Neurons in the supplementary eye field (SEF) of the macaque monkey exhibit rank selectivity, firing differentially as a function of the phase attained during the performance of a task requiring the execution of saccades to a series of objects in fixed order. The activity of these neurons is commonly thought to represent ordinal position in the service of serial-order performance. However, there is little evidence causally linking neuronal activity in the SEF to sequential behavior. To explore the role of the SEF in serial-order performance, we delivered intracortical microstimulation while monkeys performed a task requiring them to make saccades to three objects in a fixed order on each trial. Microstimulation, considered on average across all SEF sites and all phases of the trial, affected saccadic kinematics. In particular, it prolonged the reaction time, increased the peak velocity, and slightly increased the amplitude of saccades. In addition, it interfered with the monkeys' ability to select the target appropriate to a given phase of the trial. The pattern of the errors was such as would be expected if microstimulation shifted the neural representation of ordinal position toward a later phase of the trial.

Non-invasive EEG detection of very high frequency somatosensory evoked potentials featuring frequencies up to and above 1 kHz has been recently reported. Here, we establish the detectability of such components by combined low-noise EEG/MEG. We recorded SEP/SEF simultaneously using median nerve stimulation in five healthy human subjects inside an electromagnetically shielded room, combining a low-noise EEG custom-made amplifier (4.7 nV/√Hz) and a custom-made single-channel low-noise MEG (0.5 fT/√Hz @ 1 kHz). Both, low-noise EEG and MEG revealed three spectrally distinct and temporally overlapping evoked components: N20 (<100 Hz), sigma-burst (450-750 Hz), and kappa-burst (850-1200 Hz). The two recording modalities showed similar relative scaling of signal amplitude in all three frequencies domains (EEG [10 nV] ≅ MEG [1 fT]). Pronounced waveform (peak-by-peak) overlap of EEG and MEG signals is observed in the sigma band, whereas in the kappa band overlap was only partial. A decreasing signal-to-noise ratio (SNR; calculated for n = 12.000 averages) from sigma to kappa components characterizes both, electric and magnetic field recordings: Sigma-band SNR was 12.9 ± 5.5/19.8 ± 12.6 for EEG/MEG, and kappa-band SNR at 3.77 ± 0.8/4.5 ± 2.9. High-frequency performance of a tailor-made MEG matches closely with simultaneously recorded low-noise EEG for the non-invasive detection of somatosensory evoked activity at and above 1 kHz. Thus, future multi-channel dual-mode low-noise technology could offer complementary views for source reconstruction of the neural generators underlying such high-frequency responses, and render neural high-frequency processes related to multi-unit spike discharges accessible in non-invasive recordings.

The connectivity pattern of the neural network devoted to sensory processing depends on the timing of relay recruitment from receptors to cortical areas. The aim of the present work was to uncover and quantify the way the cortical relay recruitment is reflected in the shape of the brain-evoked responses. We recorded the magnetic somatosensory evoked fields (SEF) generated in 36 volunteers by separate bilateral electrical stimulation of median nerve, thumb, and little fingers. After defining an index that quantifies the shape similarity of two SEF traces, we studied the morphologic characteristics of the recorded SEFs within the 20-ms time window that followed the impulse arrival at the primary sensory cortex. Based on our similarity criterion, the shape of the SEFs obtained stimulating the median nerve was observed to be more similar to the one obtained from the thumb (same median nerve innervation) than to the one obtained from the little finger (ulnar nerve innervation). In addition, SEF shapes associated with different brain regions were more similar within an individual than between subjects. Because the SEF morphologic characteristics turned out to be quite diverse among subjects, we defined similarity levels that allowed us to identify three main classes of SEF shapes in normalcy. We show evidence that the morphology of the evoked response describes the anatomo-functional connectivity pattern in the primary sensory areas. Our findings suggest the possible existence of a thalamo-cortico-thalamic responsiveness loop related to the different classes.

OBJECTIVE

The distal-proximal representations of the finger and palm in the first somatosensory cortex (SI) were studied in humans.

METHODS

Somatosensory evoked magnetic fields (SEFs) from 11 subjects were measured, following mechanical stimulation of the skin by using a 122 channel whole head SQUID system. Sensory stimulus comprising of a 10 ms vibration at the frequency of 200 Hz was delivered to 6 successive sites in 3 cm increments, along the distal-proximal direction over the volar surface of the right index finger and palm. Using a single dipole model, the sources of the magnetic fields were estimated and mapped onto magnetic resonance images of each subject. ANOVA was used for statistics.

RESULTS

Source localization was determined on the main peak (M50) of the SEFs. All of the sources were located in the area 3b of SI. Contrary to the well-defined distal-proximal representations in the hand area of simian SI cortex, there was no statistically significant differences between the locations of the dipoles in human SI cortex evoked by stimulation of different sites.

CONCLUSIONS

The result, however, should be interpreted with caution, because it cannot be denied that the spatial separation of sources in the distal-proximal somatotopy is beyond the resolving capacity of magnetoencephalography (MEG). In addition, at variance with the discrete distal-proximal gradient in the mechanoreceptor density, there was no statistically significant differences between the signal strengths of the dipoles for stimulation of the different locations.

The purpose of this study was to assess the long-term in vivo failure rate of tubes bonded to first and second molars with a self-etching primer (SEF). A total of 810 molar tubes (414 first molar and 396 second molar) were bonded on 135 patients (56 male, 79 female; mean age 14 years) with the 3M Transbond Plus Self Etching Primer. The first-time failures of the tubes were recorded for a mean period of 26 months (range 23-29 months). Failure rates per jaw (maxilla-mandible), tooth (first and second molar), and quadrant (left, right) were analyzed with the chi(2) at alpha = 0.05 level of significance. Significant differences were found in the failure rate between first and second molars (9.66% vs 20%, respectively) as well as maxillary and mandibular molars (7.5% vs 21%, respectively). The combined, total failure rate for first and second molars was 14.80%. No difference was found between male and female failure rates for the molar tubes. First-molar tubes bonded with an SEF may show failure rates comparable with those reported in the literature for tubes bonded with conventional acid etching.

Fibroblast growth factors (FGFs) signal via four distinct high affinity cell surface tyrosine kinase receptors, termed FGFR1-FGFR4 (FGFR-FGF-receptor). Recently, a new modulator of the FGF signaling pathway, the transmembrane protein 'similar expression to FGF genes' (Sef), has been identified in zebrafish and subsequently in mammals. Sef from mouse and human inhibits FGF mitogenic activity. In the present study, we analyzed the expression of Sef in distinct rat brain areas, in the spinal cord and in peripheral nerves and spinal ganglia using semi-quantitative RT-PCR. Furthermore, we studied the cellular expression pattern of Sef in intact spinal ganglia and sciatic nerves and, in addition, after crush lesion, using in situ hybridization and immunohistochemistry. Sef transcripts were expressed in all brain areas evaluated and in the spinal cord. A neuronal expression was found in both intact and injured spinal ganglia. Intact sciatic nerves, however, showed little or no Sef expression. Seven days after injury, high Sef expression was concentrated to the crush site, and Schwann cells seemed to be the source of Sef. The labeling pattern of up-regulated Sef was complementary to the patterns of FGF-2 and FGFR1-3, which were localized proximal and distal to the crush site. These results suggest an involvement of Sef during the nerve regeneration process, possibly by fine-tuning the effects of FGF signaling.

OBJECTIVE

To clarify the characteristics relating to the temporal dynamics of the tongue primary somatosensory cortex (SI).

METHODS

We fabricated individual intraoral devices and recorded somatosensory-evoked magnetic fields (SEFs) from 10 normal subjects. The tongue was stimulated with a concentrated bipolar electrode in four areas: the right and left antero-lateral margins, and the right and left postero-lateral margins.

RESULTS

The primary component was recorded about 19 ms post-stimulation. Six components, termed 1M, 2M, 3M, 4M, 5M, and 6M, respectively, were found within 130 ms of the stimulation. These activities were detected in hemispheres both contralateral and ipsilateral to the stimulation, and were estimated to be located around the tongue SI. In addition, the latency of the contralateral hemisphere was significantly shorter than that of the ipsilateral hemisphere for all components, independent of the area stimulated.

CONCLUSIONS

Tactile stimulation of the tongue-elicited activity in the tongue SI in both hemispheres.

CONCLUSIONS

This is the first study to investigate the brain responses evoked by stimulating different areas of the tongue, using magnetoencephalography.

The purpose of this study was to describe the pharmacokinetics of and heart rate and blood pressure responses to (S)-atenolol (SATN) and (R)-atenolol (RATN) after oral administration of (S)-atenolol and (R,S)-atenolol (Tenormin) in man. Eight male subjects were given single oral doses of 50 mg of SATN as a single enantiomer formulation (SEF) and 100 mg of Tenormin (TMN) using a randomized, double-blind, 2-period, complete crossover study design. Subjects performed exercise tolerance tests (Bruce Protocol) before and 2, 4, 6, 8, 12, and 24 h after drug administration. Plasma samples were obtained 2 min before and 30 min, 1, 1.5, 2, 3, 4, 5, 6, 8, 10, 12, 16, and 24 h after dosing. Urine was collected for the first 48 h after dosing. Plasma and urine samples were analyzed for SATN and RATN by an enantioselective HPLC method. SEF and Tenormin attenuate exercise-induced increases in heart rate and systolic blood pressure. Mean changes in exercise heart rates 4 h after dosing were -38 +/- 3 bpm and -37 +/- 3 bpm for SEF and TMN, respectively, P = 0.792. Mean changes in exercise systolic blood pressure were -42 +/- 12 mm Hg and -55 +/- 14 mm Hg for SEF and TMN, respectively, P = 0.484. Mean area under the plasma level time curve (AUC0-24) and mean Cmax for SATN for SEF were significantly lower than for SATN after TMN.(ABSTRACT TRUNCATED AT 250 WORDS)

We tested for a genetic influence on magnetoencephalogram (MEG)-recorded somatosensory evoked fields (SEFs) in 20 monozygotic (MZ) and 14 dizygotic (DZ) twin pairs. Previous electroencephalogram (EEG) studies that demonstrated a genetic contribution to evoked responses generally focused on characteristics of representative brain potentials. Here we demonstrate significantly smaller amplitude differences within MZ compared to DZ twin pairs for the complete SEF time series (across left and right hand SEFs: 0.37 vs. 0.60 pT(2) and 0.28 vs. 0.39 pT(2) for primary [SI] and secondary [SII] sensory cortex activation) and higher MZ than DZ wave shape correlations (.71 vs. .44 and .52 vs. .35 for SI and SII activation). Our findings indicate a genetic influence on MEG-recorded evoked brain activity and also confirm our recent conclusion (van 't Ent, van Soelen, Stam, De Geus, & Boomsma, 2009) that higher MZ resemblance for EEG amplitudes is not trivially reflecting greater MZ concordance in intervening biological tissues.

It is currently accepted that there is a subset of patients diagnosed with Alzheimer's disease (AD) who show executive functioning (EF) impairments even in the earlier stages. These patients have been shown to present distinct psychiatric, behavioral, occupational, and even histopathological profiles. We assessed thirty patients with AD on two tasks of verbal memory (Logical Memory - LM, and the Rey Auditory-Verbal Learning Task - RAVLT), as well as classical tests of EF. AD patients were classified into either a spared EF (SEF) group if they showed impaired performance (z < -1.5 SD) in none or only one of the executive tests, or into an impaired EF (IEF) group if they showed impaired performance on two or more tasks of EF. Their performance was compared with fourteen healthy controls. SEF showed significantly more years of education than IEF, but the groups did not differ significantly on age, gender, mood symptoms, or performance on general screening tests or attentional tasks. With education as a covariate, both AD groups differed from controls on all measures of memory, but a significant difference was found between SEF and IEF patients only on the recognition phases of both logical memory (p < 0.01) and RAVLT (p = 0.02). Recognition scores significantly correlated with performance on executive tasks. Early AD patients who preserve their EF seem to have an advantage in their ability to recognize information that has been previously presented over patients with impaired EF. Such advantage seems to be strongly associated with executive performance.

The positions of the bilateral N100m sources of the auditory evoked magnetic fields (AEFs) were measured in relation to the central sulcus (CS) using an MRI-linked whole head magnetoencephalography system in 20 right-handed normal male subjects. The location of the N20m source of the median nerve-stimulated somatosensory evoked magnetic fields (SEFs), in the left hemisphere was 3.9+/-5.4 mm (mean+/-SD) posterior to that in the right hemisphere (P < 0.005). The crossing point (CP) between the CS and Sylvian fissure in the left hemisphere was 4.3+/-4.8 mm posterior to that in the right hemisphere (P < 0.001). The N100m sources were posterior to the CP in both hemispheres. The left hemispheric N100m source was 9.4+/-6.4 mm posterior to that on the right (P < 0.0001) in absolute position. The relative distance between CP and the N100m source was 22.7+/-8.5 mm in the left hemisphere and 17.7+/-5.3 mm in the right hemisphere (P < 0.01). Comparison of positions of the AEF sources and the CS as defined by the SEF demonstrated functional asymmetry of the human temporal lobe and possible source extension of the AEF-N100m beyond the Heschl gyrus over the planum temporale.

OBJECTIVE

Recent studies using electroencephalography or magnetoencephalography have shown that peripheral nerve stimulations produce short-latency high-frequency signals in the human somatosensory cortex. The present study tested whether they consist of more than one distinct type of signal.

METHODS

Somatic evoked magnetic fields (SEFs) elicited by electrical stimulation of the median nerve were measured in 12 healthy volunteers. They were analyzed using a time-frequency analysis method based on Gabor filters and another based on autoregressive moving average, and also with bispectrum and bicoherence techniques and a new dispersion curve method.

RESULTS

Signals in two separate high-frequency bands (200 and 600 Hz) were distinguished from the main signal in the low frequency (LF) range during the time period of N20m and P25m. The novel 200 Hz-band signal was seen reliably in those channels where the LF band signal was weak, so that the former was not masked by the latter. The 600 Hz signal consisted of two distinct components or parts (p1 and p2) in 10 out of 12 subjects, one peaking during ascending slope and the second during the descending slope of the N20m. The latency of the p1 was shorter than the latencies of the 200 Hz and LF signals according to the dispersion curve analysis. The inter-peak interval of p1 became shorter for later peaks in all 12 subjects. Bicoherence analysis revealed a significant phase coupling between the 200 and 600 Hz bands.

CONCLUSIONS

There are three distinct types of signal during the time period of the short-latency cortical components of the SEF -- LF which gives rise to the commonly seen waveform of the SEF, the newly found 200 Hz signal and the 600 Hz signal which consists of two components. The possible origins of the high frequency signals are discussed in light of the new set of evidence found in the present study.

We report somatosensory evoked magnetic fields (SEFs) to stimulation of the mixed posterior tibial nerve (PTN) and the sensory sural nerve (SN) in 6 healthy subjects. The first peak of the responses occurred at 39-50 ms (P40m), with a 2-3 ms longer latency for SN than PTN stimulation. Within 200 ms several other deflections followed, with interindividually varying waveforms and latencies. Magnetic field mappings indicated that the source of P40m for PTN can be modelled by a single equivalent current dipole at the primary sensorimotor cortex; for the smaller responses to SN stimulation the single dipole model was less applicable. Field patterns for later deflections differed from those of P40m, indicating that several current sources within or near the primary foot projection area are sequentially activated after stimulation of both a mixed and a sensory lower limb nerve. These late deflections could not always be satisfactorily explained by single current dipoles, suggesting more complex geometries for the underlying neural activity.

A semi-automated, variable-region-of-interest method of analysis was used to measure both global and segmental left ventricular (LV) and global right ventricular (RV) contraction with ECG-gated first-pass and equilibrium radionuclide ventriculography. Normal values were defined in 20 healthy volunteers, and in 24 symptomatic patients, the results were compared with right anterior oblique (RAO) contrast left ventriculography. The global LV ejection fraction (LVEF) obtained by equilibrium imaging in the left anterior oblique (LAO) projection correlated closely with the results obtained by the gated first-pass method in the RAO projection (r = 0.95) and those obtained with contrast left ventriculography (r = 0.94); furthermore, the interobserver variability was small (r = 0.985). The normal values for LVEF obtained using radionuclide techniques and contrast ventriculography did not differ, but with the equilibrium radionuclide method, the RV ejection fraction (RVEF) values were underestimated in comparison to those obtained by the RAO gated first-pass technique. In five patients with localised inferior segmental akinesis at contrast angiography, the RAO first-pass cine display demonstrated a corresponding wall-motion abnormality in all cases, but LAO equilibrium cine displays did so in only one out of five patients. For segmental quantitation of LV contraction, a computer programme defined the ventricular edge, divided the RAO LV images into five segments and determined both the segmental area contraction (SAC) and the counts-based segmental ejection fraction (SEF). Radionuclide SAC measurements correlated very strongly with SEF measurements (r = 0.94-0.99). Both radionuclide SAC and radionuclide SEF correlated well with contrast angiographic SAC, except in the inferobasal segment.(ABSTRACT TRUNCATED AT 250 WORDS)

Multiple lines of evidence indicate that an anatomically discrete region within the dorsal medial frontal cortex--the supplementary eye field (SEF)--is involved in oculomotor control. To delineate this role further, repetitive transcranial magnetic stimulation (rTMS; 10 Hz, 500 ms) was administered either immediately after the presentation of three-step saccade sequences, or, immediately before response execution of memory-guided saccades. In addition, the effects of changes to visuospatial and temporal order demands were examined by contrasting performance in the presence and the absence of target location information. Results revealed that the SEF supports the processing of spatial information relevant to saccade amplitude. Independently of the time of stimulation, saccade gain was reduced by rTMS applied over the SEF, though only when response execution was performed in the absence of target location information. These results provide evidence of a causal role for the SEF in oculomotor control in the absence of visual feedback.

Many forms of brain stimulation utilize the notion of state dependency, whereby greater influences are observed when a given area is more engaged at the time of stimulation. Here, by delivering intracortical microstimulation (ICMS) to the supplementary eye fields (SEF) of monkeys performing interleaved pro- and anti-saccades, we show a surprising diversity of state-dependent effects of ICMS-SEF. Short-duration ICMS-SEF passed around cue presentation selectively disrupted anti-saccades by increasing reaction times and error rates bilaterally, and also recruited neck muscles, favoring contralateral head turning to a greater degree on anti-saccade trials. These results are consistent with the functional relevance of the SEF for anti-saccades. The multiplicity of stimulation-evoked effects, with ICMS-SEF simultaneously disrupting anti-saccade performance and facilitating contralateral head orienting, probably reflects both the diversity of cortical and subcortical targets of SEF projections, and the response of this oculomotor network to stimulation. We speculate that the bilateral disruption of anti-saccades arises via feedback loops that may include the thalamus, whereas neck muscle recruitment arises via feedforward polysynaptic pathways to the motor periphery. Consideration of both sets of results reveals a more complete picture of the highly complex and multiphasic response to ICMS-SEF that can play out differently in different effector systems.

Neurons in several areas of the monkey frontal cortex exhibit rank selectivity, firing differentially as a function of the stage attained during the performance of a serial order task. The activity of these neurons is commonly thought to represent ordinal position within the trial. However, they might also be sensitive to factors correlated with ordinal position including time elapsed during the trial (which is greater for each successive stage) and the degree of anticipation of reward (which probably increases at each successive stage). To compare the influences of these factors, we monitored neuronal activity in the supplementary motor area (SMA), presupplementary motor area (pre-SMA), supplementary eye field (SEF), and dorsolateral prefrontal cortex during the performance of a serial order task (requiring a series of saccades in three specified directions), a variable reward task (in which a cue displayed early in the trial indicated whether the reward received at the end of the trial would be large or small), and a long delay task (in which the monkey had simply to maintain fixation during a period of time approximating the duration of an average trial in the serial order task). We found that rank signals were partially correlated with sensitivity to elapsed time and anticipated reward. The connection to elapsed time was strongest in the pre-SMA. The connection to anticipated reward was most pronounced in the SMA and SEF. However, critically, these factors could not fully explain rank selectivity in any of the areas tested.

The authors present two cases of primary sclerosing epithelioid fibrosarcoma (SEF) of the kidney. Both patients had a mass in the upper part of the left kidney without any primary extrarenal neoplastic lesions. Grossly, the tumors were solid masses both measuring 7.5 cm in the greatest diameter. Histologically, one of the lesions exhibited a predominantly lobular growth of round or oval small uniform epithelioid cells in variable cellularity. Circular zones of crowded tumor cells alternating with hypocellular collagenous tissue in a concentric fashion around entrapped native renal tubules were distinctive. The second case was distinctive with significant cytological atypia in the neoplastic cells and prominent reactive proliferations in the trapped renal tubules. Immunohistochemically, vimentin, bcl-2 and MUC4 were diffusely positive in both. They were negative for S-100 protein, CD34, and desmin, whereas CD99 were positive in one lesion. Fluorescence in situ hybridization assay using dual staining probes detected EWSR1-CREB3L1 fusion in each lesion, which is characteristic molecular findings of SEF. One patient presented widespread distant metastases at the time of diagnosis. In the other, no tumor deposits were detected other than primary. Both patients have been alive with 30 and 10 month follow-ups, respectively. These tumors are 6th and 7th cases of primary renal SEF in the literature confirmed by FISH study, which exhibit unique and remarkable histomorphologic features.

The feasibility of precise mapping was investigated noninvasively on the face component in predominantly unilateral primary somatosensory cortices (SI) in six healthy subjects. We recorded somatosensory evoked magnetic fields (SEFs) from the SI and secondary somatosensory cortices (SII) following the electrical stimulation of six skin sites: the infraorbital foramen, the angle of mouth, the upper lip, the lower lip, the mental foramen, and the mandibular angle. The median nerve at the wrist was stimulated as a standard of the map. The location of the equivalent current dipoles (ECDs) estimated from the distribution of magnetic fields was identified on MR images of the brain on each subject. The ECDs of the early components of SEF with peaks of 20-30 ms aligned along the SI in the hemisphere contralateral to the stimulation site. Late components with peaks of 80-150 ms were recorded from the bilateral hemispheres, and their ECDs were identified in the SII of the bilateral hemispheres. There was a distinct separation between the ECD locations representing discrete sites on the face and thumb in the SI of the contralateral hemisphere. Five sites of the face area in SI at the contralateral hemisphere were compatible with the conventional arrangement of homunculus in one subject. However, the remaining subjects had variations in the arrangement. The face area reorganization in the SI is possible to be related to the use-dependent cortical plasticity of the individual or to the perceptual experience by vision and proprioception.

OBJECTIVE

Age-related changes are well documented in the primary somatosensory cortex (SI). Based on previous somatosensory evoked potential studies, the amplitude of N20 typically increases with age probably due to cortical disinhibition. However, less is known about age-related change in the secondary somatosensory cortex (SII). The current study quantified age-related changes across SI and SII mainly based on oscillatory activity indices measured with magnetoencephalography.

METHODS

We recorded somatosensory evoked magnetic fields (SEFs) to right median nerve stimulation in healthy young and old subjects and assessed major SEF components. Then, we evaluated the phase-locking factor (PLF) for local field synchrony on neural oscillations and the weighted phase-lag index (wPLI) for cortico-cortical synchrony between SI and SII.

RESULTS

PLF was significantly increased in SI along with the increased amplitude of N20m in the old subjects. PLF was also increased in SII associated with a shortened peak latency of SEFs. wPLI analysis revealed the increased coherent activity between SI and SII.

CONCLUSIONS

Our results suggest that the functional coupling between SI and SII is influenced by the cortical disinhibition due to normal aging.

CONCLUSIONS

We provide the first electrophysiological evidence for age-related changes in oscillatory neural activities across the somatosensory areas.

Surface-enhanced Raman scattering (SERS) and surface-enhanced fluorescence (SEF) combined emissions were used in this work to the analysis of humic acids (HA). This study examined HA structure at different pH and HA concentrations and assessed the structural differences taking place in HA as a result of various amendment trials. Raman and fluorescence emissions behave in opposite ways due to the effect of the metal surface on the aromatic groups responsible for these emissions. The information afforded by these techniques can be successfully employed in the structural and dynamic analysis of these important macromolecules. The surface-enhanced emission (SEE) spectra, that is the sum of the Raman and the fluorescence emissions, were acquired by using both macro- and micro-experimental configurations in order to apply imaging and confocal Raman and fluorescence spectroscopy techniques on the analysis of HA.

BACKGROUND

The aim of this study was to evaluate the ability of 15 serotypes of Salmonella to form biofilm on polystyrene, polyvinyl chloride (PVC) and glass surfaces. .

METHODS

Initially slime production was assessed on CRA agar and hydrophobicity of 20 Salmonella strains isolated from poultry and human and two Salmonella enterica serovar Typhimurium references strains was achieved by microbial adhesion to n-hexadecane. In addition, biofilm formation on polystyrene, PVC and glass surfaces was also investigated by using MTT and XTT colorimetric assay. Further, distribution of Salmonella enterotoxin (stn), Salmonella Enteritidis fimbrial (sef) and plasmid encoded fimbrial (pef) genes among tested strains was achieved by PCR.

RESULTS

Salmonella strains developed red and white colonies on CRA and they are considered as hydrophilic with affinity values to n-hexadecane ranged between 0.29% and 29.55%. Quantitative biofilm assays showed that bacteria are able to form biofilm on polystyrene with different degrees and 54.54% of strains produce a strong biofilm on glass. In addition, all the strains form only a moderate (54.54%) and weak (40.91%) biofilm on PVC. PCR detection showed that only S. Enteritidis harbour Sef gene, whereas Pef and stn genes were detected in S. Kentucky, S. Amsterdam, S. Hadar, S. Enteritidis and S. Typhimurium.

CONCLUSIONS

Salmonella serotypes are able to form biofilm on hydrophobic and hydrophilic industrial surfaces. Biofilm formation of Salmonella on these surfaces has an increased potential to compromise food safety and potentiate public health risk.

A new method for detoxification of hydrophilic chloroorganic pollutants in effluent water was developed, using a combination of ultrasound waves, electrochemistry and Fenton's reagent. The advantages of the method are exemplified using two target compounds: the common herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) and its derivative 2,4-dichlorophenol (2,4-DCP). The high degradation power of this process is due to the large production of oxidizing hydroxyl radicals and high mass transfer due to sonication. Application of this sono-electrochemical Fenton process (SEF) treatment (at 20 kHz) with quite a small current density, accomplished almost 50% oxidation of 2,4-D solution (300 ppm, 1.2 mM) in just 60 s. Similar treatments ran for 600 s resulted in practically full degradation of the herbicide; sizable oxidation of 2,4-DCP also occurs. The main intermediate compounds produced in the SEF process were identified. Their kinetic profile was measured and a chemical reaction scheme was suggested. The efficiency of the SEF process is tentatively much higher than the reference degradation methods and the time required for full degradation is considerably shorter. The SEF process maintains high performance up to concentrations which are higher than reference methods. The optimum concentration of Fe2+ ions required for this process was found to be of about 2 mM, which is lower than that in reference techniques. These findings indicate that SEF process may be an effective method for detoxification of environmental water.