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John Cummings
02-04-1997, 11:41 PM
On 1/24 I wrote:

I trying to locate a material to make casts of vascular structures.
I've seen some used in the past; one is more latex-like, the other
more acrylic-like. Ideally they should have viscosities that are
similar to blood so extreme pressures don't distort the geometry.
Also a protocol for digestion of the tissue that reveals the vascular
structure would be of help. I've seen pictures of a vascular network
cast placed over the bones of a joint, and would like to be able to
something similar.

Thanks to all who replied!
A summary of replies follows:

REPLY #1 -----------------------------------------------------------

I don't know the name or source of this material, but one of my former
teachers, Dr. Michael LaBarbera at The University of Chicago uses it
regularly. You can reach him at mlabarbe@midway.uchicago.edu

sharon swartz

************************************************** ****
Sharon Swartz
Department of Ecology and Evolutionary Biology Box G-B206
Brown University
Providence, RI 02912
USA

phone: 401-863-1582 (office)
401-863-3549 (lab)
401-863-7544 (fax)

e-mail: sharon_swartz@brown.edu
************************************************** ****

REPLY #2 -----------------------------------------------------------

Hi:

One of the team of the University of Washington Engineered
Biomaterials (UWEB) program (J&J is a member) has developed what I
believe to be an
excellent protocol to do want you want. I'll put you in
touch by e-mail with Professor Karyn Kunzelman for details. If you'd
like to learn more about UWEB, e-mail me and I'll send you some
literature.

Buddy Ratner
University of Washington

Karyn Kunzelman replied:

Yes, we have done this in our laboratory, and Jane Grande is one of my
students who has had the most experience with this. We used a
silicone based resin to cast the structures, then dissolved the tissue
away with bleach. I mentioned your request to her, and she told me
that she had e-mailed some information to you. If you have not
received the specs on the silicone, etc., from Jane please let me
know. In addition, I would be happy to talk to you and provide futher
info, as I have done it here and in another lab in Dallas with a
different product.

Jane Grande's reply follows immediately:

REPLY #3 -----------------------------------------------------------

Hello,

I have used silicone rubber to create vascular casts. The type I used
was GE Silicones RTV-11 which is quite viscous but can be diluted with
silicone oil to make it easier to handle. The cure time for the
silicone rubber was about 4 hours although this may vary with the
amount of oil you add. In the past we have used generic bleach to
dissolve the tissue surrounding the casts.

Good luck!
Jane Grande
__________________________________________________ _______________
Jane Grande
--grande@u.washington.edu--http://weber.u.washington.edu/~grande
Bioengineering Doctoral Student, University of Washington
206-543-3159 off Cardiothoracic Surgery, Box 356310, Seattle WA
98195-6310 206-543-0325 fax

Never let your sense of morals prevent you from doing what is right!
- Salvor Hardin (Isaac Asimov)


REPLY #4 -----------------------------------------------------------

There are silicone dental impression materials that can be purchased
in a syringe type application system. These are fairly low viscosity
for silicone materials. Unfortunately, I do not know the name of the
manufacturer of this material. I would guess that the diameter of the
vien will be the limiting factor for the viscosity in terms of
distortion of the viens.

You could formulate a low viscosity silicone and put some TiO2 filler
in it to make it opaque if one of the commercial formulations is
unsuitable. Contact me if you need help with formulating a suitable
material.

Hank Oviatt

POSTER'S COMMENTS:
I've tried dental impression materials manufactured by Kerr [Mfg (313)
946-7800, Eng (800) 537-7824], and purchased through our local dental
or vet supply house. I comes in four viscosities (Wash, Medium,
Heavy, and Putty). I have found them great: they set up fast, capture
very fine detail, and do not have to be degassed. However, for my
application the set-up is a little too fast and the viscosity of the
wash is still a little high.

REPLY #5 -----------------------------------------------------------

John,

I've had pretty good luck making vascular casts using the standard
Batson's #17 corrosion casting compound (acrylic). Its made by
Analychem and distributed by Polysciences or vice versa - if you need
more exact information, I can
look it up for you. Its more viscous than blood, but rather than using
extreme pressures and distorting the geometry, I use mean physiological
pressure but don't get all the small sub-branches (I get nice casts in
rabbit tissues down
to quite a bit less than 1mm diameter though, so depending on what
you're after, that might be adequate). I believe
there are other versions of Batson's which are more/less viscous.

You might try a literature search for work by Fred Cornhill and also
Margo Roach who have done a lot of work
in this field--if you can't find anything and are interested, I can
probably dig up the references for you.

As for tissue digestion, once you have polymerized your casting
material in situ, cut out the cast (including surrounding tissue as
necessary) and just leave it all in a 20% solution
of KOH overnight--the KOH will dissolve away the tissue leaving your
cast intact.

Good luck!

Jennifer Moore
Department of Mechanical Engineering University of Toronto
Toronto, Canada
mooreja@me.utoronto.ca

POSTER'S COMMENTS: The dental casting materials mentioned earlier
(polyvinylsiloxane) seem to be only semi compatable with tissue
digestion in KOH. The surface can be left soft and tacky.

REPLY #6 -----------------------------------------------------------

Dear sir,

In reply to your question on casting of cardiovascular struc- tures,
we contacted our colleagues of anatomy. They are using two techniques:

1. Solution of:
Araldite F 8 ml
.6 g Microlith-T (colour choice green, blew, black, yellow and brown)
24 ml Dilutioner DY 026 SP
18 ml Hardener HY 2967
These materials can be obtained from Ciba Geigy.

2. Silicon technique:
Elastosil M 4601 A 9 parts
Elastosil M 4601 B 1 part
Colour pigment Fl D Red or blew 0.5-2%
These materials are obtained from a local Dutch Company


C.M.Ligtvoet
Biomedical Engineering Department
University Hospital Utrecht
The Netherlands

send by:
L.J. van Schelven
University Hospital Utrecht
Biomedical Engineering Department
F 01.125
P.O. Box 85500
NL-3508 GA Utrecht
The Netherlands

tel. +31 30 2506198
fax. +31 30 2542002


Thanks again to all those who replied!
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John F. Cummings
Ethicon Endo-Surgery JCumming@EESUS.JNJ.COM
4545 Creek Rd. V: (513) 483-3370
Cincinnati, OH 45242 F: (513) 483-8285
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