Chronic Low Dose Neutron Exposure Results in Altered Neurotransmission Properties of the Hippocampus-Prefrontal Cortex Axis in Both Mice and Rats.

The proposed deep space exploration to the moon and later to Mars will result in astronauts receiving significant chronic exposures to space radiation (SR). SR exposure results in multiple neurocognitive impairments. Recently, our cross-species (mouse/rat) studies reported impaired associative memory formation in both species following a chronic 6-month low dose exposure to a mixed field of neutrons (1 mGy/day for a total dose pf 18 cGy). In the present study, we report neutron exposure induced synaptic plasticity in the medial prefrontal cortex, accompanied by microglial activation and significant synaptic loss in the hippocampus. In a parallel study, neutron exposure was also found to alter fluorescence assisted single synaptosome LTP (FASS-LTP) in the hippocampus of rats, that may be related to a reduced ability to insert AMPAR into the post-synaptic membrane, which may arise from increased phosphorylation of the serine 845 residue of the GluA1 subunit. Thus, we demonstrate for the first time, that low dose chronic neutron irradiation impacts homeostatic synaptic plasticity in the hippocampal-cortical circuit in two rodent species, and that the ability to successfully encode associative recognition memory is a dynamic, multicircuit process, possibly involving compensatory changes in AMPAR density on the synaptic surface.

Early defects in translation elongation factor 1α levels at excitatory synapses in α-synucleinopathy.

Cognitive decline and dementia in neurodegenerative diseases are associated with synapse dysfunction and loss, which may precede neuron loss by several years. While misfolded and aggregated α-synuclein is recognized in the disease progression of synucleinopathies, the nature of glutamatergic synapse dysfunction and loss remains incompletely understood. Using fluorescence-activated synaptosome sorting (FASS), we enriched excitatory glutamatergic synaptosomes from mice overexpressing human alpha-synuclein (h-αS) and wild-type littermates to unprecedented purity. Subsequent label-free proteomic quantification revealed a set of proteins differentially expressed upon human alpha-synuclein overexpression. These include overrepresented proteins involved in the synaptic vesicle cycle, ER-Golgi trafficking, metabolism and cytoskeleton. Unexpectedly, we found and validated a steep reduction of eukaryotic translation elongation factor 1 alpha (eEF1A1) levels in excitatory synapses at early stages of h-αS mouse model pathology. While eEF1A1 reduction correlated with the loss of postsynapses, its immunoreactivity was found on both sides of excitatory synapses. Moreover, we observed a reduction in eEF1A1 immunoreactivity in the cingulate gyrus neuropil of patients with Lewy body disease along with a reduction in PSD95 levels. Altogether, our results suggest a link between structural impairments underlying cognitive decline in neurodegenerative disorders and local synaptic defects. eEF1A1 may therefore represent a limiting factor to synapse maintenance.

TNFα and IL-1ß but not IL-18 Suppresses Hippocampal Long-Term Potentiation Directly at the Synapse.

CNS inflammatory responses are linked to cognitive impairment in humans. Research in animal models supports this connection by showing that inflammatory cytokines suppress long-term potentiation (LTP), the best-known cellular correlate of memory. Cytokine-induced modulation of LTP has been previously studied in vivo or in brain slices, two experimental approaches containing multiple cell populations responsive to cytokines. In their target cells, cytokines commonly increase the expression of multiple cytokines, thus increasing the complexity of brain cytokine networks even after single-cytokine challenges. Whether cytokines suppress LTP by direct effects on neurons or by indirect mechanisms is still an open question. Here, we evaluated the effect of a major set of inflammatory cytokines including tumor necrosis factor-α (TNFα), interleukin-1ß (IL-1ß) and interleukin-18 (IL-18) on chemically-induced LTP (cLTP) in isolated hippocampal synaptosomes of mice, using fluorescence analysis of single-synapse long-term potentiation (FASS-LTP). We found that TNFα and IL-1ß suppress synaptosomal cLTP. In contrast, cLTP was not affected by IL-18, at a concentration previously shown to block LTP in hippocampal slices. We also found that IL-18 does not impair cLTP or brain-derived neurotrophic factor (BDNF) signaling in primary hippocampal neuronal cultures. Thus, using both synaptosomes and neuron cultures, our data suggest that IL-18 impairs LTP by indirect mechanisms, which may depend on non-neuronal cells, such as glia. Notably, our results demonstrate that TNFα and IL-1ß directly suppress hippocampal plasticity via neuron-specific mechanisms. A better understanding of the brain's cytokine networks and their final molecular effectors is crucial to identify specific targets for intervention.

Separation and determination of corynoxine and corynoxine B using chiral ionic liquid and hydroxypropyl-ß-cyclodextrin as additives by field-amplified sample stacking in capillary electrophoresis.

A sensitive, fast, and effective method, field-amplified sample stacking (FASS) in capillary electrophoresis, has been established for the separation and determination of corynoxine and corynoxine B. Hydroxypropyl-ß-CD (HP-ß-CD) and tetrabutylammonium-L-glutamic acid (TBA-L-Glu) were used as additives in the separation system. Electrokinetic injection was chosen to introduce sample from inlet at 10 kV for 50 s after a water plug (0.5 psi, 4 s) was injected to permit FASS. The running buffer (pH 6.1) was composed of 40 mM sodium dihydrogen phosphate solution, 130 mM HP-ß-CD, and 10 mM TBA-L-Glu and the separation voltage was 20 kV. Under the optimum conditions, corynoxine and corynoxine B were successfully enriched and separated within 12 min and the sensitivity was improved approximately by 700-900 folds. Calibration curves were in a good linear relationship within the range of 62.5-5.00 × 103  ng/mL for both corynoxine and corynoxine B. The limits of detection (S/N = 3) and quantitation (S/N = 10) were 14.9, 45.2 ng/mL for corynoxine and 11.2, 34.5 ng/mL for corynoxine B, respectively. Finally, this method was successfully applied for the determination of corynoxine and corynoxine B in the stems with hooks of Uncaria rhynchophylla and its formulations.

Calcium-sensing receptor antagonist (calcilytic) NPS 2143 specifically blocks the increased secretion of endogenous Aß42 prompted by exogenous fibrillary or soluble Aß25-35 in human cortical astrocytes and neurons-therapeutic relevance to Alzheimer's disease.

The "amyloid-ß (Aß) hypothesis" posits that accumulating Aß peptides (Aßs) produced by neurons cause Alzheimer's disease (AD). However, the Aßs contribution by the more numerous astrocytes remains undetermined. Previously we showed that fibrillar (f)Aß25-35, an Aß42 proxy, evokes a surplus endogenous Aß42 production/accumulation in cortical adult human astrocytes. Here, by using immunocytochemistry, immunoblotting, enzymatic assays, and highly sensitive sandwich ELISA kits, we investigated the effects of fAß25-35 and soluble (s)Aß25-35 on Aß42 and Aß40 accumulation/secretion by human cortical astrocytes and HCN-1A neurons and, since the calcium-sensing receptor (CaSR) binds Aßs, their modulation by NPS 2143, a CaSR allosteric antagonist (calcilytic). The fAß25-35-exposed astrocytes and surviving neurons produced, accumulated, and secreted increased amounts of Aß42, while Aß40 also accrued but its secretion was unchanged. Accordingly, secreted Aß42/Aß40 ratio values rose for astrocytes and neurons. While slightly enhancing Aß40 secretion by fAß25-35-treated astrocytes, NPS 2143 specifically suppressed the fAß25-35-elicited surges of endogenous Aß42 secretion by astrocytes and neurons. Therefore, NPS 2143 addition always kept Aß42/Aß40 values to baseline or lower levels. Mechanistically, NPS 2143 decreased total CaSR protein complement, transiently raised proteasomal chymotrypsin activity, and blocked excess NO production without affecting the ongoing increases in BACE1/ß-secretase and γ-secretase activity in fAß25-35-treated astrocytes. Compared to fAß25-35, sAß25-35 also stimulated Aß42 secretion by astrocytes and neurons and NPS 2143 specifically and wholly suppressed this effect. Therefore, since NPS 2143 thwarts any Aß/CaSR-induced surplus secretion of endogenous Aß42 and hence further vicious cycles of Aß self-induction/secretion/spreading, calcilytics might effectively prevent/stop the progression to full-blown AD.

Ciclosporin oral solution in cats: a retrospective survey of compliance with treatment and adverse effects.

OBJECTIVES: The aim of the study was to assess long-term ciclosporin oral solution compliance in cats treated for feline atopic skin syndrome (FASS). METHODS: A survey was sent by email to 114 owners who had administered ciclosporin oral solution to their cats for FASS. RESULTS: In total, 42 owners completed the survey. The population was composed of 30 domestic shorthair cats and 12 pure breeds. There were 20 males and 22 females, and the median age was 5.5 years. Ciclosporin oral solution was administered directly into the mouth in 32/42 (76%) and with food/other in 10/42 (24%) cats. The administration was considered easy in 18/42 (43%) cats, difficult in 23/42 (55%) and impossible in 1/42 (2%). Treatment was stopped in 25/42 (60%) cats. The causes were as follows: administration difficulty (nine cats, 21%); complete resolution (four cats, 10%); treatment failure (four cats, 10%); price (two cats, 4%); and other causes (two deaths, two neoplasia, one adverse effect and one lack of compliance). Adverse effects involving clinical signs were reported in 25 (60%) cats: ptyalism (8/42); dysorexia/anorexia (6/42); vomiting (4/42); diarrhoea (4/42); gingival hyperplasia (1/42); and a combination of vomiting, diarrhoea and ptyalism (2/42). In addition, altered behaviour was reported in 27/42 (64%) cats: hiding in seven cats; scared of owner in 10 cats; modification of sleeping or playing activity in six cats; inappropriate urination/defecation in two cats; aggression in one cat; and all of the above in one cat. CONCLUSIONS AND RELEVANCE: In total, 24 (57%) cats had adverse effects involving both clinical signs and altered behaviour, and only six cats had either adverse clinical signs or behavioural changes. This survey showed that behavioural changes appear to be underestimated in the cats treated with ciclosporin oral solution and this could cause treatment failure due to lack of compliance. Larger-scale studies are needed to confirm these preliminary results.

Using FASS-LTP in postmortem mice brain tissues to assess pathological synaptic function.

BACKGROUND: Study of synaptic integrity using conventional electrophysiology is a gold standard for quantitative assessment of neurodegeneration. Fluorescence assisted single-synapse long-term potentiation (FASS-LTP) provides a high throughput method to assess the synaptic integrity of neurotransmission within and between different brain regions as a measure of pharmacological efficacy in translational models. NEW METHOD: We adapted the existing method to our purpose by adding a step during the thawing of frozen samples, by an extra step of placing them on a rocker at room temperature for 30 minutes immediately following thawing with constant mixing on a shaker. This allowed for gradual, uniform thawing, effectively separating the synaptosomes. Our study demonstrates FASS-LTP on four brain regions at 6- and 12-month periods in the 3xTg-AD mouse model, treating sibling cohorts with VU0155069 (a small molecule inhibitor) or vehicle (0.9 % saline). RESULTS: Our findings demonstrate the robust ability of the FASS-LTP technique to characterize the functional synaptic integrity maintained by disease-treatment therapies in multiple brain regions longitudinally using frozen brain tissue. COMPARISON WITH EXISTING METHODS: By providing a detailed, user-friendly protocol for this well-known analysis and including a recovery step improved the ability to robustly replicate the FASS-LTP between different brain regions. This may be extrapolated to a translational use on human clinical samples to improve understanding of the therapeutic impact on synaptic performance related to glutamate neurotransmission. CONCLUSIONS: FASS-LTP method offers a robust analysis of synaptosomes isolated from frozen tissue samples, demonstrating greater reproducibility in rodent and human synapses in physiological and pathological states.

Treatments with Diquat Reveal the Relationship between Protein Phosphatases (PP2A) and Oxidative Stress during Mitosis in Arabidopsis thaliana Root Meristems.

Reversible protein phosphorylation regulates various cellular mechanisms in eukaryotes by altering the conformation, activity, localization, and stability of substrate proteins. In Arabidopsis thaliana root meristems, histone post-translational modifications are crucial for proper cell division, and they are also involved in oxidative stress signaling. To investigate the link between reactive oxygen species (ROS) and mitosis, we treated various Arabidopsis genotypes, including wild-types and mutants showing dysfunctional PP2A, with the ROS-inducing herbicide diquat (DQ). Studying the c3c4 double catalytic subunit mutant and fass regulatory subunit mutants of PP2A provided insights into phosphorylation-dependent mitotic processes. DQ treatment reduced mitotic activity in all genotypes and caused early mitotic arrest in PP2A mutants, likely due to oxidative stress-induced damage to essential mitotic processes. DQ had a minimal effect on reversible histone H3 phosphorylation in wild-type plants but significantly decreased phospho-histone H3 levels in PP2A mutants. Following drug treatment, the phosphatase activity decreased only in the stronger phenotype mutant plants (fass-5 and c3c4). Our findings demonstrate that (i) the studied PP2A loss-of-function mutants are more sensitive to increased intracellular ROS and (ii) DQ has indirect altering effects of mitotic activities and histone H3 phosphorylation. All these findings underscore the importance of PP2A in stress responses.

A pH-mediated field amplification sample stacking technique based on portable microchip electrophoresis heavy metal ion detection system.

We built a portable microchip electrophoresis heavy metal ion detection system and proposed a pH-mediated field amplified sample stacking (pH-mediated FASS) online preconcentration method. The pH-mediated FASS focuses and stacks heavy metal cations by controlling electrophoretic mobilities with a pH change between the analyte and the background electrolyte (BGE) in solution to improve the detection sensitivity of the system. We optimized and adjusted sample matrix solution (SMS) ratios and pH to create concentration and pH gradients for SMS and BGE. Furthermore, we optimize the microchannel width to improve the preconcentration effect further. The system and method analyzed soil leachates polluted with heavy metals and separated Pb2+ and Cd2+ within 90 s, obtaining their levels at 58.01 mg/L and 4.91 mg/L with sensitivity enhancement factors (SEF) of 26.40 and 43.73. Compared with inductively coupled plasma atomic emission spectrometry (ICP-AES), the detection error of the system was less than 8.80%.

Synergistic photobiomodulation with 808-nm and 1064-nm lasers to reduce the ß-amyloid neurotoxicity in the in vitro Alzheimer's disease models.

Background: In Alzheimer's disease (AD), the deposition of ß-amyloid (Aß) plaques is closely associated with the neuronal apoptosis and activation of microglia, which may result in the functional impairment of neurons through pro-inflammation and over-pruning of the neurons. Photobiomodulation (PBM) is a non-invasive therapeutic approach without any conspicuous side effect, which has shown promising attributes in the treatment of chronic brain diseases such as AD by reducing the Aß burden. However, neither the optimal parameters for PBM treatment nor its exact role in modulating the microglial functions/activities has been conclusively established yet. Methods: An inflammatory stimulation model of Alzheimer's disease (AD) was set up by activating microglia and neuroblastoma with fibrosis ß-amyloid (fAß) in a transwell insert system. SH-SY5Y neuroblastoma cells and BV2 microglial cells were irradiated with the 808- and 1,064-nm lasers, respectively (a power density of 50 mW/cm2 and a dose of 10 J/cm2) to study the PBM activity. The amount of labeled fAß phagocytosed by microglia was considered to assess the microglial phagocytosis. A PBM-induced neuroprotective study was conducted with the AD model under different laser parameters to realize the optimal condition. Microglial phenotype, microglial secretions of the pro-inflammatory and anti-inflammatory factors, and the intracellular Ca2+ levels in microglia were studied in detail to understand the structural and functional changes occurring in the microglial cells of AD model upon PBM treatment. Conclusion: A synergistic PBM effect (with the 808- and 1,064-nm lasers) effectively inhibited the fAß-induced neurotoxicity of neuroblastoma by promoting the viability of neuroblastoma and regulating the intracellular Ca2+ levels of microglia. Moreover, the downregulation of Ca2+ led to microglial polarization with an M2 phenotype, which promotes the fAß phagocytosis, and resulted in the upregulated expression of anti-inflammatory factors and downregulated expression of inflammatory factors.

Automatic Vehicle Fueling System using PLC Controlled Robotic Arm - A Simulation Design.

The objective of this research is to simulate an automatic fuelling system using a PLC LogixPro simulation. The system includes the "FASS" concept, which is Fast, Accurate, Safe and Simple, to allow car users to have an efficient fuel filling system. The design concept consists of three processes - identification of the vehicle, payment, and filling with the fuel. The first process identifies the presence of the car by the in-floor weight sensors. The weight sensor identifies the car, locks it in position, and activates the payment system. The second process activates the payment system. After payment is completed, the fuel cap will be opened to enable the system to start filling the fuel. If the payment doesn't go through the car will be released, manual operation will be initialized, and the entire system will be reset. A timer is included in the payment section to process the payment. In the third process, the filling arm is extended to the car, the fuel cap is opened, the fuel pump is inserted into the tank, and fuel is directed into the tank. Once the tank is full, filling is stopped, the pump is ejected, the fuel cap is closed, and the arm returned back to its position. Thus, an automatic vehicle fuelling system is created to overcome the problems of poor safety and longer waiting time during peak hours. The fuel cap is activated and deactivated by pressure and the sensor filler is stopped by a level sensor. The pump insert is activated and deactivated by a photosensor.

Rush immunotherapy in two cats with atopic skin syndrome.

CASE SERIES SUMMARY: Two cats with feline atopic skin syndrome (FASS) were included in this case series. They were diagnosed with FASS by a combination of history, physical examination and exclusion of other pruritic diseases. They underwent rush immunotherapy (RIT) after determination of offending environmental allergens by either serum IgE or intradermal testing. Cats were premedicated with an antihistamine and hospitalized for the day to undergo the procedure and to ensure adequate observation. Allergen extracts were administered subcutaneously at increasing concentrations every 30 mins until the maintenance dose of 20,000 protein nitrogen units/ml was reached. Both cats successfully completed RIT without any adverse reactions and their clinical signs improved afterwards. RIT appears to be an alternative treatment option for cats with FASS. Larger studies are needed to more accurately assess the safety and long-term efficacy of RIT in the feline patient, as well as the incidence of adverse reactions and optimal premedication protocol. Further evaluation of the route of injections for RIT is also warranted. RELEVANCE AND NOVEL INFORMATION: RIT has been reported to be a safe treatment option in canine atopic dermatitis. Its use in FASS is limited to a pilot study of four cats. The purpose of this series was to describe two additional cats that underwent RIT using a different premedication protocol.

Highly Sensitive SDS Capillary Gel Electrophoresis with Sample Stacking Requiring Only Nanograms of Adeno-Associated Virus Capsid Proteins.

Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) has been the method of choice in the past decades for size-based protein analysis. However, in general it requires the protein concentration in mg/mL level and thus is not practical for trace level protein analysis, not to mention the lengthy labor-intensive procedures. The SDS capillary gel electrophoresis (SDS CGE) method reported herein requires only nanogram-sized proteins loaded onto the autosampler. A sample stacking technique (e.g., head-column field-amplified sample stacking (HC FASS)) was employed, providing three orders of magnitude sensitivity enhancement compared to conventional SDS CGE. This method has been used routinely in purity analysis and characterization of adeno-associated virus (AAV) intermediates and finished gene therapeutics of AAV vectors. The sensitivity achieved is comparable to the currently most sensitive size-based protein assay silver-stained SDS PAGE. The highly sensitive sample stacking SDS CGE can be used for other types of proteins as well.

Human Albumin Impairs Amyloid ß-peptide Fibrillation Through its C-terminus: From docking Modeling to Protection Against Neurotoxicity in Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative process characterized by the accumulation of extracellular deposits of amyloid ß-peptide (Aß), which induces neuronal death. Monomeric Aß is not toxic but tends to aggregate into ß-sheets that are neurotoxic. Therefore to prevent or delay AD onset and progression one of the main therapeutic approaches would be to impair Aß assembly into oligomers and fibrils and to promote disaggregation of the preformed aggregate. Albumin is the most abundant protein in the cerebrospinal fluid and it was reported to bind Aß impeding its aggregation. In a previous work we identified a 35-residue sequence of clusterin, a well-known protein that binds Aß, that is highly similar to the C-terminus (CTerm) of albumin. In this work, the docking experiments show that the average binding free energy of the CTerm-Aß1-42 simulations was significantly lower than that of the clusterin-Aß1-42 binding, highlighting the possibility that the CTerm retains albumin's binding properties. To validate this observation, we performed in vitro structural analysis of soluble and aggregated 1 µM Aß1-42 incubated with 5 µM CTerm, equimolar to the albumin concentration in the CSF. Reversed-phase chromatography and electron microscopy analysis demonstrated a reduction of Aß1-42 aggregates when the CTerm was present. Furthermore, we treated a human neuroblastoma cell line with soluble and aggregated Aß1-42 incubated with CTerm obtaining a significant protection against Aß-induced neurotoxicity. These in silico and in vitro data suggest that the albumin CTerm is able to impair Aß aggregation and to promote disassemble of Aß aggregates protecting neurons.

Cytokines and cytokine networks target neurons to modulate long-term potentiation.

Cytokines play crucial roles in the communication between brain cells including neurons and glia, as well as in the brain-periphery interactions. In the brain, cytokines modulate long-term potentiation (LTP), a cellular correlate of memory. Whether cytokines regulate LTP by direct effects on neurons or by indirect mechanisms mediated by non-neuronal cells is poorly understood. Elucidating neuron-specific effects of cytokines has been challenging because most brain cells express cytokine receptors. Moreover, cytokines commonly increase the expression of multiple cytokines in their target cells, thus increasing the complexity of brain cytokine networks even after single-cytokine challenges. Here, we review evidence on both direct and indirect-mediated modulation of LTP by cytokines. We also describe novel approaches based on neuron- and synaptosome-enriched systems to identify cytokines able to directly modulate LTP, by targeting neurons and synapses. These approaches can test multiple samples in parallel, thus allowing the study of multiple cytokines simultaneously. Hence, a cytokine networks perspective coupled with neuron-specific analysis may contribute to delineation of maps of the modulation of LTP by cytokines.

The influence of foot and ankle injury patterns and treatment delays on outcomes in a tertiary hospital; a one-year prospective observation.

BACKGROUND: Ankle and foot fractures are amongst the most common injuries, and patterns may vary from primary care set up to tertiary hospitals. Severe foot injuries are projected to have significantly worse outcomes and surgical delays are thought to alter prognosis. METHODS: All patients with foot and ankle trauma were prospectively evaluated at a Tertiary trauma centre over one year. The incidence, fracture patterns, risk factors, and outcomes were evaluated, and cases were divided into simple foot injuries (FASS ≤ 3) and severe foot injuries (FASS>3). Injury mechanisms, associated injuries, and delays in treatment were evaluated, and outcomes were analyzed using Visual-Analogue Scale Foot and Ankle (VASFA), Maryland Foot Score (MFS) and Foot and ankle disability index (FADI). RESULTS: 294 Foot and Ankle injuries (51 females, 243 males) were encountered in 2919 trauma cases (incidence of 10%). 80 patients (27.2%) had simple foot injuries and 214 (72.8%) had severe foot injuries. 29 patients (9.9%) were below 18 years; most (65.3%) patients were between 18 and 45 years age. Road traffic accident was most commonest mode of injury, with ankle fractures (30.6%) the most common. Metatarsal fractures (27.9%) and calcaneal fractures (21.4%) were 2nd and 3rd most common injuries in the foot. Surgical delay averaged 1 day in both severe and simple injuries. Injury led to 32 (10.9%) below knee amputations. Outcome evaluation in 127 (91 severe, 36 simple injuries) patients showed mean Maryland foot score of 89.30 in simple injury group and 84.87 in severe injury group. Mean VASFA score was 82.87 (simple) and 81.87 in severe injury, and mean FADI score was 93.13 (simple) and 91.05 (severe injury). More detailed analysis revealed that more good scores (64.4%) were documented in severe injuries group, and more excellent scores (52.8%) in simple injuries group. CONCLUSION: Foot injuries constitute 10% of all orthopaedic trauma at tertiary hospitals; Majority of them are severe foot injuries, with 68.7% being open injuries. Surgical delay was similar in simple and severe foot and ankle injuries. Outcomes of severe injuries were similar to simple foot and ankle injuries, reflecting on the quality of care that could be administered to them when they present to tertiary hospitals.

Solid phase extraction for the speciation and preconcentration of inorganic selenium in water samples: a review.

Selenium is an essential element for the normal cellular function of living organisms. However, selenium is toxic at concentrations of only three to five times higher than the essential concentration. The inorganic forms (mainly selenite and selenate) present in environmental water generally exhibit higher toxicity (up to 40 times) than organic forms. Therefore, the determination of low levels of different inorganic selenium species in water is an analytical challenge. Solid-phase extraction has been used as a separation and/or preconcentration technique prior to the determination of selenium species due to the need for accurate measurements for Se species in water at extremely low levels. The present paper provides a critical review of the published methods for inorganic selenium speciation in water samples using solid phase extraction as a preconcentration procedure. On the basis of more than 75 references, the different speciation strategies used for this task have been highlighted and classified. The solid-phase extraction sorbents and the performance and analytical characteristics of the developed methods for Se speciation are also discussed.