Measuring ventilation and modelling M. tuberculosis transmission in indoor congregate settings, rural KwaZulu-Natal

SETTING: Molecular epidemiology suggests that most Mycobacterium tuberculosis transmission in high-burden settings occurs outside the home.

OBJECTIVE: To estimate the risk of M. tuberculosis transmission inside public buildings in a high TB burden community in KwaZulu-Natal, South Africa.

DESIGN: Carbon dioxide (CO₂) sensors were placed inside eight public buildings. Measurements were used with observations of occupancy to estimate infection risk using an adaptation of the Wells-Riley equation. Ventilation modelling using CONTAM was used to examine the impact of low-cost retrofits on transmission in a health clinic.

RESULTS: Measurements indicate that infection risk in the church, classroom and clinic waiting room would be high with typical ventilation, occupancy levels and visit durations. For example, we estimated that health care workers in a clinic waiting room had a 16.9–24.5% annual risk of M. tuberculosis infection. Modelling results indicate that the simple addition of two new windows allowing for cross-ventilation, at a cost of US$330, would reduce the annual risk to health care workers by 57%.

CONCLUSIONS: Results indicate that public buildings in this community have a range of ventilation and occupancy characteristics that may influence transmission risks. Simple retrofits may result in dramatic reductions in M. tuberculosis transmission, and intervention studies should therefore be considered.

GS-9857 in patients with chronic hepatitis C virus genotype 1-4 infection: a randomized, double-blind, dose-ranging phase 1 study

GS-9857, an inhibitor of the hepatitis C virus (HCV) nonstructural protein (NS) 3/4A, demonstrates potent activity against HCV genotypes 1-6 and improved coverage against commonly encountered NS3 resistance-associated variants (RAVs). In this study, the safety, tolerability, antiviral activity and pharmacokinetics (PK) of GS-9857 were evaluated in patients with chronic HCV genotype 1-4 infection. Patients with genotype 1-4 infection received placebo or once-daily GS-9857 at doses ranging from 50 to 300 mg for 3 days under fasting conditions. GS-9857 was well tolerated; all reported adverse events (AEs) were mild or moderate in severity. Diarrhoea and headache were the most commonly reported AEs. Grade 3 or 4 laboratory abnormalities were observed in 17% of patients receiving GS-9857; there were no Grade 3 or 4 abnormalities in alanine aminotransferase, aspartate aminotransferase or alkaline phosphatase levels. GS-9857 demonstrated potent antiviral activity in patients with chronic HCV infection, achieving mean and median maximum reductions in HCV RNA of ≥3 log10 IU/mL following administration of a 100-mg dose in patients with HCV genotype 1a, 1b, 2, 3 or 4 infection. The antiviral activity of GS-9857 was unaffected by the presence of pretreatment NS3 RAVs. In patients with genotype 1-4 infection, GS-9857 exhibited linear PK and was associated with a median half-life of 29-42 h, supporting once-daily dosing. Thus, the tolerability, efficacy and pharmacokinetic profile of GS-9857 support its further evaluation for treatment of patients with chronic HCV infection.

CODAM: a neural network model of consciousness

We present a review of the CODAM neural network control model of consciousness and develop it to arrive at a functional account of consciousness. The main feature is as a speed-up and error-correcting mechanism known, in engineering control theory, to be efficient in improving the speed of response and accuracy of any control system. We use the CODAM model to generate a set of predictions as to how such speed-up is achieved, as well as relate to previous explanations by CODAM of various attention-based phenomena.

Resolving some confusions over attention and consciousness

There is presently an ongoing debate about the relation between attention and consciousness. Thus debate is being fuelled by results from experimental paradigms which probe various forms of the interaction between attention and consciousness, such as the attentional blink, object-substitution masking and change blindness. We present here simulations of these three paradigms which can all be produced from a single overarching control model of attention. This model helps to suggest an explanation of consciousness as created through attention, and helps to explore the complex nature of attention. It indicates how it is possible to accommodate the relevant experimental results without needing to regard consciousness and attention as independent processes.

Emotion recognition in human–computer interaction

In this paper, we outline the approach we have developed to construct an emotion-recognising system. It is based on guidance from psychological studies of emotion, as well as from the nature of emotion in its interaction with attention. A neural network architecture is constructed to be able to handle the fusion of different modalities (facial features, prosody and lexical content in speech). Results from the network are given and their implications discussed, as are implications for future direction for the research.

Sequence analysis of the mannose-binding lectin (MBL2) gene reveals a high degree of heterozygosity with evidence of selection

Human mannose-binding protein (MBL) is a component of innate immunity. To capture the common genetic variants of MBL2, we resequenced a 10.0 kb region that includes MBL2 in 102 individuals representing four major US ethnic groups. In all, 87 polymorphic sites were observed, indicating a high level of heterozygosity (total pi=18.3 x 10(-4)). Estimates of linkage disequilibrium across MBL2 indicate that it is divided into two blocks, with a probable recombination hot spot in the 3' end. Three non-synonymous SNPs in exon 1 of the encoding MBL2 gene and three upstream SNPs form common 'secretor haplotypes' that can predict circulating levels. Common variants have been associated with increased susceptibility to infection and autoimmune diseases. The high frequencies of B, C and D alleles in certain populations suggest a possible selective advantage for heterozygosity. There is limited diversity of haplotype structure; the 'secretor haplotypes' lie on a restricted number of extended haplotypes, which could include additional linked SNPs, which might also have possible functional implications. There is evidence for gene conversion in the region between the two blocks, in the last exon. Our data should form the basis for conducting MBL2 candidate gene association studies using a locus-wide approach.

Neural activity in human primary motor cortex areas 4a and 4p is modulated differentially by attention to action

The mechanisms underlying attention to action are poorly understood. Although distracted by something else, we often maintain the accuracy of a movement, which suggests that differential neural mechanisms for the control of attended and nonattended action exist. Using functional magnetic resonance imaging (fMRI) in normal volunteers and probabilistic cytoarchitectonic maps, we observed that neural activity in subarea 4p (posterior) within the primary motor cortex was modulated by attention to action, while neural activity in subarea 4a (anterior) was not. The data provide the direct evidence for differential neural mechanisms during attended and unattended action in human primary motor cortex.

A control model of the movement of attention

A control model of the movement of the focus of attention is developed and applied to explain its observed effects on single cell activity and to various quantitative features of the Posner benefit paradigm. This supports the presence of an inverse controller and a rules component in the control model. The ability of the control model to explain a range of deficits is then analyzed, as is its relation to other modeling approaches.

Using genetic variation to study human disease

The generation of a draft sequence of the human genome has spawned a unique opportunity to investigate the role of genetic variation in human diseases. The difference between any two human genomes has been estimated to be less than 0.1% overall, but still, this means that there are at least several million nucleotide differences per individual. The study of single nucleotide polymorphisms (SNPs), the most common type of variant, is likely to contribute substantially to deciphering genetic determinants of common and rare diseases. The effort to identify SNPs has been accelerated by three developments: the availability of sequence data from the genome project, improved informatic tools for searching the former and high-throughput genotype platforms. With these new tools in hand, dissecting the genetics of disease will rapidly move forward, although a number of formidable challenges will have to be met to see its promise realized in clinical medicine.

A dynamical model for the analysis and acceleration of learning in feedforward networks

A dynamical system model is derived for feedforward neural networks with one layer of hidden nodes. The model is valid in the vicinity of flat minima of the cost function that rise due to the formation of clusters of redundant hidden nodes with nearly identical outputs. The derivation is carried out for networks with an arbitrary number of hidden and output nodes and is, therefore, a generalization of previous work valid for networks with only two hidden nodes and one output node. The Jacobian matrix of the system is obtained, whose eigenvalues characterize the evolution of learning. Flat minima correspond to critical points of the phase plane trajectories and the bifurcation of the eigenvalues signifies their abandonment. Following the derivation of the dynamical model, we show that identification of the hidden nodes clusters using unsupervised learning techniques enables the application of a constrained application (Dynamically Constrained Back Propagation-DCBP) whose purpose is to facilitate prompt bifurcation of the eigenvalues of the Jacobian matrix and, thus, accelerate learning. DCBP is applied to standard benchmark tasks either autonomously or as an aid to other standard learning algorithms in the vicinity of flat minima. Its application leads to significant reduction in the number of required epochs for convergence.

The central role of the parietal lobes in consciousness

There are now various approaches to understand where and how in the brain consciousness arises from neural activity, none of which is universally accepted. Difficulties among these approaches are reviewed, and a missing ingredient is proposed here to help adjudicate between them, that of "perspectivalness." In addition to a suitable temporal duration and information content of the relevant bound brain activity, this extra component is posited as being a further important ingredient for the creation of consciousness from neural activity. It guides the development of what is termed the "Central Representation," which is supposed to be present in all mammals and extended in humans to support self-consciousness as well as phenomenal consciousness. Experimental evidence and a theoretical framework for the existence of the central representation are presented, which relates the extra component to specific buffer working memory sites in the inferior parietal lobes, acting as attentional coordinators on the spatial maps making up the central representation. The article closes with a discussion of various open questions.

Practice-based research: lessons from community pharmacist participants

We designed this project to determine community pharmacists' opinions regarding the challenges and motivations of their recent participation in a pharmacy practice-based research study At the conclusion of a randomized, multicenter study, 87 community pharmacist-investigators were sent a questionnaire that explored four areas: motivating factors to participate, barriers to participation, communication tools used by study coordinators, and design issues for future studies. Fifty-eight (67%) completed questionnaires were returned. Key factors motivating participation in the study were desire to improve the profession and opportunity to learn. Time was the greatest barrier to participation. Pharmacy practice-based research has two distinct advantages. First, it translates clinical knowledge into direct application in the community. Second, it provides needed data to demonstrate the value of enhanced pharmacy practice. Thorough understanding of pharmacists' opinions is necessary to optimize the design of future studies.

The motion aftereffect: more than area V5/MT? Evidence from 15O-butanol PET studies

The motion aftereffect is a perceptual phenomenon which has been extensively investigated both psychologically and physiologically. Neuroimaging techniques have recently demonstrated that area V5/MT is activated during the perception of this illusion. The aim of this study was to test the hypothesis if a more broadly distributed network of brain regions subserves the motion aftereffect. To identify the neuronal structures involved in the perception of the motion aftereffect, regional cerebral blood flow (rCBF) measurements with positron emission tomography were performed in six normal volunteers. Data were analysed using SPM96. The motion-sensitive visual areas including area V5/MT were activated in both hemispheres. Additionally, the lateral parietal cortex bilaterally, the right dorsolateral prefrontal cortex, the anterior cingulate cortex and the left cerebellum showed significant increases in rCBF values during the experience of the waterfall illusion. In a further reference condition with identical attentional demand but no perception of a motion aftereffect elevated rCBF were found in these regions as well. In conclusion, our findings support the notion that the perceptual illusion of motion arises exclusively in the motion-sensitive visual area V5/MT. In addition, a more widespread network of brain regions including the prefrontal and parietal cortex is activated during the waterfall illusion which represents a non-motion aftereffect-specific subset of brain areas but is involved in more basic attentional processing and cognition.

A neural model of working memory processes in normal subjects, Parkinson's disease and schizophrenia for fMRI design and predictions

A computational model was previously developed to investigate the role of parallel basal ganglia-thalamocortical loops in solving tasks that rely on working memory. Different lesions are applied to the model in order to investigate the working memory deficits observed in Parkinson's disease and schizophrenia. The simulations predict that the working memory deficits observed in Parkinson's disease result from a local dysfunction within the brain due to a problem in the disinhibitory process arising from the basal ganglia. They also predict that the working memory deficits observed in schizophrenia involve many cortical and subcortical areas and result from a problem in selecting items in working memory which are stored in basal ganglia-thalamocortical loops. The simulations predict the temporal unfolding of neuronal activity in different brain regions, both in the normal case and in the two disease states. A specific event-related functional magnetic resonance imaging study was elaborated to test some of those predictions.

Imaging and neural modelling in episodic and working memory processes

Neuroimaging studies using positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) have revealed the involvement of distributed brain regions in memory processes mainly by the use of subtraction strategy based data analyses. Covariance analysis based data analysis strategies have been introduced more recently which allow functional interactions between brain regions of a neuronal network to be assessed. This contribution focuses on studies aiming to (1) establish the functional topography of episodic and working memory processes in young and old normal volunteers, (2) to assess functional interactions between modules of networks of brain regions by means of covariance based analyses and systems level modelling, (3) to characterise the temporal dynamics by the use of magnetoencephalography (MEG) and (4) to relate neuroimaging data to the underpinning neural networks. Male normal young and old volunteers without neurological or psychiatric illness participated in neuroimaging studies (PET, fMRI, MEG). Studies were approved by the ethical committee and federal authorities. Our results in young volunteers show distributed brain areas that are involved in memory processes (episodic and working memory) and show much of an overlap with respect to the network components. Systems level modelling analyses support the hypothesis of bihemispheric, asymmetric networks subserving memory processes and revealed both similarities in general and differences in the interactions between brain regions during episodic encoding and retrieval as well as working memory. Changes in memory function with ageing are evident from functional topographic studies in old volunteers activating more brain regions as compared to young volunteers. There are more and stronger influences of prefrontal regions in elderly volunteers comparing the functional models between old and young subjects. We discuss the way that the systems level models of the PET and fMRI results have implications for the underlying neural network functioning of the brain. This is done by developing simplifying assumptions, which lead from the equations describing the activities of the coupled neural modules to the systems level model equations. The resulting implications for the neural interactions are then discussed, in terms of a set of synaptically coupled neural modules. Finally, we consider how a similar analysis could be extended from the spatial to the temporal domain thus including the EEG and MEG results. The implication of preliminary MEG results presented here for the temporality arising in the interaction between the coupled neural modules in a working memory paradigm is discussed in terms of the previously developed neural network models arising from the PET and fMRI data.

Decomposing memory: functional assignments and brain traffic in paired word associate learning

The recent covariance structural equation model for word-pair associate encoding and retrieval (Krause, Horwitz, Taylor, Schmidt, Mottaghy, Halsband et al., 1998; Krause, Horwitz, Taylor, Schmidt, Mottaghy, Herzog et al., 1999) is analysed to deduce possible functional assignments of the various brain modules used by subjects in solving the task. Specific processing aspects are considered, in particular, that of long-term working memory sites and how they are coupled to buffer working memory sites to enable deposition and manipulation of remembered associates. The new concept of 'brain traffic' is introduced as an aid to the assessment of how important are various brain modules. A set of functional assignments is produced for the relevant modules.

Neural modeling and functional brain imaging: an overview

This article gives an overview of the different functional brain imaging methods, the kinds of questions these methods try to address and some of the questions associated with functional neuroimaging data for which neural modeling must be employed to provide reasonable answers.

Hemoglobin C associated with protection from severe malaria in the Dogon of Mali, a West African population with a low prevalence of hemoglobin S

The malaria hypothesis proposes a survival advantage for individuals with hemoglobin variants in areas of endemic Plasmodium falciparum malaria. Hemoglobin C (HbC) is a possible example in West Africa, where this hemoglobin has a centric distribution with high frequencies among certain populations including the Dogon ethnic group. To test whether HbC is associated with protection from malaria, we performed a case-control study in the Dogon of Bandiagara, Mali. HbC was present in 68 of 391 (17.4%) of uncomplicated malaria control cases, whereas it was detected in only 3 of 67 cases (4.5%) of severe malaria (odds ratio [OR], 0.22; P =. 01). Further, HbC was present in only 1 of 34 cases (2.9%) with cerebral manifestations, the most common presentation of severe malaria in this population (OR, 0.14; P =.03). Episodes of uncomplicated malaria and parasitemias (4800-205 050/microL) were identified in cases of homozygous HbC (HbCC), which indicates that P falciparum parasites are able to efficiently replicate within HbCC erythrocytes in vivo. These findings suggest that HbC does not protect against infection or uncomplicated malaria but can protect against severe malaria in the Dogon population of Bandiagara, Mali. The data also suggest that the protective effect associated with HbC may be greater than that of HbS in this population.

KTP laser therapy for bleeding from chronic radiation proctopathy

BACKGROUND

Endoscopic laser photocoagulation is commonly used to treat bleeding from the neovascular lesions of chronic radiation proctopathy. The KTP laser is an Nd/YAG-driven unit that emits light with a wavelength of 532 nm. This wavelength of energy is absorbed by hemoglobin and penetrates tissue to a depth of only 1 to 2 mm.

METHODS

Twenty-three patients were treated with KTP laser and followed for a median of 29 months (range 5 to 51 months); 21 had received radiation for prostate cancer and 2 for uterine cancer. The median age was 77 years (range 68 to 87 years). A median of 2 sessions (range 1 to 5 sessions) was performed using 4 to 10 Watts of power and a median energy of 816 Joules per session (range 204 to 2430 Joules).

RESULTS

After treatment there was a significant reduction in the frequency (p = 0.0005) of bleeding, increase in hematocrit level (p < 0.0001), improvement in activities of daily life (p = 0.01), and a reduction in use of health care resources (p < 0.0001). There was a trend toward decreased use of iron supplements (11 to 4 patients) and transfusions (4 to 0 patients). Two patients (9%) developed rectal ulcers after treatment.

CONCLUSIONS

KTP laser photocoagulation is a safe and effective therapy for bleeding from chronic radiation proctopathy that improves activities of daily living and reduces use of health care resources.

Target antigens for anti-neutrophil cytoplasmic autoantibodies (ANCA) are on the surface of primed and apoptotic but not unstimulated neutrophils

The reaction of ANCA with ANCA antigens on the surface of neutrophils may play a critical role in the pathogenesis of ANCA vasculitis. Therefore, an understanding of the circumstances that result in surface expression of these antigens is important for an understanding of pathogenic mechanisms. In this study we investigated the surface expression of ANCA antigens on quiescent, primed, and apoptotic neutrophils. ANCA antigens and other granule constituents were not detected on the surface of neutrophils in freshly heparinized blood. ANCA antigens were on the surface of neutrophils primed by in vitro incubation for 4 h and 8 h. These cells did not show evidence of apoptosis. After 24 h incubation, about 30% of the neutrophils were apoptotic, and ANCA antigens and other granule constituents were present on the surface of both apoptotic and non-apoptotic cells. Our data indicate that there are no ANCA antigens on the surface of quiescent neutrophils, but that they are on the surface of primed neutrophils before the cells become apoptotic, and remain on the surface of cells after they become apoptotic. Based on these observations, we hypothesize that ANCA can react in vivo with primed but not quiescent neutrophils. Previously published observations indicate that the interaction of ANCA with primed neutrophils results in neutrophil activation, which may be involved in the pathogenesis of ANCA vasculitis.

Toward quantitative genetic analysis of host and parasite traits in the manifestations of Plasmodium falciparum malaria

The complex human and parasite determinants that influence disease severity in Plasmodium falciparum malaria reflect thousands of years of selective pressure. Emerging genetic and genomic resources offer the prospect of unraveling interactions of these determinants.

Use of food labels and beliefs about diet-disease relationships among university students

OBJECTIVE

The purpose of this study was to measure the reported use of nutrition information on food labels by a population of university students and to determine if label users differed from non-users in terms of gender and specific beliefs related to label information and diet-disease relationships, specifically fat and heart disease and fibre and cancer.

DESIGN

A single-stage cluster sampling technique was used. Data was obtained using a self-administered, validated questionnaire.

SETTING

The present investigation took place at the University of Saskatchewan, Canada in the autumn of 1997.

SUBJECTS

: A total of 553 students in randomly selected classes in the College of Arts and Science took part in the survey (92% response rate). The sample consisted of roughly equal numbers of males and females, most between the ages of 18 and 24.

RESULTS

There were approximately equal numbers of label users and non-users among males, while label users outnumbered non-users by almost four to one among females. The importance of nutrition information on food labels was the only belief that differed significantly between label users and non-users for both sexes. For females, no other beliefs distinguished label users from non-users. However, for males, significant differences were found between label users and non-users on the beliefs that nutrition information is truthful and that a relationship between fibre and cancer exists.

CONCLUSIONS

Females appear to use food labels more often than do males. The only consistently observed difference between label users and non-users (male and female) was that users believed in the importance of nutrition information on food labels while non-users did not.

Analysis of recurrent cortico-basal ganglia-thalamic loops for working memory

We analyse a simplified form of the frontal lobe architecture of cortico-basal ganglia-thalamo-cortical loops to determine the manner in which they can learn temporal sequences as part of working memory activity. In particular, we consider how the temporal duration of activity can arise in this setting. We start from a hard-wired version in which temporally extended activity is created by the 'long' loop of cortex --> basal ganglia --> thalamus --> cortex, and show it arises from a near saddle-node bifurcation. The manner in which the transition between patterns occurs is also considered. This is then extended to analyse the temporal sequence storage and regeneration abilities of trained networks with a similar architecture. The temporal dynamics of this activity is also analysed. Implications of this for other working memory activities and for understanding the architecture of the frontal lobes are discussed in conclusion.

The network of brain areas involved in the motion aftereffect

A network of brain areas is expected to be involved in supporting the motion aftereffect. The most active components of this network were determined by means of an fMRI study of nine subjects exposed to a visual stimulus of moving bars producing the effect. Across the subjects, common areas were identified during various stages of the effect, as well as networks of areas specific to a single stage. In addition to the well-known motion-sensitive area MT the prefrontal brain areas BA44 and 47 and the cingulate gyrus, as well as posterior sites such as BA37 and BA40, were important components during the period of the motion aftereffect experience. They appear to be involved in control circuitry for selecting which of a number of processing styles is appropriate. The experimental fMRI results of the activation levels and their time courses for the various areas are explored. Correlation analysis shows that there are effectively two separate and weakly coupled networks involved in the total process. Implications of the results for awareness of the effect itself are briefly considered in the final discussion.

On the relation between brain images and brain neural networks

The relationship between brain images observed by PET and fMRI and the underlying neural activity is analysed using recent results on the detailed nature of averaged and synchronised activity of coupled neural networks and on a simplifying model of the level of blood flow caused by neural activity. The conditions on the coupled neural systems are specified that lead to structural equation models, giving support to analysis of the covariance structural equation modelling of brain imaging data. The relation between the resulting models and possible neural codes are analysed. Furthermore, a new form of structural equation model is derived, in which all neuronal activity arises as hidden variables. We discuss how the results of such analyses can be transported back to the domain of coupled temporally dynamic neural systems in the brain appropriate to EEG and MEG observations.

Hard-wired models of working memory and temporal sequence storage and generation

We develop hard-wired simulations of temporal sequence storage and generation by multi-modular networks based on the frontal lobe system (cortex, basal ganglia and thalamus). Single cell activity is shown to have been constructed so as to mimic results measured in monkeys on a similar task, indicating that a suitable form of chunking had been achieved in the models. The mathematical nature of these processes is discussed, from the viewpoint of bifurcation theory.

Functional magnetic resonance imaging in real time (FIRE): sliding-window correlation analysis and reference-vector optimization

New algorithms for correlation analysis are presented that allow the mapping of brain activity from functional MRI (fMRI) data in real time during the ongoing scan. They combine the computation of the correlation coefficients between measured fMRI time-series data and a reference vector with "detrending", a technique for the suppression of non-stimulus-related signal components, and the "sliding-window technique". Using this technique, which limits the correlation computation to the last N measurement time points, the sensitivity to changes in brain activity is maintained throughout the whole experiment. For increased sensitivity in activation detection a fast and robust optimization of the reference vector is proposed, which takes into account a realistic model of the hemodynamic response function to adapt the parameterized reference vector to the measured data. Based on the described correlation method, real-time fMRI experiments using visual stimulation paradigms have been performed successfully on a clinical MR scanner, which was linked to an external workstation for image analysis.

Network analysis in episodic encoding and retrieval of word-pair associates: a PET study

The involvement of distributed brain regions in declarative memory has been hypothesized based on studies with verbal memory tasks. To characterize episodic declarative memory function further, 14 right-handed volunteers performed a visual verbal learning task using paired word associates. The volunteers underwent positron emission tomography. 15O-butanol was used as a tracer of regional cerebral blood flow (rCBF). Inter-regional functional interactions were assessed based on within-task, across-subject inter-regional rCBF correlations. Anatomical connections between brain areas were based on known anatomy. Structural equation modelling was used to calculate the path coefficients representing the magnitudes of the functional influences of each area on the ones to which it is connected by anatomical pathways. The encoding and the retrieval network elicit similarities in a general manner but also differences. Strong functional linkages involving visual integration areas, parahippocampal regions, left precuneus and cingulate gyrus were found in both encoding and retrieval; the functional linkages between posterior regions and prefrontal regions were more closely linked during encoding, whereas functional linkages between the left parahippocampal region and posterior cingulate as well as extrastriate areas and posterior cingulate gyrus were stronger during retrieval. In conclusion, these findings support the idea of a global bihemispheric, asymmetric encoding/retrieval network subserving episodic declarative memory. Our results further underline the role of the precuneus in episodic memory, not only during retrieval but also during encoding.

Study of Cardiovascular Risk Intervention by Pharmacists (SCRIP): a randomized trial design of the effect of a community pharmacist intervention program on serum cholesterol risk

OBJECTIVE

To determine the efficacy of a program of intervention by pharmacists on lipid risk management in patients at high risk for cardiovascular events.

METHODS

Randomized, multicenter (44 sites in Alberta and Saskatchewan) study of community pharmacist intervention versus usual care in 1000 patients. Patients are those at high risk of vascular events (existing atherosclerotic vascular disease, or diabetes with > or = 1 other risk factor). After obtaining consent, the pharmacist calls the Project Office to randomize. Patients allocated to intervention receive a brochure and education about cardiovascular risk factors. Pharmacists also complete a physician contact form, which lists the patient's risk factors, medications, and any recommendations. A point-of-care cholesterol test is performed, the result is discussed with the patient, and it is entered on the contact form. If appropriate, the patient is asked to see his or her primary care physician for further assessment and/or treatment, and the form is faxed to the physician. Patients are followed up at two, four, eight, 12, and 16 weeks. During follow-up visits, pharmacists provide educational reinforcement and check for primary end point occurrence. Patients allocated to usual care receive the brochure only, with minimal follow-up. The primary end point is a composite of measurement of a complete lipid panel by the physician, or addition or modification of lipid-lowering drug therapy. Substudies will evaluate economics (third-party payer and pharmacy manager perspective), patient satisfaction, and quality of life.

CONCLUSIONS

SCRIP (Study of Cardiovascular Risk Intervention by Pharmacists) is a unique ongoing trial that is evaluating a community pharmacist intervention designed to optimize cholesterol risk management in patients at high risk for cardiovascular events.

Frequency change detection in human auditory cortex

We offer a model of how human cortex detects changes in the auditory environment. Auditory change detection has recently been the object of intense investigation via the mismatch negativity (MMN). MMN is a preattentive response to sudden changes in stimulation, measured noninvasively in the electroencephalogram (EEG) and the magnetoencephalogram (MEG). It is elicited in the oddball paradigm, where infrequent deviant tones intersperse a series of repetitive standard tones. However, little apart from the participation of tonotopically organized auditory cortex is known about the neural mechanisms underlying change detection and the MMN. In the present study, we investigate how poststimulus inhibition might account for MMN and compare the effects of adaptation with those of lateral inhibition in a model describing tonotopically organized cortex. To test the predictions of our model, we performed MEG and EEG measurements on human subjects and used both small- (<1/3 octave) and large- (>5 octaves) frequency differences between the standard and deviant tones. The experimental results bear out the prediction that MMN is due to both adaptation and lateral inhibition. Finally, we suggest that MMN might serve as a probe of what stimulus features are mapped by human auditory cortex.

Diagnostic usefulness of antineutrophil cytoplasmic autoantibody serology. Comparative evaluation of commercial indirect fluorescent antibody kits and enzyme immunoassay kits

Antineutrophil cytoplasmic autoantibodies (ANCAs) are increasingly used as serologic markers for pauci-immune crescentic glomerulonephritis and small vessel vasculitis. Many hospital laboratories and referral laboratories use commercial assay kits to detect ANCAs, despite inadequate documentation in the medical literature of kit performance. We evaluated the diagnostic sensitivity, specificity, and predictive value of 3 commercial indirect immunofluorescence assay (IFA) kits and 7 commercial enzyme immunoassay (EIA) kits for several ANCA subtypes. Serum samples from 396 patients with a variety of renal diseases were analyzed, including 146 patients with pauci-immune crescentic glomerulo-nephritis with or without systemic vasculitis. With 1 exception, the kits had more than 90% agreement with the reference standard and gave results similar to those of research laboratories. IFA diagnostic sensitivity ranged from 81% to 91% and EIA sensitivity from 75% to 84%. Maximum specificity was obtained with combined IFA and EIA. Diagnostic specificity was more than 70% for 2 of 3 IFA kits and at least 90% for 5 of 7 EIA kits. Predictive values varied with clinical manifestations. Most commercial IFA and EIA kits that were evaluated provide acceptably accurate analytic results.

Mathematical analysis of lead field expansions

The solution to the bioelectromagnetic inverse problem is discussed in terms of a generalized lead field expansion, extended to weights depending polynomially on the current strength. The expansion coefficients are obtained from the resulting system of equations which relate the lead field expansion to the data. The framework supports a family of algorithms which include the class of minimum norm solutions and those of weighted minimum norm, including FOCUSS (suitably modified to conform to requirements of rotational invariance). The weighted-minimum-norm family is discussed in some detail, making explicit the dependence (or independence) of the weighting scheme on the modulus of the unknown current density vector. For all but the linear case, and with a single power in the weight, a highly nonlinear system of equations results. These are analyzed and their solution reduced to tractable problems for a finite number of degrees of freedom. In the simplest magnetic field tomography (MFT) case, this is shown to possess expected properties for localized distributed sources. A sensitivity analysis supports this conclusion.

Observation of quantization effects in human auditory cortex

Auditory evoked magnetic fields were recorded from five human subjects using the BTi whole head system (148 channels). The stimuli were simple tone bursts with different inter-stimulus intervals (ISI). The magnetic field was also recorded from the same subjects in place without stimulation to provide baseline 'noise' measurements. Magnetic field tomography (MFT) was applied to the average data and activation curves were computed from well circumscribed regions of interest (ROI). Objective statistical measures (Kolmogorov-Smirnov test) were then used to identify latency segments with distribution significantly different from the baseline distribution. For latency segments with significant activations the dependence of the activation strength on ISI was modeled by an exponentially saturating function. In earlier studies, the characteristic time (tau) in this function was interpreted as a measure of a memory trace for auditory tones. Our analysis identified distinct levels for tau: all subjects had the same lower two levels (0.50 s and 0.69 s). Attention modulation introduced considerably higher tau values in most subjects but it did not change the two 'ground state' tau levels. To our knowledge, this is the first demonstration of quantization effects in the macro-properties of brain activity, which were universal amongst the subjects we studied.

The influence of stimulus properties, complexity, and contingency on the stability and variability of ongoing and evoked activity in human auditory cortex

The real-time, single-trial activity in the human auditory cortex was extracted from magnetoencephalographic signals. A predictor of single-trial activity was defined as the sum of the average response and a mean-free base level computed over a range of base times. For simple stimuli the residual (predicted-actual) activity had a stimulus-independent oscillatory (10 Hz) component. This component was larger and more durable in trained subjects, reaching saturation only in the most trained of the five subjects studied (S1). Changes in variability and associated reduction of the absolute value and duration of the oscillations were evident in experiments with stimuli loaded with information, saliency, or task contingency. Repetition reintroduces stimulus-independent oscillations very slowly. For S1, after training, the stimulus-independent oscillations were reestablished in the auditory cortices to the level seen for simple stimuli, except for the time periods and in the hemisphere associated with the combination of task demands and stimulus processing.

Response to Commentaries

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A three stage model of awareness: formulation and initial experimental support

The various components which together make up the complex state of consciousness require neural support involving a connected network of many brain areas at differing levels. At the lowest level is non-aware processing, of which there is not direct awareness. There are also modules involved in processing with awareness but without focussed attention. Finally there must be a set of modules involved in directing attention in a controlled manner. We expect to be able to dissociate the various components of the three-stage network by using different levels of attention. The results of an auditory experiment performed under three different levels of awareness and attention are analysed to show support for the three-stage model of awareness. The relevant auditory areas are delineated.

Cortical activity and the explanatory gap

An exploration is given of neural network features now being uncovered in cortical processing which begins to go a little way to help bridge the "Explanatory Gap" between phenomenal consciousness and correlated brain activity. A survey of properties suggested as being possessed by phenomenal consciousness leads to a set of criteria to be required of the correlated neural activity. Various neural styles of processing are reviewed and those fitting the criteria are selected for further analysis. One particular processing style, in which semiautonomous and long-lasting cortical activity "bubbles" are created by input, is selected as being the most appropriate. Further experimental criteria are used to help narrow the possible neural styles involved. This leads to a class of neural models underpinning phenomenal consciousness and to a related set of testable predictions.

Detection of cellulose with improved specificity using laser-based instruments

Specific detection of cellulose has not been possible using laser based instruments such as laser scanning confocal microscopes (LSCM) and fluorescently activated cell sorters (FACS). Common cellulose dyes are nonspecific and/or nonexcitable with common lasers. Furthermore, many lasers emit wavelengths that overlap with autofluorescence from chlorophyll and other plant molecules. We demonstrate that a cellulase and an isolated bacterial cellulose binding domain (CBD) conjugated to fluorescent dyes can be used for laser detection of cellulose with improved specificity. Cell walls of differentiating tracheary elements and spores of Dictyostelium discoideum were tested in this study. For double labeling, autofluorescence interfering with the rhodamine signal was eliminated by collecting each excitation channel separately followed by computer recombination or by using a narrow band pass barrier filter allowing simultaneous channel collection. Using these methods, cellulose and microtubules tagged with a monoclonal antibody to alpha-tubulin were effectively colocalized in chlorophyll-containing tracheary elements using a LSCM. Also, Dictyostelium discoideum spores labeled or unlabeled with CBD-FITC were separated into two populations by FACS indicating that this tag should be useful in future mutagenesis experiments. Therefore, the presence or absence of cellulose can now be analyzed using common lasers.