| hypoxanthine-guanine phosphoribosyl tranferase marker | The gene which codes for the enzyme hypoxanthine-guanine phosphoribosyl transferase. It is a selectable marker because cells which have a defective version of this gene are resistant to poisoning by toxic purine derivatives which result from the metabolic pathway that the HGPRT enzyme catalyses. (The purine derivatives are toxic because they incorporate into DNA as a result of the HGPRT enzyme's actions). Because the defective gene cannot produce the enzyme, no toxic purine derivatives are produced, the gene can therefore be selected for. (09 Oct 1997) |
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| surrogate marker | <biology> A laboratory measurement of biological activity within the body that indirectly indicates the effect of treatment on disease state. CD4 cell counts and viral load are examples of surrogate markers in HIV infection. (19 Jan 1998) |
| oncofetal marker | A tumour marker produced by tumour tissue and by foetal tissue of the same type as the tumour, but not by normal adult tissue from which the tumour arises. (05 Mar 2000) |
| time marker | An instrument that marks the time, usually in seconds or fractions of seconds, on a kymograph record in physiologic experiments. (05 Mar 2000) |
| tumor marker | <investigation, oncology> A substance in the body that usually indicates the presence of cancer. These markers are usually specific to certain types of cancer and are usually found in the blood or other tissue samples. Examples are alphafetoprotein (AFP), human chorionic gonadotropin, and lactate dehydrogenase (LDH). They may be indicators of tumour stage and grade as well as useful for monitoring responses to treatment and predicting recurrence. Many chemical groups are represented including hormones, antigens, amino and nucleic acids, enzymes, polyamines, and specific cell membrane proteins and lipids. (18 Jul 2002) |
| tumour marker | <investigation, oncology> A substance in the body that usually indicates the presence of cancer. These markers are usually specific to certain types of cancer and are usually found in the blood or other tissue samples. Examples are alphafetoprotein (AFP), human chorionic gonadotropin, and lactate dehydrogenase (LDH). They may be indicators of tumour stage and grade as well as useful for monitoring responses to treatment and predicting recurrence. Many chemical groups are represented including hormones, antigens, amino and nucleic acids, enzymes, polyamines, and specific cell membrane proteins and lipids. (18 Jul 2002) |
| linkage marker | A locus at which there is a high probability of heterozygotes (indispensible state for linkage analysis), but in itself perhaps of no clinical interest. See: marker locus. (05 Mar 2000) |