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Home >> Dictionary of Bioinformatics, Biochemistry, Biotechnology >> Diabetic Nephropathy Dicentric Chromosome
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Diabetes mellitus, type 3
Diabetes mellitus that includes a wide range of genetic effects of β-cell function, genetic disorders of insulin action and diseases of the exocrine pancreas (chronic pancreatitis, cystic fibrosis, haemochromatosis).
Diabetes mellitus, type 4
Diabetes mellitus induced by pregnancy (gestational diabetes). In addition, endocrine abnormalities such as acromegaly and Cushing’s syndrome as well as stress are known to cause diabetes mellitus.
Diabetic retinopathy
A long-term metabolism complication of diabetes mellitus that can eventually progress to blindness.
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Diabetic cataract
Along-term complication of diabetes mellitus due to high concentration of fructose and sorbitol in the lens. The sorbitol pathway is involved in the formation of fructose from glucose. Glucose is reduced by NADPH-dependent aldose reductase to sorbitol followed by oxidation of sorbitol to fructose by sorbitol dehydrogenase. In diabetic patients, there is increased activity of the sorbitol pathway and accumulation of sorbitol. Because sorbitol is incapable of diffusing through cell membranes, it causes osmotic damage, depletion of myoinositol and cataract formation.
Diabetic foot
Ulcers of the fee and lower extremities that develop in the diabetic patient due to a primary abnormality in pressure distribution secondary to diabetic neuropathy. Diminished blood supply is an important contributory factor for foot ulcers in diabetics. Microbial infections are common.
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Diabetic ketoacidosis
An acute metabolic complication of diabetes mellitus caused by cessation of insulin therapy, infection, vomiting, emotional stress, trauma or myocardial infarction. The blood glucose concentration may be 22.2-38.8 mmol/L (400-700 mg/dL) or higher. Hyperglycaemia causes glucosuria, osmotic diuresis and loss of water and electrolytes. Vomiting aggravates fluid electrolyte loss resulting in dehydration. The decrease in ECF volume results in decrease in circulating volume and renal blood flow leading to reduced GFR and Uraemia. The increase in ECF osmolality depletes ICF leading to cellular dehydration. Dehydration of cerebral cells results in confusion and coma. Insulin deficiency causes increased causes increased synthesis of ketone bodies, with consequent anion gap metabolic acidosis and decrease in plasma bicarbonate as a result of buffering.
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| A deep sighing breathing known as Kusssmaul respiration with acetone odour in the breath is a characteristic feature of diabetic ketoacidosis. Plasma sodium is decreased secondary to hyperglycaemia and plasma potassium is elevated due to decreased entry into cells. Despite hyperkalaemia, total body potassium is decreased due to urinary saline. Glucose enters cells followed by sodium-free water along the osmotic gradient. During treatment, potassium reenters cells with resultant hypokalaemia. Potassium replacement should begin as soon as plasma level starts to fall. Bicarbonate administration is indicated if the acidosis is severe.
Diabetic nephropathy A long-term metabolic complication of diabetes mellitus. Diabetic nephropathy may be diffuse or nodular. In the diffuse form, there is widening of the basement membrane. In the nodular form, deposition of periodic acid Schiff (PAS)-positive material in the glomerular tufts occurs (Kimmelsteil-Wilson lesion) with consequent increase in the renal threshold. Hyperglycaemia without glycosuria is a characteristic feature of Kimmelsteil-Wilson syndrome.
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Diabetic nephropathy is associated with proteinuria, nephritic syndrome, progressive renal failure and hypertension.
Diacylglycerol (DAG)
Lipid formed by the cleavage of inositol phospholipids in response to extracellular signals. It contains two fatty acid chains linked to glycerol and functions as a signalling molecule in the activation of protein kinase C.
Diagnostic
1. A test that is done to determine the source of a disease. 2. A method of determining the nature of a disease based on symptoms
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Diagnostic performance
(diagnostic power) In bioinformatics, refers to a measure of the ability of a discriminator to identify true matches in an individual query sequences or in a database.
Diagnostic procedure
A test or assay used to determine the presence of an organism, substance or nucleic acid sequence alteration that indicates a disease or pathogenic condition.
Diagnostics
Assays that are used to determine the presence of a DNA mutation, pathogen condition.
Diakinesis
A stage of meiosis that precedes metaphase l, and in which the separation of homologous chromosome is almost completed.
Dialysis
Removal of small molecules from a solution by diffusion through a semipermeable membrane into water.
Dialysable
The ability to undergo dialysis.
Diastereoisomers
Molecules with multiple chiral centres that exist in many forms with different physical and chemical properties.
Diastole
The lowest arterial blood pressure during the heart beat cycle, and the denominator in a blood pressure reading.
Diatomaceous earth
A finely pulverized mixture of earth composed of diatoms used as a filter or an absorbent.
Diauxic growth
Growth on a mixture of two carbons in which one carbon is used up before the other one is mobilosed. For example, E.coli preferentially uses glucose when both glucose and lactose are present.
Diauxic Shift
A shift in gene expression that occurs when cells are transferred from a rich medium to a poorer medium, or when cells in a rich medium grow and deplete their medium of nutrients.
Diazotroph
An organism capable of fixing nitrogen.
Dibasic
An acid containing two hydrogen atoms that can be replaced by basic molecules or metal ions to form a salt.
Dibasic aminoaciduria
An autosomal recessive disorder characterised by defective renal tubular reabsorption of lysine, arginine and ornithine with excessive loss in the urine. There is however, no defect cystine transport. Two types have been identified. Type l is characterised by moderate losses of the dibasic amino acids in the urine. The affected individuals are usually symptom-free. Type II, also known as lysinuric protein intolerance is more common and is seen in Finland.
There is defective transport of the dibasic amino acids across the intestinal mucosa and renal tubules with excessive loss of these amino acids in the urine. There is defective uptake of these substances n cultured fibroblasts and hepatocytes. The clinical symptoms in Type II include hepatosplenomegaly, protein intolerance, impaired urea cycle activity and ammonia intoxication. Treatment involves dietary protein restriction. Supplementation of citrulline will fuel the urea cycle.
Dicentric chromosome
The product of the fusion of two chromosome fragments, each of which has a centromere (i.e. a chromosome with two centromeres). Such a chromosome is unusable and may break when the two centromeres are pulled to opposite poles during mitosis.
Dicer
A ribonuclease in the RNase III family cleaves double-stranded RNA (dsRNA) and pre-microRNA (miRNA) into short double-stranded RNA fragments of 20-25 nucleotides termed small interfering RNA (siRNA). Dicer contains a two-base overhang on the 3’ end, two RNase III domains and one PAZ domain. Dicer catalyses the first step in the RNA interference pathway and initiates formation of the RNA induced silencing complex (RISC), whose catalytic component is an endonuclease that degrades mRNA complementary to the siRNA guide strand. See RNA interference.
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