the production of experimentally induced drug resistance in the laboratory provides valuable opportunities for investigators to study the nature and genetics of drug resistance mechanisms to a given agent, patterns of cross resistance and the mode of action of drugs. at the beginning the continuous drug exposure was chosen as a standard procedure to produce drug— resistant strains of p. falcipa...

A history of intermittent exposures to drugs of abuse can cause long-term changes in acute behavioural responses to a subsequent drug exposure. In drug-naive rats, morphine can elicit intermittent cataleptic postures followed by sustained increases in locomotor activity. Chronic intermittent morphine treatment can reduce catalepsy and increase locomotor behaviour and stereotypy induced by morph...

The camptothecin derivative topotecan has been postulated to mediate its antitumor effect through a drug-induced increase in covalent topoisomerase I-DNA complexes. If this hypothesis is correct, then schedules of exposure to topotecan that maximize the number of topoisomerase I-DNA complexes should produce the greatest cytotoxicity. We identified schedules of exposure to topotecan that maximiz...

Introduction: Prolonged and intermittent oxygen pre-exposure is associated with protection against ischemic reperfusion (IR) injury. In the current study, attempts were made to investigate the relationship between exposure to prolonged and intermittent normobaric hyperoxia (NBHO) and expression of excitatory amino acids transporters (EAATs) and TNF-α level. Method: Rats were divided into fo...

introduction: prolonged and intermittent oxygen pre-exposure is associated with protection against ischemic reperfusion (ir) injury. in the current study, attempts were made to investigate the relationship between exposure to prolonged and intermittent normobaric hyperoxia (nbho) and expression of excitatory amino acids transporters (eaats) and tnf-α level. method: rats were divided into four m...

Intermittent drug techniques refer to the "use of medication only during periods of incipient relapse or symptom exacerbation rather than continuously." The aim is to reduce the risk of adverse effects of antipsychotics by "reducing long-term medication exposure for patients who are receiving maintenance treatment while limiting risk of relapse," with a further goal of improving social function...

conclusions based on existing data, hiv infection surveillance, performance of standard precaution, and post exposure prophylaxis with anti-retroviral drugs outlined in this review article represent reasonable interim approaches to this complex problem. context human immunodeficiency virus (hiv) infection and acquired immunodeficiency syndrome (aids) concentrated in injecting drug users (idus) ...

Effects of stress on drug-induced yawning: Constant vs. intermittent stress. PHYSIOL BEHAV 58(1) 181-184, 1995.--Experiment 1 tested whether chronic exposure to immobilization, foot shock or forced swimming would result in suppression of apomorphine-, pilocarpine-, and physostigmine-induced yawning. Immobilization caused suppression of yawning, whereas foot shock and swimming resulted in increa...

conclusions the pattern of pretreatment with o2 could change this potential and highly protective strategy against cp-induced nephropathy to an ineffective or even mildly deteriorating one. therefore, o2 administration before cp injection to patients with cancer, for therapeutic purposes or as a preconditioning approach, should be performed and investigated with caution until exact effects of d...

How much, how often and how fast a drug reaches the brain determine the behavioural and neuroplastic changes associated with the addiction process. Despite the critical nature of these variables, the drug addiction field often ignores pharmacokinetic issues, which we argue can lead to false conclusions. First, we review the clinical data demonstrating the importance of the speed of drug onset a...