Barium Toxicity Effects in Soybean Plants

Barium (Ba)-induced phytotoxicity at 100, 1000, or 5000 μM Ba in soybean plants (Glycine max) was investigated under hydroponic culture conditions. Soybean growth and leaf photosynthetic activity were significantly inhibited by all three levels of Ba treatments. In the case of photosynthetic activity, 5000 μM Ba treatment shutdown stomatal opening and perturbed carbon fixation metabolism and translocation. However, 100 and 1000 μM Ba treatments shut down stomatal opening and inhibited carbon fixation, but without perturbation of leaf carbon fixation-related metabolism. Potassium (K) absorption by soybean roots was also reduced in all three Ba treatments. This decreased K absorption reduced K localization at guard cells. Barium accumulation in guard cells also inhibited K transport from epidermal cells to guard cells. This lack of K in guard cells resulted in stomatal closure. As a result of inhibition of K transport into guard cells and stomatal shutdown, photosynthetic activity and plant productivity were inhibited. Our experiment indicates that Ba has phytotoxic effects on soybean plants by inhibiting photosynthesis.     

Functional decoupling of BOLD and gamma-band amplitudes in human primary visual cortex

Although functional magnetic resonance imaging is an important tool for measuring brain activity, the hemodynamic blood oxygenation level dependent (BOLD) response is only an indirect measure of neuronal activity. Converging evidence obtained from simultaneous recording of hemodynamic and electrical measures suggest that the best correlate of the BOLD response in primary visual cortex is gamma-band oscillations ( approximately 40 Hz). Here, we examined the coupling between BOLD and gamma-band amplitudes measured with magntoencephalography (MEG) in human primary visual cortex in 10 participants. In Experiment A, participants were exposed to grating stimuli at two contrast levels and two spatial frequencies and in Experiment B square and sine wave stimuli at two spatial frequencies. The amplitudes of both gamma-band oscillations and BOLD showed tuning with stimulus contrast and stimulus type; however, gamma-band oscillations showed a 300% increase across two spatial frequencies, whereas BOLD exhibited no change. This functional decoupling demonstrates that increased amplitude of gamma-band oscillations as measured with MEG is not sufficient to drive the subsequent BOLD response.     

An evaluation of general practice websites in the UK

BACKGROUND: General practice websites are an emerging phenomenon, but there have been few critical evaluations of their content. Previously developed rating instruments to assess medical websites have been criticized for failing to report their reliability and validity. OBJECTIVES: The purpose of this study was to develop a rating instrument for assessing UK general practice websites, and then to evaluate them critically. METHODS: The STaRNet Website Assessment Tool (SWAT) was developed listing criteria that general practice websites may meet, which was then used to evaluate a random sample of websites drawn from an electronic database. A second assessor rated a subsample of the sites to assess the tool's inter-rater reliability. The setting was an information technology group of a general practice research network using a random sample of 108 websites identified from the database. The main outcome measures were identification of rating criteria and frequency counts from the website rating instrument. RESULTS: Ninety (93.3%) sites were accessible, of which 84 were UK general practice websites. Criteria most frequently met were those describing the scope of the website and their functionality. Apart from e-mail to practices, criteria related to electronic communication were rarely met. Criteria relating to the quality of information were least often met. Inter-rater reliability kappa values for the items in the tool ranged from -0.06 to 1.0 (mean 0.59). Values were >0.6 for 15 out of 25 criteria assessed in 40 sites which were rated by two assessors. CONCLUSIONS: General practice websites offer a wide range of information. They are technically satisfactory, but do not exploit fully the potential for electronic doctor-patient communication. The quality of information they provide is poor. The instrument may be developed as a template for general practices producing or revising their own websites.     

Visual word recognition: the first half second

We used magnetoencephalography (MEG) to map the spatiotemporal evolution of cortical activity for visual word recognition. We show that for five-letter words, activity in the left hemisphere (LH) fusiform gyrus expands systematically in both the posterior-anterior and medial-lateral directions over the course of the first 500 ms after stimulus presentation. Contrary to what would be expected from cognitive models and hemodynamic studies, the component of this activity that spatially coincides with the visual word form area (VWFA) is not active until around 200 ms post-stimulus, and critically, this activity is preceded by and co-active with activity in parts of the inferior frontal gyrus (IFG, BA44/6). The spread of activity in the VWFA for words does not appear in isolation but is co-active in parallel with spread of activity in anterior middle temporal gyrus (aMTG, BA 21 and 38), posterior middle temporal gyrus (pMTG, BA37/39), and IFG.     

Task-related changes in cortical synchronization are spatially coincident with the hemodynamic response

Using group functional Magnetic Resonance Imaging (fMRI) and group Magnetoencephalography (MEG) we studied two cognitive paradigms: A language task involving covert letter fluency and a visual task involving biological motion direction discrimination. The MEG data were analyzed using an adaptive beam-former technique known as Synthetic Aperture Magnetometry (SAM), which provides continuous 3-D images of cortical power changes. These images were spatially normalized and averaged across subjects to provide a group SAM image in the same template space as the group fMRI data. The results show that frequency-specific, task-related changes in cortical synchronization, detected using MEG, match those areas of the brain showing an evoked cortical hemodynamic response with fMRI. The majority of these changes were event-related desynchronizations (ERDs) in the 5-10 Hz and 15-25 Hz frequency ranges. Our study demonstrates how SAM, spatial normalization, and intersubject averaging enable group MEG studies to be performed. SAM analysis also allows the MEG experiment to have exactly the same task design as the corresponding fMRI experiment. This new analysis framework represents an important advance in the use of MEG as a cognitive neuroimaging technique and also allows mutual cross-validation with fMRI.     

Accuracy and applications of group MEG studies using cortical source locations estimated from participants' scalp surfaces

We contend that powerful group studies can be conducted using magnetoencephalography (MEG), which can provide useful insights into the approximate distribution of the neural activity detected with MEG without requiring magnetic resonance imaging (MRI) for each participant. Instead, a participant's MRI is approximated with one chosen as a best match on the basis of the scalp surface from a database of available MRIs. Because large inter-individual variability in sulcal and gyral patterns is an inherent source of blurring in studies using grouped functional activity, the additional error introduced by this approximation procedure has little effect on the group results, and offers a sufficiently close approximation to that of the participants to yield a good indication of the true distribution of the grouped neural activity. T1-weighted MRIs of 28 adults were acquired in a variety of MR systems. An artificial functional image was prepared for each person in which eight 5 x 5 x 5 mm regions of brain activation were simulated. Spatial normalisation was applied to each image using transformations calculated using SPM99 with (1) the participant's actual MRI, and (2) the best matched MRI substituted from those of the other 27 participants. The distribution of distances between the locations of points using real and substituted MRIs had a modal value of 6 mm with 90% of cases falling below 12.5 mm. The effects of this approach on real grouped SAM source imaging of MEG data in a verbal fluency task are also shown. The distribution of MEG activity in the estimated average response is very similar to that produced when using the real MRIs.     

Group imaging of task-related changes in cortical synchronisation using nonparametric permutation testing

Synthetic aperture magnetometry (SAM) is a nonlinear beamformer technique for producing 3D images of cortical activity from magnetoencephalography data. We have previously shown how SAM images can be spatially normalised and averaged to form a group image. In this paper we show how nonparametric permutation methods can be used to make robust statistical inference about group SAM data. Data from a biological motion direction discrimination experiment were analysed using both a nonparametric analysis toolbox (SnPM) and a conventional parametric approach utilising Gaussian field theory. In data from a group of six subjects, we were able to show robust group activation at the P < 0.05 (corrected) level using the nonparametric methods, while no significant clusters were found using the conventional parametric approach. Activation was found using SnPM in several regions of right occipital-temporal cortex, including the superior temporal sulcus, V5/MT, the fusiform gyrus, and the lateral occipital complex.     

Fiberoptic bronchoscopy in the diagnosis of pulmonary tuberculosis

We reviewed the records of 80 patients with culture-positive pulmonary tuberculosis. Forty (50%) had their diagnoses established by sputum smears and cultures alone, 20 (25%) by brush/wash specimens from fiberoptic bronchoscopy alone, 18 (22.5%) from both sources, and two (2.5%) by gastric smears. The average age of the patients was 71.3 years, and only 20% had symptoms typical of pulmonary tuberculosis. Our data reveal that findings in smears from fiberoptic bronchoscopy were of comparable sensitivity (80%) to those of sputum (72.5%); in 25/80 (31.25%), diagnosis was made exclusively by fiberoptic bronchoscopy. Such a high sensitivity of fiberoptic bronchoscopy in the diagnosis of pulmonary tuberculosis indicates a threefold rise (P = .018) in the number of diagnoses made in this manner compared to our figures from 1983 (10% of diagnoses made by fiberoptic bronchoscopy). Forty-three of the 80 patients (53.8%) had either a negative sputum smear or no sputum available. Thirty of the 43 patients (69.8%) had diagnostic bronchoscopy, which provided an immediate diagnosis (smear positivity) in 18 patients (60%). Transbronchial biopsy was most useful in excluding associated malignancy. Fiberoptic bronchoscopy is playing an increasingly significant role in the diagnosis of pulmonary tuberculosis. Further studies are essential to evaluate cost effectiveness, specificity of fiberoptic bronchoscopy, and the influence of the procedure on morbidity and mortality in pulmonary tuberculosis.     

The temporal frequency tuning of human visual cortex investigated using synthetic aperture magnetometry

Using synthetic aperture magnetometry (SAM) analyses of magnetoencephalographic (MEG) data, we investigated the variation in cortical response magnitude and frequency as a function of stimulus temporal frequency. In two separate experiments, a reversing checkerboard stimulus was used in the right or left lower visual field at frequencies from 0 to 21 Hz. Average temporal frequency tuning curves were constructed for regions-of-interest located within medial visual cortex and V5/MT. In medial visual cortex, it was found that both the frequency and magnitude of the steady-state response varied as a function of the stimulus frequency, with multiple harmonics of the stimulus frequency being found in the response. The maximum fundamental response was found at a stimulus frequency of 8 Hz, whilst the maximum broadband response occurred at 4 Hz. In contrast, the magnitude and frequency content of the evoked onset response showed no dependency on stimulus frequency. Whilst medial visual cortex showed a power increase during stimulation, extra-striate areas such as V5/MT exhibited a bilateral event-related desynchronisation (ERD). The frequency content of this ERD did not depend on the stimulus frequency but was a broadband power reduction across the 5-20 Hz frequency range. The magnitude of this ERD within V5/MT was strongly low-pass tuned for stimulus frequency, and showed only a moderate preference for stimuli in the contralateral visual field.     

Monitoring nutritional status in the critically ill adult

Nutritional support is an important aspect of the multidisciplinary approach to critical care medicine. During stress, visceral protein turnover is increased. However, muscle and connective tissue proteolysis is obligatory if the stressful condition persists. Through nutritional support, peripheral protein breakdown is minimized and visceral protein synthesis maximized. A delivery system of 15% to 20% dietary protein, 30% fat, 50% to 55% carbohydrate, complemented by moderate amounts of vitamins and minerals, is considered best. Optimal nutritional care depends on objective assessment of the patient's nutritional status before and during nutritional support, particularly the nutritional status of the body cell mass and the energy required for maintenance and support of reparative processes. Indicators least disturbed by factors should be selected for assessment. Individual indicators vary in critical states. After resuscitation, excess body water may increase body weight; after surgery, stress may depress albumin levels. Biometric markers of nutritional status and measurements that adequately validate and evaluate response to nutritional support are discussed.