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(ri-zis'tans) [L. resistere, to remain standing]
1. Opposition to a disease, a toxin, or to a physical force.
2. In psychoanalysis, a condition in which the ego avoids bringing into consciousness conflicts and unpleasant events responsible for neurosis; the reluctance of a patient to give up old patterns of thought and behavior. It may take various forms such as silence, failure to remember dreams, forgetfulness, and undue annoyance with trivial aspects of the treatment situation.
3. Force applied to a body part by weights, machinery, or another person to load muscles as an exercise to increase muscle strength.

airway resistance

The impedance to the flow of air into and out of the respiratory tract, measured in cm H2O/L/s. Normal airway resistance is 4 cm H2O/L/s.

antibiotic resistance

The ability of microorganisms to survive in the presence of antibiotics. Mutations have provided some bacteria with genes for enzymes that destroy antibiotics such as penicillins, cephalosporins, or aminoglycosides. Other mutations have changed the structure of bacterial cell walls formerly penetrable by antibiotics or have created new enzymes for cellular functions previously blocked by drugs. Synonym: antimicrobial resistance See: vancomycin-resistant enterococci; resistance transfer factor; methicillin-resistant Staphylococcus aureus


The indiscriminate use of antibiotics provides the selection pressure that creates ever more resistant strains.

antimicrobial resistance

Antibiotic resistance.

antiviral resistance

The developed resistance of a virus to specific antiviral therapy.

bacterial resistance

The ability of bacteria to survive and cause continuous infection in the presence of antibiotics.
See: antiviral resistance; antibiotic resistance; multidrug resistance; transfer factor

bedtime resistance

Misbehaving, stalling tactics, or temper tantrums used by children to avoid going to bed on time. Bedtime resistance may be caused by a variety of emotional or psychological factors, e.g., fear of the dark, loneliness, or the desire for more attention.

beta-lactamase resistance

The ability of microorganisms that produce the enzyme beta-lactamase (penicillinase) to resist the action of certain types of antibiotics, including some but not all forms of penicillin. Beta-lactamases make these microorganisms resistant to antibiotics by catalyzing the destruction of the beta-lactam ring that is essential for their antibacterial activity.

cross resistance

The ability of bacteria, viruses, or cancer cells to live and reproduce despite treatment with more than one drug. In cancer therapy, resistance to a wide range of unrelated drugs may occur after resistance to a single agent has developed.
Synonym: multidrug resistance; multiple drug resistance See: gene amplification

drug resistance

The ability of a disease, esp. one caused by infectious pathogens, to withstand drug treatment.

expiratory resistance

1. The impedence to airflow from the trachea, bronchi, mouth or nose during exhalation.
2. The use of a restricted orifice, or flow resistor, during positive-pressure ventilation to retard the flow of exhaled gases.
3. An objective measure of bronchospasm.

extended-spectrum beta-lactamase resistance

Abbreviation: ESBL
An enzymatically mediated antibiotic resistance found in gram-negative bacilli (such as Klebsiella pneumoniae, Enterobacter cloacae, and Pseudomonas aeruginosa), that make these bacteria resistant to cephalosporins and penicillin antibiotics.

glucocorticoid resistance

1. A rare genetically inherited insensitivity of peripheral tissues to the effects of steroid hormones produced by the adrenal cortex. Affected patients produce excessive compensatory quantities of ACTH and may be affected by hyperandrogenism or mineralocorticoid excess.
2. Insensitivity to treatment with glucocorticoid drugs, e.g., prednisone for asthma or Crohn disease.

insulin resistance

Cellular phenomena that prevent insulin from stimulating the uptake of glucose from the bloodstream and the synthesis of glycogen. Insulin resistance is one of the fundamental metabolic defects found in patients with type 2 diabetes mellitus.

manual resistance

See: resistance exercise

mechanical resistance

See: resistance exercise

multidrug resistance

Abbreviation: MDR
Cross resistance.

multiple drug resistance

Cross resistance.

peripheral resistance

The resistance of the arterial vascular system, esp. the arterioles and capillaries, to the flow of blood.

systemic vascular resistance

Abbreviation: SVR
The resistance to the flow of blood through the body's blood vessels. It increases as vessels constrict (as when a drug like norepinephrine is given) and decreases when vessels dilate (as in septic shock). Any change in the diameter, elasticity, or number of vessels recruited can influence the measured amount of resistance to the flow of blood through the body.

threshold resistance

The amount of pressure necessary in overcoming resistance to flow.

transthoracic resistance

The amount of resistance to the flow of electrical energy across the chest. This is an important factor to consider when electrical therapies such as defibrillation, cardioversion, and transthoracic pacing are used to treat abnormal cardiac rhythms.

viscous resistance

Nonelastic opposition of tissue to ventilation due to the energy required to displace the thorax and airways.

systemic vascular resistance

Abbreviation: SVR
The resistance to the flow of blood through the body's blood vessels. It increases as vessels constrict (as when a drug like norepinephrine is given) and decreases when vessels dilate (as in septic shock). Any change in the diameter, elasticity, or number of vessels recruited can influence the measured amount of resistance to the flow of blood through the body.
See also: resistance


(ri-spons') [L. responsum, an answer]
1. A reaction, e.g., contraction of a muscle or secretion of a gland, resulting from a stimulus. See: reaction
2. The total of an individual's reactions to specific conditions, e.g., the response of a patient to a certain treatment or to a challenge to the immune system.

acute phase response

Acute phase reaction.

auditory evoked response

Response to auditory stimuli determined by a method independent of the individual's subjective response. The electroencephalogram has been used to record response to sound. By measuring intensity of sound and presence of response, one can test the acuity of hearing of psychiatric patients, people who are asleep, and children too young to cooperate in a standard hearing test.

brainstem auditory evoked response

Evoked response audiometry.

clinical benefit response

Abbreviation: CBR
An improvement in at least one important symptom or element of the quality of life of a cancer patient that directly results from treatment, without any decline in any other element of the patient's quality of life.

Patient care

Some cancers are not curable or responsive to treatment with surgery, radiation, or chemotherapy. However, one or more of their most distressing symptoms may be manageable, e.g. alleviation of pain by therapy. Palliation of pain, nausea, or breathlessness, even in the absence of cure, is a clinically beneficial goal of treatment for some incurable tumors, such as cancers of the pancreas.

complete response

Abbreviation: CR
In cancer care, the eradication by treatment of all of a readily identifiable tumor. A complete response differs from a cure in that microscopic amounts of tumor the may remain in the patient and later produce a relapse.

conditioned response

See: conditioned reflex

Cushing response

See: Cushing, Harvey

defense-oriented response

A coping mechanism by which people try to protect themselves from anxiety or psychological harm.

dose response

1. The relationship between the quantity or intensity of a treatment regimen and its effect on living cells, tissues, or organisms.
2. The relationship between the intensity of an exposure, e.g., to an infectious pathogen, physical stressor, or a toxin, and its effect on living organisms.

durable response

In cancer care, a long-lasting positive reaction to tumor therapy, usually lasting at least a year.

end of treatment response

Abbreviation: EOT, ETR
In the treatment of chronic hepatitis C, the eradication of detectable virus from the blood after a complete course of antiviral therapy.

evoked response

Evoked potential.

F response

In electrodiagnostic study of spinal reflexes, the time required for a stimulus applied to a motor nerve to travel in the opposite direction up the nerve to the spinal cord and return.

galvanic skin response

The measurement of the change in the electrical resistance of the skin in response to stimuli.

histological response

The improvement in the appearance of microscopic tissue specimens after treatment of the patient with chemotherapy. Although it is not indicative of a cure, the improved appearance of biopsy specimens after treatment often suggests the patient's prognosis will improve as well.

immune response

The body's reaction to foreign antigens so that they are neutralized or eliminated, thus preventing the diseases or injuries these antigens might cause. It requires that the body recognize the antigen as nonself. There are several major components to the immune response. The nonspecific immune response, or inflammation, is the response of the body's tissues and cells to injury from any source, e.g., trauma, organisms, chemicals, ischemia. As the initial response of the immune system to any threat, it involves vascular, chemical, and white blood cell activities. The specific immune response, involving T cells and B cells, is a reaction to injury or invasion by particular organisms or foreign proteins. The cell-mediated immune response refers to the activity of T lymphocytes (T cells) produced by the thymus in response to antigen exposure. Without T cells, the body cannot protect itself against many disease-causing microbes. The loss of T cells in patients with AIDS, for example, leads to infections with many opportunistic microbes that would otherwise be relatively well tolerated by persons with intact cellular immunity. T-cell activity also is the basis for delayed hypersensitivity, rejection of tissue transplants, and responses to cancers. The humoral immune response refers to the production of antigen-specific antibodies by plasma B lymphocytes (B cells); antibodies attach to foreign antigens in the bloodstream, helping to inactivate or remove them.
See: cell-mediated immunity; humoral immunity; inflammation

inflammatory response


minor response

In cancer care, a reduction in tumor size by less than 50% but more than 25%.

parachute response

Parachute reflex.

partial response

Abbreviation: PR
In cancer care, a reduction in the size of readily identifiable tumors by 50% or more.

physiological stress response

Stress response.

primary immune response

The initial reaction to an immunogen, during which T and B lymphocytes are activated and antibodies specific to the antigen are produced. This reaction is considered relatively weak but produces large numbers of antigen-specific memory cells.

PSA response

A decrease in the level of prostate-specific antigen (PSA) of at least 50% in a patient receiving treatment for prostate cancer.

relative dose response

Abbreviation: RDR
1. A progressively increasing reaction of a cell, tissue, or organism to a stimulus.
2. A test used to estimate liver stores of vitamin A in order to identify those with marginal vitamin A deficiency.

relaxation response

The physiological responses produced when one sits quietly with the eyes closed and breathes slowly and methodically. The responses include slower heart rate, decreased blood pressure, and lowered cutaneous resistance. A brief word or phrase (such as a mantra) may be repeated to oneself to help focus the mind or reduce stray thoughts. This approach to meditation or stress reduction may be undertaken once or twice a day, usually for 10 to 30 Min. The relaxation response helps reduce anxiety, high blood pressure, pain, postmenopausal symptoms, and use of medications.

reticulocyte response

An increase in reticulocyte production in response to the administration of a hematinic agent.

secondary immune response

The rapid, strong response by T and B cells to a second or subsequent appearance of an immunogen. This occurs because of the availability of T and B lymphocyte memory cells.

somatosensory evoked response

Abbreviation: SER
Response produced by small, painless electrical stimuli administered to large sensory fibers in mixed nerves of the hand or leg. The electroencephalographic record of the character of the subsequent waves produced helps determine the functional state of the nerves involved.

stress response

The predictable physiological response that occurs in humans as a result of injury, surgery, shock, ischemia, or sepsis. Synonym: physiological stress response

This response is hormonally mediated and is divided into three distinct phases:

Ebb phase (lag phase): For 12 to 36 hr after the precipitating event, the body attempts to conserve its resources. Vital signs (heart, respiration, temperature) are less than normal. Flow phase (hypermetabolic phase): This stage peaks in 3 to 4 days and lasts 9 to 14 days, depending on the extent of the injury or infection and the person's physical and nutritional status. Carbohydrate, protein, and fat are mobilized from tissue stores and catabolized to meet the energy needs of an increased metabolic rate (hypermetabolism). Serum levels of glucose and electrolytes such as potassium can increase dramatically. If this stage is not controlled by removal of the cause or activator, multiple system organ failure or death can result. Anabolic phase (recovery): The anabolic, or healing, phase occurs as the catabolism declines and electrolyte balances are restored. Aggressive nutritional support is often necessary to promote a positive nitrogen balance.

sustained virological response

Abbreviation: SVR
In the treatment of chronic hepatitis C, having no detectable viral RNA in the blood 6 months after the completion of antiviral therapy. SVR is evidence of disease remission, and in many people, of cure.

tonic immobility response

Muscular paralysis that occurs during significant stress or injury, e.g., as an animal is fleeing or trying to fight off a predator. It is a common reaction experienced by animals and humans faced with overwhelming force, e.g., in battle or during sexual assault.

triple response

Any of the three phases of vasomotor reactions that occur when a sharp object is drawn across the skin. In order of appearance, these are red reaction, flare or spreading flush, and wheal.

ultra-rapid virological response

Abbreviation: URVR
The clearing of all hepatitis C viral RNA from the bloodstream after just 2 weeks of antiviral therapy.

unconditioned response

An inherent response rather than a learned response.
See: conditioned reflex

visual evoked response

Abbreviation: VER
A reaction produced in response to visual stimuli. While the patient is watching a pattern projected on a screen, the electroencephalogram is recorded. The characteristics of the wave form, its latency, and the amplitude of the wave can be compared with the normal, and important information concerning the function of the visual apparatus in transmitting stimuli to the brain can be obtained.

sustained virological response

Abbreviation: SVR
In the treatment of chronic hepatitis C, having no detectable viral RNA in the blood 6 months after the completion of antiviral therapy. SVR is evidence of disease remission, and in many people, of cure.
See also: response
Medical Dictionary, © 2009 Farlex and Partners
References in periodicals archive ?
The performance took my breath away at times and, no matter how hard you pushed, the SVR always felt glued to the road.
Officially the Range Rover Sport SVR is rated at 22.1mpg with emissions of 294g/km but off road the thirst grows as it goes through its paces in the mud.
For all its performance, the SVR retains the practicality of the regular F-Pace with a 650-litre boot while it also features 4G WiFi for up to eight devices and is equipped with the Jaguar's Touch Pro infotainment system with 10-inch touchscreen and a 12.3-inch HD instrument cluster.
'The F-Pace SVR delivers the handling and agility to match its performance.
According to certain reports, the high-riding SVR will borrow the F-Type SVR's supercharged 5.0-litre V8 that produces 570bhp and 516 pound-feet of torque and accelerates from zero to 60 mph in under four seconds.
Then, a novel imputation method named PSO-SVRFCM is proposed using FCM optimized by a combination of PSO and SVR.
Moreover, the final SVR rate was 26% in the pioglitazone and standard therapy as compared to 38.4% among patients on standard care groups alone.10 Despite a few available studies, data regarding the role of metformin and pioglitazone in improving SVR in patients of CHC is scanty and presently these drugs are not the part of management plan for hepatitis C.
In general, while SVR was 29% in patients using pegylated interferon (PEG-IFN) only for 48 weeks, it increased to 44-56% in patients receiving PEG-IFN and ribavirin (RIB) combination treatment (3).
The global premieres of two Range Rovers - the Range Rover SVAutobiography Dynamic and the Range Rover Sport SVR -took place today (November 14) on the Jaguar Land Rover stand at the 2017 Dubai International Motor Show.
One thing's for sure, if you're languishing on your lender's Standard Variable Rate (SVR) - the default rate you end up on when a mortgage deal ends - you'll be paying way over the odds.