multidrug resistance

resistance /re·sis·tance/ (re-zis´tans)

1. opposition, or counteracting force.

2. the natural ability of an organism to resist microorganisms or toxins produced in disease.

3. the opposition to the flow of electrical current between two points of a circuit. Symbol R or .

4. in psychiatry, conscious or unconscious defenses that prevent material in the unconscious from coming into awareness.

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airway resistance  the opposition of the tracheobronchial tree to air flow. Symbols RA, RAW.

androgen resistance  resistance of target organs to the action of androgens; the result is any of a spectrum of defects. In mild to incomplete types the person may have a definite male phenotype but infertility, or may have ambiguous genitalia. In the complete type the person has a female phenotype but XY chromosomes.

drug resistance  the ability of a microorganism to withstand the effects of a drug that are lethal to most members of its species.

electrical resistance  resistance (3).

multidrug resistance , multiple drug resistance in some malignant cell lines, resistance to many structurally unrelated chemotherapy agents in cells that have developed natural resistance to a single cytotoxic compound.

vascular resistance  the opposition to blood flow in a vascular bed.

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multidrug resistance,

1 the resistance of tumor cells to more than one chemotherapeutic agent. Resistance may be aided by a P-glycoprotein transmembrane pump that lowers the concentration of drugs in the cell.

2 the resistance of bacteria, especially Mycobacterium tuberculosis, against more than two of the antibiotics that were once effective.

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resistance [re-zis´tans]

1. opposition, or counteracting force, as opposition of a conductor to passage of electricity or other energy or substance.

2. the natural ability of a normal organism to remain unaffected by noxious agents in its environment; see also immunity.

3. in psychology or psychiatry, conscious or unconscious defenses against change, preventing repressed material from coming into awareness; they can take such forms as forgetfulness, evasions, embarrassment, mental blocks, denial, anger, superficial talk, intellectualization, or intensification of symptoms. It occurs because the blocked association or understanding would be too threatening to face at this point in the therapy; identification of what point the resistance comes at can be an important indicator of the patient's unconscious patterns.

airway resistance the opposition of the tissues of the air passages to air flow: the mouth-to-alveoli pressure difference divided by the rate of air flow. Symbol R_A or R_AW.

androgen resistance resistance of target organs to the action of androgens, resulting in any of a spectrum of defects from a normal male phenotype in which men have normal genitalia but infertility to complete androgen resistance in which the individual has a female phenotype. Complete androgen resistance is an extreme form of male pseudohermaphroditism in which the individual is phenotypically female but is of XY chromosomal sex; there may be rudimentary uterus and tubes, but the gonads are typically testes, which may be abdominal or inguinal in position. Called also testicular feminization and testicular feminization syndrome. Incomplete androgen resistance is any of various forms less than the complete type, manifested by a male phenotype with various degrees of ambiguous genitalia such as hypospadias and a small vaginal pouch, a hooded phallus, or a bifid scrotum that may or may not contain gonads.

drug resistance the ability of a microorganism to withstand the effects of a drug that are lethal to most members of its species.

insulin resistance see insulin resistance.

multidrug resistance (multiple drug resistance) a phenomenon seen in some malignant cell lines: cells that have developed natural resistance to a single cytotoxic compound are also resistant to structurally unrelated chemotherapy agents. Called also cross-resistance.

peripheral resistance resistance to the passage of blood through the small blood vessels, especially the arterioles.

pulmonary vascular resistance the vascular resistance of the pulmonary circulation; the difference between the mean pulmonary arterial pressure and the left atrial filling pressure divided by the cardiac output. Called also total pulmonary vascular resistance.

total peripheral resistance the vascular resistance of the systemic circulation: the difference between the mean arterial pressure and central venous pressure divided by the cardiac output.

total pulmonary resistance (total pulmonary vascular resistance) pulmonary vascular resistance.

vascular resistance the opposition to blood flow in a vascular bed; the pressure drop across the bed divided by the blood flow, conventionally expressed in peripheral resistance units. Symbol R or R.

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multidrug resistance,

n the adaptation of tumor cells or infectious agents to resist chemotherapeutic agents.