Biopsychosocial sequelae and recovery trajectories from whiplash injury following a motor vehicle collision

BACKGROUND CONTEXT

Five out of 10 injured in a motor vehicle collision (MVC) will develop persistent pain and disability. It is unclear if prolonged symptoms are related to peritraumatic pain/disability, psychological distress, muscle fat, lower extremity weakness.

PURPOSE

To test if widespread muscle fat infiltration (MFI) was (1) unique to those with poor recovery, (2) present in the peritraumatic stage, (3) related to known risk factors.

STUDY DESIGN/SETTING

A cohort study, single-center academic hospital.

PATIENT SAMPLES

A total of 97 men and women (age 18-65) presenting to an urban academic emergency medicine department following MVC, but not requiring inpatient hospitalization.

PRIMARY OUTCOME MEASURE

Neck disability at 12-months.

METHODS

Participants underwent magnetic resonance imaging (MRI) to quantify neck and lower extremity MFI, completed questionnaires on pain/disability and psychological distress (< 1-week, 2-weeks, 3-, and 12-months) and underwent maximum volitional torque testing of their lower extremities (2-weeks, 3-, and 12-months). Percentage score on the Neck Disability Index at 12-months was used for a model of (1) Recovered (0%-8%), (2) Mild (10%-28%), and (3) Moderate/Severe (≥ 30%). This model was adjusted for BMI and age.

RESULTS

Significant differences for neck MFI were revealed, with the Recovered group having significantly lower neck MFI than the Mild and Moderate/Severe groups at all time points. The Mild group had significantly more leg MFI at 12-months (p=.02) than the Recovered group. There were no other significant differences at any other time point. Lower extremity torques revealed no group differences. The Traumatic Injury Distress Scale (TIDS) and MFI of the neck at 1-week postinjury significantly predicted NDI score at 12-months.

CONCLUSIONS

Higher neck MFI and distress may represent a risk factor though it is unclear whether this is a pre-existing phenotype or result of the trauma.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02157038.

Is fatty infiltration in paraspinal muscles reversible with exercise in people with low back pain? A systematic review

PURPOSE

Increased fatty infiltration in paraspinal muscles has been recognized as a feature of muscle quality loss in people with Low Back Pain (LBP) and is highly associated with the severity of LBP and dysfunction. Reducing fatty infiltration has been recognized as a rehabilitation aim. An earlier systematic review published in 2014 revealed conflicting evidence for the reversibility of paraspinal muscle quality by means of exercise and no updates have been published since. A new systematic literature search is warranted.

METHOD

Pubmed, CINAHL and Embase were searched from inception to July 2022. Randomized, non-randomized controlled trials (RCT and non-RCT) and single-arm trials were included if they reported the effect of exercise on paraspinal fatty infiltration in people with LBP. Effect sizes and statistical power were calculated for (1) exercise versus control, and (2) pre-post exercise changes. Available data from the RCTs were pooled via meta-analysis when appropriate. Otherwise, data were synthesized qualitatively.

RESULTS

Two RCTs, one non-RCT and three single-arm trials met the selection criteria. Data were not pooled due to substantial clinical heterogeneity. Effect sizes from the RCTs revealed no significant difference for exercise versus control. One single-arm trial with high risk of bias demonstrated a significant pre-post difference with moderate effect size, but only at one (T12-L1) of the investigated levels.

CONCLUSION

Moderate quality evidence is available that paraspinal fatty infiltration is not reversible with exercise in people with LBP. More larger RCT's are needed to draw firmer conclusions.

Self-reported Dysphagia and Pharyngeal Volume Following Whiplash Injury

Difficulty swallowing has been reported following whiplash injury; however, the reasons remain poorly understood. A possible factor may be the observed changes in pharyngeal volume. The current exploratory study was designed to examine the prevalence of self-reported dysphagia after whiplash and the relationship with recovery status and change in pharyngeal volume. Data were available from a longitudinal study of adults with whiplash. Data included magnetic resonance imaging (MRI) of the cervical spine, the Dysphagia Handicap Index (DHI), and Neck Disability Index (NDI) collected over four timepoints (< 1 week, 2 weeks, 3 months, and 12 months post-injury). Initial cross-sectional analysis examined 60 patients with DHI data from at least one timepoint. A second, longitudinal analysis was conducted on 31 participants with MRI, NDI, and DHI data at both early (< 1-2 weeks) and late (3-12 months) timepoints. The pharynx was contoured on axial T2-weighted MRI slices using OsiriX image processing software and pharyngeal volume (mm³) was quantified. In the 60-patient cohort, prevalence of self-reported dysphagia (DHI ≥ 3) was observed in 50% of participants at least once in 12 months (M = 4.9, SD 8.16, range 0-40). In the longitudinal cohort (n = 31), mean total DHI significantly (p = 0.006) increased between early and late stages. There was no relationship (p = 1.0) between dysphagia and recovery status, per the NDI% score. Pharyngeal volume remained stable and there was no relationship between dysphagia and pharyngeal volume change (p = 1.0). This exploratory study supports the need for further work to understand the nature of dysphagia, extent of functional compromise, and the underlying pathophysiology post-whiplash.

Brain Network Disruption in Whiplash

BACKGROUND AND PURPOSE

Whiplash-associated disorders frequently develop following motor vehicle collisions and often involve a range of cognitive and affective symptoms, though the neural correlates of the disorder are largely unknown. In this study, a sample of participants with chronic whiplash injuries were scanned by using resting-state fMRI to assess brain network changes associated with long-term outcome metrics.

MATERIALS AND METHODS

Resting-state fMRI was collected for 23 participants and used to calculate network modularity, a quantitative measure of the functional segregation of brain region communities. This was analyzed for associations with whiplash-associated disorder outcome metrics, including scales of neck disability, traumatic distress, depression, and pain. In addition to these clinical scales, cervical muscle fat infiltration was quantified by using Dixon fat-water imaging, which has shown promise as a biomarker for assessing disorder severity and predicting recovery in chronic whiplash.

RESULTS

An association was found between brain network structure and muscle fat infiltration, wherein lower network modularity was associated with larger amounts of cervical muscle fat infiltration after controlling for age, sex, body mass index, and scan motion (t = -4.02, partial R ²  = 0.49, P < .001).

CONCLUSIONS

This work contributes to the existing whiplash literature by examining a sample of participants with whiplash-associated disorder by using resting-state fMRI. Less modular brain networks were found to be associated with greater amounts of cervical muscle fat infiltration suggesting a connection between disorder severity and neurologic changes, and a potential role for neuroimaging in understanding the pathophysiology of chronic whiplash-associated disorders.

Whiplash-Associated Dysphagia and Dysphonia: A Scoping Review

Swallowing and voice complaints after a whiplash injury have been observed and reported in several studies; however, variability in study design complicates current understanding of whether dysphagia and dysphonia should be recognised as potential adverse outcomes. A scoping review was conducted across six databases from 1950 to March 2019. A total of 18 studies were included for review. Data regarding study purpose, design, outcome measures, participant characteristics and outcomes reported were extracted. Level of evidence (LOE) was assessed by the American Speech-Language Language Association (ASHA)'s LOE system. All studies were exploratory, with 68% rated as poor (< 3) on quality ratings. Nearly half (n = 6) were single case reports. Only three studies investigated some type of swallow-related outcome specifically within the study aim/s. Incidence of swallow-related problems ranged from 2 to 29%, with unspecified complaints of "swallowing difficulty", "dysphagia" and fatigue and pain whilst chewing reported. Neither swallowing biomechanics nor the underlying pathophysiology of swallow or voice complaints was investigated in any study. Four case studies presented post-whiplash voice complaints; two of which described loss of pitch range. Others described hoarseness, loss of control and weak phonation. Most studies only mentioned swallow- or voice-related deficits when reporting a wider set of post-injury symptomatology and six did not describe the outcome measure used to identify the swallow and voice-related problems reported. The existing literature is limited and of low quality, contributing to an unclear picture of the true incidence and underlying mechanisms of whiplash-related dysphagia and dysphonia.

Whiplash-Associated Dysphagia: Considerations of Potential Incidence and Mechanisms

Non-specific self-reports of dysphagia have been described in people with whiplash-associated disorders (WAD) following motor vehicle collision (MVC); however, incidence and mechanistic drivers remain poorly understood. Alterations in oropharyngeal dimensions on magnetic resonance imaging (MRI), along with heightened levels of stress, pain, and changes in stress-dependent microRNA expression (e.g., miR-320a) have been also associated with WAD, suggesting multi-factorial issues may underpin any potential swallowing changes. In this exploratory paper, we examine key biopsychosocial parameters in three patients with persistent WAD reporting swallowing change and three nominating full recovery after whiplash with no reported swallowing change. Parameters included (1) oropharyngeal volume with 3D MRI, (2) peritraumatic miR-320a expression, and (3) psychological distress. These factors were explored to highlight the complexity of patient presentation and propose future considerations in relation to a potential deglutition disorder following WAD. The three participants reporting changes in swallowing all had smaller oropharyngeal volumes at < 1 week and at 3 months post injury and lower levels of peritraumatic miR-320a. At 3 months post MVC, oropharyngeal volumes between groups indicated a large effect size (Hedge's g = 0.96). Higher levels of distress were reported at both time points for those with persistent symptomatology, including self-reported dysphagia, however, this was not featured in those nominating recovery. This paper considers current evidence for dysphagia as a potentially under-recognized feature of WAD and highlights the need for future, larger-scaled, multidimensional investigation into the incidence and mechanisms of whiplash-associated dysphagia.

Watching mesoporous metal films grow during templated electrodeposition with in situ SAXS

In this paper, we monitor the real-time growth of mesoporous platinum during electrodeposition using small-angle X-ray scattering (SAXS). Previously, we have demonstrated that platinum films featuring the 'single diamond' (Fd3m) morphology can be produced from 'double diamond' (Pn3m) lipid cubic phase templates; the difference in symmetry provides additional scattering signals unique to the metal. Taking advantage of this, we present simultaneous in situ SAXS/electrochemical measurement as the platinum nanostructures grow within the lipid template. This measurement allows us to correlate the nanostructure appearance with the deposition current density and to monitor the evolution of the orientational and lateral ordering of the lipid and platinum during deposition and after template removal. In other periodic metal nanomaterials deposited within any of the normal topology liquid crystal, mesoporous silica or block copolymer templates previously published, the template and emerging metal have the same symmetry, so such a study has not been possible previously.

Ambulatory function in motor incomplete spinal cord injury: a magnetic resonance imaging study of spinal cord edema and lower extremity muscle morphometry

Study Design

This research utilized a cross-sectional design.

Objectives

Spinal cord edema length has been measured with T2-weighted sagittal MRI to predict motor recovery following spinal cord injury. The purpose of our study was to establish the correlational value of axial spinal cord edema using T2-weighted MRI. We hypothesized a direct relationship between the size of damage on axial MRI and walking ability, motor function, and distal muscle changes seen in motor incomplete spinal cord injury (iSCI).

Setting

University based laboratory in Chicago, IL USA.

Methods

Fourteen participants with iSCI took part in the study. Spinal cord axial damage ratios were assessed using axial T2-weighted MRI. Walking ability was investigated using the 6-minute walk test and daily stride counts. Maximum plantarflexion torque was quantified using isometric dynomometry. Muscle fat infiltration (MFI) and relative muscle cross sectional area (rmCSA) were quantified using fat/water separation magnetic resonance imaging.

Results

Damage ratios were negatively correlated with distance walked in 6 minutes, average daily strides, and maximum plantarflexion torque, and a negative linear trend was found between damage ratios and lower leg rmCSA. While damage ratios were not significantly correlated with MFI, we found significantly higher MFI in the wheelchair user participant group compared to community walkers.

Conclusions

Damage ratios may be useful in prognosis of motor recovery in spinal cord injury. The results warrant a large multi-site research study to investigate the value of high-resolution axial T2-weighted imaging to predict walking recovery following motor incomplete spinal cord injury.

Age- and Level-Dependence of Fatty Infiltration in Lumbar Paravertebral Muscles of Healthy Volunteers

BACKGROUND AND PURPOSE

Normative age-related decline in paravertebral muscle quality is important for reference to disease and risk identification in patients. We aimed to establish age- and vertebral level-dependence of paravertebral (multifidus and erector spinae) muscle volume and fat content in healthy adult volunteers.

MATERIALS AND METHODS

In this prospective study multifidus and erector spinae fat signal fraction and volume at lumbar levels L1-L5 were measured in 80 healthy volunteers (10 women and men per decade, 20-62 years of age) by 2-point Dixon 3T MR imaging. ANOVA with post hoc Bonferroni correction compared fat signal fraction and volume among subgroups. Pearson and Spearman analysis were used for correlations (P < .05).

RESULTS

Fat signal fraction was higher in women (17.8% ± 10.7%) than men (14.7% ± 7.8%; P < .001) and increased with age. Multifidus and erector spinae volume was lower in women (565.4 ± 83.8 cm(3)) than in men (811.6 ± 98.9 cm(3); P < .001) and was age-independent. No differences in fat signal fraction were shown between the right and left paravertebral muscles or among the L1, L2, and L3 lumbar levels. The fat signal fraction was highest at L5 (women, 31.9% ± 9.3%; men, 25.7% ± 8.0%; P < .001). The fat signal fraction at L4 correlated best with total lumbar fat signal fraction (women, r = 0.95; men, r = 0.92, P < .001). Total fat signal fraction was higher in the multifidus compared with erector spinae muscles at L1-L4 for both sexes (P < .001).

CONCLUSIONS

Lumbar paravertebral muscle fat content increases with aging, independent of volume, in healthy volunteers 20-62 years of age. Women, low lumbar levels, and the multifidus muscle are most affected. Further study examining younger and older subjects and the functional impact of fatty infiltrated paravertebral muscles are warranted.

Aligned platinum nanowire networks from surface-oriented lipid cubic phase templates

Mesoporous metal structures featuring a bicontinuous cubic morphology have a wide range of potential applications and novel opto-electronic properties, often orientation-dependent. We describe the production of nanostructured metal films 1-2 microns thick featuring 3D-periodic 'single diamond' morphology that show high out-of-plane alignment, with the (111) plane oriented parallel to the substrate. These are produced by electrodeposition of platinum through a lipid cubic phase (Q(II)) template. Further investigation into the mechanism for the orientation revealed the surprising result that the Q(II) template, which is tens of microns thick, is polydomain with no overall orientation. When thicker platinum films are grown, they also show increased orientational disorder. These results suggest that polydomain Q(II) samples display a region of uniaxial orientation at the lipid/substrate interface up to approximately 2.8 ± 0.3 μm away from the solid surface. Our approach gives previously unavailable information on the arrangement of cubic phases at solid interfaces, which is important for many applications of Q(II) phases. Most significantly, we have produced a previously unreported class of oriented nanomaterial, with potential applications including metamaterials and lithographic masks.

Glycerol prevents dehydration in lipid cubic phases

Lipid cubic phase samples dry out and undergo phase transitions when exposed to air. We demonstrate experimentally and theoretically that adding glycerol controllably lowers the humidity at which cubic phases form. These results broaden the potential applications of cubic phases and open up the potential of a new humidity-responsive nanomaterial.

Chronic administration of haloperidol and clozapine induces differential effects on the expression of Arc and c-Fos in rat brain

The modulation of genes implicated in synaptic plasticity following administration of antipsychotic drugs has been instrumental in understanding their possible mode of action. Arc (Arg 3.1) is one such gene closely associated with changes in synaptic plasticity. In this study we have investigated the changes in expression of Arc protein following acute and chronic administration of a typical antipsychotic (haloperidol) and an atypical antipsychotic (clozapine) by means of immunohistochemistry compared to the prototypic gene marker c-Fos. In dorsal striatum haloperidol (1 mg/kg) significantly increased Arc expression following both acute and chronic (21 day) administration with evidence of modulation in induction after repeated dosing. No significant changes were observed following either acute or chronic administration of clozapine (20 mg/kg). In the nucleus accumbens shell both clozapine and haloperidol induced Arc expression following acute administration, again with evidence of modulation after chronic dosing. The pattern of induction of Arc expression following haloperidol and clozapine in both dorsal and ventral striatum was similar to that for c-Fos. In medial prefrontal and cingulate cortex, Arc expression was significantly decreased by clozapine but not haloperidol without any indication of modulation following chronic dosing, whereas no significant changes in c-Fos expression were observed with either drug. Since synaptic modulation mediated by Arc is associated with down-regulation of the AMPA glutamate receptor, this study suggests a mechanism whereby enhanced glutamate receptor efficacy in medial cortical areas may be a component of antipsychotic drug action.

Parallel changes in serotonin levels in brain and blood following acute administration of MDMA

Recent studies have demonstrated a similar acute effect of 3,4- methylenedioxymethamphetamine (MDMA) in blood platelets and brain tissue via action on the serotonin transporter. To investigate the validity of blood serotonin as a peripheral marker for central serotonin in this regard, we administered MDMA (20 mg/kg i.p.) to rats and observed a parallel decrease in serotonin levels in the frontal cortex and blood at 2 h (63% and 46% respectively) with some recovery evident at 8 h (42% and 38%) and more so at 18 h (19% and 24% below control levels). Administration of a tryptophan supplement (82.5 mg/kg p.o.) to naïve rats produced parallel increases in serotonin levels 2 h later in the frontal cortex (39%) and blood (26%). Following MDMA administration, the same dose of tryptophan caused a smaller (26%) rise in brain serotonin whereas in blood it had no effect. We conclude that blood serotonin is a useful marker for brain serotonin levels in the rat following acute administration of MDMA and this finding highlights the possible use of platelet serotonin as a marker for brain serotonin in human studies involving MDMA.

Temperature requirements of Atlantic salmon Salmo salar, brown trout Salmo trutta and Arctic charr Salvelinus alpinus: predicting the effects of climate change

Atlantic salmon Salmo salar, brown trout Salmo trutta (including the anadromous form, sea trout) and Arctic charr Salvelinus alpinus (including anadromous fish) provide important commercial and sports fisheries in Western Europe. As water temperature increases as a result of climate change, quantitative information on the thermal requirements of these three species is essential so that potential problems can be anticipated by those responsible for the conservation and sustainable management of the fisheries and the maintenance of biodiversity in freshwater ecosystems. Part I compares the temperature limits for survival, feeding and growth. Salmo salar has the highest temperature tolerance, followed by S. trutta and finally S. alpinus. For all three species, the temperature tolerance for alevins is slightly lower than that for parr and smolts, and the eggs have the lowest tolerance; this being the most vulnerable life stage to any temperature increase, especially for eggs of S. alpinus in shallow water. There was little evidence to support local thermal adaptation, except in very cold rivers (mean annual temperature <6·5° C). Part II illustrates the importance of developing predictive models, using data from a long-term study (1967-2000) of a juvenile anadromous S. trutta population. Individual-based models predicted the emergence period for the fry. Mean values over 34 years revealed a large variation in the timing of emergence with c. 2 months between extreme values. The emergence time correlated significantly with the North Atlantic Oscillation Index, indicating that interannual variations in emergence were linked to more general changes in climate. Mean stream temperatures increased significantly in winter and spring at a rate of 0·37° C per decade, but not in summer and autumn, and led to an increase in the mean mass of pre-smolts. A growth model for S. trutta was validated by growth data from the long-term study and predicted growth under possible future conditions. Small increases (<2·5° C) in winter and spring would be beneficial for growth with 1 year-old smolts being more common. Water temperatures would have to increase by c. 4° C in winter and spring, and 3° C in summer and autumn before they had a marked negative effect on trout growth.

Magnetic resonance imaging study of cross-sectional area of the cervical extensor musculature in an asymptomatic cohort

Magnetic Resonance Imaging (MRI) can be regarded as the gold standard for muscle imaging; however there is little knowledge about in vivo morphometric features of neck extensor muscles in healthy subjects and how muscle size alters across vertebral segments. It is not known how body size and activity levels may influence neck muscle cross-sectional area (CSA) or if the muscles differ from left and right. The purpose of this study was to establish relative CSA (rCSA) data for the cervical extensor musculature with a reliable MRI measure in asymptomatic females within a defined age range and to determine if side-side and vertebral level differences exist. MRI of the cervical spine was performed on 42 asymptomatic female subjects within the age range of 18-45. The rCSA values for the cervical extensor muscles were measured from axial T1-weighted images. We found significant side-side rCSA differences for the rectus capitis posterior minor, major (P < 0.001), multifidus (P = 0.002), and the semispinalis cervicis/capitis (P = 0.001, P < 0.001). There were significant vertebral level differences in rCSA of the semispinalis cervicis/capitis, multifidus, splenius capitis, and upper trapezius (P < 0.001). Activity levels were shown to impact on the size of semispinalis cervicis (P = 0.027), semispinalis capitis (P = 0.003), and the splenius capitis (P = 0.004). In conclusion, measuring differences in neck extensor muscle rCSA with MRI in an asymptomatic population provides the basis for future study investigating relationships between muscular atrophy and symptoms in patients suffering from persistent neck pain. Clin.

Magnetic resonance imaging study of the morphometry of cervical extensor muscles in chronic tension-type headache

This study analyses the differences in the relative cross-sectional area (rCSA) of several cervical extensor muscles, assessed by magnetic resonance imaging (MRI), between patients with chronic tension-type headache (CTTH) and healthy controls. MRI of the cervical spine was performed on 15 CTTH females and 15 matched controls. The rCSA values for the rectus capitis posterior minor (RCPmin), rectus capitis posterior major (RCPmaj), semispinalis capitis and splenius capitis muscles were measured from axial T1-weighted images using axial MR slices aligned parallel to the C2/3 intervertebral disc. A headache diary was kept for 4 weeks in order to substantiate the diagnosis and record the pain history. CTTH patients showed reduced rCSA for both RCPmin and RCPmaj muscles (P < 0.01), but not for semispinalis and splenius capitis muscles, compared with controls. Headache intensity, duration or frequency and rCSA in both RCPmin and RCPmaj muscles were negatively correlated (P < 0.05): the greater the headache intensity, duration or frequency, the smaller the rCSA in the RCPmin and RCPmaj muscles. CTTH patients demonstrate muscle atrophy of the rectus capitis posterior muscles. Whether this selective muscle atrophy is a primary or secondary phenomenon remains unclear. In any case, muscle atrophy could possibly account for a reduction of proprioceptive output from these muscles, and thus contribute to the perpetuation of pain.

High-dose MDMA does not result in long-term changes in impulsivity in the rat

RATIONALE

Evidence suggests that recreational users of (+/-)3,4-methylenedioxymethamphetamine HCl (MDMA, "ecstasy") have cognitive and behavioral deficits and show increased impulsivity consistent with 5-hydroxytryptamine (5-HT) neurotoxicity. MDMA effects on impulsivity in users are difficult to establish being confounded by polydrug use and individual predisposition to impulsivity or behavioral inhibition.

OBJECTIVE

We previously observed a long-term anxiolytic effect of a neurotoxic dose of MDMA on elevated plus maze behavior in Dark Agouti (DA) rats while other strains were reported to show anxiogenesis. We have now examined whether MDMA influences impulsivity producing disinhibited behavior interpretable as anxiolysis.

METHODS

Impulsivity was measured using an operant visuospatial discrimination procedure. Male DA rats (n = 24) were trained to lever press for food reward in response to a light-stimulus and subsequently required to withhold responding. Correct responses, premature responses, and response latencies were used as measures of accuracy and impulsivity. Trained rats were administered MDMA (5 mg/kg, i.p. at 3-h intervals to a total of three injections). Performance was measured at 3 h and 7, 27, 49, and 80 days posttreatment.

RESULTS

There was a short-term effect of MDMA on the percentage of correct responses at 3 h and day 1 with recovery to control levels by days 7-8 and no significant long-term changes up to day 80. There was no effect of MDMA on premature responses on any of the days measured. MDMA reduced cortical 5-HT content (MDMA 363 +/- 14 ng/g and control 440 +/- 10 ng/g tissue).

CONCLUSION

These results suggest that impulsivity may not be directly altered by MDMA despite serotonergic neurotoxicity.

The acute and long-term neurotoxic effects of MDMA on marble burying behaviour in mice

When mice are exposed to harmless objects such as marbles in their cage they bury them, a behaviour sometimes known as defensive burying. We investigated the effect of an acute dose of MDMA (èecstasy') and other psychoactive drugs on marble burying and also examined the effect of a prior neurotoxic dose of MDMA or p-chloroamphetamine (PCA) on burying. Acute administration of MDMA produced dose-dependent inhibition of marble burying (EC50: 7.6 micro mol/kg). Other drugs that enhance monoamine function also produced dose-dependent inhibition: methamphetamine PCA paroxetine MDMA GBR 12909 methylphenidate. None of these drugs altered locomotor activity at a dose that inhibited burying. A prior neurotoxic dose of MDMA, which decreased striatal dopamine content by 60%, but left striatal 5-HT content unaltered, did not alter spontaneous marble burying 18 or 40 days later. However, a neurotoxic dose of PCA which decreased striatal dopamine by 60% and striatal 5-HT by 70% attenuated marble burying 28 days later. Overall, these data suggest that MDMA, primarily by acutely increasing 5-HT function, acts like several anxiolytic drugs in this behavioural model. Long-term loss of cerebral 5-HT content also produced a similar effect. Since this change was observed only after 28 days, it is probably due to an adaptive response in the brain.

Periodic habitat loss alters the competitive coexistence between brown trout and bullheads in a small stream over 34 years

1. Changes in the population density of juvenile sea trout Salmo trutta L. and bullheads Cottus gobio L. were compared in a small stream over 34 years. Both species have a similar diet and obviously live in the same general habitat. Habitat loss was most marked in seven summer droughts: severest in 1976, 1983, 1984, 1995, and less severe but followed by autumn droughts in 1969, 1989 and 1993. The contrasting effects of habitat loss on the two species were examined. 2. For both species, the Ricker curvilinear model significantly fit (P < 0.001) the relationship between initial egg density and survivor density for successive life stages, even though egg densities were much lower for bullheads than trout. These analyses provided evidence for density-dependent population regulation and also identified extreme outliers, most being for year-classes affected by summer droughts. 3. The variable effects of changes in habitable area (= % wettable area in sampling section) were quantified by using the residuals, each residual being the absolute value expressed as a percentage of the expected value from the Ricker curve. Significant relationships between the residuals and habitable area showed that habitat loss had a marked effect on survivor density, this being negative for 0+ and 1+ trout, and positive for 0+, 1+ and 2+/3+ bullheads. 4. Therefore, during periods of habitat loss in the summer months, bullhead density increased at the expense of trout density. Low flows and a decrease in wettable area were associated with a marked reduction in habitat quality for drift-feeding trout and an increase in habitat quality, and perhaps also quantity, for benthic-feeding bullheads. This case study shows that, during a major perturbation, the relationship between the densities of two species can change markedly in favour of the less numerous species. The competitive coexistence between the two species is therefore a dynamic process that changes through time with periodic changes in the environment.

Studies on the effect of MDMA ('ecstasy') on the body temperature of rats housed at different ambient room temperatures

3,4-Methylenedioxymethamphetamine (MDMA, 'ecstasy') administration to rats produces hyperthermia if they are housed in normal or warm ambient room temperature (Ta) conditions (>or=20 degrees C), but hypothermia when in cool conditions (Ta<or=17 degrees C). We have now investigated some of the mechanisms involved. MDMA (5 mg kg(-1) i.p.) produced a rapid decrease in rectal temperature in rats at Ta 15 degrees C. This response was blocked by pretreatment with the dopamine D2 receptor antagonist remoxipride (10 mg kg(-1) i.p.), but unaltered by pretreatment with the D1 antagonist SCH23390 (1.1 mg kg(-1) i.p). MDMA (5 mg kg(-1)) did not alter the tail temperature of rats at Ta 15 degrees C, but decreased the tail temperature of rats at Ta 30 degrees C. A neurotoxic dose of MDMA (three doses of 5 mg kg(-1) given 3 h apart) decreased cortical and hippocampal 5-HT content by approximately 30% 7 days later. This lesion did not influence the rise in tail temperature when rats were moved from Ta 20 degrees C to 30 degrees C compared to nonlesioned controls, but did result in a lower tail temperature than that of controls when they were returned to Ta 24 degrees C. Acute administration of MDMA (5 mg kg(-1)) to MDMA-lesioned rats produced a sustained decrease in tail temperature in rats housed at Ta 30 degrees C compared to nonlesioned controls. These data suggest that the thermoregulatory problems previously observed in MDMA-lesioned rats housed at Ta 30 degrees C result, partially, from their inability to lose heat by vasodilation of the tail, a major heat-loss organ in this species.

The role of 5-HT in the impairment of thermoregulation observed in rats administered MDMA ('ecstasy') when housed at high ambient temperature

RATIONALE

Administration to rats of a neurotoxic dose of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) produces an impairment in thermoregulation which is reflected in a prolonged hyperthermic response to a subsequent dose of MDMA given to rats housed at high ambient temperature.

OBJECTIVE

We wished to examine whether the impaired thermoregulation was associated with decreased cerebral 5-HT content produced by the prior neurotoxic dose of MDMA.

METHODS

Rats were injected with drugs decreasing 5-HT function [the tryptophan hydroxlase inhibitor p-chlorophenylalanine (PCPA), and 5-HT receptor antagonists] and rectal temperature was measured after administering MDMA to rats housed at 30 degrees C.

RESULTS

PCPA pretreatment decreased 5-HT and 5-HIAA concentrations in cortex, hippocampus and striatum by >80% and prolonged the hyperthermia induced in rats housed at 30 degrees C by administering MDMA (5 mg/kg i.p.). A similar prolongation of the hyperthermic response to MDMA was seen when rats were pretreated with methysergide (10 mg/kg i.p.) or the 5-HT(1A) antagonist WAY100635 (0.5 mg/kg s.c.).

CONCLUSIONS

Decreasing 5-HT function in diverse ways enhanced the hyperthermic response to MDMA given to rats housed at high ambient temperature. This suggests that loss of 5-HT acting on 5-HT(1A) receptors leads to impaired thermoregulation in rats and suggests that the impairment seen in MDMA pretreated rats housed at high ambient temperature is due to a loss in 5-HT function. These data could have implications for recreational users of MDMA, who may have damaged serotoninergic neurons because of prior heavy or frequent use of the drug, when taking further doses of MDMA in hot environments such as dance clubs.

Magnetic resonance imaging analysis of the upper cervical spine extensor musculature in an asymptomatic cohort: an index of fat within muscle

AIM

To establish a simple method to quantify muscle/fat constituents in cervical muscles of asymptomatic women using magnetic resonance imaging (MRI), and to determine whether there is an age effect within a defined age range.

MATERIALS AND METHODS

MRI of the upper cervical spine was performed for 42 asymptomatic women aged 18-45 years. The muscle and fat signal intensities on axial spin echo T1-weighted images were quantitatively classified by taking a ratio of the pixel intensity profiles of muscle against those of intermuscular fat for the rectus capitis posterior major and minor and inferior obliquus capitis muscles bilaterally. Inter- and intra-examiner agreement was scrutinized.

RESULTS

The average relative values of fat within the upper cervical musculature compared with intermuscular fat indicated that there were only slight variations in indices between the three sets of muscles. There was no significant correlation between age and fat indices. There were significant differences for the relative fat within the muscle compared with intermuscular fat and body mass index for the right rectus capitis posterior major and right and left inferior obliquus capitis muscles (p=0.032). Intraclass correlation coefficients for intraobserver agreement ranged from 0.94 to 0.98. Inter-rater agreement of the measurements ranged from 0.75 to 0.97.

CONCLUSION

A quantitative measure of muscle/fat constituents has been developed, and results of this study indicate that relative fatty infiltration is not a feature of age in the upper cervical extensor muscles of women aged 18-45 years.

Paradigmatic identification of MMP-2 and MT1-MMP activation systems in cardiac fibroblasts cultured as a monolayer

Activations of MMP-2 and membrane type 1-matrix metalloproteinase (MT1-MMP) have been correlated with cell migration, a key cellular event in the wound healing and tissue remodeling. We have previously demonstrated furin-dependent MMP-2 and MT1-MMP activations induced by type I collagen in cardiac fibroblasts. To understand mechanistic aspects of the regulation of MMP-2 and MT1-MMP activations by potential non-matrix factor(s) in cardiac fibroblasts, in the present study, we examined the effects of various agents including concanavalin A (ConA), a proteolytic phenotype-producing agent. We showed that treatment of cells with ConA activated pro-MMP-2, and that this activation concurred with elevated levels of cellular MT1-MMP and TIMP-2. The presence of active MT1-MMP and 43 and 36 kDa processed forms of MT1-MMP in a fraction of intracellular proteins prepared from ConA-treated cells suggests the possible internalization of differential forms of MT1-MMP. The appearance of 36 kDa processed form of MT1-MMP in conditioned media prepared from ConA-treated cells indicates the possible extracellular release of the further processed MT1-MMP fragment. Inhibition of furin in ConA-treated cells attenuated pro-MT1-MMP processing and the cellular TIMP-2 level, plus it reduced cell-released active MMP-2 in a time-dependent manner. These results suggest the involvement of furin in the ConA-induced activations of MT1-MMP and MMP-2. Furthermore, the existence of furin inhibitor-insensitive pro- and active MMP-2 species associated with ConA-treated cells implies that a mechanism independent of furin may perhaps account for the binding of the MMP-2 species to the cells. Supplementary material for this article can be found at http://www.mrw.interscience.wiley.com/suppmat/0730-2312/suppmat/94/suppmat_guo.tif.

Psychostimulants and monoamine transporters: upsetting the balance

Monoamine transporters were originally associated simply with the termination of synaptic monoamine function. In addition to amine reuptake, however, the transporters can act as ion channels that affect exocytotic neurotransmitter release and can operate in reverse mode, mediating non-exocytotic amine release. Activity at the plasma membrane is controlled by trafficking, which is modulated by interaction with both substrates and inhibitors and by cytosolic kinases and phosphatases. Monoamine transporters also constitute the principal sites of action of many psychoactive drugs, including amphetamines and cocaine, as well as therapeutic drugs for the treatment of depression, addiction and attention deficit hyperactivity disorder, each modifying the balance of presynaptic neurotransmitter function.

Lack of association between baseline plasma homocysteine concentrations and restenosis rates after a first elective percutaneous coronary intervention without stenting

OBJECTIVE

To evaluate the association between baseline homocysteine concentrations and restenosis rates in patients electively undergoing their first percutaneous coronary intervention (PCI) without stenting.

DESIGN

Prospective, single centre, observational study.

SETTING AND PATIENTS

Patients electively undergoing their first PCI without stenting at a tertiary referral centre between 1990 and 1998.

METHODS

Blood samples were collected from all patients at baseline and assayed to determine the patients' homocysteine concentrations. Patients whose PCI was successful underwent repeat angiography at a median of 6.4 (interquartile range 6-6.8) months. Their baseline and follow up angiograms were compared by quantitative coronary angiography to assess the incidence of restenosis. For the analysis, the patients were divided into two groups based on whether their baseline homocysteine concentrations were above or below the median value. These two groups were compared to determine whether there was any association between their baseline homocysteine concentrations and the incidence of restenosis at six months.

RESULTS

134 patients had a successful first PCI without stenting (involving 200 lesions). At six month angiography, restenosis was observed in 33 patients (49.3%) with baseline homocysteine concentrations above the median value and in 31 patients (46.3%) with concentrations below the median value (p = 0.74). There was no difference in the percentage of lesions developing restenosis (38 (39.6%) v 40 (38.5%), respectively, p = 0.87) or late lumen loss (0.40 mm v 0.31 mm, respectively, p = 0.24). On multivariable analysis, there was no association between homocysteine concentrations and late lumen loss (r = -0.11, p = 0.11) or the percentage diameter stenosis at follow up (r = -0.07, p = 0.32).

CONCLUSION

Baseline homocysteine concentrations were not associated with six month restenosis rates in patients electively undergoing their first PCI without stenting.

Insights into the evolution of Yersinia pestis through whole-genome comparison with Yersinia pseudotuberculosis

Yersinia pestis, the causative agent of plague, is a highly uniform clone that diverged recently from the enteric pathogen Yersinia pseudotuberculosis. Despite their close genetic relationship, they differ radically in their pathogenicity and transmission. Here, we report the complete genomic sequence of Y. pseudotuberculosis IP32953 and its use for detailed genome comparisons with available Y. pestis sequences. Analyses of identified differences across a panel of Yersinia isolates from around the world reveal 32 Y. pestis chromosomal genes that, together with the two Y. pestis-specific plasmids, to our knowledge, represent the only new genetic material in Y. pestis acquired since the the divergence from Y. pseudotuberculosis. In contrast, 149 other pseudogenes (doubling the previous estimate) and 317 genes absent from Y. pestis were detected, indicating that as many as 13% of Y. pseudotuberculosis genes no longer function in Y. pestis. Extensive insertion sequence-mediated genome rearrangements and reductive evolution through massive gene loss, resulting in elimination and modification of preexisting gene expression pathways, appear to be more important than acquisition of genes in the evolution of Y. pestis. These results provide a sobering example of how a highly virulent epidemic clone can suddenly emerge from a less virulent, closely related progenitor.

Effect of repeated ('binge') dosing of MDMA to rats housed at normal and high temperature on neurotoxic damage to cerebral 5-HT and dopamine neurones

The technique of 'binge' dosing (several doses in one session) by recreational users of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) requires evaluation in terms of its consequences on the acute hyperthermic response and long-term neurotoxicity. We examined the neurotoxic effects of this dosing schedule on 5-HT and dopamine neurones in the rat brain. When repeated (three) doses of MDMA (2, 4 and 6 mg/kg i.p.) were given 3 h apart to rats housed at 19 degrees C, a dose-dependent acute hyperthermia and long-term loss of 5-HT was observed in several brain regions (hippocampus, cortex and striatum), with an approximate 50% loss following 3 x 4 mg/kg and 65% decrease following 3 x 6 mg/kg. No decrease in striatal dopamine content was detected. When MDMA (4 mg/kg i.p.) was given repeatedly to rats housed at 30 degrees C, a larger acute hyperthermic response than that observed in rats treated at 19 degrees C environment was seen (maximum response 2.6 +/- 0.1 degrees C versus 1.3 +/- 0.2 degrees C). A long-term cerebral 5-HT loss of approximately 65% was also detected in both the cortex and hippocampus, but no loss in striatal dopamine content occurred. These data emphasize the increased acute hyperthermic response and neurotoxicity which occurs when MDMA is administered in a hot room environment compared to normal room temperature conditions, and support the view that MDMA is a selective 5-HT neurotoxin, even when a binge dosing schedule is employed and the rats are present in a hot environment.

Effect of 5-HT depletion by MDMA on hyperthermia and Arc mRNA induction in rat brain

RATIONALE

3,4-Methylenedioxymethamphetamine (MDMA) administration to rats produces an acute hyperthermic response and induces localised neuronal activation, which can be visualised via expression of immediate-early genes. The pharmacological and anatomical basis of these effects are unclear. At high doses, MDMA also causes selective neurotoxicity at serotonergic nerve terminals.

OBJECTIVE

We investigated the effect of 5-hydroxytryptamine (5-HT) depletion on the acute hyperthermic response to MDMA and the pattern of neuronal excitation indicated by Arc (activity-regulated cytoskeleton associated gene) in naive rats and following administration of MDMA at a neurotoxic dose.

METHODS

Expression of Arc mRNA was investigated by in situ hybridisation histochemistry using 35S-labelled oligonucleotide probe.

RESULTS

MDMA induced a significant hyperthermia together with increased Arc mRNA expression in cortical regions, caudate-putamen and CA1 hippocampus but not hypothalamus. At 21 days after a neurotoxic dose of MDMA, brain 5-HT and 5-HIAA levels were significantly reduced by 21-32%. In these animals, both the hyperthermic response and the pattern and extent of Arc mRNA expression induced by a subsequent dose of MDMA were unaltered. However, basal Arc expression was significantly increased in cortical regions and CA1 hippocampus.

CONCLUSION

We conclude that the acute hyperthermic response induced by MDMA is not attenuated by moderate depletion of 5-HT, further questioning mediation via a serotonergic mechanism. Arc mRNA induction by MDMA exhibits highly localised expression, which is not altered following 5-HT depletion. However, following a neurotoxic dose of MDMA, basal expression of Arc is increased, particularly in cortex and CA1, suggesting that mechanisms underlying synaptic plasticity might also be modified.

Effect of ambient temperature and a prior neurotoxic dose of 3,4-methylenedioxymethamphetamine (MDMA) on the hyperthermic response of rats to a single or repeated ('binge' ingestion) low dose of MDMA

RATIONALE

3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) administration to rats produces acute hyperthermia and long-term neurotoxic damage to 5-hydroxytryptamine (serotonin, 5-HT) neurones.

OBJECTIVE

We wished to examine MDMA-induced hyperthermia in rats housed at normal (19 degrees C) and high (30 degrees C) room temperatures and investigate the effect of a prior neurotoxic lesion.

METHODS

Rectal temperature was measured after administration of single or repeated doses of MDMA to rats housed at 19 degrees C and 30 degrees C.

RESULTS

MDMA (5 mg/kg i.p.) produced a sustained hyperthermic response in rats housed at 30 degrees C, but not in rats housed at 19 degrees C. A prior (5 weeks earlier) neurotoxic dose of MDMA (12.5 mg/kg i.p.) resulted in MDMA (5 mg/kg) producing a greater hyperthermic response in rats housed at 30 degrees C than in non-pre-treated animals. Repeated MDMA administration (binge dosing; 2, 4 or 6 mg/kg x3) produced dose-dependent hyperthermia in rats housed at 19 degrees C, with MDMA (2 mg/kg x3) having little effect. However, this dose produced significant hyperthermia (> or =2 degrees C above control values)in rats housed at 30 degrees C following the third dose. A prior neurotoxic dose of MDMA resulted in MDMA (2 mg/kg x3) producing marked hyperthermia (>1 degrees C) after the first dose and severe hyperthermia (> or =2 degrees C) after the third dose.

CONCLUSIONS

MDMA administration to rats housed at 30 degrees C produces a more severe hyperthermic response than that seen in rats housed at 19 degrees C. A prior neurotoxic dose enhances the response further in animals housed at 30 degrees C. Binge dosing produces a higher final peak response than a similar non-divided dose. This effect is more marked in animals housed at high room temperature. These data may have implications for recreational users of MDMA in hot environments, particularly those who may have damaged serotoninergic neurones because of prior heavy or frequent use of the drug.

The pharmacology and clinical pharmacology of 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy")

The amphetamine derivative (+/-)-3,4-methylenedioxymethamphetamine (MDMA, ecstasy) is a popular recreational drug among young people, particularly those involved in the dance culture. MDMA produces an acute, rapid enhancement in the release of both serotonin (5-HT) and dopamine from nerve endings in the brains of experimental animals. It produces increased locomotor activity and the serotonin behavioral syndrome in rats. Crucially, it produces dose-dependent hyperthermia that is potentially fatal in rodents, primates, and humans. Some recovery of 5-HT stores can be seen within 24 h of MDMA administration. However, cerebral 5-HT concentrations then decline due to specific neurotoxic damage to 5-HT nerve endings in the forebrain. This neurodegeneration, which has been demonstrated both biochemically and histologically, lasts for months in rats and years in primates. In general, other neurotransmitters appear unaffected. In contrast, MDMA produces a selective long-term loss of dopamine nerve endings in mice. Studies on the mechanisms involved in the neurotoxicity in both rats and mice implicate the formation of tissue-damaging free radicals. Increased free radical formation may result from the further breakdown of MDMA metabolic products. Evidence for the occurrence of MDMA-induced neurotoxic damage in human users remains equivocal, although some biochemical and functional data suggest that damage may occur in the brains of heavy users. There is also some evidence for long-term physiological and psychological changes occurring in human recreational users. However, such evidence is complicated by the lack of knowledge of doses ingested and the fact that many subjects studied are or have been poly-drug users.

Femoral neck and intertrochanteric fractures: radiographic indicators of fracture healing

Serial hip radiographs from 280 patients with proximal femoral fractures were analyzed retrospectively by 3 radiologists to evaluate conventional radiographic healing patterns. Patients with hemiarthroplasty or insufficient follow-up were excluded. In the remaining 41 patients, the fracture line and callus was assessed. Intertrochanteric fractures demonstrated increasing callus and sclerosis at the fracture site. No such association was seen in femoral neck fractures. Traditional indicators of fracture healing cannot be readily applied at the hip. Radiographic features relate more to fracture type and fixation method.

The evaluation of a new digital semi-automated system for the radiological assessment of distal radial fractures

OBJECTIVE

To compare intra- and inter-observer variation for measurements of wrist deformity using a manual method of measurement and a semi-automated digital system developed in our department.

DESIGN

Four observers measured radial angle, radial shift, radial length, palmar tilt, and dorsal shift on ten wrist-fracture films using a standardised protocol. Each observer made measurements directly from the radiograph on three occasions, and on a further three occasions digitised images were viewed and measurements made with semi-automated on-screen measurement tools.

RESULTS

Manual measurements took 12 min per case compared with 3 min for the digital system. The digital system resulted in improved intra-observer variation for all measurements and an improvement in inter-observer variation for all measurements except posterior tilt.

CONCLUSION

The new system allows greater precision in assessing fracture reduction and follow-up. Its principal application is in studies that utilise the wrist as a model for fracture healing.

In vitro evidence that 5-hydroxytryptamine increases efflux of glial glutamate via 5-HT(2A) receptor activation

Recent studies have established the presence of 5-hydroxytryptamine (5-HT)(2A) receptors on glial cells in culture and in the brain in situ. Here we used cultured C6 glioma cells to investigate the possibility that 5-HT(2A) receptors on glia regulate glutamate release from the cell. The efflux of endogenous glutamate from cultured C6 glioma cells was increased by addition of 5-HT in a concentration-dependent manner (maximal effect +200%). The efflux of serine and aspartate was not altered. The effect of 5-HT was mimicked by both the nonselective 5-HT receptor agonist quipazine and the selective 5-HT(2) receptor agonist 4-iodo-2,5-dimethoxyamphetamine (DOI; both 0.01-100 microM). The 5-HT(2A) receptor antagonists ketanserin (1 microM) and spiperone (1 microM) inhibited the glutamate response to 5-HT, quipazine, and DOI, whereas the effect of 5-HT was not inhibited by the 5-HT(2B/C) receptor antagonist SB200646 (1 microM). The effect of 5-HT on glutamate was specific in that it was reduced in low-calcium medium but was not prevented by furosemide (5 mM), which prevents cell swelling-induced glutamate release. Finally, the glutamate uptake inhibitor 2,4,trans-pyrollidine dicarboxylic acid (50 microM) did not block the 5-HT-induced efflux of glutamate, making involvement of glutamate transport unlikely. In conclusion, 5-HT stimulates the efflux of glutamate from C6 glioma cells following 5-HT(2A) receptor activation and involves a calcium-dependent mechanism.

The pharmacology of the acute hyperthermic response that follows administration of 3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') to rats

1. The pharmacology of the acute hyperthermia that follows 3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') administration to rats has been investigated. 2. MDMA (12.5 mg kg(-1) i.p.) produced acute hyperthermia (measured rectally). The tail skin temperature did not increase, suggesting that MDMA may impair heat dissipation. 3. Pretreatment with the 5-HT(1/2) antagonist methysergide (10 mg kg(-1)), the 5-HT(2A) antagonist MDL 100,907 (0.1 mg kg(-1)) or the 5-HT(2C) antagonist SB 242084 (3 mg kg(-1)) failed to alter the hyperthermia. The 5-HT(2) antagonist ritanserin (1 mg kg(-1)) was without effect, but MDL 11,939 (5 mg kg(-1)) blocked the hyperthermia, possibly because of activity at non-serotonergic receptors. 4. The 5-HT uptake inhibitor zimeldine (10 mg kg(-1)) had no effect on MDMA-induced hyperthermia. The uptake inhibitor fluoxetine (10 mg kg(-1)) markedly attenuated the MDMA-induced increase in hippocampal extracellular 5-HT, also without altering hyperthermia. 5. The dopamine D(2) antagonist remoxipride (10 mg kg(-1)) did not alter MDMA-induced hyperthermia, but the D(1) antagonist SCH 23390 (0.3 - 2.0 mg kg(-1)) dose-dependently antagonized it. 6. The dopamine uptake inhibitor GBR 12909 (10 mg kg(-1)) did not alter the hyperthermic response and microdialysis demonstrated that it did not inhibit MDMA-induced striatal dopamine release. 7. These results demonstrate that in vivo MDMA-induced 5-HT release is inhibited by 5-HT uptake inhibitors, but MDMA-induced dopamine release may not be altered by a dopamine uptake inhibitor. 8. It is suggested that MDMA-induced hyperthermia results not from MDMA-induced 5-HT release, but rather from the increased release of dopamine that acts at D(1) receptors. This has implications for the clinical treatment of MDMA-induced hyperthermia.

2-Aryl indole NK(1) antagonists: optimisation of the amide substituent

The in vivo properties of a series of 2-arylindole NK(1) antagonists have been improved, by modification of the amide substituent. The 1-(2-methoxyphenyl)piperazine amide was identified as a major area of metabolism in the lead compound 1. Replacement of this amine moiety by a 4-benzyl-4-hydroxypiperidine resulted in a compound 18 with reduced clearance and improved central duration of action.

Crossover phase behavior (discotic to calamitic) in liquid-crystalline copper complexes. Dependence on the length and position of alkoxy chains in new polycatenar bis[5-(dialkoxybenzylidine)aminotropololonato]copper(II) complexes

New polycatenar metallomesogens have been synthesized containing a tropolone core joined to benzylidine terminal rings. Variation of the position, number, and nature of alkoxy substituents on the terminal rings allows for the control of the phase behavior of the compounds. In particular, for copper complexes with 3,4-dialkoxy substitution, a change from calamitic to discotic (columnar) behavior is seen as the chain lengths are increased.

A study of the mechanisms involved in the neurotoxic action of 3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') on dopamine neurones in mouse brain

1. Administration of 3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') to mice produces acute hyperthermia and long-term degeneration of striatal dopamine nerve terminals. Attenuation of the hyperthermia decreases the neurodegeneration. We have investigated the mechanisms involved in producing the neurotoxic loss of striatal dopamine. 2. MDMA produced a dose-dependent loss in striatal dopamine concentration 7 days later with 3 doses of 25 mg kg(-1) (3 h apart) producing a 70% loss. 3. Pretreatment 30 min before each MDMA dose with either of the N-methyl-D-aspartate antagonists AR-R15896AR (20, 5, 5 mg kg(-1)) or MK-801 (0.5 mg kg(-1)x3) failed to provide neuroprotection. 4. Pretreatment with clomethiazole (50 mg kg(-1)x3) was similarly ineffective in protecting against MDMA-induced dopamine loss. 5. The free radical trapping compound PBN (150 mg kg(-1)x3) was neuroprotective, but it proved impossible to separate neuroprotection from a hypothermic effect on body temperature. 6. Pretreatment with the nitric oxide synthase (NOS) inhibitor 7-NI (50 mg kg(-1)x3) produced neuroprotection, but also significant hypothermia. Two other NOS inhibitors, S-methyl-L-thiocitrulline (10 mg kg(-1)x3) and AR-R17477AR (5 mg kg(-1)x3), provided significant neuroprotection and had little effect on MDMA-induced hyperthermia. 7. MDMA (20 mg kg(-1)) increased 2,3-dihydroxybenzoic acid formation from salicylic acid perfused through a microdialysis tube implanted in the striatum, indicating increased free radical formation. This increase was prevented by AR-R17477AR administration. Since AR-R17477AR was also found to have no radical trapping activity this result suggests that MDMA-induced neurotoxicity results from MDMA or dopamine metabolites producing radicals that combine with NO to form tissue-damaging peroxynitrites.

2-Aryl indole NK1 receptor antagonists: optimisation of indole substitution

The synthesis and biological evaluation of a series of 2-aryl indoles with high affinity for the human neurokinin-1 (hNK1) receptor are reported, concentrating on optimisation of the indole substitution.

2-Aryl indole NK1 receptor antagonists: optimisation of the 2-aryl ring and the indole nitrogen substituent

Novel 2-aryl indole hNK1 receptor ligands were prepared utilising palladium cross-coupling chemistry of a late intermediate as a key step. Compounds with high hNK1 receptor binding affinity and good brain penetration (e.g., 9d) were synthesised.

A cost-benefit analysis of RSV prophylaxis in high-risk infants

OBJECTIVE

To determine the cost and benefit of using RSV-IG and palivizumab as prophylactic therapy against respiratory syncytial virus (RSV)-associated illness in high-risk infants.

METHODS

A nonrandomized, retrospective, cohort control study was conducted comparing the outcomes of patients who received either RSV-IG or palivizumab therapy against RSV during the 1998-1999 RSV season with patients identified from the 1994-1995 RSV season who would have been eligible to receive prophylaxis had either agent been available at that time. Medical record reviews were conducted to gather data regarding the costs associated with both the administration of the prophylactic drugs and the treatment of RSV-associated hospitalizations in both groups. Decision analysis was used to determine the average cost per patient for both groups. A cost-benefit analysis was then conducted to determine the return on investment, if any, for the use of these drugs. A sensitivity analysis was also conducted to determine the robustness of the data.

RESULTS

Patients who received RSV-IG or palivizumab had a hospitalization rate of 1.6% compared with 25% for the group who did not receive prophylactic drugs. The average costs for the RSV prophylaxis group were less per patient $3,733 compared with $4,258 in the group who did not receive prophylaxis. The benefit is a 23.4% lower chance of hospitalization for each infant or, in dollar figures, $3,985 ($17,031 x 0.234). The benefit-cost ratio is 1.15:1 ($3,985:3,461). The benefits, therefore, exceed the costs associated with the prophylaxis program. The prophylaxis program saved healthcare dollars by preventing RSV-related hospital-izations.

CONCLUSIONS

Results demonstrate that when used according to our institution's criteria, RSV prophylaxis is of benefit to our institution.

Electrochemical characterization of a templated insulating polymer-modified electrode

The controllable permselective behavior oftemplated poly(1,2-diaminobenzene)-modified electrodes is illustrated. The electrochemical behavior of polymer films prepared from several media, conventional aqueous solution, liquid crystalline micellar solution, and liquid crystalline hexagonal phase solution, were compared using several cationic and anionic redox probes. Films deposited from the hexagonal liquid crystalline phase were shown to be ion selective, allowing positively charged ions through to react at the electrode surface while excluding negatively charged ions. This permselective behavior was unique to the hexagonally templated films and was not exhibited by films deposited from either the conventional aqueous or the micellar media (which were completely blocking to both types of ion). In addition, it was shown that by altering the ionic strength of the background electrolyte control over the charge selective behavior of the hexagonally templated films was possible.

A neurotoxic dose of 3,4-methylenedioxymethamphetamine (MDMA; ecstasy) to rats results in a long-term defect in thermoregulation

RATIONALE

3,4-Methylenedioxymethamphetamine (MDMA; "ecstasy") administration to rats produces damage to cerebral 5-HT nerve endings; however, the long-term functional consequences of this damage are poorly understood.

OBJECTIVE

To confirm that MDMA administration produces a long-term effect on thermoregulation and investigate the mechanisms involved.

METHODS

Male Dark Agouti rats were injected with a neurotoxic dose of MDMA (12.5 mg/kg i.p.). Five to 6 weeks later, they were exposed to high ambient temp (30 degrees C) for 60 min followed by a return to normal temp (20 degrees C), with rectal temperature being measured under both conditions. Further groups of MDMA-pretreated rats were challenged with 8-OH-DPAT and their temperature response measured.

RESULTS

MDMA administration produced acute hyperthermia. Rectal temperature had normalised 24 h later and was similar to saline-injected controls over the following 15 days. MDMA administration produced a 37% loss in hypothalamic 5-HT content 18 days later. When MDMA-pretreated rats were subjected to high ambient temperature 33 days posttreatment, they displayed both a faster rise in rectal temperature and sustained hyperthermia when returned to normal conditions. There was no difference in their hypothermic response to the 5-HT1A agonist 8-OH-DPAT.

CONCLUSIONS

A neurotoxic dose of MDMA resulted in impaired thermoregulation when rats were exposed to high ambient temperature. 5-HT1A receptor mechanisms were unaltered. Impaired serotonergic function following MDMA presumably alters the neurotransmitter balance, thereby compromising thermoregulation. Heavy recreational users of MDMA may also have impaired thermoregulation and thus be at greater risk of an acute adverse response to MDMA in a hot crowded dance environment.