Dialysis refers to the separation of larger particles from smaller ones through a membrane that is selectively permeable. The artificial kidney machine is usually the device that accomplishes dialysis of human blood. A tube is used to connect the kidney machine to the patient's radial artery. Blood leaves the artery and enters the machine where it flows to one side of a selectively permeable membrane made out of cellulose acetate. The other side of the membrane is bathed with an artificial fluid called di alysate.
The dialysate has the same electrolyte concentration as normal plasma. Any excess electrolytes in the patient's blood move through the selectively permeable membrane, much the way normal diffusion occurs. Waste materials from the blood, such as urea, also diffuse into the dialysate. Blood proteins and blood cells are too large to filter across the membrane so they remain in the blood. Since only about 500 ml of blood is cleansed at once time, a single dialysis session can last from 4 to 6 hours. Dialysis is normally performed three times weekly.
Disadvantages to this type of dialysis are that it is time-consuming and anticoagulants must be added to the patient's blood to keep it flowing.
Another form of hemodialysis has recently been developed. Continuous ambulatory peritoneal dialysis employs the peritoneum as the selectively permeable membrane. A catheter connects the individual's peritoneal cavity with a bag of dialysis solution. The solution enters the peritoneal cavity by gravity, and exchange occurs between the blood and dialysate. When finished, the fluid is removed from the peritoneal cavity and discarded. The advantage of this method is that is allows the person to complete the dialysis process at home during sleeping hours. A drawback is the danger of infection.
Evidence is mounting to suggest that high fiber diets reduce the incidence of colon cancer and possibly breast cancer.
This works as follows:
A diet high in fat but low in fiber is correlated with increased risks of colon cancer and breast cancer in women. Individuals who are normal in weight, consume greater amounts of fiber, and reduce their fat intake to less than 30% of their daily calories reduce their risks.
Fiber in the diet helps materials move through the digestive tract. Without fiber, intestinal contents become compacted and are not defecated daily. Toxic by-products of metabolism and in undigested foods accumulate in the intestines, exposing the intestinal wall to mutagenic compounds. Over time, these mutagens can trigger mutations in DNA and cell growth can become uncontrolled, producing a malignant tumor.
In women, wheat bran has the additional benefit of binding very tightly to estrogen in the digestive tract. Excess estrogen is then removed during defecation. One form of estrogen, the C-16 form, is dangerous because it triggers the growth of breast cells when no growth is necessary (such as it is during puberty). Interestingly enough, American women have higher levels of estrogen, and thus denser breasts, than Asian women as a group. Asian women eat more fiber and less fat. Removal of excess estrogen is one easy way women can help reduce their risk of breast cancer. Others are to keep body weight within a normal range for height, reduce intake of dietary fats, and exercise regularly.
The newest recommendation from the U.S. National Cancer Institute is for Americans to eat five fruits and vegetables per day. The "5 A Day for Better Health Program" encourages people to eat more fruits and vegetables, which increases fiber and replaces more fat-laden foods. Other ways to increase fiber are to add the following items to the diet: popcorn, beans, bran cereals, whole wheat breads, fruits with skins, and corn.