moved toward the first arm distal end.

2. The device of claim 1, wherein the first arm is integrally formed with the receiving tube.

3. The device of claim 1, wherein the first arm is welded to the receiving tube.

4. The device of claim 1, wherein the first arm extends along an axis substantially parallel to a longitudinal axis of the containment tube.

5. The device of claim 1, wherein the distal end of the first arm includes a tissue-piercing member extending laterally inward toward the second arm.

6. The device of claim 1, wherein the second arm is biased toward the open configuration and is constrained by an inner surface of the receiving tube in the closed configuration.

7. The device of claim 1, wherein the flexible member is coupled to the receiving tube via a sleeve, a proximal end of the sleeve is coupled to the distal end of the flexible member, and a distal end of the sleeve is releasably coupled to the proximal end of the receiving tube.

8. The device of claim 1, wherein an inner surface of one of the first and second arms comprises hooks, undercuts, and barbs for capturing target tissue.

9. The device of claim 1, wherein an inner surface of the first arm is curved such that a longitudinal edge thereof extends toward the second arm to form a cup-shaped tissue receiving pocket.

10. The device of claim 1, wherein the distal tip of the second arm includes a window extending therethrough configured to receive the distal tip of the first arm.

11. The device of claim 9, wherein the inner surface comprises one of teeth, staples, grooves, and a structured surface to grip tissue received between the first and second arms.

12. The device of claim 1, further comprising a control element.

13. The device of claim 6, wherein the second arm is made of a compliant material.

14. The device of claim 13, wherein the compliant material comprises one of nitinol and stainless steel.

Technical Field

The present invention claims priority from U.S. provisional patent application serial No. 62/333,615 filed on 9/5/2016; the disclosure of which is incorporated herein by reference.

Background

Physicians are increasingly willing to perform more aggressive interventions and therapeutic endoscopic procedures, including, for example, removal of larger lesions (e.g., cancerous masses), tunneling under the mucosal layer of the Gastrointestinal (GI) tract to treat tissue beneath the mucosa, full thickness removal of tissue, insertion of a device through the GI tract and subsequent penetration of the GI organ to treat tissue outside the GI tract, and endoscopic treatment/repair of post-operative problems (e.g., post-operative leaks, damage to surgical sutures, anastomotic fistulas). These procedures may increase the risk of perforating or damaging the wall of the GI tract, or may require closure of the GI tract wall as part of the procedure. Endoscopic closure can reduce the cost, trauma, and inconvenience associated with these procedures. However, conventional endoscopic tissue closure devices may not be sufficient to close certain tissue defects.

Disclosure of Invention

The present invention relates to a device for treating tissue comprising a receiving tube extending longitudinally from a proximal end to a distal end and comprising a channel extending therethrough, the receiving tube being releasably coupled to a proximal portion of the device; and a first arm rigidly secured to the distal end of the receiving tube to extend distally therefrom in combination with the second arm, a proximal end of the second arm being slidably received within the receiving tube such that the second arm is movable between an open configuration in which the second arm is laterally moved away from the first arm and a distal end of the second arm is distally moved past the distal end of the first arm, and a closed configuration in which the second arm is moved toward the first arm and a distal end of the second arm is proximally moved toward the distal end of the first arm.

In one embodiment, the first arm extends along an axis substantially parallel to the longitudinal axis of the receiving tube.

In one embodiment, the distal end of the first arm includes a tissue-piercing member that extends laterally inward toward the second arm.

In one embodiment, the second arm is biased towards the open configuration and is constrained by the inner surface of the receiving tube in the closed configuration.

In one embodiment, the second arm is made of a compliant material.

In one embodiment, the compliant material comprises one of nitinol and stainless steel.

In one embodiment, the inner surface of one of the first and second arms includes hooks, undercuts, and barbs for capturing target tissue.

In one embodiment, the inner surface of the first arm is curved such that its longitudinal edge extends towards the second arm to form a cup-shaped tissue receiving pocket.

In one embodiment, the first arm includes a broad inner surface that forms a tissue receiving pocket in one plane.

In one embodiment, the inner surface includes one of teeth, staples, grooves, and a structured surface to grip tissue received between the first and second arms.

The present invention also relates to a method of forming superelastic nitinol arms for a tissue gripping device, comprising: inserting nitinol stock into recesses of a female portion of a mold assembly, the recesses sized and shaped to have a desired geometry for arms of a tissue gripping device; mating a male portion of a mold assembly to a female portion, the male portion including complementary geometry protrusions sized and shaped to be received within the recesses of the female portion to configure the nitinol stock into a desired geometry with arms; placing the mating male and female portions of the mold assembly in a fluid bath having a temperature of about 500 ℃ to process a nitinol feedstock having a desired geometry; and removing the mold assembly from the fluid bath and water quenching the mold assembly to solidify the nitinol feedstock into the desired geometry.

In one embodiment, once the nitinol feedstock reaches 500 ℃, the mold assembly is removed from the fluid bath and water quenched.

In one embodiment, the water quench cools the nitinol feedstock to room temperature.

In one embodiment, the recess of the female portion comprises a curved portion to form a corresponding curve in the arm.

In one embodiment, the protrusion of the male portion includes a portion for stamping out a desired characteristic in the arm.

The invention also relates to a method for treating a tissue defect, comprising: inserting a clamping device into a target area within a living body in a closed configuration through a working channel of an endoscope, the clamping device comprising a receiving tube; a first arm rigidly secured to the distal end of the receiving tube and extending distally therefrom; and a second arm movably housed within the receiving tube; moving the clamping device from the closed configuration to an open configuration in which the second arm is moved laterally away from the first arm and the distal end of the second arm is moved distally past the distal end of the first arm; piercing a first tissue with a distal end of a first arm along a first side of a tissue defect; moving the clamping device toward a second tissue along a second side of the tissue defect, the second side being opposite the first side; grasping a second tissue with a distal end of a second arm; and moving the clamping device toward a closed configuration in which the second arm is pulled laterally toward the first arm and a distal end of the second arm is pulled proximally toward a distal end of the first arm such that the second tissue is pulled toward the second tissue, thereby closing the tissue defect.

In one embodiment, the clamping device is moved toward the closed configuration prior to moving the clamping device toward the second tissue; and moving the clamping device toward the open configuration prior to grasping a second tissue.

In one embodiment, the method includes locking the clamping device in the closed configuration and deploying the clamping device.

In one embodiment, the clamping device is moved between the open and closed configurations via a control element releasably coupled to the proximal end of the second arm, the control element being released from the second arm to deploy the clamping device.

In one embodiment, in the closed configuration, the distal ends of the first and second arms are substantially longitudinally aligned.

Drawings

Fig. 1 shows a longitudinal side view of a device according to a first exemplary embodiment of the present invention in an open configuration;

FIG. 2 shows a longitudinal side view of the device of FIG. 1 in a closed configuration;

FIG. 3 shows a longitudinal side view of a portion of an arm of the device of FIG. 1;

FIG. 4 shows another longitudinal side view of a portion of an arm of the device of FIG. 1;

FIG. 5 shows a front view of the portion of the arm of the device of FIG. 4 as seen from its distal end;

FIG. 6 shows a side view of the device of FIG. 1 in a closed configuration inserted into a target tissue;

FIG. 7 shows a side view of the device of FIG. 1 with a first arm of the device grasping a first side of the tissue defect in an open configuration;

FIG. 8 shows a side view of the device of FIG. 1 with a second arm of the device grasping a second side of the tissue defect in an open configuration;

FIG. 9 shows a side view of the device of FIG. 1 moved to a closed configuration to close a tissue defect;

FIG. 10 shows a perspective view of an apparatus according to an alternative embodiment of the invention;

FIG. 11 shows a perspective view of a device according to another alternative embodiment of the present invention;

FIG. 12 shows a perspective view of an arm of the device of FIG. 1;

FIG. 13 illustrates a perspective view of a mold assembly according to an exemplary embodiment of the present invention;

FIG. 14 shows a side view of the mold assembly of FIG. 13; and

FIG. 15 shows a perspective view of a female mold half of the mold assembly of FIG. 13.

Detailed Description

The present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The present invention relates to an endoscopic clamping device for treating tissue perforations, defects and/or bleeding. In particular, the exemplary embodiments of the present invention describe an endoscopic clip comprising a first jaw rigidly fixed to a receiving tube; and a second jaw slidably received within the receiving tube for movement between an open configuration and a closed configuration. In the open configuration, the distal end of the second jaw extends laterally away from and distally past the distal end of the first jaw such that target tissue may be received therebetween. In the closed configuration, the second jaw is retracted into the receiving tube such that the second jaw is moved laterally inward and toward the distal end of the first jaw to grasp target tissue therebetween. It should be noted that the terms "proximal" and "distal" as used herein are intended to refer to directions toward (proximal) and away from (distal) a user of the device.

As shown in fig. 1 to 9, a clamping device 100 according to an exemplary embodiment of the present invention includes a clip 102 which can be inserted into a living body to a target tissue to be treated through, for example, a working channel of an endoscope. Clip 102 is releasably attached to the proximal portion with sufficient flexibility to allow it to be passed through an endoscope-e.g., through a working channel of an endoscope inserted through a natural body lumen accessed through a natural body lumen orifice, even as the endoscope traverses tortuous paths of the body. For example, the proximal portion may include a flexible member made of a coil of wire or any other suitable flexible structure. As shown in fig. 1-2, the clip 102 includes a first arm 104 rigidly secured to a distal end 110 of a receiving tube 108; and a second arm 106 slidably received within a longitudinal channel 112 of the receiving tube 108. The clip 102 is movable between an open configuration in which the distal end 114 of the second arm 106 extends distally and laterally away from the distal end 116 of the first arm 104, and a closed configuration in which the distal end 114 of the second arm 106 extends toward the first arm 104 such that the distal end 114 of the second arm 106 is substantially longitudinally aligned with the distal end 116 of the first arm 104. In use, as shown in fig. 6-9, the clip 102 is inserted into a target area of a living body and moved to an open configuration such that the first capture characteristic 118 of the first arm 104 captures a first portion of tissue along a first side of a tissue defect to be treated. As the first portion of tissue is captured by the first arm 104, the clip 102 is moved toward the second side of the tissue defect so that the second capture feature 120 on the second arm 106 can capture the second portion of tissue along the second side of the tissue defect. Subsequently, the clip 102 can be moved toward the closed configuration such that the first and second portions of tissue are moved toward one another to close the tissue defect. Because the clips 102 allow access to the first and second sides of the tissue defect, the device 100 may be particularly suited for treating large tissue openings/defects.

The receiving tube 108 extends longitudinally from the proximal end 122 to the distal end 110 and includes a passage 112 extending longitudinally therethrough. The proximal end 122 of the channel 112 is releasably coupled to a flexible member (not shown) of the proximal portion of the device 100 so that the clip 102 including the receiving tube 108 can be deployed therefrom for implantation in the body. The receiving tube 108 may be coupled to the flexible member, for example, via a sleeve releasably coupled to the receiving tube 108 via a cantilever arm of the sleeve received within a corresponding window at the proximal end of the receiving tube 108, substantially as described in U.S. patent application publication No. 2014/0088616 ("the' 616 application") to Clerc et al and assigned to boston scientific international, inc. The entire disclosure of the "616" application is incorporated herein by reference. The cantilever of the sleeve may, for example, be biased to disengage from the receiving tube 108, but held in position locked into the window of the receiving tube by a support structure that disengages from the sleeve arm when the control element connected to the proximal end of the second arm 106 is detached therefrom. The control element may be coupled to the second arm 106 via a control member, as described in U.S. patent application publication No. 2014/0088616, or in another embodiment, may be coupled directly to the second arm 106. The control element may be disengaged from the second arm 106 when the control element is pulled proximally relative to the receiving tube 108 to exceed a predetermined load. When the control element is disengaged from the second arm 106, in this embodiment, the locking tab of the second arm 106 moves radially outward to engage a portion of the receiving tube 108, thereby locking the clip 102 in the closed configuration. Although a particular mechanism for locking and deploying the clip 102 is described above, the clip 102 may also be deployed from a proximal portion of the device 100 and/or locked in the closed configuration via any of a variety of known clip deployment and locking mechanisms.

The first arm 104 extends distally from the distal end 110 of the receiving tube 108 to a distal end 116. In this embodiment, the first arm 104 is integrally formed with the receiving tube 108. However, in alternative configurations, the first arm 104 may be rigidly secured to the receiving tube 108 via any known connection mechanism, such as, for example, welding. In one embodiment, the first arm 104 extends from the distal end 110 of the receiving tube 108 along an axis substantially parallel to the longitudinal axis of the receiving tube 108. The first arm 104 extends from a proximal end 124 connected to the receiving tube 108 to a distal end 116. The distal end 116 may be bent or flexed to include a distal tip 126 that extends laterally inward toward the longitudinal axis of the clip 102 such that the distal tip 126 may hook or grip the target tissue received between the first and second arms 104, 106. As shown in fig. 3, the distal end 116 may also include a first capture feature 118, which may be configured, for example, as an undercut along the side of the first arm 104 facing the second arm 106. Alternatively or additionally to the undercut, as shown in fig. 4-5, the first capture feature 118 may comprise a barb stamped into the first arm 104 to extend toward the second arm 106. The first capture characteristic 118 may be configured to extend from a side or inner surface 128 of the first arm 104 to face any of the various elements of the second arm 106.

In one embodiment, as shown in fig. 1-2, the inner surface of the first arm 104 may be cup-shaped or curved such that its longitudinal edge curves toward the second arm 106 forming a cup-shaped pocket in which tissue may be received. In another embodiment, as shown in FIG. 10, the first arm 104 'may have a broad (non-cup-shaped) inner surface 128' that forms a tissue-receiving pocket in one plane. The inner surface 128' may include teeth, pegs, grooves, and/or structured surfaces to provide additional grip to tissue received between the first and second arms. The distal end 116 'of the first arm 104' may also include a hook or other tissue-piercing member, such as a point or barb for hooking or grasping tissue.

The proximal end of the second arm 106 is slidably received within the channel 112 of the receiving tube 108 such that the second arm 106 is movable relative thereto between open and closed configurations. The proximal end of the second arm 106 may be connected to a control element extending proximally therefrom through the receiving tube 108 and the proximal portion of the device 100 to be controlled by the user. The control element may be moved longitudinally relative to the device 100 to move the clip 102 between the open and closed configurations. The second arm 106 is made of a compliant material that allows the second arm 106 to move between the open and closed configurations. The second arm 106 may be movable between open and closed configurations via, for example, a living hinge. In one embodiment, the second arm 106 may be biased toward the open configuration such that when the second arm 106 is moved distally relative to the receiving tube 108 toward the open configuration, the second arm 106 reverts to the biased configuration and moves laterally away from the first arm 104 as the distal end 114 of the second arm 106 moves distally past the distal end 116 of the first arm 104. In the closed configuration, the second arm 106 is pulled proximally into the channel 112 and constrained by the inner surface of the receiving tube 108 such that as the distal end 114 of the second arm 106 is moved toward the distal end 116 of the first arm 104, the second arm 106 is moved laterally toward the first arm 104. In one embodiment, the distal ends 116, 114 of the first and second arms 104, 106, respectively, may be substantially longitudinally aligned in the closed configuration.

Similar to the first arm 104, the distal end 114 of the second arm 106 may be inwardly flexed or bent to form a distal tip 130 that extends laterally inward toward the longitudinal axis of the clip 102 such that the distal tip 130 hooks or grips tissue received between the first and second arms 104, 106. The distal tip 130 may include a second capture feature 120 for grasping tissue, such as, for example, a point or barb. Alternatively or additionally to the tissue gripping features located at the distal tip 130, the distal end 114 of the second arm 106 may include tissue gripping/capturing features, such as undercuts and/or barbs, as described above with respect to the first arm 104 and as shown in fig. 3-5.

In one embodiment, the distal ends 116, 114 of the first and second arms 104, 106, respectively, are substantially longitudinally aligned in the closed configuration such that the distal tips 126, 130 are substantially aligned and face each other. In another embodiment, as shown in fig. 11, the distal tip 130 "of the second arm 106" includes a window 132 "extending therethrough for receiving the distal tip 126" of the first arm 104 "therein. Thus, in the closed configuration, the distal tip 126 "of the first arm 104" is received within the window 132 "of the second arm 106" when grasping tissue. Alternatively, the second arm 106 "may be allowed to be pulled proximally of the first arm 104" such that the distal end 114 "of the second arm 106" may be pulled proximally past the distal end 116 "of the first arm 104".

As shown in fig. 6-9, an exemplary method of using the device 100 includes inserting a clip 102 in a closed configuration through, for example, a working channel of an endoscope to a target area within a living body. As described above, the clip 102 can access discrete portions of tissue, making the clip 102 particularly suitable for treating large tissue defects. Once at the target area, as shown in fig. 6, the clip 102 is moved to the open configuration and manipulated such that the distal end 116 of the first arm 104 hooks or grips the first portion of tissue along the first side of the tissue defect, as shown in fig. 7. The first portion of tissue may be captured by the hook at the distal tip 126 of the first arm 104 and/or the first capture feature 118, which may include, for example, an undercut or barb. Once the first portion of tissue is captured by the first arm 104, the clip 102 is moved toward the second portion of tissue along a second side of the tissue defect (e.g., opposite the first side). The clip 102 can be moved toward the closed configuration prior to moving the clip 102 toward the second portion of tissue. Thus, after reaching the second portion of tissue, the clip 102 returns to the open configuration such that the second arm 106 is moved laterally and distally relative to the first arm 104 to hook and/or grasp the second portion of tissue via the distal end 114 of the second arm 106, as shown in fig. 8. A second portion of the tissue may be captured by the distal tip 130 and/or the second capture characteristic 120. The gripping characteristics as described with respect to fig. 10 and 11 may be used to provide greater gripping force on the first and second portions of tissue between the first and second arms 104, 106.

Once the second portion of tissue has been captured/hooked, the clip 102 is moved to the closed configuration to pull the second arm 106 towards the first arm 104. As described above, as the distal end 114 of the second arm 106 is moved toward the distal end 116 of the first arm 104, the second arm 106 is moved laterally toward the first arm 104, as shown in fig. 9, thereby pulling the first and second portions of tissue captured via the distal ends 116, 114, respectively, toward one another. Thus, tissue along the first and second sides of the tissue defect is drawn together to close the tissue defect. Once the tissue defect has been closed, the clip 102 may be locked in the closed configuration and deployed to separate it from the proximal portion of the device 100, as desired, as will be understood by those skilled in the art. For example, a control element connected to the proximal end of the second arm 106 may be pulled proximally relative to the receiving tube 108 until a predetermined threshold load is exceeded, and the control element is separated from the second arm 106. In this embodiment, disengaging the control element from the second arm 106 in turn allows the locking tab of the second arm 106 to engage the receiving tube 108, thereby locking the second arm 106 relative thereto in the closed configuration. Proximal movement of the control element also facilitates release of the receiving tube 108 from the proximal portion of the device 100, thereby releasing the clip 102 so that it will remain within the body as the proximal portion of the device 100 is withdrawn from the body. The clip 102 will then fall out as the natural healing process progresses, as will be understood by those skilled in the art.

As described above, the second arm 106 of the clip 102 may, for example, be made of a compliant material, such as, for example, nitinol. In one embodiment, as shown in fig. 12, the second arm 106 may be formed via a superelastic nitinol forming process, and the second arm 106 includes a mold assembly 200, as shown in fig. 13-15, that includes a male mold 202 and a female mold 204 that are created to configure the nitinol in a desired geometry. The mold assembly 200 may improve the accuracy of the properties provided in the nitinol material and allow multiple metal sheets to be formed at once, thereby reducing cost and increasing throughput capability. Unlike conventional nitinol forming processes, the male and female dies 202, 204 do not need to be attached to any machinery, such as, for example, a press. Conversely, the male and female dies 202, 204 can include mating features, such as, for example, bolts or pins, that allow the dies 202, 204 to be bonded together while containing the nitinol material such that the nitinol material is configured into a desired geometry. The combined male and female dies 202, 204 with the nitinol deployed would then be placed in a fluid bath set at about 500 ℃ to treat the nitinol. For example, nitinol may be treated at a temperature between 450 and 550 degrees celsius for 2 to 20 minutes. In one embodiment, after the nitinol is treated at 55 degrees celsius for about 10 minutes, the mold assembly 200 is removed from the bath and immediately water quenched so that the nitinol material retains its desired shape. The water quenching ensures that the nitinol component is immediately cooled to room temperature, thereby limiting the amount of time that the nitinol component remains at an elevated temperature. Ideally, the nitinol component is immediately cooled after the nitinol has reached 500 ℃. Thus, while the above method describes treating the nitinol for approximately 10 minutes, this time may vary depending on the amount of time required to heat the nitinol to 500 ℃.

To create the desired nitinol composition (e.g., the second arm 106 shown in fig. 12), the mold assembly 200 is created in 3D so that complex geometric properties can be created in nitinol. For example, as shown in fig. 13 and 15, the female mold half 204 of the mold assembly 200 includes a recess 206 sized and shaped to create the desired size and shape of the second arm 106. The recess 206 may include a curved portion 208 along a portion of its length to create a corresponding radius 138 in the second arm 106 that biases the arm 106 toward the open configuration, as described above. The master 204 can also include an opening 210 for receiving mating features,

such as, for example, bolts or pins, for joining the male mold half 202 to the female mold half 204.

As shown in fig. 13 and 14, the female mold half 202 may include a complementary geometrically shaped protrusion 212 sized and shaped to be received within the recess 206 of the female mold half 204 such that when the male and female mold halves 202, 204 are mated or joined to one another, the nitinol material received within the recess 206 is molded to the desired size and shape of the second arm 106. For example, the protrusion may include a first portion 214 sized and shaped to stamp out the shape 134 (e.g., a rectangle) of the length of the second arm 106 and a second portion 216 that protrudes from the first portion 214 to add the feature 136 (e.g., an opening) in the second arm 106.

While the female and male dies 204, 202 are shown and described as including a single recess 206 and complementary protrusion 212, respectively, the die assembly 200 can also be designed to include multiple recesses 206 and protrusions 212 such that multiple arms 106 are formed at once, which reduces cost while increasing throughput output. Further, although the male and female dies 202, 204 are described as including particular design characteristics, the male and female dies 202, 204 can include any of a variety of geometric characteristics designed to create a desired geometry of the second arm 106.

Variations in the structure and method of the invention may be made without departing from the spirit and scope of the invention. Thus, the present invention is intended to cover modifications and variations of this invention that may be considered by those skilled in the art.