Neuromuscular responses to hydration in moderate to warm ambient conditions during self-paced high-intensity exercise

OBJECTIVE

To examine the neuromuscular responses to 60 minutes of self-paced high-intensity exercise punctuated with 6 × 1-minute "all-out" sprints at 10-minute intervals in moderate (19.8°C, SEM 0.3) and warm (33.2, SEM 0.1), humid (∼64% relative humidity) conditions with either complete hydration (CH) or without hydration (NF).

DESIGN

Seven subjects (mean age 20.6 years (SE 1.1), mass 73.8 kg (SE 4.5), peak power 288 W (SE 11.3)) performed the time trial on four separate occasions, which were differentiated by ambient temperature and fluid ingestion. For each sprint interval, distance, power output and electromyographic (EMG) data from the rectus femoris and vastus lateralis muscles were recorded.

RESULTS

The NF trials resulted in a reduction in body mass for the moderate and warm conditions of 1.7% and 2.1%, respectively. Final rectal temperatures were not different among conditions (∼38.7°C). Total body sweating was higher in the warm condition (19.1-21.3 ml/kg per hour) compared with the moderate condition (16.1-16.5 ml/kg per hour; p<0.05). Neither fluid ingestion nor ambient temperature altered total distance cycled for any of the trials (range 30.1-32.6 km). The normalised integrated EMG (as percentage of maximal voluntary contraction) when compared with the first sprint increased from sprint three for the rectus femoris muscle in both no and complete hydration but decreased for the vastus lateralis muscle. The mean percentile frequency shift increased for both the vastus lateralis and rectus femoris muscles in both no and complete hydration.

CONCLUSIONS

These results suggest that the integrity of the neuromuscular system is adjusted according to hydration status and ambient temperatures during intense self-paced cycling.

Normalized lengthening peak torque is associated with temporal twitch characteristics in elderly women but not young women

AIM

To determine if greater normalized torque during maximal effort lengthening actions in elderly women compared with young women is related to age-associated adjustments in neural activation and/or contractile function.

METHODS

The right knee extensors of 14 young women (21-30 years) and 12 elderly women (65-78 years) were assessed for isometric, shortening and lengthening peak torque, electromyography (EMG) activity, and isometric twitch contractile properties. Knee extensor contractile tissue volume was determined using magnetic resonance imaging.

RESULTS

Normalized torque was determined as peak torque per unit of knee extensor contractile tissue volume. Normalized torque during the isometric and shortening actions was similar between age groups (P > 0.05); however, lengthening normalized torque was significantly higher for the elderly women (P < 0.05). In the young women, a significant relationship existed between normalized torque and EMG for all muscle actions (P < 0.05), while no association was found between normalized torque and temporal twitch characteristics for any muscle action (P > 0.05). In the elderly women, a significant relationship existed between normalized torque and EMG for the isometric and shortening muscle actions (P < 0.05), but not for lengthening normalized torque and EMG (P > 0.05). Furthermore, no association existed between isometric and shortening normalized torque, and temporal twitch characteristics in the elderly women (P > 0.05); however, a significant relationship existed between lengthening normalized torque, and the rate of relaxation and contraction duration (P < 0.05).

CONCLUSIONS

The greater capacity to develop lengthening peak torque relative to contractile tissue volume in the elderly women appeared to be associated with age-related adjustments in the temporal twitch characteristics rather than neural activation.

Occupational asthma caused by cellulase and lipase in the detergent industry

Three employees from two different detergent companies were investigated for occupational asthma, using skin prick tests, serum specific IgE, and specific bronchial challenge. Two were challenged with lipase and one with cellulase. All three cases had immunological evidence of sensitisation to the detergent enzymes with which they worked. Bronchial challenge in each provoked a reproducible dual asthmatic response, which reproduced their work related symptoms. These are the first reported cases of occupational asthma attributable to cellulase and lipase in the detergent industry. Four of the most common enzymes used in this industry have now been reported to cause occupational asthma; continued vigilance and caution are needed when working with these or other enzymes.

Age, diet and injury affect the survival of facial motoneurons

Using the model of facial nerve avulsion, we have compared the effects of injury, age and diet on motoneuronal survival. One to four weeks after nerve avulsion, 50-75% motoneuron loss was quantified in ad libitum-fed rats aged 7 days (neonate), 6 months (adult) and 24 months (aging) at the time of injury. Evidence of apoptosis was found for neonatal rats at 3 days post-injury, but not for neonates examined 7 days or adult or aging rats examined 1 month after injury. Non-operated, ad libitum-fed rats showed no significant loss of facial motoneurons by 24 months. Surprisingly, non-operated rats whose food intake was restricted to 15 g standard rat chow per day from the age of 6 months lost 50% of their motoneurons by 24 months. Facial nerve avulsion of 24-month-old rats raised on this restricted diet did not result in any additional loss of motoneurons one month after injury. These results challenge the common view that aging results in neuronal loss and that dietary restriction is universally beneficial.

A reproducible and variable intensity cycling performance protocol for warm conditions

This study was undertaken to assess the reproducibility of a variable intensitycycling protocol using subjects of varying abilities, under warm humid conditions. Eleven subjects (Age 21.4+/-2.6 years; VO2peak 3.30+/-0.9 l x min(-1); peak power 322.8+/-86.3 W; mean+/-SD) performed a 60 min cycling trial punctuated with six one-min "all-out" sprints at 10-min intervals on three occasions 5-14 days apart. Ambient temperature and relative humidity were set at 33+/-0.7 degrees C and 63+/-2.0%, respectively. Subjects used their own bicycle mounted to an electromagnetic trainer and were only permitted to monitor elapsed time and heart rate. Repeatability was assessed using the limits of agreement which were best between trials 2 and 3 where the distance cycled was -0.54 km below and 1.34 km above the distance cycled for trial 2. The co-efficient of variation (CV) for distance for three trials was 3.58%. For trials 1 and 2 the CV was 3.54% (r = 0.97, p< 0.001) decreasing to 1.34% (r = 0.99, p< 0.001) for trials 2 and 3. The intra-class correlation for three trials was 0.93. Distance for trial 1 (26.3+/-5.0 km; p< 0.05) was less than trials 2 (27.7+/-5.7 km) and 3 (28.1+/-5.6 km). It was concluded that repeatability for this performance protocol with cyclists of varying abilities In warm humid conditions was acceptable given at least one familiarisation trial. However, it is not yet known whether other protocols designed for moderate environments are applicable to less favorable conditions. Further studies are needed before results of treatment effects under differing ambient conditions can be fully understood and assigned appropriate significance.

Ethanol impairs insulin-stimulated mitochondrial function in cerebellar granule neurons

Ethanol impairs insulin-stimulated survival and mitochondrial function in immature proliferating neuronal cells due to marked inhibition of downstream signaling through P13 kinase. The present study demonstrates that, in contrast to immature neuronal cells, the major adverse effect of chronic ethanol exposure (50 mM) in post-mitotic rat cerebellar granule neurons is to inhibit insulin-stimulated mitochondrial function (MTT activity, MitoTracker Red fluorescence, and cytochrome oxidase immunoreactivity). Ethanol-impaired mitochondrial function was associated with increased expression of the p53 and CD95 pro-apoptosis genes, reduced Calcein AM retention (a measure of membrane integrity), increased SYTOX Green and propidium iodide uptake (indices of membrane permeability), and increased oxidant production (dihydrorosamine fluorescence and H2O2 generation). The findings of reduced membrane integrity and mitochondrial function in short-term (24 h) ethanol-exposed neurons indicate that these adverse effects of ethanol can develop rapidly and do not require chronic neurotoxic injury. A role for caspase activation as a mediator of impaired mitochondrial function was demonstrated by the partial rescue observed in cells that were pre-treated with broad-spectrum caspase inhibitors. Finally, we obtained evidence that the inhibitory effects of ethanol on mitochondrial function and membrane integrity were greater in insulin-stimulated compared with nerve growth factor-stimulated cultures. These observations suggest that activation of insulin-independent signaling pathways, or the use of insulin sensitizer agents that enhance insulin signaling may help preserve viability and function in neurons injured by gestational exposure to ethanol.

[Not Available]

I am an enrolled nurse on the conversion course and my indepth study concerns nutrition and elderly people. Part of my remit is to introduce a tool. Can anyone help? I would be grateful for any information.

Power transcranial Doppler ultrasound in the detection of intracranial aneurysms

BACKGROUND AND PURPOSE

We sought to perform a large, prospective, multicenter, blinded study comparing power transcranial color duplex sonography (power TCDS) with intra-arterial digital subtraction angiography (IADSA) in the detection of intracranial aneurysms.

METHODS

Contemporaneous TCDS and IADSA examinations were performed in 171 subjects with suspected intracranial aneurysm. Via the temporal bone window, a 2-dimensional hand-held noncontrast transcranial duplex ultrasound imaging system was used operating in power and spectral modes. Sonographers were blinded to clinical history and results of brain CT and IADSA.

RESULTS

We found that 157 subjects (92%) had an adequate bone window. Sensitivity per patient was 0.78 (95% CI, 0.66 to 0.87) and 0.46 (95% CI, 0.36 to 0.56) for any anterior circulation aneurysms. Sensitivity was 0.35 (95% CI, 0.24 to 0.46) for aneurysms </=5 mm and 0.81 (95% CI, 0.62 to 0.94) for aneurysms >5 mm. Accuracy was lower for aneurysms on the cavernous and terminal internal carotid arteries, including posterior communicating artery origin (0.71; 95% CI, 0.63 to 0.79), than for those on the anterior (0.82; 95% CI, 0.74 to 0.89) or the middle cerebral arteries (0.79; 95% CI, 0.71 to 0.86).

CONCLUSIONS

Power TCDS is a promising, inexpensive, noninvasive test for anterior circulation intracranial aneurysms but is less sensitive per aneurysm than alternatives such as CT angiography or MR angiography. Sensitivity is poor for aneurysms </=5 mm in diameter. The internal carotid artery is the most difficult segment to interpret.

Ageing is not associated with a decline in neuromuscular innervation or reduced specific force in men aged 20 and 50 years

The exact mechanisms responsible for the decline in strength with age are yet to be completely elucidated. Three proposed mechanisms responsible for the detrimental effect of increasing age on strength include changes in muscle mass, specific force and/or neuromuscular innervation. Thus, the purpose of this investigation was to determine if the age-related reduction in peak isometric strength was primarily associated with changes in muscle cross-sectional area, neuromuscular innervation and/or specific force. The cross-sectional area of the knee extensor muscles (QCSA) was estimated in 13 younger men (YM; 20.8 +/- 1.6 years) and eight middle-aged men (MM; 53.8 +/- 4.2 years) prior to performing a series of four maximal voluntary isometric contractions on an isokinetic dynamometer at an angle of 60 degrees knee flexion. Peak force was determined and surface electromyography was sampled from the rectus femoris muscle during each maximal voluntary contraction. The cross-sectional area of the knee extensor muscles, peak force and integrated electromyography (IEMG) were significantly lower in the MM (P<0.01). However, when peak force and peak IEMG values were corrected for QCSA, there were no significant differences between age groups. These results suggest that the reduction in peak isometric force observed in the MM was primarily associated with quantitative changes in muscle mass, rather than reduced neuromuscular innervation or specific force. Therefore, preserving muscle mass through resistance training may significantly reduce the age-associated differences in peak strength and assist in promoting quality of life and functional independence in older adults.

Evidence for neuromuscular fatigue during high-intensity cycling in warm, humid conditions

The purpose of this study was to examine and describe the neuromuscular changes associated with fatigue using a self-paced cycling protocol of 60-min duration, under warm, humid conditions. Eleven subjects [mean (SE) age 21.8 (0.8) years; height 174.9 (3.0) cm; body mass 74.8 (2.7) kg; maximum oxygen consumption 50.3 (1.8) ml.kg.min-1] performed one 60-min self-paced cycling time trial punctuated with six 1-min "all out" sprints at 10-min intervals, while 4 subjects repeated the trial for the purpose of determining reproducibility. Power output, integrated electromyographic signal (IEMG), and mean percentile frequency shifts (MPFS) were recorded at the mid-point of each sprint. There were no differences between trials for EMG variables, distance cycled, mean heart rate, and subjective rating of perceived exertion for the subjects who repeated the trial (n = 4). The results from the repeated trials suggest that neuromuscular responses to self-paced cycling are reproducible between trials. The mean heart rate for the 11 subjects was 163.6 (0.71) beats.min-1. Values for power output and IEMG expressed as a percentage of that recorded for the initial sprint decreased during sprints 2-5, with normalised values being 94%, 91%, 87% and 87%, respectively, and 71%, 71%, 73%, and 77%, respectively. However, during the final sprint normalised power output and IEMG increased to 94% and 90% of initial values, respectively. MPFS displayed an increase with time; however, this was not significant (P = 0.06). The main finding of this investigation is the ability of subjects to return power output to near initial values during the final of six maximal effort sprints that were included as part of a self-paced cycling protocol. This appears to be due to a combination of changes in neuromuscular recruitment, central or peripheral control systems, or the EMG signal itself. Further investigations in which changes in multiple physiological systems are assessed systematically are required so that the underlying mechanisms related to the development of fatigue during normal dynamic movements such as cycling can be more clearly delineated.

Oxygen free radical injury is sufficient to cause some Alzheimer-type molecular abnormalities in human CNS neuronal cells

Cell loss and neuritic/cytoskeletal lesions represent two of the major categories of dementia-associated structural abnormalities in Alzheimer's disease (AD). Cell loss is ultimately mediated by apoptosis and mitochondrial DNA damage due to enhanced sensitivity to oxidative stress, but the mechanism responsible for the neuritic/cytoskeletal lesions including the abnormal proliferation of cortical neurites is not known. This study examines the potential role of oxygen free radical injury as a factor contributing to both cell death and neuritic sprouting cascades in AD. PNET2 human neuronal cells were treated with H2O2 (8 micro M to 88 micro M) for 24 hours and then analyzed for viability, DNA damage, and pro-apoptosis, survival, and sprouting gene expression and signaling. H2O2-treatment resulted in dose-dependent increases in cell death due to genomic and mitochondrial DNA damage associated with increased levels of 8-OHdG and the p53 and CD95 pro-apoptosis genes, reduced levels of the Bcl-2 survival gene, activation of JNK and p38 stress kinases, and inhibition of PI3 kinase survival signaling. However, the H2O2-treated cells also manifested increased expression of growth and sprouting molecules, including GAP-43, nitric oxide synthase 3, neuronal thread protein (NTP; approximately 17 kD and approximately 21 kD forms), proliferating cell nuclear antigen, and phospho-Erk MAPK, and normal levels of the AD-associated approximately 41 kD NTP species, cyclin dependent kinase 5 (cdk-5), and phospho-tau. In addition, the H2O2-treated cells had increased levels of p25, the catalytically active and stable cleavage product of p35, which regulates cdk-5 activity. Previous studies demonstrated p25 accumulation in AD brains and p25-induced hyperphosphorylation of tau and neuronal apoptosis. The findings herein suggest that oxygen free radical injury in human CNS neuronal cells is sufficient to cause some but not all of the pro-death and pro-sprouting molecular abnormalities that occur in AD.

Oxidative stress and hypoxia-like injury cause Alzheimer-type molecular abnormalities in central nervous system neurons

Neuronal loss and neuritic/cytoskeletal lesions (synaptic disconnection and proliferation of dystrophic neurites) represent major dementia-associated abnormalities in Alzheimer's disease (AD). This study examined the role of oxidative stress as a factor contributing to both the cell death and neuritic degeneration cascades in AD. Primary neuron cultures were treated with H2O2 (9-90 microM) or desferrioxamine (2-25 microM) for 24 h and then analyzed for viability, mitochondrial mass, mitochondrial function, and pro-apoptosis and sprouting gene expression. H2O2 treatment causes free-radical injury and desferrioxamine causes hypoxia-type injury without free radical generation. The H2O2-treated cells exhibited sustained viability but neurite retraction, impaired mitochondrial function, increased levels of the pro-apoptosis gene product CD95/Fas, reduced expression of N2J1-immunoreactive neuronal thread protein and synaptophysin, and reduced distribution of mitochondria in neuritic processes. Desferrioxamine treatment resulted in dose-dependent neuronal loss associated with impaired mitochondrial function, proliferation of neurites, and reduced expression of GAP-43, which has a role in path-finding during neurite outgrowth. The results suggest that oxidative stress can cause neurodegeneration associated with enhanced susceptibility to apoptosis due to activation of pro-apoptosis genes, neurite retraction (synaptic disconnection), and impaired transport of mitochondria to cell processes where they are likely required for synaptic function. In contrast, hypoxia-type injury causes neuronal loss with proliferation of neurites (sprouting), impaired mitochondrial function, and reduced expression of molecules required to form and maintain synaptic connections. Since similar abnormalities occur in AD, both oxidative stress and hypoxic injury can contribute to AD neurodegeneration.

Intravenous sedation in pediatric dentistry using midazolam, nalbuphine and droperidol

PURPOSE

The purpose of this pilot investigation was to study the efficacy, physiologic responses, and safety of a multi-drug intravenous conscious sedation technique in an outpatient setting in children who demonstrated uncooperative behavior when comprehensive restorative dental treatment was attempted.

METHODS

Using a time-based sedation record, the physiologic responses of 153 healthy children, age range 23 months to 14.5 years, were measured after they had received midazolam (Versed), nalbuphine (Nubain), and droperidol (Inapsine), each administered intravenously, and nitrous oxide and oxygen administered by nasal mask, while each child received comprehensive restorative or surgical dental care. Each patient was monitored according to the American Academy of Pediatrics Sedation Guidelines. Heart rate and rhythm, blood pressure, respiratory rate, hemoglobin oxygen saturation, end-tidal CO2, level of sedation, and behavioral responses were recorded preoperatively, at 5 minute intervals during treatment and in recovery until discharge. Sedation was titrated to Level 2 or 3 during treatment as defined by the American Academy of Pediatric Dentistry Reference Manual.

RESULTS

For each child, the sedation level was judged to be either acceptable or optimal for the completion of all planned dental treatment. There were no sedation failures. Children under 20 kg required significantly higher dosages of each sedative medication than children more than 20 kg to achieve the same level of sedation (P < 0.001, ANOVA). There were no episodes of intraoperative vomiting, hypotension, cardiac arrhythmias, respiratory depression requiring respiratory support, or dysphoria during treatment, in the recovery period, or after discharge.

CONCLUSION

This multi-drug intravenous conscious sedation technique is a safe and effective method to control the behavior of uncooperative children who require comprehensive dental treatment.

Accuracy of a miniature intracranial pressure monitor, its function during magnetic resonance scanning, and assessment of image artifact generation

OBJECTIVE

We examined the accuracy and repeatability of an intracranial pressure (ICP) monitor (Codman MicroSensor; Johnson & Johnson Professional, Inc., Raynham, MA) in a nonmagnetic environment and during magnetic resonance imaging (MRI). The resulting image artifact generation was calculated. ICP monitoring is essential in management of severe head injury, but few ICP monitoring devices are compatible with use in an MRI scanner. The use of MRI to assess head injury is increasing, and developing safe methods of continuously monitoring ICP may improve patient care.

METHODS

A water manometer was used as the standard for comparison. We assessed pressure readings from the ICP monitor in a nonmagnetic environment using a standard and a long connector cable between the pressure transducer and display unit. This long cable permitted testing during MRI sequences because the display unit could be distanced from the magnet. Accuracy was determined during T2-weighted imaging, proton spectroscopy, and diffusion-weighted imaging, and artifact generation was assessed.

RESULTS

We found a high degree of accuracy for repeated measurements over a clinical pressure range using both standard and long connector cables outside the MRI room. During MRI scanning, the ICP monitor was accurate during T2 and proton spectroscopy sequences. Accuracy during diffusion-weighted imaging, however, was clinically unacceptable. This ICP monitor creates a reduction in signal-to-noise ratio in the received signal during T2-weighted imaging and proton spectroscopic imaging, with the obtained images still radiologically interpretable.

CONCLUSION

The Codman ICP monitor is sufficiently accurate and free of artifact generation to be used during most clinical MRI applications. This could enhance patient monitoring and safety.

The use of diffusion tensor imaging in quantifying the effect of dexamethasone on brain tumours

The role of dexamethasone in the treatment of patients with brain tumours remains poorly understood. In this study the self-diffusion parameters of extracellular water within primary intracranial tumours and peritumoural tissue, and their response to dexamethasone, have been measured using MR diffusion tensor imaging. Maps of the mean diffusivity <D> and two measures of diffusion anisotropy were obtained from six patients before, and typically 48-72h after, commencing dexamethasone treatment. A significant decrease in <D> of either tumour (p < 0.02) or oedematous brain (p < 0.04) was observed in three patients. No significant changes were noted in either of the two calculated diffusion anisotropy indices before and after steroid treatment in any of the six patients.

1H spectroscopic imaging of acute head injury--evidence of diffuse axonal injury

Using single slice two-dimensional spectroscopic imaging (SI), nine acute head injury patients and six controls have been successfully scanned. The problems presented by the need for ITU monitoring of these patients during MR scanning was overcome using MR compatible monitoring equipment. In previous studies of head injury which used proton spectroscopy, single voxel localisation procedures have meant that the spatial extent of the spectral data has been limited. With spectral data from a whole axial slice, we have been able to identify NAA abnormalities in regions remote to any T2 visible lesions. This suggests that SI (of NAA in particular) will be useful for the diagnosis of diffuse axonal injury.

A macrolactam inhibitor of T helper type 1 and T helper type 2 cytokine biosynthesis for topical treatment of inflammatory skin diseases

T lymphocytes play a critical part in inflammatory skin diseases but are targeted by available therapies that have only partial efficacy, significant side-effects, or both. Because psoriasis, atopic dermatitis, and allergic contact hypersensitivity are associated with T helper type 1 (Th1), T helper type 2 (Th2), or mixed Th1-Th2 cell subsets and cytokine types, respectively, there is a need for a better broad-based inhibitor. The macrolactam ascomycin analog, ABT-281, was found to inhibit potently T cell function across species and to inhibit expression of multiple cytokines in human peripheral blood leukocytes which have been found in human skin disease cells and tissues. These included immunoregulatory Th1 (interleukin-2 and interferon-gamma) and Th2 (interleukin-4 and interleukin-5) cytokines. ABT-281 was shown to have potent topical activity (ED50 = 0.6% in acetone/olive oil) in a stringent swine model of allergic contact hypersensitivity, but its potency was markedly reduced compared with ascomycin when administered systemically due to more rapid clearance. Topical application of 3% ABT-281 in acetone/olive oil over 25% of the body surface in swine resulted in undetectable blood levels. Compared with a wide potency range of topical corticosteroids in clinical formulations, 0.3% and 1% ABT-281 ointments profoundly inhibited dinitrochlorobenzene-induced contact hypersensitivity in the pig by 78% and 90%, respectively, whereas super-potent steroids such as clobetasol propionate only inhibited in the 50% range and mild to moderate potency steroids such as fluocinolone acetonide were inactive. The potent topical activity of ABT-281 in swine, its superior efficacy, its rapid systemic clearance following uptake into the bloodstream, and its ability to inhibit cytokine biosynthesis of both Th1 and Th2 cell subsets, suggests that it will have a broad therapeutic value in inflammatory skin diseases, including psoriasis, atopic dermatitis, and allergic contact dermatitis.

Production and evaluation of guidelines for the management of inflammatory bowel disease: the Leicester experience

Consensus guidelines for the management of patients with inflammatory bowel disease were produced by gastroenterologists, gastrointestinal surgeons and a cross-section of general practitioners (GPs) from Leicestershire in order to develop a seamless pattern of care with a common approach to diagnosis and treatment. It was hoped that the guidelines would encourage a movement towards care in the community for many patients with stable disease and so speed up new consultation rates. The study then assessed the impact of these guidelines on the referral letters of GPs to hospital consultants, the prediction of disease and adherence to them on re-referring patients after discharge. The guidelines were distributed to all 487 GPs in the Leicester Health Authority area and the gastroenterology teams within the hospitals. The value of the guidelines was assessed by an audit of referral letters, the length of time from referral letter to out-patient appointment, both before and after the launch of the guidelines, adherence to the guidelines on re-referral, and monitoring the outcome of the discharged patients. Whilst the guidelines may have helped GPs to manage stable patients in the community, the content of referral letters and the diagnostic abilities of GPs were not seen to improve since the launch of the guidelines. However, only 5% of stable patients who were discharged from one clinic were re-referred for inflammatory bowel disease.

Studies of acute ischemic stroke with proton magnetic resonance spectroscopy: relation between time from onset, neurological deficit, metabolite abnormalities in the infarct, blood flow, and clinical outcome

BACKGROUND AND PURPOSE

Proton magnetic resonance spectroscopy (MRS) can be used to study metabolite abnormalities in the brains of stroke patients. We have used it to examine the relations between the metabolites in the infarct (N-acetylaspartate [NAA] and lactate) and the time lapse from stroke to MRS, the presenting neurological deficit, infarct size and swelling (on MRI), blood flow to the infarct (estimated by transcranial Doppler ultrasound), and clinical outcome.

METHODS

Patients with symptoms of a moderate to large cortical infarct underwent serial proton MRS (Siemens 1.5 Magnetom) within 4 days, from 5 to 10, and from 11 to 35 days after the stroke. A long echo time PRESS single voxel or chemical shift imaging acquisition was used. Transcranial Doppler ultrasound was performed daily in the first week and twice per week thereafter until the final MRS. Clinical features and baseline demographic data were collected independently by a stroke physician and 6-month outcome by postal questionnaire.

RESULTS

Fifty patients underwent at least 1 MRS examination. Reduced NAA in the infarct within the first 4 days was related to the clinical stroke syndrome, more extensive infarction, more severely reduced blood supply to the infarct, and the presence of lactate. The presence of lactate was related to large infarcts and reduced NAA. Swelling in the infarct was most closely associated with large infarcts and reduced blood supply but not reduced NAA or the presence of lactate. Clinical outcome was most closely related to the extent of the infarct (more than to the clinical syndrome)--the larger the infarct the worse the outcome--but not to the metabolite concentrations alone.

CONCLUSIONS

The reduction in NAA (but not the presence of lactate) in a visible infarct was related to the reduction in blood flow to the infarct, which in turn was related to infarct extent and clinical outcome.

Diffusion anisotropy measurements in ischaemic stroke of the human brain

Magnetic resonance diffusion imaging was performed on 12 patients presenting with symptoms of acute ischaemic stroke (1-6 days post-ictus). Apparent diffusion coefficient (ADC) and diffusion anisotropy measurements were obtained from ischaemic and contralateral normal regions. ADC measurements were decreased by around 40% in ischaemic regions, indicated by an average stroke to normal ratio of 0.56 +/- 0.04 (p < 0.0001). The measured anisotropy was shown to be significantly increased in ischaemic regions, using both standard deviation and volume ratio anisotropy indices, which gave stroke to normal ratios of 1.78 +/- 0.27 (p = 0.003) and 0.87 +/- 0.05 (p = 0.005) respectively. The effects of gradient interactions, image registration, noise contamination and rotational variance and their implications for the results obtained in this study are discussed.

Does the size of intracranial aneurysms change with intracranial pressure? Observations based on color "power" transcranial Doppler ultrasound

OBJECT

The authors sought to determine whether the increased pulsatility of aneurysms, compared with normal intracranial arteries, on color "power" transcranial Doppler (TCD) ultrasound was due to a true change in aneurysm size and whether aneurysm dimensions change with intracranial pressure (ICP).

METHODS

The authors studied nine patients who had suffered recent subarachnoid hemorrhages complicated by hydrocephalus requiring intraventricular cerebrospinal fluid drainage, in whom the presence of an aneurysm was confirmed on angiographic examination. Color "power" TCD studies of the intracranial arteries and aneurysm were obtained through the temporal bone window before and after insertion of the ventricular drain and then at different known ICPs. Of the nine patients studied, four were examined both before and after insertion of a ventricular drain. At high ICPs, aneurysms appeared very "pulsatile" and the maximum cross-sectional area was small, whereas at low ICPs, aneurysms appeared larger and were much less pulsatile. The normal arteries did not change significantly in terms of pulsatility or maximum cross-sectional area at different levels of ICP.

CONCLUSIONS

The change in aneurysm size visualized with the aid of color power TCD is likely to be real. Aneurysm dimensions vary with ICP levels; the lesions are larger and less pulsatile at low ICPs and smaller but more pulsatile at high ICPs.

Observer variability in the measurement of the size of intracranial aneurysms using power TCD

This study assessed the observer variability for measurement of intracranial aneurysmal size visualized on color "power" Transcranial Doppler Ultrasound (TCD). Patients with recent subarachnoid hemorrhage underwent color "power" TCD blind to angiography. Identified aneurysms were measured from the frozen image (in real time or from video tape) using the trackball function. Two observers measured the maximum (systolic) and minimum (end diastolic) area of each aneurysm, and an adjacent reference artery. Each observer was blind to the other's results. Interobserver variability was assessed using the Bland and Altman technique. Thirty-nine aneurysms were identified in 32 patients in 10 months. The maximum cross-sectional area of the aneurysm was 38:41 mm2 (observer 1:observer 2), and the mean difference was -3 mm2 (95% confidence interval [CI] of the difference -5.4-1.46 mm2). The maximum cross-sectional area of the reference artery was 26:28 mm2 (observer 1:observer 2), and the mean difference was -2 mm2 (95% CI -5.7-1.2 mm2). Neither difference was significant. Intraobserver reliability also was good. The measurement of intracranial aneurysm and artery size with power TCD is reliable sufficiently for use in longitudinal studies of changes in aneurysm size.

Clinical responses to ingested fungal alpha-amylase and hemicellulase in persons sensitized to Aspergillus fumigatus?

alpha-Amylase and hemicellulase, derived from culture of Aspergillus species, are commonly added to flour as improvers during baking. Two cases of women occupationally sensitized to alpha-amylase who developed allergic symptoms after eating baked bread have been reported. With a randomized, controlled study design, we have investigated whether similar responses occur in those sensitized to Aspergillus species. Seventeen subjects with positive skin prick tests to Aspergillus fumigatus were studied. Symptomatic and physiologic responses after ingestion of bread baked with alpha-amylase and hemicellulase were compared, in a crossover fashion, with those after ingestion of bread baked without enzymes. No increase in respiratory or other symptoms, lung function, or nonspecific bronchial hyperreactivity was reported after ingestion of the enzyme-containing bread. We conclude that important clinical reactions to alpha-amylase and hemicellulase in baked bread do not frequently occur in those sensitized to Aspergillus species.

Reproducibility of metabolite peak areas in 1H MRS of brain

We studied the reproducibility of metabolite signals (from N-acetyl aspartate [NAA], choline, and creatine) measured with a standard single-voxel proton magnetic resonance spectroscopy technique (PRESS, TE = 135 ms, 8 ml VOI) in vitro and in two groups of normal volunteers. Spectral peak areas were quantified both by integration and by curve-fitting. In the in vitro study, the "between-days" variability (coefficient of variation [CV]) of measurements ranged from 0.9% to 2.3%. In the first group of volunteers (n = 12), single voxel spectroscopic measurements (8 ml VOI, 256 acquisitions [ACQs]) were made from mirror-image parts of the right and left hemispheres on 2 separate days. The "between-days" CV of measurements ranged from 9% to 18% for metabolite areas, and from 10% to 26% for metabolite area ratios. There were no significant differences between quantification method or hemisphere. After checking and optimising the MR scanner performance (in fact, it was virtually optimal), the second group (n = 4) each had six sequential single voxel spectroscopic measurements (each of 64 ACQs) from the right hemisphere (without moving the voxel) on each of 4 separate days. Even when the metabolites were measured from the same place in the same hemisphere sequentially six times in a 20-min period, the "within-run" CVs ranged from 4.4% to 17.2% for metabolite areas and from 9.7% to 17.0% for metabolite area ratios. The between-days CVs for the subjects ranged from 7.7% to 25.8% (metabolite areas) and from 10.1% to 22.6% (metabolite area ratios). The variability is due to a combination of random noise, subject motion, baseline artefacts in the spectra, and uncertainties in repositioning the VOIs. It is likely to represent the best reproducibility possible with 8-ml VOIs in cooperative, healthy volunteers carefully positioned on each occasion in a standard clinical scanner. Changes in metabolite levels in individuals must therefore be of the order of 20-40% before we can be reasonably confident of measuring them. Reproducibility in patients, who may be less cooperative, will probably be no better, and this must be taken into account in the interpretation of MRS studies in patients with brain pathology; for example, stroke, head injury, and tumours.

Asthma following occupational exposure to Lycopodium clavatum in condom manufacturers

Occupational asthma in two women employed in the manufacture of condoms is reported. The spores of Lycopodium clavatum, used as a rubber dusting agent, were identified as the causative agent.

Cyclophosphamide-associated carcinoma of urothelium: modalities for prevention

The relationship between the cyclophosphamide metabolite acrolein and hemorrhagic cystitis is well documented. Its role in inducing bladder cancer is not clear. There are at least 35 cases of cyclophosphamide-associated bladder cancer in the literature to date. We report 3 additional cases of transitional cell carcinoma of the bladder. Literature assessing the relative risk of bladder cancer associated with cyclophosphamide therapy is reviewed as are methods for decreasing the toxic effects on the urothelium of the metabolite acrolein.

Thallium 201 kinetics in stunned myocardium characterized by severe postischemic systolic dysfunction

The hypothesis tested in this study was that despite the presence of severe postischemic myocardial dysfunction ("stunning"), the extraction and subsequent intracellular washout of thallium 201 should be preserved as long as irreversible sarcolemmal membrane injury was avoided. To produce myocardial stunning, 19 open-chested dogs with a critical left anterior descending coronary artery (LAD) stenosis underwent 10 5-minute periods of total LAD occlusion, each interspersed by 10 minutes of reperfusion by reflow through the critical stenosis. In another 12 control dogs observed for the same time period, no LAD occlusions were performed after placement of the critical stenosis. Hemodynamics, regional myocardial thickening by quantitative two-dimensional echocardiography, and microsphere-determined regional blood flows were serially measured. In 18 stunned dogs, systolic thickening in the LAD zone was markedly reduced to 0.4 +/- 2.4% at 40 minutes after the 10th reperfusion period compared with 32.5 +/- 2.2% thickening (p less than 0.001) in 12 control dogs at a matched time. The 201Tl first-pass extraction fraction determined by a double-isotope method using intracoronary 201Tl administration was comparable after the 10th reflow in a subgroup of 13 stunned (0.78) and six control (0.79) dogs. The T1/2 for the intracellular washout rate was also not significantly different in another group of six stunned (60 +/- 13 minutes) and six control (53 +/- 14 minutes) dogs, nor was the percentage of the 201Tl dose initially distributed in the interstitial compartment (11 +/- 3% vs. 7 +/- 2%). Systemic hemodynamics and regional flows were comparable in the two groups at 40 minutes after the 10th reflow. No dog had evidence of myocardial necrosis by triphenyl tetrazolium chloride staining. Thus, normal myocardial 201Tl extraction and washout kinetics are observed in a canine model of severe postischemic dysfunction (stunning) produced by repetitive brief LAD occlusions. These findings might have important clinical implications concerning the application of rest 201Tl scintigraphy for evaluation of perfusion and viability in patients with coronary artery disease and regional myocardial asynergy that is ultimately reversible.