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Biomedical engineering

Versatile rubber

Latex is a raw material used in the control of obesity and in products used by diabetics

Fapesp1daniel das nevesFrom the latex extracted from Amazonian rubber trees researchers from the University of Brasília (UnB) are developing new products for the health area, aimed mainly at diabetic patients. “This is a raw material that’s easy to handle and cheap, because a liter of latex costs around R$17,” says Professor Suélia Rodrigues Fleury Rosa, from the Engineering and Innovation Laboratory at UnB, Gama Campus, some 30 km. from the federal capital and the research coordinator. The first project developed by the group is an esophageal prosthesis for controlling obesity and Type 2 diabetes. “This is a biocompatible and flexible device, the function of which is to control the ingestion of food by reducing the diameter of the esophagus, an organ that functions like a connecting tube between the pharynx and stomach,” says Suélia. When it is inserted in the esophagus by endoscopy, the device, which can be used for up to 10 days, resists the passage of food, making ingestion slower due to the need for prolonged chewing. “This effect on chewing influences the mechanisms that unleash the feeling of being satiated and helps reduce the food eaten by obese patients, leading to weight loss and improved glycemic levels,” says Suélia.

In experimental tests carried out on dogs, comparable endoscopies done before placing the module in the esophagus and after removing the device, which remained in the organism between 7 and 15 days, showed that the whole area of the organ remained unaltered in any way.

Currently, in addition to bariatric surgery – stomach reduction, which is the last recourse against extreme obesity, but one that imposes a series of limitations on patients – other forms of treatment exist, also classified as surgical and less radical. These are the so-called restrictive techniques, like the adjustable gastric band and the intragastric balloon, which are similar to the module created at UnB, called the esophageal flow controller (EFC). The main difference between them is where they are located, because the two devices that are in use act by compressing the stomach.

The adjustable gastric band consists of a silicone tape placed around the upper part of the stomach. The band is subsequently inflated, leading to a narrowing of the organ, which reduces its capacity by around 30 milliliters, which in turn restricts the volume of food ingested. “This technique is indicated for patients who are not too obese, since the weight loss is around 20%; for people who don’t like sweets and alcohol,” says Suélia. “Among the post-surgical complications are dilation of the esophagus because of difficulty in emptying the organ, total obstruction of the stomach and infection because of contact with digestive liquid.”  The other technique is the intragastric balloon, a spherical silicone prosthesis introduced via the mouth and placed in the stomach. It is a useful technique for curbing the ingestion of food that is syrupy or solid, but not liquid. “Alcoholic drinks and other liquids that are high in calories are well tolerated and when used compulsively become the cause of the failure of this method to achieve any weight loss,”  emphasizes the researcher. The UnB device is shaped like a cylindrical balloon, eight-centimeters long, with a smooth inner surface and an undulating outer surface with grooves. The deflated balloon is applied by endoscopy to the upper part of the organ. After it has been placed in the correct position it is inflated with oxygen. “The objective of the treatment is that the patient learns to chew and eat correctly with the help of a speech therapist, specialist doctors and psychologists,” says Suélia. The EFC development project, which began to take shape in 2006, when Suélia was doing her PhD, received the Santander Entrepreneurship, Science and Innovation Prize in 2008 and the Young Inventor Prize from the Federal District Research Foundation in 2009. The idea came from observing that people with obstructive pathologies of the esophagus, like a lower esophageal ring and esophageal membranes lose a lot of weight, but do not suffer from malnutrition.

Innovative method
“My mentor was Professor Fátima Mrué, from the Federal University of Goiás (UFG), who since 1994 has been studying latex,” says Suélia. With Professor Joaquim Coutinho Netto, from the Riberao Preto School of Medicine  of the University of São Paulo, Fátima developed a latex-based biomembrane, used as a dressing for chronic wounds (read more about this subject in issue 88 of Pesquisa FAPESP ), launched commercially under the name of Biocure by Pele Nova Biotecnologia. For developing the esophageal prosthesis, the researcher received guidance and advice from professors Adson Ferreira da Rocha, at the School of Technology at UnB, and José da Conceição Carvalho, at the School of Medicine of UFG.

The next step in the project consists of testing the prosthesis on five volunteers for a period of 10 days. “The expected weight loss is around a kilo a day,” says Suélia. “The study with a small group is due to the innovation of the method and also so that any issues referring to the methodology, risks and discomfort can be treated with a greater degree of safety.” The request to test volunteers is being evaluated by the Ethics and Research Committee from the Federal University of Goiás, where the tests will be done, and by the National Ethics in Research Commission (Conep), which is linked to the Ministry of Health. “The human test phase is likely to last for almost a year and a half,”  she says. After this, if all goes according to plan, the researcher intends to establish a partnership with a company for manufacturing the product.

Latex was also the raw material chosen for use in manufacturing the insole that controls the pressure of the tread in diabetics, as a way of guarding against future amputations. “When a diabetic treads incorrectly, because of bad circulation in the feet, sores begin to appear at some more sensitive points, which end up evolving to the loss of toes, or even part of the foot,” says Suélia. The insole will contain a low-cost electronic circuit that will monitor the tread of the patients. “This control will make it possible to carry out precise physiotherapy so that the sore does not evolve,” she reports. It will also be possible to include chemical products in its composition that will help in the regeneration of tissue. Another possibility that is being studied is to place a low frequency laser on the item to help with the regeneration of damaged tissue. A patent has already been deposited for the insole and is being analyzed by the university’s ethics committee for testing on people.

In a third project the latex, after it has been dried in an oven and submitted to vulcanization, is used to make an intelligent mattress, for people who spend long periods of time lying down, such as diabetics, people in intensive care units and hospitalized newborns, as a way of avoiding bedsores. What is different about this mattress is that the innerspring sections will be inflated and deflated automatically by an internal pre-programmed circuit. “The objective is to distribute the pressure evenly, but not continuously,” says Suélia. A small-scale mattress is being tested by the team of researchers to evaluate the timespan which a particular point on the skin can withstand pressure, how long it can stand the pressure for, and other parameters. Based on this information the mattress will be designed in accordance with the needs of each patient. The three studies form part of a project called Bioenglatex – the development of  latex devices applied to medicine.