Monitoring working memory load during computer-based tasks with EEG pattern recognition methods

We assessed working memory load during computer use with neural network pattern recognition applied to EEG spectral features. Eight participants performed high-, moderate-, and low-load working memory tasks. Frontal theta EEG activity increased and alpha activity decreased with increasing load. These changes probably reflect task difficulty-related increases in mental effort and the proportion of cortical resources allocated to task performance. In network analyses, test data segments from high and low load levels were discriminated with better than 95% accuracy. More than 80% of test data segments associated with a moderate load could be discriminated from high- or low-load data segments. Statistically significant classification was also achieved when applying networks trained with data from one day to data from another day, when applying networks trained with data from one task to data from another task, and when applying networks trained with data from a group of participants to data from new participants. These results support the feasibility of using EEG-based methods for monitoring cognitive load during human-computer interaction.

High resolution evoked potential imaging of the cortical dynamics of human working memory

High resolution evoked potentials (EPs), sampled from 115 channels and spatially sharpened with the finite element deblurring method, were recorded from 8 subjects during working memory (WM) and control tasks. The tasks required matching each stimulus with a preceding stimulus on either verbal or spatial attributes. All stimuli elicited a central P200 potential that was larger in the spatial tasks than in the verbal tasks, and larger in the WM tasks than in the control tasks. Frequent, non-matching stimuli elicited a frontal, positive peak at 305 msec that was larger in the spatial WM task relative to the other tasks. Irrespective of whether subjects attended to verbal or spatial stimulus attributes, non-matching stimuli in the WM tasks also elicited an enhanced P450 potential over the left frontal cortex, followed by a sustained potential over the superior parietal cortex. A posterior P390 potential elicited by infrequent, matching stimuli was smaller in amplitude for both spatial and verbal WM tasks compared to control tasks, as was a central prestimulus CNV. These results indicate that WM is a function of a distributed system with both task-specific and task-independent components. Lesion studies and course temporal resolution functional imaging methods, such as PET and fMRI, tend to paint a fairly static picture of the cortical regions which participate in the performance of WM tasks. In contrast, the fine-grain time resolution provided by imaging brain function with EP methods provides a dynamic picture of subsecond changes in the spatial distribution of WM effects over the course of individual trials, as well as evidence for differences in the activity elicited by matching and non-matching stimuli within sequences of trials. This information about the temporal dynamics of WM provides a critical complement to the fine-grain spatial resolution provided by other imaging modalities.

Mapping cognitive brain function with modern high-resolution electroencephalography

High temporal resolution is necessary to resolve the rapidly changing patterns of brain activity that underlie mental function. While electroencephalography (EEG) provides temporal resolution in the millisecond range, which would seem to make it an ideal complement to other imaging modalities, traditional EEG technology and practice provides insufficient spatial detail to identify relationships between brain electrical events and structures and functions that are visualized by magnetic resonance imaging (MRI) or positron emission tomography (PET). Recent advances overcome this problem by recording EEGs from more electrodes, by registering EEG data with anatomical information from each subject's MRI, and by correcting the distortion that is caused by volume conduction of EEG signals through the skull and scalp. Along with its ability to record how brains think when performing everyday activities in the real world, these advances make modern EEG an invaluable complement to other functional neuroimaging modalities.

A metabolomic study of low estimated GFR in non-proteinuric type 2 diabetes mellitus

AIMS/HYPOTHESIS

We carried out a urinary metabolomic study to gain insight into low estimated GFR (eGFR) in patients with non-proteinuric type 2 diabetes.

METHODS

Patients were identified as being non-proteinuric using multiple urinalyses. Cases (n = 44) with low eGFR and controls (n = 46) had eGFR values <60 and ≥60 ml min(-1) 1.73 m(-2), respectively, as calculated using the Modification of Diet in Renal Disease formula. Urine samples were analysed by liquid chromatography/mass spectrometry (LC/MS) and GC/MS. False discovery rates were used to adjust for multiple hypotheses testing, and selection of metabolites that best predicted low eGFR status was achieved using least absolute shrinkage and selection operator logistic regression.

RESULTS

Eleven GC/MS metabolites were strongly associated with low eGFR after correction for multiple hypotheses testing (smallest adjusted p value = 2.62 × 10(-14), largest adjusted p value = 3.84 × 10(-2)). In regression analysis, octanol, oxalic acid, phosphoric acid, benzamide, creatinine, 3,5-dimethoxymandelic amide and N-acetylglutamine were selected as the best subset for prediction and allowed excellent classification of low eGFR (AUC = 0.996). In LC/MS, 19 metabolites remained significant after multiple hypotheses testing had been taken into account (smallest adjusted p value = 2.04 × 10(-4), largest adjusted p value = 4.48 × 10(-2)), and several metabolites showed stronger evidence of association relative to the uraemic toxin, indoxyl sulphate (adjusted p value = 3.03 × 10(-2)). The potential effect of confounding on the association between metabolites was excluded.

CONCLUSIONS/INTERPRETATION

Our study has yielded substantial new insight into low eGFR and provided a collection of potential urinary biomarkers for its detection.

Towards measurement of brain function in operational environments

In operational environments that demand sustained vigilance or that involve multiple tasks competing for limited attentional resources, continuous monitoring of the mental state of the operator could decrease the potential for serious errors and provide valuable information concerning the ergonomics of the tasks being performed. There is widespread discussion and appreciation of the basic feasibility of utilizing neurophysiological measurements to derive accurate, reliable, rapid and unobtrusive assessments of mental state. However, progress in transitioning this idea into practical applications has been impeded by the fact that at present no convenient, inexpensive and effective means exists to derive a meaningful index of brain activity outside of laboratory settings. In this paper, we review some recent advances in recording technology and signal processing methods that will help overcome this limitation. For example, rapid progress is being made in the engineering of recording systems that are small, rugged, portable and easy-to-use, and thus suitable for deployment in operational environments. Progress is also being made in the development of signal processing algorithms for detecting and correcting recording artifacts and for increasing the amount of useful information that can be derived from brain signals. Finally, results from basic research studies suggest that accurate and reliable inferences about the mental load and alertness of an individual can be derived from neurophysiological measures in a practical fashion. These research and engineering successes suggest that it is reasonable to expect that in the near term a basic enabling technology will be deployed that will permit routine measurement of brain function in operational environments.

Cytostatic effects of 3,3'-diindolylmethane in human endometrial cancer cells result from an estrogen receptor-mediated increase in transforming growth factor-alpha expression

3,3'-Diindolylmethane (DIM), a major in vivo product of indole-3-carbinol (I3C), is a promising anticancer agent derived from vegetables of the Brassica genus including broccoli, Brussels sprouts and cabbage. We report here that DIM has a potent cytostatic effect in cultured human Ishikawa endometrial cancer cells. A combination of northern blot and quantitative PCR analyses revealed that DIM induced the level of TGF-alpha transcripts by approximately 4-fold within 24 h of indole treatment. DIM also induced a 4-fold increase in the activity of the estrogen response marker, alkaline phosphatase (AP). Co-treatment of cells with the estrogen receptor (ER) antagonist ICI, or with the inhibitor of PKA-mediated activation of the ER, H89, ablated the DIM induction of both TGF-alpha expression and AP activity. Furthermore, DIM increased the maximum stimulatory effect of estrogen on TGF-alpha expression. Co-treatment with the protein synthesis inhibitor, cycloheximide, abolished the inductive effects of DIM, indicating differences in the mechanistic requirements of DIM and estrogen. DIM treatment also stimulated levels of secreted TGF-alpha protein by >10-fold. The ectopic addition of TGF-alpha inhibited the growth of Ishikawa cells, whereas incubation with a TGF-alpha antibody partially reversed the growth inhibitory effects of DIM. Taken together, these results extend our previous findings of the ligand independent estrogen receptor agonist activity of DIM, and uncover an essential role for the stimulation in TGF-alpha expression and the TGF-alpha activated signal transduction pathway in the potent cytostatic effects of DIM in endometrial cancer cells.

Deblurring

In most instances, traditional EEG methodology provides insufficient spatial detail to identify relationships between brain electrical events and structures and functions visualized by magnetic resonance imaging or positron emission tomography. This article describes a method called Deblurring for increasing the spatial detail of the EEG and for fusing neurophysiologic and neuroanatomic data. Deblurring estimates potentials near the outer convexity of the cortex using a realistic finite element model of the structure of a subject's head determined from their magnetic resonance images. Deblurring is not a source localization technique and thus makes no assumptions about the number or type of generator sources. The validity of Deblurring has been initially tested by comparing deblurred data with potentials measured with subdural grid recordings. Results suggest that deblurred topographic maps, registered with a subject's magnetic resonance imaging and rendered in three dimensions, provide better spatial detail than has heretofore been obtained with scalp EEG recordings. Example results are presented from research studies of somatosensory stimulation, movement, language, attention and working memory. Deblurred ictal EEG data are also presented, indicating that this technique may have future clinical application as an aid to seizure localization and surgical planning.

Electroencephalographic imaging of higher brain function

High temporal resolution is necessary to resolve the rapidly changing patterns of brain activity that underlie mental function. Electroencephalography (EEG) provides temporal resolution in the millisecond range. However, traditional EEG technology and practice provide insufficient spatial detail to identify relationships between brain electrical events and structures and functions visualized by magnetic resonance imaging or positron emission tomography. Recent advances help to overcome this problem by recording EEGs from more electrodes, by registering EEG data with anatomical images, and by correcting the distortion caused by volume conduction of EEG signals through the skull and scalp. In addition, statistical measurements of sub-second interdependences between EEG time-series recorded from different locations can help to generate hypotheses about the instantaneous functional networks that form between different cortical regions during perception, thought and action. Example applications are presented from studies of language, attention and working memory. Along with its unique ability to monitor brain function as people perform everyday activities in the real world, these advances make modern EEG an invaluable complement to other functional neuroimaging modalities.

Ethnic differences in glycaemic control in adult Type 2 diabetic patients in primary care: a 3-year follow-up study

OBJECTIVE

To evaluate ethnic differences and characteristics related to glycaemic control in patients with Type 2 diabetes in primary care.

RESEARCH DESIGN AND METHODS

Prospective cohort study; 500 adult patients with Type 2 diabetes, who were not on insulin therapy, were followed up annually for 3 years. HbA(1c) at baseline and 3-year changes and subsequent insulin therapy were related to baseline characteristics.

RESULTS

Malay patients had significantly higher HbA(1c) (mean 8.7% +/- sd 1.66) compared with Chinese (8.2 +/- sd 1.67) and Indian (8.2 +/- sd 1.55) (P = 0.032) at baseline, and consistently for all years of HbA(1c) assessment (P = 0.017). At baseline, Malay patients were significantly more obese than Chinese or Indians (P < 0.001); fewer of them received structured shared-care intervention (P = 0.001), but they had a significantly higher glucose control educational score (P < 0.05). Multivariable analyses showed that HbA(1c) at baseline was significantly related to age (P = 0.001), BMI (P = 0.031) and ethnicity (P = 0.002). HbA(1c) declined significantly over 3 years in the whole population and in all ethnic groups. Significantly greater HbA(1c) declines were associated with higher baseline HbA(1c), structured shared-care intervention and non-insulin therapy. Correcting for differences on these factors, the decline in HbA(1c) in Malays was significantly less than in the Chinese. Insulin therapy was associated with higher baseline HbA(1c) and higher BMI.

CONCLUSIONS

Malay ethnicity was associated with persistently poor glycaemic control. Sociocultural and behavioural factors should be addressed in improving care for patients with poorly controlled diabetes.

Reduced GFR and albuminuria in Chinese type 2 diabetes mellitus patients are both independently associated with activation of the TNF-alpha system

AIMS/HYPOTHESIS

The involvement of chronic inflammation in albuminuria and renal function was investigated in a cross-sectional study of 320 type 2 diabetic Chinese patients from the Singapore Diabetes Cohort Study.

METHODS

Plasma levels of TNF-alpha and its two cellular receptors and of IL-6 and C-reactive protein (CRP) were measured. A composite TNF-alpha score was extracted using principal component analysis. Multiple linear regression analysis was implemented to evaluate the relationship between log( e ) (ln) albumin:creatinine ratio (ACR) and estimated GFR (eGFR) with the inflammatory variables and other clinical covariates. A Bonferroni correction was applied based on the total number of variables entered into regression analyses.

RESULTS

ln ACR was significantly associated with TNF-alpha score independently of eGFR even after a Bonferroni correction. TNF-alpha score was also significantly associated with eGFR independently of ln ACR even after correction for multiple testing. These findings were similar when the individual molecules of the TNF-alpha system were analysed separately instead of using the composite TNF-alpha score. No association was observed for IL-6 and CRP with either renal trait. Diabetes duration was a significant predictor for ln ACR but not eGFR. Conversely, age was significantly associated with eGFR but not ln ACR.

CONCLUSIONS/INTERPRETATION

Activation of the TNF-alpha system may potentially exert independent effects on ln ACR and eGFR in type 2 diabetes. Because of the study design, one may also consider the possibility that changes in these renal traits may conversely be responsible for such an inflammatory response.

Conformational modulation of human cytochrome P450 2E1 by ethanol and other substrates: a CO flash photolysis study

The alcohol-inducible cytochrome P450 2E1 is a major human hepatic P450 which metabolizes a broad array of endogenous and exogenous compounds, including ethanol, low-molecular weight toxins, and fatty acids. Several substrates are known to stabilize this P450 and inhibit its cellular degradation. Furthermore, ethanol is a known modulator of P450 2E1 substrate metabolism. We examined the CO binding kinetics of P450 2E1 after laser flash photolysis of the heme-CO bond, to probe the effects of ethanol and other substrates on protein conformation and dynamics. Ethanol had an effect on the two kinetic parameters that describe CO binding: it decreased the rate of CO binding, suggesting a decrease in the protein's conformational flexibility, and increased the photosensitivity, which indicates a local effect in the active site region such as strengthening of the heme-CO bond. Other substrates decreased the CO binding rate to varying degrees. Of particular interest is the effect of arachidonic acid, which abolished photodissociation in the absence of ethanol but had no effect in the presence of ethanol. These results are consistent with a model of P450 2E1 whereby arachidonic acid binds along a long hydrophobic binding pocket and blocks exit of CO from the heme region.

Ultraviolet disinfection of contact lenses

To evaluate the efficacy of ultraviolet (UV) radiation as a method of disinfecting contact lenses and their storage solutions, we contaminated soft lenses (Bausch & Lomb Optima 38), rigid gas permeable (RGP) lenses (Oxyflow F-30), and their storage solutions with three common bacteria. Escherichia coli (E.c.), Staphylococcus epidermis (S.e.), and Serratia marcescens (S.m.). The storage solutions used were saline solution and RGP conditioning solution. We determined the exposure times to 253.7-nm wavelength UV radiation necessary to disinfect the contact lenses and solutions. The decimal reduction values (D values) found for UV radiation were 10 to 200 hundred times shorter than reported for currently available disinfection systems. For E.c., sterilization was attained after 100 s of exposure. For S.e. and S.m., sterilization occurred after 300 s of exposure. Different contact lens solutions transmit UV radiation to various degrees, with saline solution passing more than 90% of the UV radiation. Thus, our results indicate that UV radiation is an effective and rapid method of disinfecting contact lenses and their storage solutions.

Implications of electrolyte dispersion for high resolution EEG methods

The effective recording area of an EEG electrode is its electrical contact area with the scalp. With techniques that employ wet electrolyte, this area is primarily determined by the extent of electrolyte dispersion rather than by the size of the electrode. The effective recording areas of 10 widely distributed EEG electrodes embedded in an elasticized stretch hat were measured on 7 subjects using a digital multimeter. On average, conventionally prepared electrodes were associated with an electrolyte (standard gel) spread of approximately 1 cm in each of four directions (above, below, right and left of the electrode's center). This implies that EEG electrodes prepared with wet electrolyte should not be spaced less than 2 cm apart unless special precautions are taken to prevent the spread of electrolyte, and that in most circumstances there is little advantage to methods for designating the 3-D coordinates of an electrode that have a measurement error of less than 1 cm.

Sutureless cartilage graft laryngotracheal reconstruction using fibrin sealant

OBJECTIVE

To determine whether fibrin sealant can replace suture as a means of holding a cartilage graft securely in the trachea.

DESIGN

Randomized blinded control study comparing the use of fibrin sealant vs sutures in laryngotracheal reconstruction in ferrets. We compared results at 7 and 30 days.

SUBJECTS

Forty ferrets randomized into 2 groups of 20: fibrin sealant and sutures. Within each group, half were studied at 7 days and the rest at 30 days. No ferrets were withdrawn from study because of adverse effects of the intervention.

INTERVENTION

A carved costal cartilage graft was placed in the anterior cricoid split incision, and was secured with either fibrin sealant or sutures. All animals were extubated after recovery from anesthesia. Specimens were examined grossly and histologically.

RESULTS

All animals survived until humanely killed. The pathologist, unaware of the groupings, measured lumen expansion in millimeters, cartilage graft migration, mucosal in-growth, degree of inflammation, graft integration, and graft viability. The fibrin sealant group had statistically significant (P<.05) better results in mucosal in-growth. In no categories was the suture group better than the fibrin sealant group. In comparing 7-day with 30-day results, the 30-day group had significantly better results in inflammation and graft viability.

CONCLUSIONS

Fibrin sealant can be used in place of sutures with improvement in mucosal growth in costal cartilage laryngotracheal reconstruction in the experimental animal model. Use of fibrin sealant (instead of sutures) may result in less surgical trauma and edema, less surgical time, and faster recovery.

Effects of putative stressors in public aquaria on locomotor activity, metabolic rate and cortisol levels in the Mozambique tilapia Oreochromis mossambicus

Mozambique tilapia Oreochromis mossambicus were housed individually during 7 days in a continuous flow-trough respirometry system and daily exposed to one of three treatments: (1) a series of knocks on the side of the aquarium, (2) a series of photo-flashes and (3) control group. Exposure to photo-flashes did not change locomotor activity but decreased both night-time and daytime oxygen consumption throughout the experiment. Knocking induced a short-lived increase in locomotor activity and tended to increase oxygen consumption, but this latter effect was not significant. Night-time oxygen consumption was not affected by knocking exposure. Cortisol levels assayed from fish-holding water collected at the end of the experiment were significantly lower in subjects exposed to photo-flashes than in subjects exposed to knocks or controls. Males did not respond differently than females to the treatments in any of the measurements taken. In summary, the data reported here suggest that exposure to repetitive photo-flashes, but not knocking, suppressed normal energy metabolism and cortisol levels. These effects were present hours to a half day after exposure to the flashes.

Differential cellular zinc levels in metastatic and primary nasopharyngeal carcinoma

Zinc levels are known to be elevated in certain cancer tissues. In this study, zinc content in metastatic and primary nasopharyngeal carcinoma (NPC) cells were quantitated by X-ray microanalysis at the ultrastructural level. Zinc levels of cancer cells derived from the cervical lymph node of a patient with metastatic carcinoma and that from the nasopharynx biopsy of another NPC patient with no clinical evidence of secondary spread, were analyzed. X-ray microanalysis revealed significantly higher cellular zinc levels in metastatic NPC cells. Zinc is a known anti-apoptotic agent and tumor response to radiotherapy is linked with apoptosis or programmed cell death. Raised zinc levels observed here could provide the biological basis for the observation of a higher percentage of distant metastasis in cervical node positive NPC patients treated by radiotherapy (the mainstay of treatment for NPC) as compared to those without regional nodal disease.

Application of aqueous two-phase extraction for separation and purification of various adeno-associated viruses

OBJECTIVE

Adeno-associated viruses (AAVs) are widely used as gene therapy vectors due to their safety, stability, and long-term expression characteristics. The objective of this work is to develop an aqueous two-phase system (ATPS) as a universal platform for the separation and purification of AAVs.

RESULTS

This study utilized polyethylene glycol (PEG)/salt ATPSs to separate and purify various AAV serotypes, including AAV5, AAV8, and AAV9, which focusing on serotype-specific performance and partial empty capsid removal. The results showed that all the AAV serotypes were mainly enriched in the interphase of ATPS, with achieving high recovery (> 95%) and impurity removal (> 95%). The PEG/sodium citrate ATPS was serotype-independent, but the process optimization of component concentrations for each serotype was necessary to attain the best performance. Notably, a single-step aqueous two-phase extraction also demonstrated the ability to remove some amount of empty capsids from the crude cell lysate, with removal rate ranging from 4 to 25%.

CONCLUSIONS

The results demonstrated the practical applicability of PEG/sodium citrate ATPS in separating and purifying different AAV serotypes, which addressing key challenges in gene therapy vector production.

Abstract P1-05-20: Fluorescent Hyaluronan Probes Distinguish Heterogeneous Breast Cancer Cell Subsets and Predict their Invasive Behavior

Background: Tumor heterogeneity is a determining factor in diagnosis and therapy of breast cancer (Bca). We investigated Bca cellular heterogeneity by a functional fluorescent hyaluronan (HA) probe, and monitored its binding characteristics in relation to the degree of Bca aggression. HA is a polysaccharide ligand for CD44 and RHAMM receptors, which are linked to cell plasticity and predict poor clinical outcome in Bca.

Methods: Fluorescent HA probes, multiplexed profiling, and cell sorting strategies were developed and used to detect/capture tumor cell subpopulations with differences in HA binding (HA−/low vs. HAhigh) and HA receptors surface display. Whereas we concentrated on the most metastatic cell line, MDA-MB-231, we also monitored the presence of subpopulations in other Bca lines and showed heterogeneity in all.

Results: The HA probe binding was highly heterogeneous, and the highest binding level was detected in highly invasive triple-negative basal subtypes such as MDA-MB-231. HA probes bound to the cell surface but also accumulated in cytoplasm and nucleus. Binding levels were dramatically reduced upon ‘reversion’ of highly malignant cells to a non-malignant phenotype in three-dimensional cultures, suggesting that the level of cellular binding to fluorescent HA probe provides a measure of malignant behavior. Comparison between HAhigh and HA−/low subpopulations revealed surprising differences in morphology, proliferation and invasion in culture, which were retained in two in vivo models. HAhigh subpopulations exhibited higher levels of invasion but surprisingly lower levels of proliferation compared to either unsorted parental cells or the HA−/low subpopulation.

Conclusions: Querying HA binding in Bca lines reveals an unexpected heterogeneity with respect to tumor phenotype in vivo, morphology in 3D, invasion and proliferation. These results may aid in diagnosis and therapy of invasive Bca subpopulations and early sorting of cancer patients needing intensive chemotherapy.

Keywords: Heterogeneity, 3D cultures, Hyaluronan, CD44, RHAMM/HMMR, Tumor phenotype, Breast cancer, Invasion.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-05-20.

Relation between morbidity and current treatment in patients who present with acute asthma to polyclinics

BACKGROUND

It has been suggested that resources for asthma intervention should be focused mainly on patients in the community who experience a high burden of disease. These are who patients who have acute exacerbations which require urgent treatment.

AIM

To assess the morbidity and identify deficiencies in the treatment of patients who present for urgent treatment of acute exacerbations to primary care clinics.

PATIENTS

Adult patients who received urgent treatment for acute exacerbation of bronchial asthma

SETTING

4 primary care polyclinics.

METHODS

A cross-sectional survey of consecutive patients which related regular preventive treatment to current asthma activity. Poor asthma control was defined as step 2 or higher (American National Asthma Education and Prevention Program, report II, 1997) or > or = 2 emergency room visits in 6 months.

RESULTS

There were 116 patients of whom 53% were women. The mean (SD) age was 45(15) years and duration of current exacerbation 3 (3) days. The acute symptoms were successfully treated in 93% of patients. Quick relief medication was used regularly in 91% and inhaled corticosteroids (ICS) in 55%. Oral salbutamol was prescribed in 14% of patients. The asthma was poorly controlled in 54%. In the poorly controlled group 33% were not on regular ICS treatment and 64% were not receiving "add on" medication.

CONCLUSIONS

Patients treated for acute asthma in primary care clinics: (1) were older and had less acutely severe exacerbations than those who presented to emergency rooms, (2) over half had poorly controlled asthma and (3) a third of patients with poor asthma control were inadequately treated.