U.S. patent number RE36,628 [Application Number 08/950,602] was granted by the patent office on 2000-03-28 for method of manufacturing a differentially heat treated catheter guide wire.
This patent grant is currently assigned to Terumo Kabushiki Kaisha. Invention is credited to Kyuta Sagae, Yoshiaki Sugiyama.
United States Patent |
RE36,628 |
Sagae , et al. |
March 28, 2000 |
Method of manufacturing a differentially heat treated catheter
guide wire
Abstract
A catheter guide wire is provided for guiding a catheter into a
body cavity such as a blood vessel. The base material constituting
the wire is made of an elastic alloy wire and subjected to a heat
treatment such that its flexibility is sequentially increased from
its proximal to distal end portions. A thermoplastic resin or/and a
coil spring can be applied to at least the distal end portion of
the wire base material. A method of manufacturing the catheter
guide wire is also provided. The method is characterized in that
the leading end side of the base material is divided into a
plurality of areas and subjected to a heat treatment by changing
the heat treatment temperature and the time conditions in units of
the areas so that the flexibility of the base material is
sequentially increased from the proximal to distal end portions of
the leading end side.
Inventors: |
Sagae; Kyuta (Fuji,
JP), Sugiyama; Yoshiaki (Fuji, JP) |
Assignee: |
Terumo Kabushiki Kaisha (Tokyo,
JP)
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Family
ID: |
27563140 |
Appl.
No.: |
08/950,602 |
Filed: |
October 16, 1997 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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671972 |
Jun 28, 1996 |
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357570 |
Dec 15, 1994 |
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657895 |
Feb 19, 1991 |
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381391 |
Jul 5, 1989 |
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Reissue of: |
760813 |
Sep 16, 1991 |
05171383 |
Dec 15, 1992 |
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Foreign Application Priority Data
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Jan 7, 1987 [JP] |
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62-1468 |
Dec 25, 1987 [WO] |
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PCT/JP87/01031 |
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Current U.S.
Class: |
148/537; 148/563;
148/564; 148/676; 148/902; 600/585; 604/525; 604/530 |
Current CPC
Class: |
A61M
25/09 (20130101); A61M 2025/09083 (20130101); A61M
2025/09141 (20130101) |
Current International
Class: |
A61M
23/00 (20060101); C12D 008/06 (); A61M
023/00 () |
Field of
Search: |
;148/402,563,564,676,902,537 ;604/95,164,170,280,282,525,530
;128/772,657,902 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 013 604 |
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Jul 1980 |
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EP |
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0141006 |
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May 1985 |
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EP |
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0 161 066 |
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Nov 1985 |
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EP |
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59-048643 |
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Mar 1984 |
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JP |
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59-219443 |
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Dec 1984 |
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JP |
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60-063066 |
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Apr 1985 |
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JP |
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60-138547 |
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Sep 1985 |
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JP |
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61-106173 |
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May 1986 |
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JP |
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8 5011444 |
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Apr 1985 |
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WO |
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Other References
Derwint Abs C85-008892 (of Japan 59-125,448), 1985. .
Derwint Abs C85-008891 (of Japan 59-125,447), 1985. .
K. Watanabe, "Studies on New Superelastic NiTi Orthodontic Wire,"
vol. 23, No. 61 (1982); English abstract only. .
G. Andreasen et al., "Laboratory and clinical analysis of nitinol
wire," A. J. Orthod., vol. 73, No. 2, pp. 142-151 (1978)..
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Primary Examiner: Wyszomierski; George
Attorney, Agent or Firm: Morrison & Foerster LLP
Parent Case Text
.[.This application is a division of application Ser. No.
07/657,895, filed Feb. 19, 1991, now abandoned, which is a
continuation of Ser. No. 07/381,391 filed Jul. 5, 1989, now
abandoned..]. .Iadd.This application is a continuation of
application Ser. No. 08/671,972, filed Jun. 28, 1996, now
abandoned, which is a continuation of application Ser. No.
08/357,570, filed Dec. 15, 1994 now abandoned, which is a Reissue
of U.S. Pat. No. 5,171,383, issued Dec. 15, 1992, which is a
divisional of application Ser. No. 07/657,895, filed Feb. 19, 1991,
abandoned, which is a continuation of application Ser. No.
07/381,391, filed Jul. 5, 1989, now abandoned. .Iaddend.
Claims
We claim:
1. A method of making a catheter guide wire for guiding a catheter,
said method comprising:
forming a wire member comprising a superelastic Ni-Ti alloy wire as
a base material, said base material having a proximal end portion
and a leading end side;
dividing said leading end side of said base material into a
plurality of areas along the length thereof and a distal end
portion, said plurality of areas comprising an intermediate portion
between said proximal and distal end portions; and
subjecting only said intermediate portion and said distal end
portion to a primary heat treatment at a temperature of 400.degree.
to 500.degree. C. for about two hours, and then subjecting only
said distal end portion to a secondary heat treatment at a
temperature of about 200.degree. C. for about 24 hours, whereby
said proximal end portion is not heat treated after cold rolling,
such that said distal end portion, after said primary and secondary
heat treatments, has a yield stress of approximately 5 to 7
kg/mm.sup.2, and at least one of said areas at said intermediate
portion, after said heat treatment, has a yield stress of
approximately 11 to 12 kg/mm.sup.2.
2. A method according to claim 1, comprising forming said wire
member so as to have a proximal end portion having an outer
diameter ranging from 0.2 to 0.4 mm.
3. A method of making a catheter guide wire for guiding a catheter,
said method comprising:
forming a wire member comprising a superelastic Ni-Ti alloy wire as
a base material, said base material having a proximal end portion
and a leading end side;
dividing said leading end side of said base material into a
plurality of areas along the length thereof and a distal end
portion, said plurality of areas comprising an intermediate portion
between said proximal and distal end portions; and
subjecting only said intermediate portion and said distal end
portion to a primary heat treatment at a temperature of 400.degree.
to 500.degree. C. for about two hours, and thereafter subjecting
only said distal end portion to a secondary heat treatment at a
temperature of about 200.degree. C. for about 24 hours, whereby
said proximal end portion is not heat treated after cold rolling,
such that, after said primary and secondary heat treatments,
flexibility of the guide wire is increased from said proximal end
portion to said distal end portion thereof.
4. A method according to claim 3, comprising forming said wire
member so as to have a proximal end portion having an outer
diameter ranging from 0.2 to 0.4 mm. .Iadd.
5. A process for forming a guide wire for a catheter, said guide
wire having a proximal end and a distal end, comprising:
forming a Ni-Ti alloy wire;
cold rolling said Ni-Ti alloy wire;
forming said distal end portion and said proximal end portion of
said guide wire, said distal end portion having a diameter that is
less than a diameter of said proximal end portion; and
subsequently heat treating said distal end portion of said guide
wire so as to make said distal end portion more flexible than said
proximal end portion. .Iaddend..Iadd.6. A process for forming a
guide wire for a catheter, said guide wire having a proximal end
and a distal end, comprising:
forming a Ni-Ti alloy wire;
cold rolling said Ni-Ti alloy wire;
forming said distal end portion and said proximal end portion of
said guide wire, said distal end portion having a diameter that is
less than a diameter of said proximal end portion;
subsequently heat treating said distal end portion of said guide
wire so as to make said distal end portion more flexible than said
proximal end portion; and
forming a thermoplastic resin layer on said guide wire.
.Iaddend..Iadd.7. A process for forming a guide wire for a
catheter, said guide wire having a proximal end and a distal end,
comprising:
forming a Ni-Ti alloy wire;
cold rolling said Ni-Ti alloy wire;
forming said distal end portion and said proximal end portion of
said guide wire, said distal end portion having a diameter that is
less than a diameter of said proximal end portion;
subsequently heat treating said distal end portion of said guide
wire so as to make said distal end portion more flexible than said
proximal end portion; and
mounting a coil spring around at least a portion of said guide
wire.
.Iaddend..Iadd.8. A process for forming a guide wire for a
catheter, said guide wire having a proximal end and a distal end,
comprising:
forming a Ni-Ti alloy wire;
cold rolling said Ni-Ti alloy wire;
forming said distal end portion and said proximal end portion of
said guide wire, said distal end portion having a diameter that is
less than a diameter of said proximal end portion;
subsequently heat treating said distal end portion of said guide
wire so as to make said distal end portion more flexible than said
proximal end portion;
forming a thermoplastic resin layer on said guide wire; and
mounting a coil spring around at least a portion of said guide
wire. .Iaddend.
Description
TECHNICAL FIELD
The present invention relates to a catheter guide wire for guiding
a clinical or testing catheter to a predetermined portion of a body
cavity such as a blood vessel, a digestive tract, and a windpipe
and holding it therein, and a method of manufacturing the same.
PRIOR ART
When a catheter is to be guided to a branching peripheral portion
of a blood vessel or the like, first, a guide wire must be guided
to a target portion. In this case, since a target portion is
generally thin and thus tends to be easily damaged, the distal end
portion of the guide wire must be flexible so that it will not
damage a blood vessel wall, will follow the shape of the blood
vessel well even if the blood vessel is curved, and can be inserted
in a complex branching blood vessel. Meanwhile, the proximal end
portion of the guide wire must have torque transmitting performance
so that a manual operation performed at the proximal end portion is
transmitted to the distal end portion. Thus, the proximal end
portion of the guide wire must have comparatively high
rigidity.
According to a conventional catheter guide wire having the above
characteristics, a coil guide wire is made of a stainless steel
wire or a piano wire, or a guide wire is made of a plastic
monofilament. In each of these guide wires, its sectional area is
decreased from its proximal to distal end portion, and the guide
wire forms a main portion having relatively high rigidity and a
relatively flexible distal end portion.
However, plastic deformation can easily occur in these conventional
guide wires, and some manual operation can kink the guide wires. A
kinked portion becomes an obstacle during introduction of a
catheter, thus rendering smooth introduction operation of a
catheter impossible as well as greatly degrading its torque
transmitting performance.
A catheter guide wire free from such kinking deformation uses a
very elastic alloy (e.g., Ni-Ti alloy) as a core member (see
Japanese Patent Disclosure (Kokai) No. 60-63066).
A guide wire using a very elastic alloy is flexible and can restore
its original shape after it is deformed to a considerable degree
(strain of about 8%). Therefore, such a guide wire cannot be easily
broken during operation and will not easily attain a bending
tendency. However, such guide wire has a high elasticity at its
distal end portion and is thus infavorable in terms of flexibility.
Then the diameter of its proximal end portion is 0.5 mm or less,
the rigidity is insufficient and the torque transmitting
performance is poor.
DISCLOSURE OF THE INVENTION
The present invention has been made in view of the above situation
and has as its object to provide a catheter guide wire wherein its
distal end portion is very flexible, buckling deformation is
difficult to occur, and its proximal end portion is very rigid,
thus having a good torque transmitting performance to the distal
end portion, and a method of manufacturing the same.
In order to solve the above problems, according to the present
invention, a wire member made of an elastic alloy, and preferably a
very elastic alloy, is used as a core member of a catheter guide
wire and subjected to a heat treatment by changing the treatment
conditions along its longitudinal direction, so that the rigidity
at its proximal end portion becomes comparatively high, the
flexibility at its distal end portion is increased, and kinking
deformation will not easily occur in its distal end portion.
More specifically, according to the present invention, there is
provided a catheter guide wire having leading and trailing end
sides, characterized in that the guide wire comprises a wire member
made of an elastic alloy member, at least the leading end side
thereof has an outer diameter equal to or smaller than a minimum
inner diameter of a catheter, and the wire member is subjected to a
heat treatment so that its flexibility is sequentially increased
from a proximal to distal end portion of the leading end side
thereof.
Note that the catheter guide wire can be fabricated by using as a
core member a wire member made of an elastic alloy member subjected
to the heat treatment described above and forming a cover layer of
a thermoplastic resin on the core member.
The core member preferably uses a very elastic alloy such as an
Ni-Ti alloy, a Cu-Zn-Al alloy, a Cu-Al-Ni alloy, and an Fe-Mn
alloy. The core member is preferably tapered such that a diameter
at its distal end portion is smaller than that at its proximal end
portion. A contrast medium such as a tungsten powder can be added
to the thermoplastic resin layer.
A flexible coil spring having an outer diameter equal to or smaller
than a minimum inner diameter of the catheter can be mounted to
surround at least the distal end portion of the wire member.
In this case, the coil spring is preferably made of a material
having a high X-ray impermeability in order to allow an X-ray
photographing to be easily confirmed. Therefore, the presence of
the coil spring is advantageous in giving a sufficient thickness in
an X-ray image without badly affecting the flexibility of the guide
wire.
As a result, the coil spring is made of a material selected from a
group consisting of stainless steel, platinum, a platinum alloy and
a palladium alloy, and preferably has a thickness of 0.01 to 0.15
mm, more preferably 0.05 to 0.1 mm.
Furthermore, according to the present invention, there is provided
a method of manufacturing a catheter guide wire fabricated by using
an elastic alloy wire as a base material, characterized in that a
leading end side of the base material is divided into a plurality
of areas, and a heat treatment is performed by changing the
temperatures and time in units of the areas so that the flexibility
of the base material is sequentially increased from the proximal to
distal end portion of the leading end side.
In a conventional catheter guide wire, a diameter at a proximal end
portion of a wire member made of an elastic alloy or a very elastic
alloy is merely increased, and a diameter at its distal end portion
is relatively decreased, thereby making the proximal end portion
rigid and the distal end portion flexible. Unlike such a
conventional catheter guide wire, according to the present
invention, a wire member is subjected to a heat treatment by
sequentially changing the confunction along its longitudinal
direction. As a result, the physical characteristics of the wire
member can be set in an ideal state as a catheter guide wire.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of a catheter guide wire according to an
embodiment of the present invention;
FIG. 2 is a graph of strain-stress curves of the core member of the
guide wire according to the embodiment of the present invention;
and
FIGS. 3 and 4 respectively represent a sectional view of a catheter
guide wire on which a coil spring is mounted according to another
embodiment of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the present invention will be described
with reference to the accompanying drawings.
FIG. 1 is a sectional view of a catheter guide wire taken along the
longitudinal direction according to an embodiment of the present
invention. Referring to FIG. 1, reference numeral 1 denotes a core
member; and 2, a thermoplastic resin layer entirely covering core
member 1.
Core member 1 is a wire member made of an elastic alloy wire such
as a piano wire, and preferably a very elastic alloy such as an
Ni-Ti alloy. Core member 1 can have a uniform diameter of 0.2 to
0.4 mm, or can be tapered toward its distal end such that the
diameter at its proximal end portion is 0.2 to 0.4 mm and the
diameter at its distal end portion is 0.01 to 0.1 mm. In this
specification, a very elastic alloy is defined as an alloy whose
recoverable elastic strain is as large as several % to more than
ten % and whose stress level does not exceed a predetermined value
even if the strain is increased. The very elastic alloy generally
comprises an Ni-Ti, Cu-Zn-Al, Cu-Al-Ni, or Fe-Mn alloy. If an Ni-Ti
alloy is employed, it preferably contains 49 to 58 atm. % of Ni and
a balance of Ti, and more preferably 49 to 51 atm. % of Ni and a
balance of Ti. If a Cu-Zn-Al alloy is employed, it preferably
contains 38.5 to 41.5 wt. % of Zn, 1 to 10 wt. % of ADP, and a
balance of Cu. If a Cu-Al-Ni alloy is employed, it preferably
contains 14 to 14.5 wt. % of Al, 3 to 4.5 wt. % of Ni, and a
balance of Cu. If an Fe-Mn alloy is employed, it preferably
contains 28 to 32 wt. % of Mn, 6 wt. % of Si, and a balance of Fe.
A heat treatment is performed by changing the treatment conditions.
As a result, the guide wire can have the following physical
characteristics in its areas (1) to (III) as shown in FIG. 1.
(1) Proximal end portion (I)
When the guide wire is guided from, e.g., a straight great blood
vessel (e.g., a descending aorta) to an arteriole (e.g., a coronary
artery), proximal end a comparatively small number of bent
portions. Proximal and portion (I) has a comparatively high
rigidity and is difficult to deform. Therefore, forward/backward
movement and rotation externally applied to the catheter can be
easily transmitted to the distal end portion (II--III) through a
blood vessel retaining an introducer (not shown).
(2) Intermediate portion (II)
Intermediate portion (II) has an elasticity so that it can easily
follow a blood vessel curve of a comparatively large curve and can
return to its initial shape when deformation caused by the curve is
removed. Although it is flexible, intermediate portion (II) hardly
attains a bending tendency and is difficult to break.
(3) Distal end portion (III)
When distal end portion (III) is inserted in a small, curved blood
vessel, it can easily follow the blood vessel shape due to its
flexibility, and thus will not damage the blood vessel wall. When a
blood vessel has phatologic factor such as arteriosclerosis, the
flexibility of distal end portion (III) is important.
Thermoplastic resin layer 2 is provided as needed in order to
protect the inner surface of the blood vessel, to prevent formation
of thrombus on an outer surface of the guide wire during operation
of the guide wire, and not to form a difference in outer diameter
between the proxital end portion and the distal end portion. For
example, saturated aliphatic polyether urethane is used to form
layer 2. A contrast medium can be mixed in the thermoplastic resin
in advance in order to increase the contrast of the guide wire
through X-ray photographing. For example, 40 to 600 parts by weight
(with respect to 100 parts by weight of thermoplastic resin) of a
tungsten powder can be mixed as the contrast medium. Note that
saturated aliphatic polyether polyurethane is favorable for
compounding of tungsten.
FIG. 2 shows the physical characteristics (strain-stress curve) at
the respective portions of the core member of the present invention
after a heat treatment. A heat treatment can be performed in an
atmosphere of an inert gas (Ar or He), vacuum (.times.10-2 Torr or
less) or outer atmosphere. Although a heat treatment can be
performed in an outer atmosphere, it is preferably performed in a
vacuum in view of embrittlement of the material, and more
preferably in an inert gas. The values in FIG. 2 are obtained by
cutting the core member sample into 70-mm long pieces starting from
its distal end and subjecting the respective samples to a tension
test.
Core member: Ni-Ti alloy wire (diameter: 0.4 mm) (49 atm. % of Ni
and a balance of Ti)
Heat treatment conditions:
______________________________________ Tension Area of Test Guide
Wire Heat Treatment Conditions Sample No.
______________________________________ Distal end About 2 hrs. at
400 to 500.degree. C. (1) (2) portion (III) and about 24 hrs. at
200.degree. C. (in outer atmosphere) Intermediate About 2 hrs. at
400 to 500.degree. C. (3) (4) (5) portion (II) (in outer
atmosphere) Proximal end No heat treatment after (6) portion (I)
cold rolling ______________________________________
The physical characteristics at the respective portions of core
member 1 are not limited to those shown in FIG. 2 and can be
arbitrarily adjusted and selected in accordance with specific
applications.
FIG. 3 is a partial sectional view of a catheter guide wire
according to another embodiment of the present invention.
Thermoplastic resin layer 2 is formed on the entire surface of core
member 1 in the same manner as in FIG. 1, and coil spring 3 having
a thickness of 0.08 mm is mounted on an outer surface of resin
layer 2 excluding its leading and trailing end faces. Note that
coil spring 3 may be provided at only the distal end portion of the
guide wire. The outer diameter of the guide wire may be
conveniently selected to conform with the inner diameter of a blood
vessel to be inserted. Generally, however, the outer diameter of
the guide wire may be selected within a range of from 0.2 to 2.0
mm.
When coil spring 3 is applied on resin layer 2 in this manner, the
physical characteristics of the guide wire are as flexible at its
distal end portion as shown in FIG. 1 and highly resistive to
buckling deformation due to the high flexibility of the coil spring
3, relatively high in rigidity at its proximal end portion and
excellent in X-ray photographing.
Coil spring 3 can be provided to directly surround core member 1
without intervening thermoplastic resin layer 2.
FIG. 4 shows an example of such a structure of the guide wire,
wherein the coil spring 3 is directly wound around the outer wall
of core member 1, with its distal and proximal end portions being
fixed to core member 1 through a soldering material 4 made for
example of Sn-Ag (96:4) alloy.
As described above, according to the catheter guide wire of the
present invention, a wire member made of an elastic alloy is used
as a core member and subjected to a heat treatment by sequentially
changing the treatment conditions along its longitudinal direction.
As a result, the proximal end portion of the guide wire has
predetermined rigidity required in accordance with its application,
and its distal end portion has predetermined flexibility.
Industrial Application
The guide wire as proposed by this invention is useful for guiding
a clinical or testing catheter to a predetermined portion of a body
cavity such as blood vessel, a digestive tract and a windpipe, and
holding it therein for a period of time.
* * * * *