•Arsenic effects on nitrification were revealed using FBR enriched cultures.•Nitrification was not affected by 100mg AsTOT/L at neutral pH.•150–200mg AsTOT/L inhibited ammonium oxidation by ...25%.•As(III) oxidation to As(V) decreased arsenic toxicity to nitrification.•FBR enrichment consisted of C. Nitrospira defluvii and other nitrifying species.
Mining and mineral processing of gold-bearing ores often release arsenic to the environment. Ammonium is released when N-based explosives or cyanide are used. Nitrification of simulated As-rich mining waters was investigated in batch bioassays using nitrifying cultures enriched in a fluidized-bed reactor (FBR). Nitrification was maintained at 100mg AsTOT/L. In batch assays, ammonium was totally oxidized by the FBR enrichment in 48h. As(III) oxidation to As(V) occurred during the first 3h attenuating arsenic toxicity to nitrification. At 150 and 200mg AsTOT/L, nitrification was inhibited by 25%. Candidatus Nitrospira defluvii and other nitrifying species mainly colonized the FBR. In conclusion, the FBR enriched cultures of municipal activated sludge origins tolerated high As concentrations making nitrification a potent process for mining water treatment.
Both increased and decreased health service usage and unmet care needs are more prevalent among unemployed people than in the general population.
This study investigates the associations of ...substance-related and mood disorders among long-term unemployed people with styles of healthcare attendance in Finland.
The study material consisted of the health register information on 498 long-term unemployed people in a project screening for work disabilities. The data were analysed by mixed methods: qualitative typological analysis was applied to identify differential healthcare attendance styles, and the associations of the obtained styles with mental health disorders were analysed quantitatively by multinomial logistic regression.
Three styles, characterized as smooth, faltering and marginalized, were identified. Compared with participants with the smooth attendance style without mental disorders, those with the faltering style had tenfold relative risk for substance-related disorder and fourfold relative risk for mood disorder. Those with the marginalized style had fivefold relative risk for substance-related disorder and twofold relative risk for mood disorder. Adjusting for background characteristics did not alter the statistical significance of substance-related disorder. In the case of mood disorders, the statistical significance persisted throughout the adjustments in the faltering style.
Dysfunctional use of health services is more common among people with substance-related or mood disorders, who are at risk of drifting towards long-term unemployment and work disabilities. The early detection of those with faltering or marginalized healthcare attendance style may prevent prolonged unemployment, enable rehabilitation measures and reduce the risk of disability pensions.
•Earlier inconsistent findings reporting both more or less frequent visits to health care among unemployed people seem to be explained by qualitative differences rather than quantitative figures.•Among people who are or may later drift towards long-term unemployment, work disabilities and substance-related or mood disorders, the risk for faltering or marginalized style of healthcare attendance is increased.•More active screening of long-term unemployed people, especially those with faltering or marginalized healthcare attendance style, and of guiding them to rehabilitative services particularly tailored for the unemployed people is important and may prevent a permanent disability to work.
Prospective clinical case-control study.
The aim of this study was to use diffusion tensor imaging (DTI) to assess the state of cerebral white matter tracts after spinal cord injury (SCI). The DTI ...metrics were evaluated in relation to neurological deficits and to the size and level of the spinal cord lesions.
Tampere University Hospital, Tampere, Finland.
Thirty-four patients (n=34) with clinically complete and incomplete SCI were evaluated using the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI). DTI metrics (fractional anisotropy (FA) and apparent diffusion coefficient (ADC)) were calculated for multiple levels along the course of the corticospinal tract. The state of the spinal cord after injury was assessed using conventional magnetic resonance imaging (MRI). DTI parameters were compared with 40 orthopedically injured control subjects.
Statistically significant differences in the DTI values between patients and controls were detected in the posterior area of the centrum semiovale. In this area, the FA values were lower in the patients compared with controls (P=0.008). For patients with clinically complete injury, the difference was even more significant (P=0.0005). Motor and sensory scores of the ISNCSCI correlated positively with FA and negatively with ADC values of the centrum semiovale. A moderate association was observed between the macroscopic changes in the spinal cord and the DTI abnormalities in the centrum semiovale.
In patients with chronic SCI, DTI changes can be observed in the cerebral white matter. These alterations are associated with the clinical state of the patients.
Mining often leads to nitrate and metal contamination of groundwater and water bodies. Denitrification of acidic water was investigated in two up-flow fluidized-bed reactors (FBR) and using batch ...assays. Bacterial communities were enriched on ethanol plus nitrate in the FBRs. Initially, the effects of temperature, low-pH and ethanol/nitrate on denitrification were revealed. Batch assays showed that pH 4.8 was inhibitory to denitrification, whereas FBR characteristics permitted denitrification even at feed pH of 2.5 and at 7–8 °C. Nitrate and ethanol were removed and the feed pH was neutralized, provided that ethanol was supplied in excess to nitrate. Subsequently, Fe(II) and Cu impact on denitrification was investigated within batch tests at pH 7. Iron supplementation up to 100 mg/L resulted in iron oxidation and soluble concentrations ranging from 0.4 to 1.6 mg/L that stimulated denitrification. On the contrary, 0.7 mg/L of soluble Cu significantly slowed denitrification down resulting in about 45 % of inhibition in the first 8 h. Polymerase chain reaction—denaturant gradient gel electrophoresis demonstrated the co-existence of different denitrifying microbial consortia in FBRs.
Dechloromonas denitrificans
and
Hydrogenophaga caeni
were present in both FBRs and mainly responsible for nitrate reduction.
The dispersion of nitrogenous compounds and heavy metals into the environment is frequent during mining activities. The effects of nickel (Ni) and cobalt (Co) on denitrification of simulated mine ...waters were investigated in batch bioassays and fluidized-bed reactors (FBRs). At pH 7, batch tests revealed that Co did not exhibit inhibition on denitrification even at 86.6 mg/L. Ni showed to be inhibitory at 50 and 100 mg/L by decreasing nitrate removal efficiencies of 18 and 65 %, respectively. In two FBRs, operated at 7–8 and 22 °C, 5.5 mg/L Ni did not affect nitrate and nitrite removals because of FBR potential of diluting soluble Ni feed concentration. On the contrary, the effluent pH clearly decreased in both FBR1 and FBR2 because of nickel sulfide precipitation and Ni inhibition of the last two steps of denitrification. When Ni injection was stopped, the process recovered more slowly at 22 than 7–8 °C. This is the first study reporting the effect of Ni on denitrification in biological FBRs.
Mice carrying mutated human APPswe and PS1 (A246E) transgenes (A/P mice) show age-dependent memory impairment in hippocampus-dependent tasks. Moreover, the mice show normal learning in the water maze ...within a day but impairment across days. We recorded LTP in a slice preparation (CA1) and in chronically implanted animals (dentate gyrus, or DG) at 17–18 months of age. The genotypes did not differ in the basal synaptic transmission. Also, LTP induction and its maintenance over 60 min did not differ between A/P and control mice. However, the fEPSP enhancement in vivo decayed to 77% of its maximum in 24 h in A/P mice while remaining at 96% in control mice. The time course of the LTP decay in the A/P mice corresponds to their behavioral impairment and indicates that Aβ accumulation in the dentate gyrus may interfere with the signal transduction pathways responsible for memory consolidation.
Fast spiking interneurons in the CA1 area of the dorsal hippocampus were recorded from and filled with biocytin in anesthetized rats. The full extent of their dendrites and axonal arborizations as ...well as their calcium binding protein content were examined. Based on the spatial extent of axon collaterals, local circuit cells (basket and O-LM neurons) and long-range cells (bistratified, trilaminar, and backprojection neurons) could be distinguished. Basket cells were immunoreactive for parvalbumin and their axon collaterals were confined to the pyramidal layer. A single basket cell contacted more than 1500 pyramidal neurons and 60 other parvalbumin-positive interneurons. Commissural stimulation directly discharged basket cells, followed by an early and late IPSPs, indicating interneuronal inhibition of basket cells. The dendrites of another local circuit neuron (O-LM) were confined to stratum oriens and it had a small but high-density axonal terminal field in stratum lacunosum-moleculare. The fastest firing cell of all interneurons was a calbindin-immunoreactive bistratified neuron with axonal targets in stratum oriens and radiatum. Two neurons with their cell bodies in the alveus innervated the CA3 region (backprojection cells), in addition to rich axon collaterals in the CA1 region. The trilaminar interneuron had axon collaterals in strata radiatum, oriens and pyramidale with its dendrites confined to stratum oriens. Commissural stimulation evoked an early EPSP-IPSP-late depolarizing potential sequence in this cell. All interneurons formed symmetric synapses with their targets at the electron microscopic level. These findings indicate that interneurons with distinct axonal targets have differential functions in shaping the physiological patterns of the CA1 network.
Sharp wave bursts, induced by a cooperative discharge of CA3 pyramidal cells, are the most synchronous physiological pattern in the hippocampus. In conjunction with sharp wave bursts, CA1 pyramidal ...cells display a high-frequency (200 Hz) network oscillation (ripple). In the present study extracellular field and unit activity was recorded simultaneously from 16 closely spaces sites in the awake rat and the intracellular activity of CA1 pyramidal cells during the network oscillation was studied under anesthesia. Current source density analysis of the high-frequency oscillation revealed circumscribed sinks and sources in the vicinity of the pyramidal layer. Single pyramidal cells discharged at a low frequency but were phase locked to the negative peak of the locally derived field oscillation. Approximately 10% of the simultaneously recorded pyramidal cells fired during a given oscillatory event. Putative interneurons increased their discharge rates during the field ripples severalfold and often maintained a 200 Hz frequency during the oscillatory event. Under urethane and ketamine anesthesia the frequency of ripples was slower (100-120 Hz) than in the awake rat (180-200 Hz). Halothane anesthesia prevented the occurrence of high-frequency field oscillations in the CA1 region. Both the amplitude (1-4 mV) and phase of the intracellular ripple, but not its frequency, were voltage dependent. The amplitude of intracellular ripple was smallest between -70 and -80 mV. The phase of intracellular oscillation relative to the extracellular ripple reversed when the membrane was hyperpolarized more than -80 mV. A histologically verified CA1 basket cell increased its firing rate during the network oscillation and discharged at the frequency of the extracellular ripple. These findings indicate that the intracellularly recorded fast oscillatory rhythm is not solely dependent on membrane currents intrinsic to the CA1 pyramidal cells but it is a network driven phenomenon dependent upon the participation of inhibitory interneurons. We hypothesize that fast field oscillation (200 Hz) in the CA1 region reflects summed IPSPs in pyramidal cells as a result of high-frequency barrage of interneurons. The sharp wave associated synchronous discharge of pyramidal cells in the millisecond range can exert a powerful influence on retrohippocampal targets and may facilitate the transfer of transiently stored memory traces from the hippocampus to the entorhinal cortex.
The intrahippocampal distribution of axon collaterals of individual CA3 pyramidal cells was investigated in the rat. Pyramidal cells in the CA3 region of the hippocampus were physiologically ...characterized and filled with biocytin in anesthetized animals. Their axonal trees were reconstructed with the aid of a drawing tube. Single CA3 pyramidal cells arborized most extensively in the CA1 region, covering approximately two-thirds of the longitudinal axis of the hippocampus. The total length of axon collaterals in the CA3 region was less than in CA1 and the axon branches tended to cluster in narrow bands (200-800 microns), usually several hundred microns anterior or posterior to the cell body. The majority of the recurrent collaterals of a given neuron remained in the same subfield (CA3a, b, or c) as the parent cell. CA3a neurons innervated predominantly the basal dendrites, whereas neurons located proximal to the hilus (CA3c) terminated predominantly on the apical dendrites of both CA1 and CA3 cells. Two cells, with horizontal dendrites and numerous thorny excrescences at the CA3c-hilus transitional zone, were also labeled and projected to both CA3 and CA1 regions. All CA3 neurons projected some collaterals to the hilar region. Proximal (CA3c) neurons had numerous collaterals in the hilus proper. One CA3c pyramidal cell in the dorsal hippocampus sent an axon collaterals to the inner third of the molecular layer. CA3c pyramidal cells in the ventral hippocampus had extensive projections to the inner third of the dentate molecular layer, as well as numerous collaterals in the hilus, CA3, and CA1 areas, and several axon collaterals penetrated the subiculum. The total projected axon length of a single neuron ranged from 150 to 300 mm. On the basis of the projected axon length and bouton density (mean interbouton distance: 4.7 microns), we estimate that a single CA3 pyramidal cell can make synapses with 30,000-60,000 neurons in the ipsilateral hippocampus. The concentrated distribution of the axon collaterals ("patches") indicates that subpopulations of neurons may receive disproportionately denser innervation, whereas innervation in the rest of the target zones is rather sparse. These observations offer new insights into the physiological organization of the CA3 pyramidal cell network.
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