Sixth Annual Report Of The Dow Corning Center For Aid To Medical Research

Since 1959 the use of silicone foam and rubber in prosthetic applications has increased significantly. Moreover, the medical and surgical applications of the silicones have been continuously expanding.

For these reasons it is believed that readers of the Inter-Clinic Information Bulletin will find this Annual Report of interest. It is reprinted here by permission of the Dow-Corning Center for Aid to Medical Research.

September 1, 1965

Sixth Anual Report of the Dow Corning Cernter for Aid to Medical Research

In thinking about the past six years of operation of the Dow Corning Center for Aid to Medical Research, it is apparent our original objectives still hold, so that a review of our history might be in order for those who have come to us lately.

In 1958, the Dow Corning Corporation found itself in a dilemma. It was recognized that the medical profession had need of the silicones which the Corporation manufactured, but it was felt that sales of these very specialized items would be so miniscule as to make it impossible to handle them as industrial products. At the same time, it was recognized that there was an inherent social obligation in having materials that were needed so badly by the general public. To resolve this, the Board of Directors decided to set up a special organization within the Research Department of the Corporation, and in August, 1959, the Dow Corning Center for Aid to Medical Research was organized. As the original objectives stated, the Center would "...serve the medical profession on a non-profit basis by:

  1. providing technical aid in the use of silicones in medicine and surgery

  2. acting as a clearing house for information about the medical uses of silicones

  3. cooperating in research in or-ganosilicon chemistry in relation to the human body."

Somewhat to our surprise, these efforts resulted in a modest demand for some of the specialized items we helped develop, and in 1962, the Dow Corning Corporation formed the Medical Products Division to manufacture and sell such materials. This was a welcome development, since for the first time the doctor was ensured of a continuing supply of the items on which he had worked.

The objectives of the Center have remained the same, however. We have continued to work with the medical profession on an academic basis, and commercial aspects are not the deciding factor in our attempts to supply information and material.

In fulfilling our obligations during the past year, for instance, we have answered close to 5,000 letters received from medically-oriented persons all over the world; some 218 visitors came to Midland to discuss their problems with us.

Our work continues to be of a varied and fascinating nature. The use of silicone fluids for soft tissue augmentation continues to show promise, and an IND for this purpose now allows limited clinical testing by the authorized investigators.

Artificial heart investigations are growing in numbers and in depth. In fact, this complex area of research is expanding so rapidly that it is becoming very difficult for us to service all the requests to the degree we would like. Some 25 research groups have contacted us in relation to this problem alone. The recent NHI feasibility contracts have stimulated interest by others, also.

We continue to work on many other new areas as well as to improve old ones. Some of the more active and interesting are:

  1. Corneal implants for lamellar keratoplasty

  2. Artificial heart valves

  3. Intervertebral disc replacement

  4. Artificial tendons

  5. Improved soft tissue replacements for plastic surgery

  6. Surgical repair of nerves

  7. Detached retina repair

  8. Blood oxygenators.

There are, of course, many other new concepts and developments. It continues to be a matter of deep satisfaction to us to be able to contribute to some of the tremendous advancements now being made in the field of medicine.

We continue to receive requests for information relative to the properties and methods of handling the various silicone materials. The information sheets we prepared on these subjects some years ago have been revised, and the new listing is at the end of this report. They are available upon request.

Respectfully submitted, Silas Braley, Director

Information Sheets Available From Dow Corning Center For Aid To Medical Research

Heat-Vulcanizing, Medical Grade Silicone Elastomers : The chemistry of Silastic(R) heat-vulcanizing silicone rubbers is discussed in a general manner. Various stocks that are available for medical use are described, as well as fabrication processes for making useful shapes from the puttylike raw silicone rubber.

Room-Temperature-Vulcanizing (RTV) Medical Grade Silicone Elastomers: The Silastic® RTV medical grade silicone elastomers are initially thick liquid materials that vulcanize at room temperature within a short time after the catalyst is added. RTV materials are used where heat cannot be tolerated. The chemistry of the room-temperature-vulcanizing silicone rubbers is described in a general manner. The RTV materials used in medical applications are described, and general instructions for their use given.

Comparison of Implantable Medical Grade Silicone Elastomers: This is a table that summarizes the properties of the Silastic® silicone elastomers that are commonly used in medical applications. It compares the room-temperature-vulcanizing silicone rubbers to the heat-vulcanizing types.

Gas Transmission Rates of Plastic Films: Silicone rubber shows an oxygen, carbon dioxide and water vapor diffusion rate very much higher than other films. This table compares the rate of diffusion of silicone rubber with eleven plastic films.

Silicone Coating Resins Used in Medicine: Metal parts in medical usage are sometimes coated with a silicone resin to keep the blood and tissues from contact with them. Means of applying and removing the resins are given.

Siliconizing Surfaces: Silicone coatings on surfaces delay the clotting of blood and make the surfaces non-wetting. This paper indicates the optimum procedure for siliconizing various surfaces such as glass, plastics and metal.

Silicone Defoamers in Blood Oxygenators: There is need for eliminating the bubbles in the blood in heart-lung machines. Advantages and disadvantages of using silicone antifoams and methods of application are discussed.

® — Silastic is the registered trademark of Dow Corning for its brand of silicone rubber.