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Home >> Dictionary of Bioinformatics, Biochemistry, Biotechnology >> Cycloserine - Cytogenetic Map
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Cyclins
A family of proteins that regulates the cell cycle by activating cyclin-dependent protein kinases. These proteins accumulate throughout the cell cycle and are subsequently destroyed by proteolysis during mitosis.
Cyclodextrin
A cyclic polymer of dextrose.
Cycloheximide
An inhibitor of protein biosynthesis that binds to the 60S subunit of eukaryotes and inhibits the peptidyl transferase reaction. It inhibits yeast and other fungi but not bacteria. It is used as a fungicide.
Cyclophosphamide
The most useful and versatile anticancer agent.
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It is an alkylating agent that binds covalently to DNA.
Cyclophosphamide
Cycloserine
An antibiotic produced by Streptomycetes that blocks bacterial cell wall synthesis. Since it is structurally similar to the amino acid D-alanine, it inhibits incorporation of D-alanine into the cell wall.
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Cystinosis
A rare disorder of cystine transport characterised by the accumulation of cystine in the lysosomes. The intralysosomal deposition of cystine crystals is widespread and is especially high in the reticuloendothelial system as well as in the cornea, conjunctive, lymph nodes and leucocytes. The condition is inherited as an autosomal recessive trait. Infantile, juvenile and adult forms have been recognised. There is an impaired efflux of cystine from lysosomes with defective interchange of cystine between lysosomes and other cellular and extracellular compartments.
As a consequence, there is increased deposition of cystine in the lysosomes of body tissues. The plasma levels of cystine are however, not elevated.
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The excretion of cystine is increased as part of a generalized Fanconi syndrome. Cystine crystals can be detected in the cornea, leucocytes or in biopsies of rectal mucosa. Quantification of cystine in the peripheral blood lymphocytes or cultured fibroblasts confirms diagnosis. Prenatal diagnosis cane be made in cultured amniotic fluid. Symptomatic treatments is given to prevent fluid, electrolyte and pH imbalance. Adequate fluid intake should be maintained to prevent dehydration.
Cystinuria
A disorder characterised by excessive urinary excretion of the dibasic amino acids cystine, ornithine, arginine and lysine. The disorder is common and inherited as an autosomal recessive trait with a frequency of 1 in 10,000 to 15,000. The excessive excretion of the dibasic amino acids is due to defective transport across the renal tubules and intestinal mucosa. Due to high urinary concentrations of cystine, which is relatively insoluble, precipitation of cystine with consequent formation of renal calculi may occur.
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Three variants of Cystinuria have been recognised: In Type I, there is defective intestinal transport of cystine, ornithine, arginine and lysine in homozygotes, with normal excretory patterns of these amino acids in heterozygotes. In Type II, the intestinal transport of lysine is absent but that of cystine is normal. The cystine-basic aminoaciduria in heterozygotes is lower than that seen in homozygotes. In Type III, the intestinal transport of the four amino acids, is functional and cystine basic aminoaciduria in heterozygotes occurs to a lesser extent that that seen in Type II. The clinical manifestation include haematuria, renal colic, obstructive uropathy and infection. Recurrent urolithiasis causes progressive renal insufficiency.
The presence of cystine in urinary tract stones can be detected by the nitroprusside test. The amino acid excretion pattern can be examined by chromatography or electrophoresis.
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The urinary concentration of cystine can be decreased by increasing fluid intake, alkalinisation of urine which increases the solubility of cystine and administration of D-penicullamine to form penicillamine-cystine mixed disulphide, which is more soluble.
Cytidine
A Pyridimine nucleoside present in DNA and RNA.
Cytidine
Cytidine monophosphate (CMP)
The nitrogenous base cytosine attached to a ribose containing one phosphate group at its 5’-end.
Cytidine triphosphate (CTP)
The nitrogenous base cytosine attached to a ribose containing three phosphate residues.
Cytochalasins
A family of drugs produced by certain fungi that inhibits cell motility by interfering with polymerization of actin filaments.
Cytochrome-c
An electron carrier in the cell respiratory chain that plays a key role in drug detoxification. CYP is a mixed function Oxidase that catalysed hydroxylation reactions and acids in solubilising molecules so that they can be excreted.
Cyclosporin
An immunosuppressive drug that functions by inhibiting T cell activation.
Cyproterone acetate
An anticancer agent useful in the treatment of prostate cancer. It binds to the receptor for 5-dihydrotesterone in the prostate and reduces the stimulatory effects to testosterone.
Cysteine
An amino acid containing a sulfhydryl (-SH) group in its side chain.
Cystic fibrosis
A multisystem disease characterised by decreased exocrine pancreatic secretion, chronic respiratory infection, malabsorption and abnormal sweat gland and urogenital functions. The gene responsible for cystic fibrosis encodes cystic fibrosis transmembrane regulator (CFTR), a protein concerned with the regulation of transmembrane chloride transport.
Cytochrome P450-dependent side chain cleavage (P450scc)
An enzyme complex that accomplishes oxidative side chain cleavage of cholesterol, the rate limiting step in steroid hormone biosynthesis that takes place in the mitochondrion. P450scc is activated by an ACTH-dependent steroidogenic acute regulatory protein (STAR) and inhibited by aminogluthethimide.
Cytochromes
Haem proteins that function as electron carriers in oxidative phosphorylation and photosynthesis.
Cytogenetic map
The representation of a chromosomes on staining and examination by microscopy as distinct light and dark bands. This gives each chromosomes a unique morphological appearance and allows visualization of cytogenetic abnormalities such as deletions or inversions.
Cytogenetics
The study of chromosomes and their implications in genetics, cellular activity and variability.
Cytohets
Heteroplasmic cells. In lower eukaryotes, cytohets arise spontaneously with biparental cytoplasmic inheritance. In higher eukaryotes, cytohets arise when cytoplasmic genes of one parent are not destroyed. These aberrant cells are termed biparental zygotes.
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