Room-temperature ionic liquids: a novel versatile lubricant

Alkylimidazolium tetrafluoroborates are promising versatile lubricants for the contact of steel/steel, steel/aluminium, steel/copper, steel/SiO2, Si3N4/SiO2, steel/Si(100), steel/sialon ceramics and Si3N4/sialon ceramics; they show excellent friction reduction, antiwear performance and high load-carrying capacity.

Heartbeat classification using morphological and dynamic features of ECG signals

In this paper, we propose a new approach for heartbeat classification based on a combination of morphological and dynamic features. Wavelet transform and independent component analysis (ICA) are applied separately to each heartbeat to extract morphological features. In addition, RR interval information is computed to provide dynamic features. These two different types of features are concatenated and a support vector machine classifier is utilized for the classification of heartbeats into one of 16 classes. The procedure is independently applied to the data from two ECG leads and the two decisions are fused for the final classification decision. The proposed method is validated on the baseline MIT-BIH arrhythmia database and it yields an overall accuracy (i.e., the percentage of heartbeats correctly classified) of 99.3% (99.7% with 2.4% rejection) in the "class-oriented" evaluation and an accuracy of 86.4% in the "subject-oriented" evaluation, comparable to the state-of-the-art results for automatic heartbeat classification.

Two Arabidopsis mutants that overproduce ethylene are affected in the posttranscriptional regulation of 1-aminocyclopropane-1-carboxylic acid synthase

The Arabidopsis mutants eto1 (ethylene overproducer) and eto3 produce elevated levels of ethylene as etiolated seedlings. Ethylene production in these seedlings peaks at 60 to 96 h, and then declines back to almost wild-type levels. Ethylene overproduction in eto1 and eto3 is limited mainly to etiolated seedlings; light-grown seedlings and various adult tissues produce close to wild-type amounts of ethylene. Several compounds that induce ethylene biosynthesis in wild-type, etiolated seedlings through distinct 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) isoforms were found to act synergistically with eto1 and eto3, as did the ethylene-insensitive mutation etr1 (ethylene resistant), which blocks feedback inhibition of biosynthesis. ACS activity, the rate-limiting step of ethylene biosynthesis, was highly elevated in both eto1 and eto3 mutant seedlings, even though RNA gel-blot analysis demonstrated that the steady-state level of ACS mRNA was not increased, including that of a novel Arabidopsis ACS gene that was identified. Measurements of the conversion of ACC to ethylene by intact seedlings indicated that the mutations did not affect conjugation of ACC or the activity of ACC oxidase, the final step of ethylene biosynthesis. Taken together, these data suggest that the eto1 and eto3 mutations elevate ethylene biosynthesis by affecting the posttranscriptional regulation of ACS.

Increased pulmonary artery elastolytic activity in adult rats with monocrotaline-induced progressive hypertensive pulmonary vascular disease compared with infant rats with nonprogressive disease

In a rat model of pulmonary hypertension induced by monocrotaline, medial hypertrophy of the pulmonary arteries is associated with enhanced production (synthesis) of insoluble elastin relative to accumulation and an increased number of elastin fragments, features suggestive of an elastolytic process. In the present study, we measured and characterized pulmonary artery (PA) elastolytic activity at time points before as well as coincident with the progression of medial hypertrophy in monocrotaline-injected adult male Sprague-Dawley rats. We also determined whether medial hypertrophy is preceded by ultrastructural changes in elastin. Since medial hypertrophy develops but fails to progress in rats injected with monocrotaline at 8 days of age, we assessed whether, compared with adult rats, there were also structural and biochemical differences in elastin and elastolytic activity. A twofold increase in elastolytic activity per milligram tissue was observed 2 days after monocrotaline injection in adult rats (p less than 0.01), and there was an increased number of breaks in the internal elastic lamina (IEL) at 4 days (p less than 0.05) (i.e., before the development of medial hypertrophy). Associated with the progression of medial hypertrophy between 16 and 28 days after monocrotaline injection, there was a further threefold increase in elastolytic activity per milligram tissue by 28 days (p less than 0.01). Susceptibility of the elastolytic activity to specific inhibitors suggested that one or more serine elastases is involved. In infant rats in which medial and right ventricular hypertrophy fail to progress in severity between 16 and 28 days after monocrotaline injection, we did not measure an increase in elastolytic activity, nor was there evidence of an increase in the number of breaks in the IEL at 4 days, suggesting a lack of increased elastolytic activity at an earlier time point. The total content of PA elastin in infant rats, although increased compared with control rats (p less than 0.01), was not associated with heightened production and appeared ultrastructurally as thicker laminae (p less than 0.05) rather than as fragments previously reported in adult rats.

Amyloid-beta proteins activate Ca(2+)-permeable channels through calcium-sensing receptors

The amyloid-beta peptides (A beta) are produced in excess in Alzheimer's disease (AD) and may contribute to neuronal dysfunction and degeneration. This study provides strong evidence for a novel cellular target for the actions of A beta, the phospholipase C-coupled, extracellular Ca(2+)-sensing receptor (CaR). We demonstrate that A beta(s) produce a CaR-mediated activation of a Ca(2+)-permeable, nonselective cation channel (NCC), probably via elevation in cytosolic Ca2+ (Cai), in cultured hippocampal pyramidal neurons from normal rats and from wild type mice but not those from mice with targeted disruption of the CaR gene (CaR -/-). A beta(s) also activate NCC in CaR-transfected but not in nontransfected human embryonic kidney (HEK293) cells. Thus aggregates of A beta deposited on hippocampal neurons in AD could appropriately activate the CaR, stimulating Ca(2+)-permeable channels and causing sustained elevation of Cai with resultant neuronal dysfunction.

Expression of extracellular calcium-sensing receptor in human osteoblastic MG-63 cell line

We have previously shown the expression of the extracellular calcium (Ca2+o)-sensing receptor (CaR) in osteoblast-like cell lines, and others have documented its expression in sections of murine, bovine, and rat bone. The existence of the CaR in osteoblasts remains controversial, however, since some studies have failed to document its expression in the same osteoblast-like cell lines. The goals of the present study were twofold. 1) We sought to determine whether the CaR is expressed in the human osteoblast-like cell line, MG-63, which has recently been reported by others not to express this receptor. 2) We investigated whether the CaR, if present in MG-63 cells, is functionally active, since most previous studies have not proven the role of the CaR in mediating known actions of Ca2+o on osteoblast-like cells. We used immunocytochemistry and Western blotting with the specific, affinity-purified anti-CaR antiserum 4637 as well as Northern blot analysis and RT-PCR using a riboprobe and PCR primers specific for the human CaR, respectively, to show readily detectable CaR protein and mRNA expression in MG-63 cells. Finally, we employed the patch-clamp technique to show that an elevation in Ca2+o as well as the specific, allosteric CaR activator NPS R-467 (0.5 microM), but not its less active stereoisomer NPS S-467 (0.5 microM), activate an outward K+ channel in MG-63 cells, strongly suggesting that the CaR in MG-63 cells is not only expressed but is functionally active.

Expression of E-selectin on endothelial cells of small veins in human colorectal cancer

E-selectin is an adhesion molecule of endothelial cells that binds to cancer cells mediated by sialyl Lewis A (sLea) or sialyl Lewis X (sLe(x)). It is suspected to be involved in hematogenous metastasis of tumors. Therefore, it is worth examining E-selectin expression in human colorectal cancer and its hepatic metastasis. In the present study, E-selectin was clearly revealed on the endothelial cells of small vessels adjacent to cancer nests both in primary and in metastatic nests in immunohistochemistry. In these tissues, E-selectin was observed on the endothelial cells lining the lumen of small vessels. Its expression adjacent to cancer nests appears to be induced through some stimuli by cancer cells, since its degree of expression is inversely correlated to the distance of the blood vessels from the cancer nests (p < 0.001). Endothelial cells adjacent to the metastatic lesion expressed E-selectin more extensively than those adjacent to the primary foci. This is also in line with the finding on serum E-selectin levels which were significantly elevated in the metastatic group as compared with the non-metastatic group. The serum E-selectin level may provide useful information in the diagnosis for hepatic metastasis of colorectal cancer, although the results are still tentative.

Expression of midkine in the early stage of carcinogenesis in human colorectal cancer

It has been suggested that a heparin-binding growth factor, midkine (MK), plays an important role in carcinogenesis because of its frequent overexpression in various malignant tumours. To clarify whether or not MK contributes to the early stage of carcinogenesis, we examined the status of MK mRNA in 20 adenomas with moderate- and severe-grade dysplasia, 28 carcinomas and 28 corresponding normal tissues, by means of Northern blotting. The MK expression level was significantly more elevated in adenomas than in normal tissues (P < 0.001, unpaired Student's t-test). A difference was also observed between carcinomas and the corresponding normal tissues (P < 0.04, paired Student's t-test). Moreover, MK immunostaining was positive in the adenomas with moderate- and severe-grade dysplasia and in the carcinomas, but not in mild-grade dysplasia or in normal tissues. These findings were in line with those on Western blotting. In three patients with both adenomas with moderate- or severe-grade dysplasia and carcinomas, elevated MK expression was observed in the neoplastic lesions. This is the first report of the association of elevated MK expression with the early stage of carcinogenesis in humans.

Calcium-sensing receptor in the rat hippocampus: a developmental study

The extracellular Ca2+ (Ca2+(o))-sensing receptor (CaR) plays a key role in maintaining near constancy of Ca2+(o) in mammals through its presence in parathyroid gland and kidney. The CaR is also present in brain, and although its role(s) in the brain is not known, it is possible that small changes in Ca2+(o) modify essential physiological and pathological processes, since calcium is crucial for numerous neuronal functions. Northern analysis has revealed that the CaR mRNA is present in hippocampus and several other regions of the brain. The hippocampus is an important site for learning and memory, but the relevance of the CaR to these processes is unknown. Long-term potentiation (LTP), a putative in vitro analog of memory, can only be induced after 7-10 days postnatally in rat hippocampus. Therefore, in the present study we determined the time course for the developmental expression of the CaR in rat hippocampus to assess its relationship to the development of other important hippocampal functions, such as the capacity for induction of LTP. Northern and Western analyses showed that CaR mRNA and protein were expressed at low levels at 5 days postnatally but then increased markedly at 10 days. A high level of receptor expression, due primarily to an increase in a 7.5 kb transcript, persisted until 30 days, when it gradually decreased by 3-fold to reach the adult level of expression. In situ hybridization histochemistry and immunohistochemistry revealed CaR mRNA and protein in pyramidal cells of all the layers of hippocampus and in granule cells of the dentate gyrus. The results show that CaR expression rises at a time when LTP can first be induced in hippocampus and persists at high levels during the time when brain development is proceeding most rapidly. Further studies are needed to determine the role of the CaR in the development of important aspects of the function of hippocampus and other regions of brain, including LTP.

The endogenous vascular elastase that governs development and progression of monocrotaline-induced pulmonary hypertension in rats is a novel enzyme related to the serine proteinase adipsin

We showed previously a cause and effect relationship between increased activity of an endogenous vascular elastase (EVE) and experimentally induced pulmonary hypertension in rats. We now report the isolation and characterization of EVE. Degenerate oligonucleotides synthesized to homologous sequences in serine elastases were used in a PCR with rat pulmonary artery (PA) cDNA. The PCR product hybridized to a 1.2-kb mRNA and the intensity of hybridization was threefold increased in RNA from rat hypertensive PA at a timepoint when EVE activity was increased. The PCR product was used to screen a cDNA library and sequences obtained encoded rat adipsin. We then used immunoaffinity to purify EVE. An antibody to the elastin-binding protein was used to remove this competitor of elastase from the PA extract and the elastolytic activity increased 100-fold. The enzyme was purified using an antibody that recognizes NH2-terminal sequences of serine proteinases and the eluate was further purified using an antibody raised against recombinant adipsin. A single band at 20 kD immunoreactive with the adipsin antibody was resolved as an active enzyme on an elastin substrate gel. Immunogold labeling with an antibody to an adipsin peptide sequence localized EVE to PA smooth muscle cells. This is the first isolation of EVE; it appears to be a novel enzyme related to the serine proteinase adipsin originally found in adipose tissue.

Agonists of the Ca(2+)-sensing receptor (CaR) activate nonselective cation channels in HEK293 cells stably transfected with the human CaR

Calcium (Ca2+) ions serve multiple roles both intra- and extracellularly. We recently cloned a cell surface, Cao(2+)-sensing receptor (CaR) that plays a central role in Cao2+ homeostasis by enabling direct regulation by Cao2+ of parathyroid hormone (PTH) secretion and the function of other tissues involved in mineral ion homeostasis. In parathyroid cells, the CaR activates phospholipase C, thereby raising the levels of inositol trisphosphate (IP3) and releasing Ca2+ from intracellular stores. High Cao2+ also activates Ca2+ influx into parathyroid cells through poorly defined mechanisms that may involve Ca(2+)-permeable, nonselective cation channels (NCC). We now show that human embryonic kidney (HEK293) cells also have NCC and, furthermore, that these channels are regulated by the CaR. We have utilized the cell-attached configuration of the patch clamp technique to characterize the properties of these channels as well as their regulation by various CaR agonists added to the external bath solution. The polycationic CaR agonist, neomycin (100 microM), as well as an elevated concentration of Cao2+ (3 mM), both of which activate the cloned CaR, significantly increased the probability of channel opening (Po) in HEK cells stably transfected with the CaR but not in nontransfected HEK cells which do not contain the receptor. Thus, the activation of the CaR enhances the activity of Ca(2+)-permeable NCC in these cells, which could contribute to the sustained increase in Cai2+ in parathyroid cells which is observed in response to elevated Cao2+. The CaR may also regulate the membrane functions of other CaR-expressing cells (e.g., those in the brain), at least in part, by modulating similar channels.

Modulation by polycationic Ca(2+)-sensing receptor agonists of nonselective cation channels in rat hippocampal neurons

We recently cloned an extracellular calcium (Ca2+0)-sensing receptor (CaR) from bovine parathyroid. The CaR is also expressed in various regions of brain, suggesting that it could potentially mediate some of the well-known but poorly understood effects of Ca2+0 on neuronal function. We have now examined the effects of polycationic CaR agonists on the activity of nonselective cation channels (NCC) in cultured rat hippocampal neurons, using the cell-attached configuration of the patch clamp technique and applying CaR active agents to the external bath solution. The polycationic CaR agonist, neomycin (100 microM), as well as an elevated concentration of Ca2+0 (3 mM), which is known to activate the cloned CaR, significantly increased the probability of channel opening (Po). The polyamine, spermine (300 microM), which also mimics the actions of Ca2+0 on the cloned CaR, produced similar changes in Po in rat hippocampal neurons. Elevation of Ca2+0 also increased Po for a similar NCC in HEK293 cells transfected with the cloned human CaR but not in nontransfected HEK cells. Thus the CaR can regulate the activity of Ca(2+)-permeable NCC in hippocampal neurons and could potentially modulate key functions of these cells, including neurotransmission and neuronal excitability.

Expression of extracellular calcium-sensing receptor by human lens epithelial cells

The extracellular calcium-sensing receptor (CaR) confers the capacity to sense small changes in the extracellular Ca2+ concentration (Ca2+o) not only upon cells involved in maintaining systemic Ca2+ homeostasis but also upon those not directly involved in this process. Since high Ca2+o is known to affect various physiological processes in lens epithelium both in health and in disease states (e.g., the formation of cataracts in hypocalcemic states), we investigated the expression and function of the CaR in these cells. By RT-PCR and immunocytochemistry the CaR is expressed in human lens epithelial cells in culture. In addition, the open state probability of a Ca(2+)-activated potassium (K+) channel with a conductance of 82 +/- 3 pS is significantly increased by elevating Ca2+o to 3.0 mM or by application of 100 microM neomycin, both effective CaR agonists. Therefore, our data suggest that human lens-epithelial cells express the CaR, which may be functionally linked to Ca(2+)-activated K+ channels and, perhaps, to other ion channels involved in ionic homeostasis in the lens.

Quantitation of SU11248, an oral multi-target tyrosine kinase inhibitor, and its metabolite in monkey tissues by liquid chromatograph with tandem mass spectrometry following semi-automated liquid–liquid extraction

SU11248 is a potent inhibitor of PDGFR, VEGFR, KIT, and Flt3, and is currently under Phase I clinical evaluation as an anticancer drug. A sensitive and specific analytical method for the quantitation of SU11248 and its metabolite in several monkey tissues (liver, kidney, brain and white fat) using LC-MS-MS following semi-automated liquid-liquid extraction (LLE) was developed and validated. Amounts of 50 mg of tissue were homogenized using an ultrasonic processor. After addition of the stable labelled internal standard (IS) and ammonium hydroxide (0.3%), samples were extracted with 2.5 ml of tert-butyl methyl ether. Following centrifugation, aliquots of 1.8 ml of the organic phase were transferred into a 96-well plate. The Packard Multiprobe II robotic liquid handler was used to perform all steps mentioned above. The organic phase was dried and the residue was reconstituted with 800 microl of 15 mM ammonium formate buffer solution (pH 3.25) using a Tomtec Quadra 96 workstation. Aliquots of 10 microl of the resulting solution were injected into the LC-MS-MS system. A Symmetry Shield C8 column (50 mm x 2.1 mm, 3.5 microm) was used to perform the chromatographic analysis. The mobile phase was 15 mM ammonium formate buffer solution (pH 3.25)-acetonitrile (74:26 (v/v)) with a flow-rate of 0.35 ml/min. Retention times of the metabolite and SU11248 were about 2.5 and 3.5 min, respectively. Total cycle time was 5 min. MS detection used the Applied Biosystems-MDS Sciex API 3000 with TurbolonSpray interface and multiple reaction monitoring (MRM) operated in positive ion mode. The method was validated for both compounds over the calibration range of about 2 and 2000 ng/g. The suitability and robustness of the method for in vivo samples were confirmed by analysis of monkey tissues from animals dosed with SU11248.

Design of experiment and data analysis by JMP (SAS institute) in analytical method validation

Validation of an analytical method through a series of experiments demonstrates that the method is suitable for its intended purpose. Due to multi-parameters to be examined and a large number of experiments involved in validation, it is important to design the experiments scientifically so that appropriate validation parameters can be examined simultaneously to provide a sound, overall knowledge of the capabilities of the analytical method. A statistical method through design of experiment (DOE) was applied to the validation of a HPLC analytical method for the quantitation of a small molecule in drug product in terms of intermediate precision and robustness study. The data were analyzed in JMP (SAS institute) software using analyses of variance method. Confidence intervals for outcomes and control limits for individual parameters were determined. It was demonstrated that the experimental design and statistical analysis used in this study provided an efficient and systematic approach to evaluating intermediate precision and robustness for a HPLC analytical method for small molecule quantitation.

Galpha(i2) but not Galpha(i3) is required for muscarinic inhibition of contractility and calcium currents in adult cardiomyocytes

Parasympathetic stimulation of the heart acts through M(2)-muscarinic acetylcholine receptors to regulate ion channel activity and subsequent inotropic status. Although muscarinic signal transduction is mediated via pertussis toxin-sensitive G proteins Galpha(i/o), the specific signal transduction requirements of Galpha(i2) and Galpha(i3) in mediating muscarinic regulated L-type calcium currents (I(Ca, L)), intracellular calcium, and cell contractility remain to be determined. Adult ventricular myocytes were isolated from Galpha(i2)-null mice, Galpha(i3)-null mice, and their wild-type littermates. Cell shortening, intracellular calcium levels, and I(Ca, L) were all measured in response to isoproterenol, a beta-adrenergic receptor agonist, and carbachol, a cholinergic receptor agonist. With isoproterenol stimulation, myocytes from all groups demonstrated a marked increase in calcium currents, correlating with augmented intracellular calcium transient amplitude and cell shortening. Carbachol significantly attenuated the isoproterenol response in wild-type and Galpha(i3)-null cells but had no effect in Galpha(i2)-null cells. This study demonstrates that Galpha(i2), but not Galpha(i3), is required for muscarinic inhibition of the beta-adrenergic response in adult murine ventricular myocytes.

Targeted inactivation of alphai2 or alphai3 disrupts activation of the cardiac muscarinic K+ channel, IK+Ach, in intact cells

Cardiac muscarinic receptors activate an inwardly rectifying K+ channel, IK+Ach, via pertussis toxin (PT)-sensitive heterotrimeric G proteins (in heart Gi2, Gi3, or Go). We have used embryonic stem cell (ES cell)-derived cardiocytes with targeted inactivations of specific PT-sensitive alpha subunits to determine which G proteins are required for receptor-mediated regulation of IK+Ach in intact cells. The muscarinic agonist carbachol increased IK+Ach activity in ES cell-derived cardiocytes from wild-type cells, in cells lacking alphao, and in cells lacking the PT-insensitive G protein alphaq. In cells with targeted inactivation of alphai2 or alphai3, channel activation by both carbachol and adenosine was blocked. Carbachol-induced channel activation was restored in the alphai2- and alphai3-null cells by reexpressing the previously targeted gene and guanosine 5'-[gamma-thio] triphosphate was able to fully activate IK+Ach in excised membranes patches from these mutants. In contrast, negative chronotropic responses to both carbachol and adenosine were preserved in cells lacking alphai2 or alphai3. Our results show that expression of two specific PT-sensitive alpha subunits (alphai2 and alphai3 but not alphao) is required for normal agonist-dependent activation of IK+Ach and suggest that both alphai2- and alphai3-containing heterotrimeric G proteins may be involved in the signaling process. Also the generation of negative chronotropic responses to muscarinic or adenosine receptor agonists do not require activation of IK+Ach or the expression of alphai2 or alphai3.

HONO Budget and Its Role in Nitrate Formation in the Rural North China Plain

Nitrous acid (HONO) is a major precursor of tropospheric hydroxyl radical (OH) that accelerates the formation of secondary pollutants. The HONO sources, however, are not well understood, especially in polluted areas. Based on a comprehensive winter field campaign conducted at a rural site of the North China Plain, a box model (MCM v3.3.1) was used to simulate the daytime HONO budget and nitrate formation. We found that HONO photolysis acted as the dominant source for primary OH with a contribution of more than 92%. The observed daytime HONO could be well explained by the known sources in the model. The heterogeneous conversion of NO₂ on ground surfaces and the homogeneous reaction of NO with OH were the dominant HONO sources with contributions of more than 36 and 34% to daytime HONO, respectively. The contribution from the photolysis of particle nitrate and the reactions of NO₂ on aerosol surfaces was found to be negligible in clean periods (2%) and slightly higher during polluted periods (8%). The relatively high OH levels due to fast HONO photolysis at the rural site remarkably accelerated gas-phase reactions, resulting in the fast formation of nitrate as well as other secondary pollutants in the daytime.

An intelligent mobile vehicle navigator based on fuzzy logic and reinforcement learning

In this paper, an alternative training approach to the EEM-based training method is presented and a fuzzy reactive navigation architecture is described. The new training method is 270 times faster in learning speed; and is only 4% of the learning cost of the EEM method. It also has very reliable convergence of learning; very high number of learned rules (98.8%); and high adaptability. Using the rule base learned from the new method, the proposed fuzzy reactive navigator fuses the obstacle avoidance behaviour and goal seeking behaviour to determine its control actions, where adaptability is achieved with the aid of an environment evaluator. A comparison of this navigator using the rule bases obtained from the new training method and the EEM method, shows that the new navigator guarantees a solution and its solution is more acceptable.

Consequences of urban pollution upon skin status. A controlled study in Shanghai area

OBJECTIVE

After preliminary studies aimed at measuring pertinent biochemical parameters, potentially modified in subjects exposed to bad environmental conditions, a dedicated study was performed in Shanghai city to evaluate the effect of Urban pollution upon human skin and to collect feedback from the volunteers under study.

METHODS

This study was performed during summer 2008 in two different districts of Shanghai, on 159 local residents: 79 subjects from Xu Jia Hui (a centre Shanghainese area), more exposed to pollution, and 80 subjects from Chong Ming, an agricultural region closely located north of Shanghai (<100 kms) and less exposed to pollution, according to official data. Biochemical parameters were measured on skin, and feedback from volunteers was collected through a graduated 'Likert scale' questionnaire under a point scale (strongly agree, agree, disagree, strongly disagree and none).

RESULTS

The study demonstrated significant differences in several biochemical parameters measured in Chong Ming area, as compared to Urban area, with an increased ratio of squalene/lipids, a lower level of lactic acid and a better cohesion of stratum corneum. Both sebum excretion rate and sebum casual levels did not differ between the two districts. The volunteer's feedback evidenced a perceived link between pollution and their skin problems.

CONCLUSION

This study demonstrated a significant impact of the pollution upon the skin status, as illustrated by changes in superficial biochemical parameters and volunteers' perception.