Drug – bio-affecting and body treating compositions – Whole live micro-organism – cell – or virus containing – Genetically modified micro-organism – cell – or virus
Reexamination Certificate
1999-05-26
2004-01-06
McDermott, Corrine (Department: 3738)
Drug, bio-affecting and body treating compositions
Whole live micro-organism, cell, or virus containing
Genetically modified micro-organism, cell, or virus
C623S023650, C623S915000, C435S401000
Reexamination Certificate
active
06673339
ABSTRACT:
BACKGROUND
1. Field of the Invention
The invention is directed to a prosthetic kidney, to methods of making the prosthetic kidney and to methods of treating kidney disease with the prosthetic kidney.
2. Description of the Background
The kidneys remove metabolic wastes from the blood, control fluid balance by maintaining homeostasis, and provide important regulatory activities by secreting hormones. Normally about 20% of the blood pumped by the heart is treated by the kidneys.
Nephrons, the functional unit of the kidneys, treat blood by three processes: filtration, reabsorption, and secretion. Each kidney contains about one million nephrons, each consisting of a renal corpuscle and a renal tubule. The shape of a nephron resembles a miniature funnel with a very long convoluted stem. Blood enters the renal corpuscle, through the glomerulus. The filtrate from the blood enters the glomerular capsule, also called Bowman's capsule, and flows through the renal tubule. The renal tubule comprises four parts, the proximal convoluted tubule, the loop of Henle, the distal convoluted tubule and the collecting tubule.
The renal corpuscle comprises a tangled cluster of blood capillaries called a glomerulus which is about 200 microns in diameter surrounded by a thin walled saclike structure called a glomerular capsule. Blood enters and exits the glomerulus through the afferent and the efferent arteriole. While in the glomerulus, blood pressure causes water and various dissolved substances to be filtered out to the glomerular capillaries into the glomerular capsule as glomerular filtrate.
The relative concentration of some of the substances in plasma, glomerular filtrate and urine is shown in Table I and Table II. These values may vary depending on many factors such as fluid consumption, medication, age, diet, health and kidney function of the patient.
TABLE I
Glomerular
Plasma
Filtrate
Urine
Substance
(mEq/l)
(mEq/l)
(mEq/l)
Sodium
142
142
128
Potassium
5
5
60
Calcium
4
4
5
Magnesium
3
3
15
Chlorine
103
103
134
Bicarbonate
27
27
14
Sulfate
1
1
33
Phosphate
2
2
40
TABLE II
Plasma
Glomerular Filtrate
Urine
Substance
(mg/100 ml)
(mg/100 ml)
(mg/100 ml)
Glucose
100
100
0
Urea
26
26
1820
Uric Acid
4
4
53
Creatinine
1
1
196
The total rate of glomerular filtration typically is about 180 liters per day per person. Most of this volume is returned to the bloodstream via the process of reabsorption. Reabsorption is the movement of substances out of the renal tubules into the blood. Substances reabsorbed comprise water, glucose and other nutrients, sodium and other ions. Reabsorption begins in the proximal convoluted tubules and continues in the loop of Henle, distal convoluted tubules and collecting tubules.
Secretion is the process by which substances and fluids move into the distal and collecting tubules from blood in the capillaries around these tubules. Substances secreted are hydrogen ions, potassium ions, ammonia, and certain drugs. Kidney tubule secretion plays a crucial role in maintaining the body's acid/base balance.
Homeostasis is maintained by the body by specialized hormones which affect the functions of the kidneys. The pituitary hormone ADH (antidiuretic hormone) decreases the amount of urine produced by making distal and collecting tubules permeable to water. Aldosterone, secreted by the adrenal gland controls the kidney tubules reabsorption of salt and other electrolytes. Primarily, aldosterone stimulates the tubules to reabsorb sodium at a faster rate.
While hormones affect kidney function, the kidneys also produce hormones to regulate the function of other organs. Erythropoietin is a hormone secreted by the kidney cells to regulate the rate of red blood cell formation. Renin, a second hormone secreted by the kidneys regulates blood pressure. In addition, the kidneys activate vitamin D, which is involved in skeletal integrity.
To summarize, blood is treated and urine is formed as a result of glomerular filtration of blood plasma, tubular reabsorption and tubular secretion. In tubular reabsorption, substances such as glucose, amino acids, proteins, creatine, lactic acid, citric acid, uric acid, ascorbic acid, phosphate ions, sulfate ion, calcium, potassium ions, sodium ions water and urea are reabsorbed. In tubular secretion, penicillin, creatinine, histamine, phenobarbital, hydrogen ions, ammonia, and potassium are secreted.
When both kidneys in a patient fail, the blood pressure may rise, fluid may collect in the body, waste levels may build up to a harmful level in the blood and red blood cell production may be reduced. When this happens, treatment is needed to replace the function of the failed kidneys. Treatments for renal dysfunction include hemodialysis, peritoneal dialysis, and kidney transplants.
Hemodialysis is a treatment procedure that cleans and filters the blood of a patient with renal inadequacy. The treatment procedure reduces the levels of harmful wastes, extra salt and fluids. Hemodialysis also helps control blood pressure and maintains the proper balance of chemicals such as potassium, sodium, and chloride in the body.
Hemodialysis uses a dialyzer, or special filter, to treat blood. During treatment, blood from a patient travels through tubes into an external dialyzer. The dialyzer filters out wastes and extra fluids and returns the newly cleaned blood into the body. A typical treatment regimen may comprise three hemodialysis treatments per week for two to four hours each time. During treatment, mobility is limited, but a patient can engage in activities which do not require excessive movements such as reading and writing.
The disadvantages of hemodialysis include side effects and complications caused by rapid changes in the patient's body fluid and chemical balance during treatment. Muscle cramps and hypotension are two common side effects. Hypotension, a sudden drop in blood pressure, may cause extreme weakness and dizziness.
It usually takes a few months for a patient to adjust to the side effects of hemodialysis. Side effects may be reduced by strict adherence to the proper diet and the consumption of medicines as directed. A proper diet helps to reduce the wastes that build up in a patient's blood and reduces the load of the kidney. A dietitian is needed to help plan meals according to a physician's instructions.
Further disadvantages of hemodialysis include high cost and frequent and lengthy travel to a dialysis center. An alternative to dialysis centers is home dialysis. A helper is required for home dialysis and both the patient and the helper require special training. In addition, space is required for storing the machine and supplies at home.
Peritoneal dialysis uses the patient's abdomen lining, the peritoneal membrane, to filter blood. A cleansing solution, called dialysate, travels through a special tube into the patient's abdomen. Fluid, wastes, and chemicals pass from tiny blood vessels in the peritoneal membrane into the dialysate. After several hours, the dialysate is drained from the abdomen, taking the wastes from the blood with it. The abdomen is then filled with fresh dialysate and the cleaning process begins again.
The dialysis procedure involves various degrees of difficulties and significant treatment times. While treatment regimens vary, they generally pose significant inconveniences. Typical treatment regimen may comprise, for example, thirty to forty minutes every four to six hours, ten to twelve hours every night, thirty-six to forty-two hours per week, or 24 hour treatment sessions. In addition, special reduced calorie, potassium restricted diets are required in addition to dialysis.
Possible complications of peritoneal dialysis include peritonitis, or infection of the peritoneum. The procedure of peritoneal dialysis comprises many steps where pathogens such as bacteria may be introduced into the body. Symptoms of peritonitis include inflammation, exudations of serum fibrin cells and pus, nausea, dizziness, fever, abdominal pain, tenderness, constipation and vomiting. To avoid peritonitis, care is needed
Ashkar Samy
Atala Anthony
Yoo James J.
Children's Medical Center Corporation
Engellenner Thomas
McDermott Corrine
Nutter & McClennen & Fish LLP
Pellegrino Brian E
LandOfFree
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