Age-related Changes in Auditory Cortex Without Detectable Peripheral Alterations: A Multi-level Study in Sprague-Dawley Rats.

Aging is often considered to affect both the peripheral (i.e. the cochlea) and central (brainstem and thalamus-cortex) auditory systems. We investigated the effects of aging on the cochlea, brainstem and cortex of female Sprague-Dawley rats. The auditory nerve threshold remained stable between the ages of nine and 21 months, as did distortion product otoacoustic emissions and the number of ribbon synapses between inner hair cells and nerve fibers. The first clear signs of aging appeared in the brainstem, in which response amplitude decreased, with thresholds remaining stable until the age of 15 months, and increasing slightly thereafter. The responses of primary auditory cortex neurons revealed specific effects of aging: at 21 months, receptive fields were spectrally narrower and the temporal reliability of responses to communication sounds was lower. However, aging had a null or even positive effect on neuronal responses in the presence of background noise, responses to amplitude-modulated sounds, and responses in gap-detection protocols. Overall, inter-animal variability remained high relative to the variability across groups of different ages, for all parameters tested. Behavioral performance for the modulation depth of amplitude modulation noise was worse in 21-month old animals than in other animals. Age-related alterations of cortical and behavioral responses were thus observed in animals displaying no signs of aging at the peripheral level. These results suggest that intrinsic, central aging effects can affect the perception of acoustic stimuli independently of the effects of aging on peripheral receptors.

Sound Coding in the Auditory Nerve: From Single Fiber Activity to Cochlear Mass Potentials in Gerbils.

Auditory nerve fibers (ANFs) convey acoustic information from the sensory cells to the brainstem using an elaborated neural code based on both spike timing and rate. As the stimulus tone frequency increases, time coding fades and ceases, resulting in high-frequency tone encoding that relies mostly on the spike discharge rate. Here, we recapitulated our recent single-unit data from gerbil's auditory nerve to highlight the most relevant mode of coding (spike timing versus spike rate) in tone-in-noise. We report that high-spontaneous rate (SR) fibers driven by low-frequency tones in noise are able to phase lock ∼30 dB below the level that evoked a significant elevation of the discharge rate, whereas medium- and low-SR fibers switch their preferential mode of coding from rate coding in quiet, to time coding in noise. For high-frequency tone, the low-threshold/high-SR fibers reach their maximum discharge rate in noise and do not respond to tones, whereas medium- and low-SR fibers are still able to respond to tones making them more resistant to background noise. Based on these findings, we first discuss the ecological function of the ANF distribution according to their spontaneous discharge rate. Then, we point out the poor synchronization of the low-SR ANFs, accounting for the discrepancy between ANF number and the amplitude of the compound action potential of the of the auditory nerve. Finally, we proposed a new diagnostic tool to assess low-SR fibers, which does not rely on the onset response of the ANFs.

Cochlear NMDA receptor blockade prevents salicylate-induced tinnitus.

Large doses of aspirin produce reversible hearing loss and tinnitus. These effects have been attributed to the salicylate ion, the active component of aspirin. Salicylate acts as a competitive antagonist at the anion-binding site of prestin, the motor protein of sensory outer hair cells. This provides an explanation for the hearing loss induced by aspirin. However, the molecular mechanism of salicylate-induced tinnitus remains obscure. One physiological explanation is that salicylate ototoxicity is likely to originate in an alteration to arachidonic acid metabolism. Arachidonic acid potentiates NMDA receptor currents. We therefore tested the involvement of cochlear NMDA receptors in the occurrence of tinnitus. Tinnitus was assessed with a behavioural test based on an active avoidance paradigm. Results showed that the tinnitus induced by salicylate may be suppressed by the introduction of NMDA antagonists into the cochlear fluids. To determine if the activation of NMDA receptors was linked to cyclooxygenase inhibition, we investigated the effect of mefenamate (a potent cyclooxygenase inhibitor). Since NMDA antagonists also blocked mefenamate-induced tinnitus, we suggest that salicylate-induced tinnitus is mediated by cochlear NMDA receptors through the inhibition of cyclooxygenase activity. Target cochlear NMDA receptors may therefore present a therapeutic strategy for the treatment of tinnitus.

Chemical synaptic transmission in the cochlea.

The last two decades have witnessed major progress in the understanding of cochlear mechanical functioning, and in the emergence of cochlear neurochemistry and neuropharmacology. Recent models describe active processes within the cochlea that amplify and sharpen the mechanical response to sound. Although it is widely accepted that outer hair cells (OHCs) contribute to these processes, the nature of the medial efferent influence on cochlear mechanics needs further clarification. Acetylcholine (ACh) is the major transmitter released onto OHCs during the stimulation of these efferents. The inhibitory influence of this system is mediated by post- and presynaptic nicontinic and muscarinic receptors and the role of other neuroactive substances [gamma-aminobutyric acid (GABA), calcitonin gene-related peptide (CGRP), adenosine 5'-triphosphate (ATP) or nitric oxide (NO)] remains to be determined. The inner hair cells (IHCs) that transduce the mechanical displacements into neural activity, release glutamate on receptor-activated channels of AMPA, kainate, and NMDA types. This synapse is in turn controlled and/or regulated by the lateral efferents containing a cocktail of neuroactive substances (ACh, GABA, dopamine, enkephalins, dynorphin, CGRP). This glutamatergic nature of the IHCs is responsible for the acute destruction of the nerve endings and subsequently for neuronal death, damage usually described in various cochlear diseases (noise-induced hearing losses, neural presbycusis and certain forms of sudden deafness or peripheral tinnitus). These pathologies also include a regrowth of new dendritic processes by surviving neurons up to IHCs. Understanding the subtle molecular mechanisms which underly the control of neuronal excitability, synaptic plasticity and neuronal death in cochlear function and disease is a very important issue for the development of future therapies.

[Percutaneous closure of three septal defects by two Amplatz occluders implanted during the same procedure]. / Fermeture percutanée de 3 communications interauriculaires par 2 dispositifs d'Amplatz implantés au cours d'un même cathétérisme.

Multiple atrial septal defects can be closed by interventional catheterisation. The procedure requires an accurate morphological evaluation: number of defects, distance from their edges to the main cardiac structures, resistance of the septum. The authors report the case of a 63 year old woman presenting with cardiac failure in whom 3 atrial septal defects were diagnosed. All 3 defects were successfully closed by the implantation of two Amplatz devices. Control echocardiography at 6 months showed the occluders in a normal position with no residual shunt and the patient was asymptomatic.

Are there good and bad responders to prehospital thrombolysis in the acute phase of myocardial infarction? OPTIMAL study rationale.

The effectiveness of thrombolytics has been clearly demonstrated in more than half the cases in the large cohorts of patients selected for trials during the acute phase of myocardial infarction. At individual level, thrombolysis will clinically either succeed or fail so, for the medical team managing the patient, choice of treatment may be likened to a gamble which in the best of cases (most often) leads to an uncomplicated success and, in the worst of cases, failure worsened by a severe complication. OPTIMAL is a multidisciplinary and multicentre, prospective cohort study associating mobile medical teams and interventional cardiology units to test the hypothesis that the outcome of prehospital thrombolysis does not depend on chance alone but also varies according to demographic, etiological, clinical and logistic factors involved in the occurrence and management of myocardial infarction. The primary objective of this French study, conducted over one year on more than 800 subjects, is to identify the predictors of the results of prehospital thrombolysis from a very early angiographic evaluation. The results for this cohort may be useful for setting up appropriate management strategies for acute myocardial infarction, from the prehospital phase (thrombolysis or not) up to in-hospital orientation of the patients (angiography room or Intensive Care Unit) and to determine the most judicious time for coronary angiography. OPTIMAL is to date the largest prospective serie of prehospital thrombolysis evaluated by an early angiographic control.

Validation of the French-language version of the OTOSPEECH automated scoring software package for speech audiometry.

OBJECTIVES: To validate a novel speech audiometry method using customized self-voice recorded word lists with automated scoring. PATIENTS AND METHODS: The self-voice effect was investigated by comparing results with prerecorded or self-recorded CVC (consonant-vowel-consonant) word lists. Then customized lists of 3-phoneme words were drawn up using the OTOSPEECH software package, and their scores were compared to those for reference lists. Finally, the customized list scores were compared on automated (Dynamic Time Warping [DTW]) versus manual scoring. RESULTS: Self-voice did not change scores for perception of CVC words at 10, 20 and 30 dB (ANOVA>0.05). Scores obtained with pre-recorded and self-recorded lists correlated (n=10, R(2)=0.76, P<0.01). Customized list scores correlated strongly with the reference cochlear lists of Lafon in normal-hearing (n=77, R(2)=0.83, P<0.001) and hearing-impaired populations (n=13, R(2)=0.89, P<0.001). Results on the automated and manual scoring methods correlated in both populations (n=77, R(2)=0.71, P<0.01; and n=13, R(2)=0.76, P<0.01, respectively), with DTW scores ranging from 24.17 to 53.24. CONCLUSIONS: Automated scoring of customized self-voice recorded lists for speech audiometry displayed results similar to conventional audiometric techniques.

Prevention of trauma-induced cochlear fibrosis using intracochlear application of anti-inflammatory and antiproliferative drugs.

Cochlear fibrosis is a common finding following cochlear implantation. Evidence suggests that cochlear fibrosis could be triggered by inflammation and epithelial-to-mesenchymal cell transition (EMT). In this study, we investigate the mechanisms of cochlear fibrosis and the risk/benefit ratio of local administration of the anti-inflammatory drug dexamethasone (DEX) and antimitotic drug aracytine (Ara-C). Cochlear fibrosis was evaluated in cochlear fibrosis models of rat cochlear slices in vitro and in KLH-induced immune labyrinthitis and platinum wire cochlear implantation-induced fibrosis in vivo. Cochleae were invaded with tissue containing fibroblastic cells expressing α-SMA (alpha smooth muscle actin), which along with collagen I, fibronectin, and laminin in the extracellular matrix, suggests the involvement of a fibrotic process triggered by EMT in vitro and in vivo. After perilymphatic injection of an adenoviral vector expressing GFP in vivo, we demonstrated that the fibroblastic cells derived from the mesothelial cells of the scalae tympani and vestibuli. Activation of inflammatory and EMT pathways was further assessed by ELISA analysis of the expression of IL-1ß and TGF-ß1. Both markers were elevated in vitro and in vivo, and DEX and Ara-C were able to reduce IL-1ß and TGF-ß1 production. After 5days of culture in vitro, quantification of calcein-positive cells revealed that Ara-C was 30-fold more efficient in preventing fibrosis, and provoked less sensory hair cell loss, than DEX. In KLH-induced immune labyrinthitis and platinum wire-implanted models, Ara-C was more efficient in preventing proliferation of fibrosis with less side effects on hair cells and neurons than DEX. In conclusion, DEX and Ara-C both prevent fibrosis in the cochlea. Analysis of the risk/benefit ratio favors the use of Ara-C for preventing cochlear fibrosis.

Loss of function of Ywhah in mice induces deafness and cochlear outer hair cells' degeneration.

In vertebrates, 14-3-3 proteins form a family of seven highly conserved isoforms with chaperone activity, which bind phosphorylated substrates mostly involved in regulatory and checkpoint pathways. 14-3-3 proteins are the most abundant protein in the brain and are abundantly found in the cerebrospinal fluid in neurodegenerative diseases, suggesting a critical role in neuron physiology and death. Here we show that 14-3-3eta-deficient mice displayed auditory impairment accompanied by cochlear hair cells' degeneration. We show that 14-3-3eta is highly expressed in the outer and inner hair cells, spiral ganglion neurons of cochlea and retinal ganglion cells. Screening of YWHAH, the gene encoding the 14-3-3eta isoform, in non-syndromic and syndromic deafness, revealed seven non-synonymous variants never reported before. Among them, two were predicted to be damaging in families with syndromic deafness. In vitro, variants of YWHAH induce mild mitochondrial fragmentation and severe susceptibility to apoptosis, in agreement with a reduced capacity of mutated 14-3-3eta to bind the pro-apoptotic Bad protein. This study demonstrates that YWHAH variants can have a substantial effect on 14-3-3eta function and that 14-3-3eta could be a critical factor in the survival of outer hair cells.

A peptide inhibitor of c-Jun N-terminal kinase protects against both aminoglycoside and acoustic trauma-induced auditory hair cell death and hearing loss.

Hearing loss can be caused by a variety of insults, including acoustic trauma and exposure to ototoxins, that principally effect the viability of sensory hair cells via the MAP kinase (MAPK) cell death signaling pathway that incorporates c-Jun N-terminal kinase (JNK). We evaluated the otoprotective efficacy of D-JNKI-1, a cell permeable peptide that blocks the MAPK-JNK signal pathway. The experimental studies included organ cultures of neonatal mouse cochlea exposed to an ototoxic drug and cochleae of adult guinea pigs that were exposed to either an ototoxic drug or acoustic trauma. Results obtained from the organ of Corti explants demonstrated that the MAPK-JNK signal pathway is associated with injury and that blocking of this signal pathway prevented apoptosis in areas of aminoglycoside damage. Treatment of the neomycin-exposed organ of Corti explants with D-JNKI-1 completely prevented hair cell death initiated by this ototoxin. Results from in vivo studies showed that direct application of D-JNKI-1 into the scala tympani of the guinea pig cochlea prevented nearly all hair cell death and permanent hearing loss induced by neomycin ototoxicity. Local delivery of D-JNKI-1 also prevented acoustic trauma-induced permanent hearing loss in a dose-dependent manner. These results indicate that the MAPK-JNK signal pathway is involved in both ototoxicity and acoustic trauma-induced hair cell loss and permanent hearing loss. Blocking this signal pathway with D-JNKI-1 is of potential therapeutic value for long-term protection of both the morphological integrity and physiological function of the organ of Corti during times of oxidative stress.

Study of LDL and acetylated LDL endocytosis by mononuclear cells in HIV infection.

Activated lymphocytes have a high level of low density lipoprotein (LDL) uptake as compared to resting lymphocytes, whereas scavenger receptors for acetylated LDL (Ac-LDL) are expressed on limited number of immune cells, i.e., monocytes/macrophages. The endocytosis of LDL and Ac-LDL by mononuclear cells was studied during in vitro and in vivo HIV infection, in order to use LDL and Ac-LDL as carriers of antiviral and/or immunomodulatory drugs towards lymphocytes and monocytes. The uptake of LDL and Ac-LDL was analyzed by cytofluorimetry. LDL endocytosis in PHA/IL2-activated lymphocytes was higher than in resting lymphocytes. In vitro HIV infection of PHA/IL2-activated lymphocytes did not alter the high LDL endocytosis in lymphocytes. CD4+ and CD8+ cells. In a group of 12 symptomatic patients there was no alteration of LDL endocytosis in lymphocytes, CD4 and CD8 lymphocytes. In another group of 23 individuals, the Ac-LDL endocytosis mediated by CD14+ monocytes was unaltered in asymptomatic patients (n = 6) and in some symptomatic patients (n = 6, CD14+ cells > 100/mm3). On the contrary, in other symptomatic patients (n = 11, CD14+ cells < 100/mm3), the number of Ac-LDL+ CD14+ cells decreased, whereas their efficiency of Ac-LDL endocytosis increased as compared to those of other HIV+ patients. In conclusion, the use of lipoproteins as carriers to increase the drug delivery to CD4+ lymphocytes and to CD14+ monocytes can be envisaged, since: (i) the LDL endocytosis was not impaired in CD4 lymphocytes of HIV+ patients, and (ii) the Ac-LDL uptake by monocytes was altered only in some patients of stage IV.

Stent placement compared with balloon angioplasty for small coronary arteries: in-hospital and 6-month clinical and angiographic results.

BACKGROUND: Stenting has been demonstrated to be superior to balloon angioplasty in de novo focal lesions located in large native vessels. However, in small vessels, the benefit of stenting remains questionable. METHODS AND RESULTS: A total of 381 symptomatic patients with de novo focal lesion located on a small coronary segment vessel (<3 mm) were randomly assigned to either stent implantation (192 patients; 197 lesions) or standard balloon angioplasty (189 patients; 198 lesions). The primary end point was the angiographic restenosis rate at 6 months, as determined by quantitative coronary angiography. On intention-to-treat analysis, angiographic success rate and major adverse cardiac events were comparable: 97.9% and 4.6% versus 93.9% and 5.8% in the stent group and the balloon group, respectively. After the procedure, a larger acute gain was achieved with stent placement (1.35+/-0.45 versus 0.94+/-0.47 mm, P=0.0001), resulting in a larger minimal lumen diameter (2.06+/-0.42 versus 1.70+/-0.46 mm, P=0.0001). At follow-up (obtained in 91% of patients), angiographic restenosis rate was 21% in the stent group versus 47% in the balloon group (P=0.0001), a risk reduction of 55%. Repeat target lesion revascularization was less frequent in the stent group (13% versus 25%, P=0.0006). CONCLUSIONS: Elective stent placement in small coronary arteries with focal de novo lesions is safe and associated with a marked reduction in restenosis rate and subsequent target lesion revascularization rate at 6 months.

Carvedilol for prevention of restenosis after directional coronary atherectomy : final results of the European carvedilol atherectomy restenosis (EUROCARE) trial.

BACKGROUND: In addition to its known properties as a competitive, nonselective beta and alpha-1 receptor blocker, carvedilol directly inhibits vascular myocyte migration and proliferation and exerts antioxidant effects that are considerably greater than those of vitamin E or probucol. This provides the basis for an evaluation of carvedilol for the prevention of coronary restenosis. METHODS AND RESULTS: In a prospective, double-blind, randomized, placebo-controlled trial, 25 mg of carvedilol was given twice daily, starting 24 hours before scheduled directional coronary atherectomy and continuing for 5 months after a successful procedure. The primary end point was the minimal luminal diameter as determined during follow-up angiography 26+/-2 weeks after the procedure. Of 406 randomized patients, 377 underwent attempted atherectomy, and in 324 (88.9%), a

[Coronary-bronchial artery fistula and two-vessel coronary disease treated by embolisation of the anastomosis and coronary angioplasty]. / Fistule coronaro-bronchique et lesions coronaires bitronculaires, traitées par embolisation de l'anastomose puis par angioplastie coronaire.

Coronary-bronchial artery fistulae are rare and may present with broncho-pulmonary haemorrhage and myocardial ischaemia. The authors report the case of a coronary-bronchial artery fistula associated with bronchiectasis responsible for haemoptysis and discovered at coronary angiography performed during an acute coronary syndrome. Radical treatment by embolisation of this fistula allowed the use of platelet inhibitors and anticoagulants for the coronary angioplasty performed secondarily. This method is an interesting alternative to surgical ligature.

[Percutaneous embolisation of a iatrogenic fistula between the internal mammary artery and the coronary vein]. / Embolisation percutanée d'une fistule iatrogène entre l'artère mammaire interne et la veine coronaire. Revue de la littérature à propos d'une observation.

Latrogenic fistula between the aorta and coronary vein is a rare complication of coronary bypass surgery due to accidental venous or arterial graft onto a coronary vein. The authors report a case of a patient admitted to hospital 2 months after coronary bypass surgery for cardiac failure due to a iatrogenic fistula by implantation of the left internal mammary artery on the great coronary vein. This presentation led to the choice of percutaneous embolisation of the fistula by the release of 6 coils. Based on a review of the literature, this clinical case illustrates the feasibility and value of percutaneous embolisation of iatrogenic fistulae.

[Prescriptions following acute coronary syndrome]. / Ordonnance de sortie après syndrome coronaire aigu.

Each year in France, 150,000 to 180,000 new patients are the subject of prescriptions following acute coronary syndrome with or without ST segment elevation. There are two targets of the treatment, atherosclerosis, a diffuse, evolving trouble which, in this situation, is coming out of an unstable phase, and the myocardium, which has often been revascularised and has suffered deterioration of its contractile and electrophysiological characteristics to a greater or lesser extent. Prescriptions, based on proven factors and always centred on hygiene and dietary advice and the use of a combination of statins and aspirin, are adapted to suit the atherosclerotic and myocardial risk assessed for the individual patient. The prescription starts off the secondary preventive phase. It marks the first stage of the follow up, which is inevitable though of variable duration, for a disease which may evolve. It is the first step in the accompaniment of an attentive, informed patient whose confidence has been restored and who must now avoid falling into the double trap of not taking the treatment sufficiently seriously or of obsessively over-reacting.

[Evaluation of therapeutic strategies for myocardial infarction: the ESTIM Midi-Pyrénées survey]. / Evalualion des stratégies thérapeutiques dans l'infarctus du myocarde: le registre ESTIM Midi-Pyrénées.

UNLABELLED: The aim of the ESTIM Midi-Pyrénées survey was to monitor the management of acute coronary syndrome with ST segment elevation by cardiologists and emergency departments in the Midi-Pyrénées region. Over a period of 2 years between June 2001 and June 2003, 1287 patients presenting with acute coronary syndrome within the first 24 hours were recruited prospectively. The initial management of these patients was undertaken either by a mobile medical team in the pre-hospital phase, or in a hospital emergency department, non-interventional cardiology department or an interventional cardiology department in 51.8%, 28.8%, 9.6% et 9.9% of cases respectively. Depending on these four modes of initial management, the median time for initial management was 1h30, 2h45, 4h30 et 4h respectively. Emergency coronary reperfusion was proposed in 89.6% of cases. Of the patients in whom reperfusion was attempted within the first 12 hours, 33.7% underwent pre-hospital thrombolysis (median delay of 1h48), 35.8% underwent thrombolysis in hospital (median delay 3h), and 30.4% underwent primary angioplasty (median delay 4h40). Thrombolysis was followed by angioplasty in 80% of cases. A combined approach with thrombolysis and angioplasty was applied in 41% of patients. At one month the rate of major cardiac events, death, and/or subsequent myocardial infarction was 12%. Multivariate analysis revealed that the only significant adverse prognostic features were: not offering reperfusion [Odds ratio (OR) 4, confidence interval (CI) 2.3-3.7] and age [OR 3.8, CI 2.3-6.2]. The method of reperfusion did not influence the subsequent outcome in this regional survey. CONCLUSION: pre-hospital management allows early revascularisation. In our region there was no significant prognostic difference between pre-hospital thrombolysis and primary angioplasty. It shows that the logistic and therapeutic potentials of prehospital care are not being sufficiently exploited.

[Long-term follow-up after primary angioplasty: is stenting beneficial?]. / Angioplastie primaire a long-terme: quel bénéfice des endoprothèses?

BACKGROUND: Primary stenting leads to a better short-term outcome than balloon angioplasty for acute myocardial infarction in randomised trials. However few data are available about the long-term outcome of primary stenting in acute myocardial infarction (AMI). OBJECTIVES: The aim of this study was to compare the three-year outcome after primary stenting versus balloon angioplasty in patients with acute myocardial infarction. METHODS: We conducted a retrospective study including 157 patients with AMI in a single center. Patients underwent balloon angioplasty (N = 48) or primary stenting (N = 109) within six hours after the onset of chest pain. We looked at the outcome during three years focusing on global mortality, major adverse cardiac events (MACE), reinterventions and target vessel revascularization (TVR). RESULTS: The two groups are similar for their baseline characteristics. No difference was noted for in-patient mortality in the balloon angioplasty group and the primary stenting group (2.1 vs 2.8%; P = ns). The three-year mortality was not significantly different in the two groups. Regarding MACE (27.8 vs 31.7; P = 0.95), reinterventions (20.4 vs 24.7%; P = 0.98) and TVR (18.6 vs 17.8%; P = 0.69), both groups were statistically not different. CONCLUSION: In the long-term patients treated with stent placement have similar rates of MACE, reinterventions or TVR than patients undergoing balloon angioplasty. If few studies noted a benefit in short-term outcomes, primary stenting doesn't improve the prognosis of acute myocardial infarction on long-term follow-up, which is dependent on atherosclerosis.

[Cardiovascular protection and prevention in patients with cardiac conditions and diabetes]. / Protection cardiovasculaire du coronarien et du diabétique: l'important, c'est la dose.

Good glycemic control can have a positive effect on the course and prognosis of coronary disease during and after myocardial infarction. It also reduces the risk of its onset. Both postprandial and fasting blood glucose must be normalized. Optimal treatment of coronary patients should include reduction of risk factors and 4 drugs: a beta-blocker at an effectively beta-blocking dose, aspirin at a daily dose between 75 and 100 mg, a statin that leads to an LDL-cholesterol level less than 1 g/L, and an angiotensin-converting enzyme inhibitor, with a demonstrated dose-effect relation. Efficacy is best when compliance is considered an essential objective.

Shift in HIV resistance genotype after treatment interruption and short-term antiviral effect following a new salvage regimen.

OBJECTIVE: To investigate the changes in genotypic drug-resistance pattern, plasma HIV RNA and CD4 cell count after treatment interruption and assess the short-term antiviral effect of a new salvage regimen. DESIGN: Prospective study of 38 patients with multiple failing regimens who had completely stopped all medication for 3 months before a three to five-drug regimen was reintroduced according to clinical guidelines. METHODS: Patients were tested for HIV resistance before and after treatment interruption by population-based sequencing and clonal analysis of selected patients. RESULTS: Discontinuation of therapy for 3 months was associated with a median increase in HIV RNA of 0.4 log10 and a median decrease in CD4 cell count of 43 x 10(6)/l. Sixty-one per cent of patients had a shift from the drug-resistant genotype to a predominantly wild-type genotype. The patients significantly likely to show genotype reversion were those in Centers for Disease Control groups A or B, who had been exposed to few drugs, had a low plasma HIV RNA, or a high CD4 cell count. The only independent factor predicting genotype reversion was the clinical stage. The median change in plasma HIV RNA at month 3 after treatment reintroduction was -2.3 log10 copies/ml in patients who had genotype reversion compared with -0.6 log10 copies/ml in patients without genotype reversion (P = 0.004). CONCLUSION: Suspending treatment for 3 months after multiple failures could be a suitable strategy for optimizing salvage therapy provided it is instituted early, before the HIV disease becomes too advanced.