Astrocytes release D-serine by a large vesicle

Long-term potentiation (LTP) of synaptic transmission in the CA1 region of the hippocampus depends on the activation of N-methyl-D-aspartate receptors (NMDARs), which can be regulated by Ca²⁺-dependent release of D-serine from astrocytes. The detailed mechanism underlying astrocytic d-serine release is still unknown. In hippocampal slices prepared from Sprague-Dawley rats, we found that clamping astrocytic [Ca²⁺] at 100-150 nM or puffing artificial cerebrospinal fluid (ACSF) into the extracellular space (weak mechanical stimulation) enhanced the synaptic activation of NMDARs. The enhancement was blocked by the NMDAR glycine site antagonist 5,7-dichlorokynurenic acid, glycine saturation, and infusion of astrocytes with D-amino acid oxidase and the serine racemase inhibitor L-erythro-3-hydroxyaspartate, suggesting the involvement of astrocytic D-serine release. Intracellular 100-150 nM [Ca²⁺] or puffing ACSF stimulated astrocytes to generate D-serine-containing large vesicles (1-3 μm), exocytotic fusion of which released D-serine. The formation of astrocytic large vesicles involved the intracellular fusion of small vesicles and/or other organelles. Spontaneous fusion of large vesicles occurred occasionally in astrocytes at rest, contributing to baseline D-serine levels, which increased the rising slope of NMDAR post-burst potentiation (PBP) without altering the PBP peak amplitude. Thus, under physiological conditions, astrocytic D-serine release by large vesicles facilitated weak theta-burst (TBS consisting of five bursts), but not strong TBS (TBS consisting of 10 bursts) stimulation-induced LTP.

The use of a bone-anchored device as a hard-wired conduit for transmitting EMG signals from implanted muscle electrodes

The use of a bone-anchored device to transmit electrical signals from internalized muscle electrodes was studied in a sheep model. The bone-anchored device was used as a conduit for the passage of a wire connecting an internal epimysial electrode to an external signal-recording device. The bone-anchored device was inserted into an intact tibia and the electrode attached to the adjacent M. peroneus tertius. "Physiological" signals with low signal-to-noise ratios were successfully obtained over a 12-week period by walking the sheep on a treadmill. Reliable transmission of multiple muscle signals across the skin barrier is essential for providing intuitive, biomimetic upper limb prostheses. This technology has the potential to provide a better functional and reliable solution for upper limb amputee rehabilitation: attachment and control.

Effect of HMGB1/NF-κB in hyperbaric oxygen treatment on decreasing injury caused by skin flap grafts in rats

BACKGROUND

Skin flap grafting (SFG) is a common surgical operation, and hyperbaric oxygen treatment (HBOT) is an important strategy for restoring the grafted skin flap. Thus, we employed a rat skin flap grafting model treated with HBO, and expression levels of high mobility group protein 1 (HMGB1) and NF-kappaB (nuclear factor-kappaB) were characterized.

MATERIALS AND METHODS

Forty rats were randomly assigned to 5 groups: (1) sham-operation (SH), (2) ischemia followed by reperfusion 3 days after operation (IR3d), (3) ischemia followed by reperfusion 5 days after operation (IR5d), (4) ischemia followed by reperfusion and HBOT 3 days after operation (HBO3d), and (5) ischemia followed by reperfusion and HBOT 5 days after operation (HBO5d). Elevated pedicled skin flaps were designed (size, 9 cm × 6 cm), and feeding vessels were clamped. The microvascular clamp was removed 3 h later and flow was restored. In the HBO3d and HBO5d groups, rats received 1 h of hyperbaric oxygen (HBO) starting immediately after surgery for 3 days and 5 days, respectively. Upon completion of animal experiments, rats were euthanized by general anesthesia, and blood samples were taken for testing. The tissues were sectioned for western blotting and immunohistochemical staining.

RESULTS

Expression of HMGB1 and NF-κB proteins in the HBO groups was lower than in the IR groups.

CONCLUSIONS

The results suggest that HBOT can be used to reduce ischemia-reperfusion (IR) injury of skin flap grafts.

Downregulation of CD94/NKG2A inhibitory receptor on decreased γδ T cells in patients with systemic lupus erythematosus

γδ T cells are characterized by recognizing conserved endogenous and stress-induced antigens without antigen presentation. It has been show that γδ T cells play an important role in anti-tumour/microbe responses, but their function in autoimmune diseases is yet not clear. Here, we reported the quantity and phenotype of peripheral blood γδ T cells from systemic lupus erythematosus (SLE). Both the percentages of γδ T cells in peripheral blood and among CD3(+) T cells of patients with SLE were significantly decreased, regardless of disease activity. However, activating marker CD69 and HLA-DR was upregulated, while inhibiting receptor CD94/NKG2A was downregulated in γδ T cells of patients with SLE. The expression of CD69 is negatively correlated with the quantity of γδ T cells. Moreover, the expression of CD94/NKG2A remained low even with antigen stimulation on those γδ T cells. Our results suggested that the low expression level of CD94/NKG2A upon γδ T cell activation might lead to the over-activation of γδ T cells in patients with SLE. These findings will be useful in elucidating the roles of γδ T cells in SLE pathogenesis.

Epithelioid hemangioendothelioma: occasionally encountered and potentially harmful

Epithelioid hemangioendothelioma (EH) is a rare neoplasm which can arise from any vascularised tissue and has the potential to metastasise. Correct diagnosis can be challenging as it has a variety of presentations and can mimic other pathology. We present a case arising from the brachial artery at the level of the antecubital fossa. Incision biopsies showed benign fatty tissue only; leading to delayed diagnosis, delayed excision and prolonged patient discomfort. This case shows the importance of exercising clinical judgement as negative incision biopsies were, with hindsight, not representative of the lesion.

Reduced anxiety-like behavior and central neurochemical change in germ-free mice

BACKGROUND

There is increasing interest in the gut-brain axis and the role intestinal microbiota may play in communication between these two systems. Acquisition of intestinal microbiota in the immediate postnatal period has a defining impact on the development and function of the gastrointestinal, immune, neuroendocrine and metabolic systems. For example, the presence of gut microbiota regulates the set point for hypothalamic-pituitary-adrenal (HPA) axis activity.

METHODS

We investigated basal behavior of adult germ-free (GF), Swiss Webster female mice in the elevated plus maze (EPM) and compared this to conventionally reared specific pathogen free (SPF) mice. Additionally, we measured brain mRNA expression of genes implicated in anxiety and stress-reactivity.

KEY RESULTS

Germ-free mice, compared to SPF mice, exhibited basal behavior in the EPM that can be interpreted as anxiolytic. Altered GF behavior was accompanied by a decrease in the N-methyl-D-aspartate receptor subunit NR2B mRNA expression in the central amygdala, increased brain-derived neurotrophic factor expression and decreased serotonin receptor 1A (5HT1A) expression in the dentate granule layer of the hippocampus.

CONCLUSIONS & INFERENCES

We conclude that the presence or absence of conventional intestinal microbiota influences the development of behavior, and is accompanied by neurochemical changes in the brain.

A sex comparison of the anatomy and function of the main olfactory bulb-medial amygdala projection in mice

We previously reported that some main olfactory bulb (MOB) mitral/tufted (M/T) cells send a direct projection to the "vomeronasal" amygdala in female mice and selectively respond to volatile male mouse urinary odors. We asked whether MOB M/T cells that project to the vomeronasal amygdala exist in male mice and whether there is a sexually dimorphic response of these neurons to volatile male urinary pheromones. Gonadectomized male and female mice received bilateral injections of the retrograde tracer, Cholera toxin-B (CTb) into the medial amygdala (Me), which is part of the vomeronasal amygdala. All subjects were then treated with estradiol benzoate and progesterone before being exposed to volatile male urinary odors whereupon they were sacrificed 90 min later. Sections of the MOB were immunostained for Fos protein and/or CTb. Male mice, like females, displayed a small population of MOB M/T cells that project to the Me. While the general localization of these cells was similar in the two sexes, there were statistically significant sex differences in the percentage of MOB M/T cells in the anterior and posterior medial segments of the MOB that were retrogradely labeled by CTb. Male urinary volatiles stimulated equivalent, significant increases in Fos expression by MOB M/T neurons projecting to the Me in the two sexes. By contrast, in the same mice exposure to male urinary volatiles stimulated a significant increase in Fos expression by mitral cells in the accessory olfactory bulb (AOB) only in female subjects. Thus any sexually dimorphic behavioral or neuroendocrine responses to male urinary volatiles likely depend on the differential processing of these odor inputs in the AOB and/or other downstream forebrain structures after their detection by the main olfactory system.

Sulforhodamine 101 induces long-term potentiation of intrinsic excitability and synaptic efficacy in hippocampal CA1 pyramidal neurons

Sulforhodamine 101 (SR101) has been extensively used for investigation as a specific marker for astroglia in vivo and activity-dependent dye for monitoring regulated exocytosis. Here, we report that SR101 has bioactive effects on neuronal activity. Perfusion of slices with SR101 (1 microM) for 10 min induced long-term potentiation of intrinsic neuronal excitability (LTP-IE) and a long-lasting increase in evoked EPSCs (eEPSCs) in CA1 pyramidal neurons in hippocampal slices. The increase in intrinsic neuronal excitability was a result of negative shifts in the action potential (AP) threshold. The N-methyl D-aspartate receptor (NMDAR) antagonist, AP-5 (50 microM), blocked SR101-induced LTP-IE, but glutamate receptor blockers, AP-5 (50 microM), MCPG (200 microM), and MSOP (100 microM), only partially blocked SR101-induced potentiation of eEPSCs. SR101 induced an enhancement of evoked synaptic NMDAR currents, suggesting that SR101 enhances activation of synaptic NMDARs. SR101-induced LTP-IE and potentiation of synaptic transmission triggered spontaneous neuronal firing in slices and in vivo epileptic seizures. Our results suggest that SR101 is an epileptogenic agent that long-lastingly lowers the AP threshold to increase intrinsic neuronal excitability and enhances the synaptic efficacy to increase synaptic inputs. As such, SR101 can be used as an experimental tool to induce epileptic seizures.

Effect of variation in argon content of calibration gases on determination of atmospheric carbon dioxide

Carbon dioxide (CO(2)) is a greenhouse gas that makes by far the largest contribution to the global warming of the Earth's atmosphere. For the measurements of atmospheric CO(2) a non-dispersive infrared analyzer (NDIR) and gas chromatography are conventionally being used. We explored whether and to what degree argon content can influence the determination of atmospheric CO(2) using the comparison of CO(2) concentrations between the sample gas mixtures with varying Ar amounts at 0 and 18.6 mmol mol(-1) and the calibration gas mixtures with Ar at 8.4, 9.1, and 9.3 mmol mol(-1). We newly discovered that variation of Ar content in calibration gas mixtures could undermine accuracy for precise and accurate determination of atmospheric CO(2) in background air. The differences in CO(2) concentration due to the variation of Ar content in the calibration gas mixtures were negligible (<+/-0.03 micromol mol(-1)) for NDIR systems whereas they noticeably increased (<+/-1.09 micromol mol(-1)) especially for the modified GC systems to enhance instrumental sensitivity. We found that the thermal mass flow controller is the main source of the differences although such differences appeared only in the presence of a flow restrictor in GC systems. For reliable monitoring of real atmospheric CO(2) samples, one should use calibration gas mixtures that contain Ar content close to the level (9.332 mmol mol(-1)) in the ambient air as possible. Practical guidelines were highlighted relating to selection of appropriate analytical approaches for the accurate and precise measurements of atmospheric CO(2). In addition, theoretical implications from the findings were addressed.

Perchlorate production by ozone oxidation of chloride in aqueous and dry systems

Overwhelming evidence now exists that perchlorate is produced through natural processes and can be ubiquitously found at environmentally relevant concentrations in arid and semi-arid locations. A number of potential production mechanisms have been hypothesized and ClO(4)(-) production by ozone oxidation of surface bound Cl(-) was demonstrated. However, no information concerning the impact of concentration, final reaction products distribution, impact of reaction phase, or oxidation of important oxychlorine intermediates has been reported. Using IC-MS-MS analysis and replicate oxidation experiments, we show that exposing aqueous solutions or Cl(-) coated sand or glass surfaces to O(3) (0.96%) generated ClO(4)(-) with molar yields of 0.007 and 0.01% for aqueous Cl(-) solutions and 0.025 and 0.42% for Cl(-) coated sand and glass, respectively. Aqueous solutions of Cl(-) produced less ClO(4)(-) than Cl(-) coated sand or glass as well as a higher ratio of ClO(3)(-) to ClO(4)(-). Reduction of the initial Cl(-) mass resulted in substantially higher molar yields of ClO(4)(-) and ClO(3)(-). In addition, alkaline absorbers that captured gaseous products contained substantial quantities of Cl(-), ClO(3)(-), and ClO(4)(-). Solutions of possible oxychlorine intermediates (OCl(-) and ClO(3)(-)) exposed to O(3) produced only scant amounts of ClO(4)(-) while a ClO(2)(-) solution exposed to O(3) produced substantial molar yields of ClO(4)(-) (4% molar yield). Scanning electron microscopy coupled with energy energy-dispersive X-ray analysis demonstrated a significant loss of Cl(-) and an increase in oxygen on the Cl(-) coated silica sand exposed to O(3). While the experimental conditions are not reflective of natural conditions this work clearly demonstrates the relative potential of Cl(-) precursors in perchlorate production and the likely importance of dry aerosol oxidation over solution phase reactions. It also suggests that ClO(2)(-) may be a key intermediate while ClO(3)(-) and OCl(-) are unlikely to play a significant role.

The morbidity of the button-over-nail technique for zone 1 flexor tendon repairs. Should we still be using this technique?

The button-over-nail technique is commonly used to fix the core suture to the distal phalanx for flexor digitorum profundus repairs in zone 1. We report a retrospective study of 23 consecutive patients who had a repair of the flexor digitorum profundus tendon in zone 1 using the button-over-nail technique. Fifteen patients experienced a complication, of which ten were directly related to the button-over-nail technique. Complications included nail deformities, fixed flexion deformities of the distal interphalangeal joint, infections and prolonged hypersensitivity. Two patients required amputation of the fingertip. We recommend that the button-over-nail technique should be avoided or used only with caution and with close attention to the details of the technique.

The early radiological follow-up of a medial rotational design of total knee arthroplasty

The objective of this study was to investigate the hypothesis that the increased constraint of a medial rotational knee promotes earlier loosening of the prosthesis. All patients with a Freeman-Samuelson 1000 knee arthroplasty (medial pivot design), (group 1), or a Freeman-Samuelson Modular knee arthroplasty, (group 2), with a minimum follow-up of 2 years (mean follow-up 4 years) were identified from our unit's arthroplasty database, and matched as closely as possible for age, length of follow-up and pre-operative diagnosis. Standardised anteroposterior and lateral radiographs were analysed for component migration and radiolucent lines as recommended by the Knee Society. There were 48 knees in each group. There were no failures in group 2. There was one failure requiring revision of the tibial component in group 1. There was no significant difference in overall radiolucent line scores between the two groups (p=0.66, at 5 years). Progressive radiolucent lines were detected in similar numbers of patients in both groups (FS1000 8/48, FSM 7/48, p=0.84). Our early radiological survey suggests that the increased constraint of the medial pivot knee prosthesis does not result in an increased incidence of radiographic loosening.