Protein kinase C acts as a molecular detector of firing patterns to mediate sensory gating in Aplysia

Habituation of a behavioral response to a repetitive stimulus enables animals to ignore irrelevant stimuli and focus on behaviorally important events. In Aplysia, habituation is mediated by rapid depression of sensory synapses, which could leave an animal unresponsive to important repetitive stimuli, making it vulnerable to injury. We identified a form of plasticity that prevents synaptic depression depending on the precise stimulus strength. Burst-dependent protection from depression is initiated by trains of 2-4 action potentials and is distinct from previously described forms of synaptic enhancement. The blockade of depression is mediated by presynaptic Ca2+ influx and protein kinase C (PKC) and requires localization of PKC via a PDZ domain interaction with Aplysia PICK1. During protection from depression, PKC acts as a highly sensitive detector of the precise pattern of sensory neuron firing. Behaviorally, burst-dependent protection reduces habituation, enabling animals to maintain responsiveness to stimuli that are functionally important.

Laser-guidance-based cell deposition microscope for heterotypic single-cell micropatterning

Cell patterning methods enable researchers to control specific homotypic and heterotypic contact-mediated cell-cell and cell-ECM interactions and to impose defined cell and tissue geometries. To micropattern individual cells to specific points on a substrate with high spatial resolution, we have developed a cell deposition microscope based on the laser-guidance technique. We discuss the theory of optical forces for generating laser guidance and the optimization of the optical configuration (NA ≈ 0.1) to manipulate cells with high speed in three dimensions. Our cell deposition microscope is capable of patterning different cell types onto and within standard cell research devices and providing on-stage incubation for long-term cell culturing. Using this cell deposition microscope, rat mesenchymal stem cells from bone marrow were micropatterned with cardiomyocytes into a substrate microfabricated with polydimethylsiloxane on a 22 mm × 22 mm coverglass to form a single-cell coculturing microenvironment, and their electrophysiological property changes were investigated during the coculturing days.

Regression to normoglycaemia by fenofibrate in pre-diabetic subjects complicated with hypertriglyceridaemia: a prospective randomized controlled trial

AIMS

Lipotoxicity has recently been shown to be an important risk factor underlying the pathogenesis of pre-diabetes. However, clinical evidence supporting the treatment of pre-diabetes by improving lipotoxicity is lacking. Here, we conducted an open-label, randomized, controlled trial to investigate whether fenofibrate, the widely used hypolipidaemic agent, might benefit pre-diabetes, with metformin and diet control, the recommended intervention methods, as positive controls.

METHODS

Newly diagnosed pre-diabetes patients (n = 120) with hypertriglyceridaemia (plasma triglyceride levels between 1.8 and 4.5 mmol/l) were randomly assigned by computer-generated randomization sequence to either control group (no intervention), fenofibrate group (200 mg once a day), metformin group (500 mg three times a day) or diet-controlled group (diet recommendation). Plasma biochemistry examination was performed every 2 months. The primary endpoint was the outcome of the natural course of pre-diabetes, evaluated by oral glucose tolerance test after 6-month follow-up.

RESULTS

Twenty subjects in the fenofibrate group, 24 subjects in the metformin group and 25 subjects in both the diet-controlled group and the control group finished the trial. Fenofibrate, metformin and diet control had protective effects on hypertriglyceridaemic pre-diabetes, evidenced by 53.3, 70 and 30% participants regressed to normoglycaemia, respectively. The effects of fenofibrate and metformin were comparable (P > 0.05), while diet control was less effective (P < 0.05). Liver damage occurred in six subjects in the fenofibrate group and gastrointestinal symptoms occurred in four subjects in the metformin group. No serious adverse events occurred.

CONCLUSION

Controlling lipotoxicity by fenofibrate could effectively ameliorate the natural course of hypertriglyceridaemic pre-diabetes.

Estimating mercury emissions from a zinc smelter in relation to China's mercury control policies

Mercury concentrations of flue gas at inlet/outlet of the flue gas cleaning, electrostatic demister, reclaiming tower, acid plant, and mercury contents in zinc concentrate and by-products were measured in a hydrometallurgical zinc smelter. The removal efficiency of flue gas cleaning, electrostatic demister, mercury reclaiming and acid plant was about 17.4%, 30.3%, 87.9% and 97.4% respectively. Flue gas cleaning and electrostatic demister captured 11.7% and 25.3% of the mercury in the zinc concentrate, respectively. The mercury reclaiming tower captured 58.3% of the mercury in the zinc concentrate. About 4.2% of the mercury in the zinc concentrate was captured by the acid plant. Consequently, only 0.8% of the mercury in the zinc concentrate was emitted to the atmosphere. The atmospheric mercury emission factor was 0.5 g t(-1) of zinc produced for the tested smelter, indicating that this process offers the potential to effectively reduce mercury emissions from zinc smelting.

Influence of eutrophication on the distribution of total mercury and methylmercury in hydroelectric reservoirs

The distribution of mercury (Hg) and the characteristics of its methylation were investigated in Wujiangdu (WJD) and Yinzidu (YZD) reservoirs in Guizhou province, China. The two reservoirs are characterized by high and low levels of primary productivity, respectively. Mercury species in water samples from depth profiles in both reservoirs and from interface water in the WJD were analyzed each season during 2007. The concentrations of total Hg (HgT(unf)) and methylmercury (MeHgT(unf)) in unfiltered water samples from the WJD varied from 3.0 to 18 pmol dm(-3) and from 0.17 to 15 pmol dm(-3), respectively; ranges were 2.0 to 9.5 pmol dm(-3) for HgT(unf) and 0.14 to 2.2 pmol dm(-3) for MeHgT(unf) in the YZD. Elevated methylmercury concentrations in water samples from the bottom water and water-sediment interface demonstrated an active net Hg methylation in the downstream reach of the WJD. There was no discernable Hg methylation occurring in the YZD, nor in the upstream and middle reaches of the WJD. The results suggest that high primary productivity resulting from cage aquaculture activities in the WJD is an important control on Hg methylation in the reservoir, increasing the concentrations of MeHg in water in the Wujiang River basin Southwestern China.

Serotonin stimulation of cAMP-dependent plasticity in Aplysia sensory neurons is mediated by calmodulin-sensitive adenylyl cyclase

Calmodulin (CaM)-sensitive adenylyl cyclase (AC) in sensory neurons (SNs) in Aplysia has been proposed as a molecular coincidence detector during conditioning. We identified four putative ACs in Aplysia CNS. CaM binds to a sequence in the C1b region of AC-AplA that resembles the CaM-binding sequence in the C1b region of AC1 in mammals. Recombinant AC-AplA was stimulated by Ca(2+)/CaM. AC-AplC is most similar to the Ca(2+)-inhibited AC5 and AC6 in mammals. Recombinant AC-AplC was directly inhibited by Ca(2+), independent of CaM. AC-AplA and AC-AplC are expressed in SNs, whereas AC-AplB and AC-AplD are not. Knockdown of AC-AplA demonstrated that serotonin stimulation of cAMP-dependent plasticity in SNs is predominantly mediated by this CaM-sensitive AC. We propose that the coexpression of a Ca(2+)-inhibited AC in SNs, together with a Ca(2+)/CaM-stimulated AC, would enhance the associative requirement for coincident Ca(2+) influx and serotonin for effective stimulation of cAMP levels and initiation of plasticity mediated by AC-AplA.

Effects of surfactant replacement on alveolar overdistension and plasma cytokines in ventilator-induced lung injury

BACKGROUND

Overdistension of the lung causes ventilator-induced lung injury (VILI) accompanied by surfactant abnormalities and inflammatory changes. We investigated the effects of surfactant replacement on overdistension of the terminal airspaces and plasma cytokine levels in VILI.

METHODS

VILI was induced by high-pressure ventilation (HPV) in rats anesthetized with pentobarbital, followed by ventilation for 2 h in the maintenance mode (tidal volume=10 ml/kg, positive end-expiratory pressure = 7.5 cmH(2)O) with or without surfactant replacement. The sizes of the terminal airspaces were determined after fixing the lungs at an airway pressure of 10 cmH(2)O on deflation. Cytokine levels were assessed by enzyme-linked immunosorbent assay.

RESULTS

The mean ratio of the largest terminal airspace size class (> or = 64,000 microm(2)) was increased from 13.4% to 32.0% by HPV (P<0.05). After maintenance-mode ventilation, the ratio decreased to 16.1% with surfactant replacement (P<0.05), but increased to 44.6% without surfactant replacement (P<0.05). Mean macrophage inflammatory protein-2 (MIP-2) levels in the plasma increased from <0.02 to 6.9 ng/ml with HPV (P<0.05), and further increased to > or = 11.8 ng/ml, regardless of surfactant replacement after maintenance-mode ventilation. Similar tendencies were observed in the interleukin (IL)-6 and IL-10 levels. Tumor necrosis factor-alpha levels were almost negligible during the experiment.

CONCLUSION

In rats with VILI, surfactant replacement reversed overdistension of the terminal airspaces that may induce barotrauma, but not upregulation of MIP-2, IL-6, and IL-10 within 2 h.

IFN{gamma} regulates retinal pigment epithelial fluid transport

The present experiments show that IFNgamma receptors are mainly localized to the basolateral membrane of human retinal pigment epithelium (RPE). Activation of these receptors in primary cultures of human fetal RPE inhibited cell proliferation and migration, decreased RPE mitochondrial membrane potential, altered transepithelial potential and resistance, and significantly increased transepithelial fluid absorption. These effects are mediated through JAK-STAT and p38 MAPK signaling pathways. Second messenger signaling through cAMP-PKA pathway- and interferon regulatory factor-1-dependent production of nitric oxide/cGMP stimulated the CFTR at the basolateral membrane and increased transepithelial fluid absorption. In vivo experiments using a rat model of retinal reattachment showed that IFNgamma applied to the anterior surface of the eye can remove extra fluid deposited in the extracellular or subretinal space between the retinal photoreceptors and RPE. Removal of this extra fluid was blocked by a combination of PKA and JAK-STAT pathway inhibitors injected into the subretinal space. These results demonstrate a protective role for IFNgamma in regulating retinal hydration across the outer blood-retinal barrier in inflammatory disease processes and provide the basis for possible therapeutic interventions.

Prospective study of T cell receptor utilization following the induction of murine thyroiditis

Murine experimental autoimmune thyroiditis (EAT) is a well established model of autoimmune disease initiated by immunization with thyroglobulin. We have previously analyzed the T cell receptor (TcR) V gene families used by the intrathyroidal lymphocytic infiltrate in CBA/J mice with well established thyroiditis EAT and have implicated T cells expressing the mTcR V beta 13 gene family. We have now proceeded to examine the time course of mTcR V gene family use following immunization with mTg. We used a radiolabelled RT-PCR technique with oligonucleotides detecting 17 mouse TcR V beta gene families to examine the heterogeneity of the amplified V-D-J (CDR3) fragments. As previously, the TcR V beta 13 amplifications showed the expression of two similar homogeneous CDR3 sizes consistent with two clonally expanded T cell populations. However, such T cell clonal expansion was observed to peak at day 25 and by 90 days had markedly diminished despite the continuing presence of extensive histologic infiltration. An additional immunization with mTg at 63 days failed to maintain the mTcR V beta 13 clonal presence. Further confirmation of these observations was obtained by direct analysis of intrathyroidal T cells rescued from mice with EAT. Such intrathyroidal T cells, 25 days after mTg, demonstrated a marked increase in mTcR V13 expressing T cells to 9.4% compared to 2% of T cells in peripheral blood. It appeared, therefore, that in EAT the accumulation of V13 expressing T cells was a transient phenomenon which peaked at 25 days after immunization. The persistence of an intrathyroidal infiltration indicated that such T cells must have been accompanied by the accumulation and recruitment of additional selected bystander T cells. Such non-specific T cells may also have an integral role in the progression of autoimmune thyroiditis.

A combinatorial multicomponent plug mixer for systems chemistry

We report the construction and testing of a combinatorial multicomponent plug mixer (CMPM) chip that generates a large number of mix ratios. The CMPM chip has been designed to study ribonucleotide reductase (RNR) protein-protein/protein-ligand interaction networks. The 4-component chip is capable of 5400 different combinations in a 30 plug cycle. CMPM chips were tested producing fluorescent dye and dihydrofolate reductase NADPH/MX mixtures with plug lengths of 2 mm.

Trans-synaptic plasticity: presynaptic initiation, postsynaptic memory

A novel mechanism of persistent facilitation induced by serotonin at Aplysia synapses depends upon rapid postsynaptic protein synthesis and increased responsiveness to glutamate; whereas the memory for this synaptic change is postsynaptic, the initiating signal may be an increase in spontaneous release of glutamate from the presynaptic terminals.

Sharing risk management: an implementation model for cardiovascular absolute risk assessment and management in Australian general practice

PURPOSE

Despite considerable work in developing and validating cardiovascular absolute risk (CVAR) algorithms, there has been less work on models for their implementation in assessment and management. The aim of our study was to develop a model for a joint approach to its implementation based on an exploration of views of patients, general practitioners (GPs) and key informants (KIs).

METHODS

We conducted six focus group (three with GPs and three with patients) and nine KI interviews in Sydney. Thematic analysis was used with comparison to highlight the similarities and differences in perspectives of participants.

RESULTS

Conducting CVAR was seen as more acceptable for regular patients rather than new patients for whom GPs had to attract their interest and build rapport before doing so at the next visit. GPs' interest and patients' positive attitude in managing risk were important in implementing CVAR. Long consultations, good communication skills and having a trusting relationship helped overcome the barriers during the process. All the participants supported engaging patients to self-assess their risk before the consultation and sharing decision making with GPs during consultation. Involving practice staff to help with the patient self-assessment, follow-up and referral would be helpful in implementing CVAR assessment and management, but GPs, patients and practices may need more support for this to occur.

CONCLUSIONS

Multiple strategies are required to promote the better use of CVAR in the extremely busy working environment of Australian general practice. An implementation model has been developed based on our findings and the Chronic Care Model. Further research needs to investigate the effectiveness of the proposed model.

Cardiovascular risk management and its impact in Australian general practice patients with type 2 diabetes in urban and rural areas

OBJECTIVE

To investigate the cardiovascular disease (CVD) risk management and its impact on Australian general practice patients with type 2 diabetes in urban and rural areas between 2000 and 2002, and to compare trends over time and differences between urban and rural areas.

DESIGN AND METHODS

Population-based repeated cross-sectional study. 6305 patient records from 2000 to 2002 were extracted from registers of diabetes type 2 patients held by 16 Divisions of General Practice (250 practices) across Australia. Multivariate logistic regression comparing urban and rural patients at differing time-periods and comparing trend changes was conducted using multilevel analysis.

RESULTS

Prescribing of antihypertensive and lipid-lowering medications was infrequent but increased in both urban and rural areas from 2000 to 2002 (p<0.05), while attendance at other allied health professionals did not. While the proportion of patients meeting targets for high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol increased in both areas over time, only in urban areas were there improvements in total cholesterol and blood pressure over time. The proportion of patients meeting targets for HDL-C, triglycerides and smoking cessation were higher in urban areas than in rural areas by 2002.

CONCLUSIONS

Despite a number of national initiatives to improve general practice care and specifically support better care in rural areas, cardiovascular risk management and its impact in Australian general practice patients with type 2 diabetes was still suboptimal during the study period especially among patients from rural areas. Greater effort will be required to reduce the disparity in risk factor prevention for CVD between urban and rural people with type 2 diabetes in Australia.

Quality of diabetes care and coronary heart disease absolute risk in patients with type 2 diabetes mellitus in Australian general practice

OBJECTIVE

To examine the quality of diabetes care and prevention of cardiovascular disease (CVD) in Australian general practice patients with type 2 diabetes and to investigate its relationship with coronary heart disease absolute risk (CHDAR).

METHODS

A total of 3286 patient records were extracted from registers of patients with type 2 diabetes held by 16 divisions of general practice (250 practices) across Australia for the year 2002. CHDAR was estimated using the United Kingdom Prospective Diabetes Study algorithm with higher CHDAR set at a 10 year risk of >15%. Multivariate multilevel logistic regression investigated the association between CHDAR and diabetes care.

RESULTS

47.9% of diabetic patient records had glycosylated haemoglobin (HbA1c) >7%, 87.6% had total cholesterol >or=4.0 mmol/l, and 73.8% had blood pressure (BP) >or=130/85 mm Hg. 57.6% of patients were at a higher CHDAR, 76.8% of whom were not on lipid modifying medication and 66.2% were not on antihypertensive medication. After adjusting for clustering at the general practice level and age, lipid modifying medication was negatively related to CHDAR (odds ratio (OR) 0.84) and total cholesterol. Antihypertensive medication was positively related to systolic BP but negatively related to CHDAR (OR 0.88). Referral to ophthalmologists/optometrists and attendance at other health professionals were not related to CHDAR.

CONCLUSIONS

At the time of the study the diabetes and CVD preventive care in Australian general practice was suboptimal, even after a number of national initiatives. The Australian Pharmaceutical Benefits Scheme (PBS) guidelines need to be modified to improve CVD preventive care in patients with type 2 diabetes.

Serotonin receptor antagonists discriminate between PKA- and PKC-mediated plasticity in aplysia sensory neurons

Highly selective serotonin (5-hydroxytryptamine, 5-HT) receptor antagonists developed for mammals are ineffective in Aplysia due to the evolutionary divergence of neurotransmitter receptors and because the higher ionic strength of physiological saline for marine invertebrates reduces antagonist affinity. It has therefore been difficult to identify antagonists that specifically block individual signaling cascades initiated by 5-HT. We studied two broad-spectrum 5-HT receptor antagonists that have been characterized biochemically in Aplysia CNS: methiothepin and spiperone. Methiothepin is highly effective in inhibiting adenylyl cyclase (AC)-coupled 5-HT receptors in Aplysia. Spiperone, which blocks phospholipase C (PLC)-coupled 5-HT receptors in mammals, does not block AC-coupled 5-HT receptors in Aplysia. In electrophysiological studies, we explored whether methiothepin and spiperone can be used in parallel to distinguish between the AC-cAMP and PLC-protein kinase C (PKC) modulatory cascades that are initiated by 5-HT. 5-HT-induced broadening of the sensory neuron action potential in the presence of tetraethylammonium/nifedipine, which is mediated by modulation of the S-K+ currents, was used an assay for the AC-cAMP cascade. Spike broadening initiated by 5 microM 5-HT was unaffected by 100 microM spiperone, whereas it was effectively blocked by 100 microM methiothepin. Facilitation of highly depressed sensory neuron-to-motor neuron synapses by 5-HT was used as an assay for the PLC-PKC cascade. Spiperone completely blocked facilitation of highly depressed synapses by 5 microM 5-HT. In contrast, methiothepin produced a modest, nonsignificant, reduction in the facilitation of depressed synapses. Interestingly, these experiments revealed that the PLC-PKC cascade undergoes desensitization during exposure to 5-HT.

[In vitro study of the effects of pioglitazone on endothelial cell functions of human umbilical vein and the mechanisms involved]

OBJECTIVE

To determine whether pioglitazone (PIO) has effects on human umbilical vein endothelial cells (HUVECs) in vitro and to clarify the possible mechanisms therein involved.

METHODS

The HUVECs were selected to be a model, which was cultured with 5.5 mmol/L glucose (control group), 30 mmol/L glucose (high glucose group), and 30 mmol/L glucose+PIO at 10(-9), 10(-7), 10(-5) mol/L respectively (PIO+high glucose groups). The effects of the drugs on the endothelial dysfunction induced by high glucose were studied. The role of protein kinase C (PKC) alpha and delta in the endothelial dysfunction induced by high glucose and the effects of PIO were assessed. The translocation of PKCdelta or PKCalpha in a single HUVEC was observed by Laser-Scanning Confocal Microscope, and the expression analysis was conducted quantificationally by Western blotting.

RESULTS

High glucose could induce HUVECs apoptosis; the concentration of NO reduced and the level of sICAM-1 increased in high glucose group. PIO could inhibit the increasing apoptosis peaks induced by high glucose and could reverse the concentration of NO and sICAM-1 to normal level. PIO could inhibit the translocation of PKCa from plasm to nucleus in HUVECs induced by high glucose; it also could inhibit the translocation of PKCdelta from nucleus to plasm and membrane in HUVECs. PIO could inhibit the increasing expression of PKCdelta in HUVECs induced by high glucose. The expression level of PKCalpha in the high glucose group was not significantly different from that in the control.

CONCLUSION

PIO could correct the endothelial cell dysfunction induced by high glucose, and this drug action of PIO may be effected via the inhibition of PKCalpha and PKCdelta.

Single-crystalline Sb-doped SnO2 nanowires: synthesis and gas sensor application

The synthesis of semiconducting Sb-doped SnO2 nanowires in mass production by an in situ doping approach are reported, and the ethanol sensing results demonstrated that Sb-doped SnO2 nanowires have a promising application for the fabrication of gas sensors with low resistance, and quick response and recovery times.