| diphosphate | <chemistry> Two phosphate groups linked by esterification. Released in many of the synthetic steps involving nucleotide triphosphates (e.g. Protein and nucleic acid elongation). Rapid cleavage by enzymes that have high substrate affinity ensures that these reactions are essentially irreversible. (18 Nov 1997) |
|---|---|
| diphosphates | Inorganic salts of phosphoric acid that contain two phosphate groups. (12 Dec 1998) |
| diphosphonates | Organic compounds which contain p-c-p bonds, where p stands for phosphonates or phosphonic acids. These compounds affect calcium metabolism. They inhibit ectopic calcification and slow down bone resorption and bone turnover. Technetium complexes of diphosphonates have been used successfully as bone scanning agents. (12 Dec 1998) |
| diphosphopyridine nucleotide | nAD |
| diphosphothiamin | The diphosphoric ester of thiamin, a coenzyme of several (de)carboxylases, transketolases, and alpha-oxoacid dehydrogenases. Synonym: aneurine pyrophosphate, cocarboxylase, diphosphothiamin. (05 Mar 2000) |
| diphosphotransferases | <enzyme> A class of phosphotransferases that catalyses the transfer of diphosphate-containing groups. Registry number: EC 2.7.6 (12 Dec 1998) |
| diphtheria | <infectious disease> An acute infectious disease caused by toxigenic strains of Corynebacterium diphtheriae, acquired by contact with an infected person or a carrier of the disease, which is usually confined to the upper respiratory tract. It is characterised by the formation of a tough membrane (false membrane or pseudomembrane) attached firmly to the underlying tissue that will bleed if forcibly removed. In the most serious infections the membrane begins in the tonsillar (faucial) area on one tonsil and may spread to involve the other tonsil, uvula, soft palate and pharyngeal wall, from where it may extend to the larynx, trachea and bronchial tree and may cause bronchial obstruction and death by hypoxia. Diphtheria also occurs in a cutaneous form and may rarely involve the eyes, middle ear, buccal mucosa, genitalia and umbilical stump, usually secondarily. Systemic effects, chiefly myocarditis and peripheral neuritis, are caused by the exotoxin produced by C. Diphtheriae. Synonym: Bretonneau's angina. Origin: Gr. Diphthera = leather (18 Nov 1997) |
| diphtheria antitoxin | An equine antitoxin against the toxin of corynebacterium diphtheriae, used for the treatment of diphtheria. It is to be differentiated from diphtheria toxoid which is used for the prevention of diphtheria. (12 Dec 1998) |
| diphtheria antitoxin unit | The antitoxin activity of 0.0628 mg standard diphtheria antitoxin. (05 Mar 2000) |
| diphtheria toxin | <protein> An ab exotoxin (62 kD) coded by _ corynephage of virulent Corynebacterium diphtheriae strains (that can produce a repressor of toxin production). The B subunit binds to receptors on the surface of the target cell and facilitates the entry of the enzymically active A subunit (21 kD) that ADP ribosylates elongation factor 2, thereby halting mRNA translation. (18 Nov 1997) |
| diphtheria toxoid | The formaldehyde-inactivated toxin of corynebacterium diphtheriae. It is generally used in mixtures with tetanus toxoid and pertussis vaccine (dtp) or with tetanus toxoid alone (dt for paediatric use and td, which contains 5- to 10-fold less diphtheria toxoid, for other use). Diphtheria toxoid is used for the prevention of diphtheria; diphtheria antitoxin is for treatment. (12 Dec 1998) |
| diphtheria-tetanus-pertussis vaccine | A vaccine consisting of diphtheria toxoid, tetanus toxoid, and pertussis vaccine. It is usually given to infants three times at two-month intervals, generally at 2, 4, and 6 months of age. The vaccine protects against diphtheria, tetanus, and whooping cough. In most cases the vaccine causes only a temporary fever and discomfort, but in a few cases serious neurological side effects have been observed. (12 Dec 1998) |
| diphtherial | Relating to diphtheria, or the membranous exudate characteristic of this disease. Synonym: diphtheric. (05 Mar 2000) |
| diphtheric | Relating to diphtheria, or the membranous exudate characteristic of this disease. Synonym: diphtheric. (05 Mar 2000) |
| diphtheritic | <medicine> 1. Pertaining to, or connected with, diphtheria. 2. Having characteristics resembling those of diphtheria; as, diphtheritic inflammation of the bladder. Source: Websters Dictionary (01 Mar 1998) |