Nanoparticles for fingermark detection: an insight into the reaction mechanism

This publication presents one of the first uses of silicon oxide nanoparticles to detect fingermarks. The study is not confined to showing successful detection of fingermarks, but is focused on understanding the mechanisms involved in the fingermark detection process. To gain such an understanding, various chemical groups are grafted onto the nanoparticle surface, and parameters such as the pH of the solutions or zeta potential are varied to study their influence on the detection. An electrostatic interaction has been the generally accepted hypothesis of interaction between nanoparticles and fingermarks, but the results of this research challenge that hypothesis, showing that the interaction is chemically driven. Carboxyl groups grafted onto the nanoparticle surfaces react with amine groups of the fingermark secretion. This formation of amide linkage between carboxyl and amine groups has further been favoured by catalyzing the reaction with a compound of diimide type. The research strategy adopted here ought to be applicable to all detection techniques using nanoparticles. For most of them the nature of the interaction remains poorly understood.

Evaluation of a polymerase chain reaction-restriction fragment length polymorphism assay for dermatophyte and nondermatophyte identification in onychomycosis.

BACKGROUND: Dermatophytes are the main cause of onychomycoses, but various nondermatophyte filamentous fungi are often isolated from abnormal nails. The correct identification of the aetiological agent of nail infections is necessary in order to recommend appropriate treatment. OBJECTIVE: To evaluate a rapid polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay based on 28S rDNA for fungal identification in nails on a large number of samples in comparison with cultures. METHODS: Infectious fungi were analysed using PCR-RFLP in 410 nail samples in which fungal elements were observed in situ by direct mycological examination (positive samples). The results were compared with those previously obtained by culture of fungi on Sabouraud agar from the same nail samples. RESULTS: PCR-RFLP identification of fungi in nails allowed validation of the results obtained in culture when Trichophyton spp. grew from infected samples. In addition, nondermatophyte filamentous fungi could be identified with certainty as the infectious agents in onychomycosis, and discriminated from dermatophytes as well as from transient contaminants. The specificity of the culture results relative to PCR-RFLP appeared to be 81%, 71%, 52% and 63% when Fusarium spp., Scopulariopsis brevicaulis, Aspergillus spp. and Candida spp., respectively, grew on Sabouraud agar. It was also possible to identify the infectious agent when direct nail mycological examination showed fungal elements, but negative results were obtained from fungal culture. CONCLUSIONS: Improved sensitivity for the detection of fungi in nails was obtained using the PCR-RFLP assay. Rapid and reliable molecular identification of the infectious fungus can be used routinely and presents several important advantages compared with culture in expediting the choice of appropriate antifungal therapy.

Manual reaction times and brain dynamics after 'awake surgery' of slow-growing tumors invading the parietal area. A case report

Primary objectives: Awake surgeries of slow-growing tumours invading the brain and guided by direct electrical stimulation induce major brain reorganizations accompanied with slight impairments post-operatively. In most cases, these deficits are so slight after a few days that they are often not detectable on classical neuropsychological evaluations. Consequently, this study investigated whether simple visuo-manual reaction time paradigms would sign some level of functional asymmetries between both hemispheres. Importantly, the visual stimulus was located in the saggital plane in order to limit attentional biases and to focus mainly on the inter-hemispheric asymmetry. Methods and procedures: Three patients (aged 41, 59 and 59 years) after resections in parietal regions and a control group (age¼44, SD¼6.9) were compared during simple uni- and bimanual reaction times (RTs). Main outcomes and results: Longer RTs were observed for the contralesional compared to the ipsilesional hand in the unimanual condition. This asymmetry was reversed for the bimanual condition despite longer RTs. Conclusion and clinical implications: Reaction time paradigms are useful in these patients to monitor more precisely their functional deficits, especially their level of functional asymmetry, and to understand brain (re)organization following slowgrowing lesions.

Quantification of thermotolerant campylobacter in Swiss water treatment plants, by real-time quantitative polymerase chain reaction

A total of 49 wastewater samples from 23 different wastewater treatment plants (WWTPs) were analyzed using real-time quantitative polymerase chain reaction for the presence and quantity of thermotolerant campylobacters. Thermotolerant campylobacters were detected in 87.5% (21/24) and 64% (16/25) of untreated and treated wastewater samples, respectively. Their concentration was sufficiently high to be quantified in 20.4% (10/49) of the samples. In these samples, the concentration ranged from 68 000 to 2292 000 cells/L in untreated wastewater and from 10 800 to 28 000 cells/L in treated water. We conclude that thermotolerant campylobacters present a health hazard for workers at WWTPs in Switzerland. [Authors]

Differential stress reaction of human colon cells to oleic-acid-stabilized and unstabilized ultrasmall iron oxide nanoparticles.

Therapeutic engineered nanoparticles (NPs), including ultrasmall superparamagnetic iron oxide (USPIO) NPs, may accumulate in the lower digestive tract following ingestion or injection. In order to evaluate the reaction of human colon cells to USPIO NPs, the effects of non-stabilized USPIO NPs (NS-USPIO NPs), oleic-acid-stabilized USPIO NPs (OA-USPIO NPs), and free oleic acid (OA) were compared in human HT29 and CaCo2 colon epithelial cancer cells. First the biophysical characteristics of NS-USPIO NPs and OA-USPIO NPs in water, in cell culture medium supplemented with fetal calf serum, and in cell culture medium preconditioned by HT29 and CaCo₂ cells were determined. Then, stress responses of the cells were evaluated following exposure to NS-USPIO NPs, OA-USPIO NPs, and free OA. No modification of the cytoskeletal actin network was observed. Cell response to stress, including markers of apoptosis and DNA repair, oxidative stress and degradative/autophagic stress, induction of heat shock protein, or lipid metabolism was determined in cells exposed to the two NPs. Induction of an autophagic response was observed in the two cell lines for both NPs but not free OA, while the other stress responses were cell- and NP-specific. The formation of lipid vacuoles/droplets was demonstrated in HT29 and CaCo₂ cells exposed to OA-USPIO NPs but not to NS-USPIO NPs, and to a much lower level in cells exposed to equimolar concentrations of free OA. Therefore, the induction of lipid vacuoles in colon cells exposed to OA utilized as a stabilizer for USPIO NPs is higly amplified compared to free OA, and is not observed in the absence of this lipid in NS-USPIO NPs.

Peripheral Nerve Neuropathy is Associated with a Glial Reaction in the Gracile Nucleus Associated with a regulation of the GABA transporter GAT-1

Allodynia (pain in response to normally non painful stimulation) and paresthesia (erroneous sensory experience) are two debilitating symptoms of neuropathic pain. These stem, at least partly, from profound changes in the non-nociceptive sensory pathway that comprises large myelinated neuronal afferents terminating in the gracile and cuneate nuclei. Further than neuronal changes, well admitted evidence indicates that glial cells (especially in the spinal cord) are key actors in neuropathic pain, in particular the possible alteration in astrocytic capacity to reuptake neurotransmitters (glutamate and GABA). Yet, the possibility of such a changed astrocytic scavenging capacity remains unexplored in the dorsal column pathway. The present study was therefore undertaken to assess whether peripheral nerve injury (spared nerve injury model, SNI) could trigger a glial reaction, and especially changes in glutamate and GABA transporters, in the gracile nucleus. SNI surgery was performed on male Sprague-Dawley rats. Seven days after surgery, rats were used for immunofluorescence (fixation and brain slicing), western-blot (fresh brain freezing and protein extraction) or GABA reuptake on synaptosomes. We found that SNI results in a profound glial reaction in the ipsilateral gracile nucleus. This reaction was characterized by an enhanced immunolabelling for microglial marker Iba1 as well as astrocytic protein GFAP (further confirmed by western-blot, p <0.05, n = 7). These changes were not observed in sham animals. Immunofluorescence and western-blot analysis shows that the GABA transporter GAT-1 is upregulated in the ipsilateral gracile nucleus (p <0.001; n = 7), with no detectable change in GAT-3 or glutamate transporters EAAT-1 and EAAT-2. Double immunoflurescence shows that GAT-1 and GFAP colocalize within the same cells. Furthermore, the upregulation of GFAP and GAT-1 were shown to occur all along the rostrocaudal axis of the gracile nucleus. Finally, synaptosomes from ipsilateral gracile nucleus show an increased capacity to reuptake GABA. Together, the data presented herein show that glial cells in the gracile nucleus react to neuropathic lesion, in particular through an upregulation of the GABA transporter GAT-1. Hence, this study points to role of an increased GABA transport in the dorsal column nuclei in neuropathic pain, calling attention to GAT-1 as a putative future pharmacological target to treat allodynia and paresthesia.

Early, low-level auditory-somatosensory multisensory interactions impact reaction time speed.

Several lines of research have documented early-latency non-linear response interactions between audition and touch in humans and non-human primates. That these effects have been obtained under anesthesia, passive stimulation, as well as speeded reaction time tasks would suggest that some multisensory effects are not directly influencing behavioral outcome. We investigated whether the initial non-linear neural response interactions have a direct bearing on the speed of reaction times. Electrical neuroimaging analyses were applied to event-related potentials in response to auditory, somatosensory, or simultaneous auditory-somatosensory multisensory stimulation that were in turn averaged according to trials leading to fast and slow reaction times (using a median split of individual subject data for each experimental condition). Responses to multisensory stimulus pairs were contrasted with each unisensory response as well as summed responses from the constituent unisensory conditions. Behavioral analyses indicated that neural response interactions were only implicated in the case of trials producing fast reaction times, as evidenced by facilitation in excess of probability summation. In agreement, supra-additive non-linear neural response interactions between multisensory and the sum of the constituent unisensory stimuli were evident over the 40-84 ms post-stimulus period only when reaction times were fast, whereas subsequent effects (86-128 ms) were observed independently of reaction time speed. Distributed source estimations further revealed that these earlier effects followed from supra-additive modulation of activity within posterior superior temporal cortices. These results indicate the behavioral relevance of early multisensory phenomena.

Adverse tissue reaction to corrosion at the neck-stem junction after modular primary total hip arthroplasty.

Complications related to the neck-stem junction of modular stems used for total hip arthroplasty (THA) are generating increasing concern. A 74-year-old male had increasing pain and a cutaneous reaction around the scar 1 year after THA with a modular neck-stem. Imaging revealed osteolysis of the calcar and a pseudo-tumour adjacent to the neck-stem junction. Serum cobalt levels were elevated. Revision surgery to exchange the stem and liner and to resect the pseudo-tumour was performed. Analysis of the stem by scanning electron microscopy and by energy dispersive X-ray and white light interferometry showed fretting corrosion at the neck-stem junction contrasting with minimal changes at the head-neck junction. Thus, despite dry assembly of the neck and stem on the back table at primary THA, full neck-stem contact was not achieved, and the resulting micromotion at the interface led to fretting corrosion. This case highlights the mechanism of fretting corrosion at the neck-stem interface responsible for adverse local tissue reactions. Clinical and radiological follow-up is mandatory in patients with dual-modular stems.

Transferring control demands across incidental learning tasks - Stronger sequence usage in serial reaction task after shortcut option in letter string checking

After incidentally learning about a hidden regularity, participants can either continue to solve the task as instructed or, alternatively, apply a shortcut. Past research suggests that the amount of conflict implied by adopting a shortcut seems to bias the decision for vs. against continuing instruction-coherent task processing. We explored whether this decision might transfer from one incidental learning task to the next. Theories that conceptualize strategy change in incidental learning as a learning-plus-decision phenomenon suggest that high demands to adhere to instruction-coherent task processing in Task 1 will impede shortcut usage in Task 2, whereas low control demands will foster it. We sequentially applied two established incidental learning tasks differing in stimuli, responses and hidden regularity (the alphabet verification task followed by the serial reaction task, SRT). While some participants experienced a complete redundancy in the task material of the alphabet verification task (low demands to adhere to instructions), for others the redundancy was only partial. Thus, shortcut application would have led to errors (high demands to follow instructions). The low control demand condition showed the strongest usage of the fixed and repeating sequence of responses in the SRT. The transfer results are in line with the learning-plus-decision view of strategy change in incidental learning, rather than with resource theories of self-control.

Metabolic and structural rearrangement during dark-induced autophagy in soybean (Glycine max L.) nodules: An electron microscopy and P-31 and C-13 nuclear magnetic resonance study

The effects of dark-induced stress on the evolution of the soluble metabolites present in senescent soybean (Glycine max L.) nodules were analysed in vitro using C-13- and P-31-NMR spectroscopy. Sucrose and trehalose were the predominant soluble storage carbons. During dark-induced stress, a decline in sugars and some key glycolytic metabolites was observed. Whereas 84% of the sucrose disappeared, only one-half of the trehalose was utilised. This decline coincides with the depletion of Gln, Asn, Ala and with an accumulation of ureides, which reflect a huge reduction of the N-2 fixation. Concomitantly, phosphodiesters and compounds like P-choline, a good marker of membrane phospholipids hydrolysis and cell autophagy, accumulated in the nodules. An autophagic process was confirmed by the decrease in cell fatty acid content. In addition, a slight increase in unsaturated fatty acids (oleic and linoleic acids) was observed, probably as a response to peroxidation reactions. Electron microscopy analysis revealed that, despite membranes dismantling, most of the bacteroids seem to be structurally intact. Taken together, our results show that the carbohydrate starvation induced in soybean by dark stress triggers a profound metabolic and structural rearrangement in the infected cells of soybean nodule which is representative of symbiotic cessation.

Pathogenic attack and carbon reallocation in soybean leaves (Glycine max. L.): Reinitiation of the glyoxylate cycle as a defence reaction

Pathogenic attack by the fungus Botrytis cinerea (primary pathogen) on soybean leaves (Glycine max. L.; cv. Maple arrow) results in a hypersensitive response (necrotising infected leaves), in the establishment of local acquired resistance, as well as in the systemic induction of genes coding for pathogenesis-related proteins. It now appears that, concomitantly with these already well documented defence reactions, the pathogenic attack also induces the carbon reallocation mechanism based on the reinitiation of the glyoxylate cycle (pseudo-senescence of the infected leaves).