Definitions

Acinar. Pertaining to the grape-shaped secretory portions of a gland.

Adipose tissue. Fat-containing tissue found generally under the skin.

Alginate. A polysaccharide carbohydrate of mannuronic and guluronic acids derived from seaweed. The sodium salt is liquid, and gels in the presence of calcium. Used by ISM and as the bulk polymer in the thin sheet.

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Allele. Any one of a series of two or more different genes that may occupy the same position on a specific chromosome.

Allogenic. Pertaining to different gene constitutions within the same species.

Allograft. A transplant between individuals of the same species (see autograft and xenograft) e.g. two unrelated humans, or between siblings.

Transplants between closely related (syngeneic) strains of the same species are closer to autografts. Most transplants in humans are allografts (e.g. kidney from a cadaver doner or from a living related donor). The best model for human allograft is an allograft in a higher mammal such as a dog or a monkey. (Allografts in mice are different from allografts in higher mammals and succeed under conditions that would fail in a dog.)

Amino acid. An organic acid with an amino group, normally on the alpha carbon; the building blocks of proteins.

Antibody. An immune or protective protein that reacts specifically with an antigen. Made by B-lymphocytes.

Antigen. Any substance that stimulates the immune response, especially the antibody response.

Antigenic. Pertaining to the degree to which a substance that acts as an antigen in an individual.

Antiserum. Serum taken from an animal that has been immunized; mixture of several antibodies. A single antigen will normally stimulate several different B-lymphocyte clones.

Anti-islet antibody. An antibody against antigens found on the surface of islet cells.

Anti-insulin antibody. An antibody against insulin.

Anti-lymphocyte serum (ALS). Antiserum against lymphocytes; may be used to kill lymphocytes and temporarily make an individual more tolerant of a transplant.

Atherosclerosis. Progressive decay of the lining of arteries.

Athymic. Without a thymus. The thymus gland in the neck is the site for maturation of T-cells.

Athymic (nude) mouse. An inbred strain of mouse with a poorly functioning immune system that does not reject tissue. Useful as a "test tube" for growing human tissue.

Autograft. A transplant between genetically identical individuals of the same species (see allograft and xenograft) e.g. two identical twins, or between members of inbred strains of laboratory animals who are virtually genetically identical.

Autoimmune. Attack of self antigens by the immune system. Related to diseases, including rheumatoid arthritis, lupus, and IDDM.

Autotransplants. Transplantation of tissue from self or from an identical twin. Autotransplants are not rejected because the tissue type is identical.

Beta Cell. A cell that secretes insulin found in the islets of Langerhans.

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Bio-Artificial Pancreas. An implantable medical device that secretes insulin in response to glucose made from islets of Langerhans and a polymer matrix to protect the living islets.

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Biocompatible. Compatible with living tissue.

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Bioengineered cell. Any cell that has had its genetic properties altered with the goal of making the cell useful.

Bioincompatible. Incompatible with living tissue. Usually manifests through fibrosis.

Blood glucose / blood sugar. Concentration of the sugar glucose in the blood. The normal level is 5 mM (80 mg/dL); elevated blood sugar is the definition of diabetes.

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B-lymphocyte. A white blood cell that specializes in producing antibodies. Sometimes called a B-cell (not to be confused with a beta cell, also sometimes called a B cell).

Cell Line. A cell that can grow through many division and retain useful properties. May have been modified by genetic engineering.

Chromosome. One of the bodies in the cell nucleus that is the bearer of genes. There are normally 46 in man.

Collagen. The major protein of the white fibers of collective tissue, cartilage, and bone. Important in fibrosis.

Collagenase. An enzyme that catalyzes the hydrolysis of collagen.

Creatinine. A component of urine and the final product of creatine catabolism.

Cryopreservation. Preservation with extreme cold, usually liquid nitrogen.

Cushingoid. Resembling the signs and symptoms of Cushing's disease or syndrome, obesity, moon face, acne.

Cyclosporin. A fungal metabolite that selectively inhibits T-helper lymphocyte cells.

Cytology. The study of cells.

Cytoplasm. The substance of a cell exclusive of the nucleus.

C-peptide. A protein produced in beta cells as a byproduct of insulin manufacture. Measured to determine beta cell viability and activity.

Dendritic cell. A specialized lymphoid cell related to the macrophage found in many tissues. Has some role in immune surveillance.

Diabetes. Abnormally elevated blood sugar. "Diabetes" was first used in medicine to describe patients with voluminous urine production. Patients with "a diabetes" appeared to drink large volumes of water and pass it immediately into urine. Diabetes now refers exclusively to diabetes mellitus, a form of diabetes in which the urine is sweet (mellitus means "honey"). With the discovery that patients with diabetes (sugary urine) always had elevated blood sugar, the disease was redefined in terms of blood sugar, measured either fasting or during the period following a meal. Thus diabetes is abnormally elevated blood sugar.

Diabetes is divided into type I or insulin-dependent diabetes mellitus (IDDM) which requires insulin to prevent ketosis, and type II or non-insulin-dependent diabetes mellitus (NIDDM) which does not require insulin to prevent ketosis.

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Diabetes Physiology. The interplay between food, exercise and hormones.

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Electron microscope. A microscope that uses electrons rather than photons (light) to make an image. Electron microscopy permits higher magnification than optical microscopy.

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Endocrine. Secreting internally, most often into the systemic circulation.

Endothelium. A layer of flat cells lining the blood and lymph vessels.

Enzymatic. Of or pertaining to enzymes, protein catalysts.

Euglycemia. "Good blood sugar": maintenance of blood sugar near the natural level of 5 mM (80 mg/dL).

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Exocrine. Secreting externally, most often into a duct.

Fibroblast. A cell present in connective tissue, capable of forming collagen fibers.

Fibrosis/Fibrotic reaction. Segregation of tissue by collagen laid down by fibroblasts. Occurs in response to most materials implanted into the body. Familiar example is encapsulation of a splinter.

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First-phase insulin response. Rapid release of insulin by beta cells in the first minutes following glucose stimulation.

Gestational diabetes. Less severe diabetes that only manifests during the stress of pregnancy.

Glucagon. A hormone that stimulates the liver to release glucose into the blood. An insulin counter hormone. Produced by A cells in the islets of Langerhans.

Glucose. The main carbohydrate fuel in the human body.

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Glucose oxidase. An enzyme that oxidizes glucose to glucuronic acid; used to detect glucose in meters.

Glycemia. Blood sugar.

Glycosuria. Presence of sugar in the urine.

Glycosylated hemoglobin. Hemaglobin to which glucose has been covalently attached. Used to measure average blood sugar.

Hepatic. Of or pertaining to the liver.

Hyperglycemia. Elevated blood sugar.

Hypoglycemia. Low blood sugar.

IDDM. Insulin-dependent diabetes mellitus (IDDM) is a disease characterized by elevated blood glucose and the absence of the hormone insulin. Without insulin, glucose is not utilized efficiently and accumulates in the blood. IDDM is treated with insulin injections. High blood sugar is the result of low to zero insulin secretion by the islets of Langerhans, the cells that normally produce insulin. In this form of diabetes the islets are incapacitated and the cells that normally secrete insulin are attacked by the body's own immune system.

The size and timing of insulin injections are influenced by measurements of blood sugar.

IDE. Investigational Device Exemption, the formal application to the FDA to perform a human study with an experimental device.

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Immune. Resistant to an infectious disease.

Immune system. Cells and organs that confer immunity from disease, including lymphocytes, lymph nodes and vessels, thymus gland, and bone marrow.

Immunohistochemical. Staining tissues with antibodies and dyes.

Immunosuppression. Suppression of the immune system. Most commonly done with drugs such as cyclosporin.

Insulin. A hormone, produced by the beta cells of the islets of Langerhans of the pancreas, that regulates the metabolism of glucose and other nutrients.

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Insulin Pump. A mechanical device that delivers insulin constantly or frequently.

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Insulin Receptor. A hormone receptor found on the surface of liver, muscle and fat cells, which binds insulin and signals the cell to take up more sugar.

Intravenous Glucose Tolerance Test (IVGTT). A test to assess glucose disposal.

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Insulitis. Inflammation of islets of Langerhans.

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Islet of Langerhans. Cluster of endocrine cells found in the pancreas; secretes insulin and other metabolic hormones.

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Islet Transplantation. Implantation of purified islets of Langerhans into a mammal with diabetes.

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K Value. The reported value from an intravenous glucose tolerance test (IVGTT); an assessment of glucose disposal. Learn more:

Ketoacidosis. The appearance of keto acids in blood, leading to further metabolic derangements.

Langerhans. The discoverer of the endocrine pancreas, called islets of Langerhans.

Lymphokine. A hormone released by a lymphocyte affecting primarily other lymphocytes (e.g. interferon, interleukin-2).

Lysine. An amino acid with a positively charged side chain: CH(NH2)(COOH)-(CH2)4-NH3+.

Macrophage. Literally big eater; a large ameboid mononuclear phagocyte.

Mesenteric. Pertaining to the sheets of tissue connecting the intestines to the dorsal side of the abdominal cavity.

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Microencapsulation. Process to putting cells such as islets of Langerhans into small capsules, each of which contains at most one islet. Small capsules are sometimes call coatings.

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Microvasculature. Small blood vessels in the body, especially capillaries.

Monoclonal antibody. Antibodies produced by hybridomas, having uniform structure and activity.

Neuropathy. Disease of nerves.

NIDDM. Non-insulin-dependent diabetes mellitus (NIDDM) is a disease characterized by elevated blood glucose and the presence of the hormone insulin. Typically the insulin is relatively ineffective at lowering blood sugar, and the islet of Langerhans compensate by producing higher levels of insulin.

Nonimmunogenic. Not eliciting an immune response; not antigenic.

Omentum. A vascularized peritoneal fold from the stomach to the transverse colon hanging like an apron in front of the intestines. A mesentery.

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Oxygen, diffusion of. Movement of oxygen from a region of higher to a region of lower concentration.

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Pancreas. The pancreas secretes digestive enzymes through the pancreatic duct into the small intestine. Islets of Langerhans are one to three per cent of the pancreas.

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Pancreatectomy. Surgical removal of the pancreas.

Pancreatic duct. A duct through which drain digestive juices into the lumen of the gut.

Pancreatic polypeptide. A hormone produced in the islets of Langerhans.

Pancreatitis. Inflammation of the pancreas.

Parathyroid. Glands adjacent to the thyroid producing parathyrin.

Perfusion. Pumping a fluid through the lumen of a vessel, e.g. pancreatic duct or renal artery.

Peritoneal cavity. Cavity between the ventral side of the abdomen and the abdominal viscera.

Plasma cell. A terminally differentiated B-lymphocyte producing large amounts of antibody.

Polylysine. A peptide polymer of lysine. May contain any number up to tens of thousands of lysine monomers.

Proislet. A cluster of partially differentiated cells found in the fetal or newborn pancreas that are fated to become an islet.

Pseudoislet. A synthetic islet made from beta cells.

Renal. Pertaining to the kidneys.

Retina. Tissue at the back of the eye that converts lights into information for the rain to process.

Retinopathy. Disease of the retina. Common in diabetes.

Somatostatin. A hormone capable of inhibiting the release of growth hormone.

Steroid. A large family of chemical substances, comprising many hormones, vitamins, body constituents, and drugs, each containing the tetracyclic cyclopenta[alpha]phenanthrene skeleton.

Streptozotocin. A drug which selectively destroys beta cells; used to induce diabetes in experimental animals.

Syngeneic. Two individuals of the same species so closely related as to be nearly identical (compare with allogenic, two outbred individuals of the same species).

Thoracic duct. The common duct where lymph enters blood circulation near the heart.

Thrombosis. Clotting of blood.

Tight Control. The attempt by diabetic care professionals working with the diabetic to achieve near euglycemia without hypoglycemia.

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T-lymphocyte. A lymphocyte that matured in the thymus gland and is involved in the cellular (as opposed to the antibody) immune response.

Type I diabetes. IDDM.

Type II diabetes. NIDDM.

Vasculature. The blood vessels.

Xenograft. A transplant between species (see autograft and allograft) e.g. pig to dog, human to rat.