MODULATION OF CALCIUM CHANNELS IN ARTERIAL SMOOTH-MUSCLE CELLS BY DIHYDROPYRIDINE ENANTIOMERS

The actions of the optical enantiomers of BAY K 8644 and Sandoz 202,791 were studied on barium inward currents recorded using the whole-cell configuration of the patch clamp technique from enzymatically isolated smooth muscle cells from the rabbit ear artery. The enantiomers were applied by bath perfusion or rapidly by a concentration jump technique, which enabled the study of drug action under equilibrium and nonequilibrium conditions. A larger effect of agonists was seen on peak inward current in 110 mM Ba when small rather than large depolarizations were applied. The midpoint voltage of the steady-state inactivation curve of IBa was -12.8 +/- 1.9 mV (n = 4) in the absence of drug, -16.4 +/- 2.5 mV (n = 4) in 1 microM (+)202,791, and -31.4 +/- 0.4 mV (n = 4) in 1 microM (-)202,791. The rate of onset of action of the agonist and antagonist enantiomers of BAY K 8644 and Sandoz 202,791 was studied by rapid application during 20-ms depolarizing steps from different holding potentials to +30 mV at 1 or 0.2 Hz. The drugs were applied as concentration jumps between two single pulses of a pulse train. The rates of onset of drug action on peak IBa during a 1-Hz pulse train were concentration dependent over the range of 100 nM-3 microM for both (+) and (-)202,791. The rate of onset of inhibition of peak current by antagonist enantiomers was not significantly influenced by the test pulse frequency. At a holding potential of -60 mV, the onset rate of the increase in peak IBa on application of 1 microM of agonist enantiomers (+)202,791 or (-)BAY K 8644 during a train of pulses occurred with mean time constants of 2.1 +/- 0.7 s (n = 7) and 2.3 +/- 0.2 s (n = 4), respectively. The onset of current increase on application of 1 microM (+)202,791 during a single voltage clamp step to 20 mV was faster, with a mean time constant of 380 +/- 80 ms (n = 3)

Rapid reduction versus abrupt quitting for smokers who want to stop soon: a randomised controlled non-inferiority trial

Background: The standard way to stop smoking is to stop abruptly on a quit day with no prior reduction in consumption of cigarettes. Many smokers feel that reduction is natural and if reduction programmes were offered, many more might take up treatment. Few trials of reduction versus abrupt cessation have been completed. Most are small, do not use pharmacotherapy, and do not meet the standards necessary to obtain a marketing authorisation for a pharmacotherapy.\ud Design/Methods: We will conduct a non-inferiority andomised trial of rapid reduction versus standard abrupt cessation among smokers who want to stop smoking. In the reduction arm,participants will be advised to reduce smoking consumption by half in the first week and to 25% of baseline in the second, leading up to a quit day at which participants will stop smoking completely.This will be assisted by nicotine patches and an acute form of nicotine replacement therapy. In the abrupt arm participants will use nicotine patches only, whilst smoking as normal, for two weeks prior to a quit day, at which they will also stop smoking completely. Smokers in either arm will have standard withdrawal orientated behavioural support programme with a combination of nicotine patches and acute nicotine replacement therapy post-cessation.\ud Outcomes/Follow-up: The primary outcome of interest will be prolonged abstinence from smoking, with secondary trial outcomes of point prevalence, urges to smoke and withdrawal\ud symptoms. Follow up will take place at 4 weeks, 8 weeks and 6 months post-quit day

Hydrogen peroxide detection with quartz-enhanced photoacoustic spectroscopy using a distributed-feedback quantum cascade laser

A quartz-enhanced photoacoustic spectroscopy sensor system was developed for the sensitive detection of hydrogen peroxide (H2O2) using its absorption transitions in the v6 fundamental band at ∼7.73 μm. The recent availability of distributed-feedback quantum cascade lasers provides convenient access to a strong H2O2 absorption line located at 1295.55 cm−1. Sensor calibration was performed by means of a water bubbler that generated titrated average H2O2vapor concentrations. A minimum detection limit of 12 parts per billion (ppb) corresponding to a normalized noise equivalent absorption coefficient of 4.6 × 10−9 cm−1W/Hz1/2 was achieved with an averaging time of 100 s

Antiphospholipid Antibodies Bind ATP: A putative Mechanism for the Pathogenesis of Neuronal Dysfunction

Antiphospholipid antibodies (aPL) generated in experimental animals cross-react with ATP. We therefore examined the possibility that aPL IgG from human subjects bind to ATP by affinity column and an enzyme linked immunosorbent assay (ELISA). Sera with high levels of aPL IgG were collected from 12 patients with the antiphospholipid syndrome (APS). IgG fractions from 10 of 12 APS patients contained aPL that could be affinity-bound to an ATP column and completely eluted with NaCl 0.5 M. A significant (>50%) inhibition of aPL IgG binding by ATP 5 mM was found in the majority. Similar inhibition was obtained with ADP but not with AMP or cAMP. All the affinity purified anti-ATP antibodies also bound β2-glycoprotein-I (β2-GPI, also known as apolipoprotein H) suggesting that, similar to most pathogenic aPL, their binding depends on this serum cofactor. We further investigated this possibility and found that the binding of β2-GPI to the ATP column was similar to that of aPL IgG in that most was reversed by NaCl 0.5 M. Furthermore, addition of β2-GPI to aPL IgG significantly increased the amount of aPL binding to an ATP column. We conclude that aPL IgG bind ATP, probably through β2-GPI. This binding could interfere with the normal extracellular function of ATP and similar neurotransmitters

Excision of sympathetic ganglia and the rami communicantes with histological confirmation offers better early and late outcomes in Video assisted thoracoscopic sympathectomy

<p>Abstract</p> <p>Background</p> <p>Video-Assisted Thoracoscopic Sympathectomy (VATS) is an established minimally invasive procedure for thoracic sympathetic blockade in patients with hyperhidrosis, facial flushing and intractable angina. Various techniques using clips, diathermy and excision are used to perform sympathectomy. We present our technique of excision of the sympathetic chain with histological proof and the analysis of the early and late outcomes.</p> <p>Methods</p> <p>We evaluated 200 procedures in 100 consecutive patients, who underwent Video Assisted Thoracoscopic Sympathectomy by a single surgeon in our centre between September 1996 to March 2007. All patients had maximum medical therapy prior to surgery and were divided into 3 groups based on indications, Group 1(hyperhidrosis: 48 patients), Group 2 (facial flushing: 26 patients) and Group 3(intractable angina: 26 patients). The demography and severity of symptoms for each group were analysed. The endpoints were success rate, 30 day mortality, complications and patient's satisfaction.</p> <p>Results</p> <p>99 patients had bilateral VATS sympathectomy and 1 had unilateral sympathectomy. The conversion rate to open was 1(1%). All patients had successful removal of ganglia proven histologically with no perioperative mortality in our series. The complications included pneumothorax (5%), acute coronary syndrome (2%), transient Horner's syndrome (1%), transient paraesthesia (1%), wound infection (4%), compensatory hyperhidrosis (18%), residual flushing (3%) and wound pain (5%). There were five late deaths in the intractable angina group at a mean follow up of 36.7 months. Overall success rates of abolishing the symptoms were 96.3%, 87.5% and 95.2% for Group 1, 2 and 3 respectively.</p> <p>Conclusion</p> <p>Excision of the sympathetic chain with histological confirmation during VATS sympathectomy is a safe and effective method in treating hyperhidrosis, facial flushing and intractable angina with good long term results and satisfaction.</p

Checklists in the operating room: Help or hurdle? A qualitative study on health workers' experiences

<p>Abstract</p> <p>Background</p> <p>Checklists have been used extensively as a cognitive aid in aviation; now, they are being introduced in many areas of medicine. Although few would dispute the positive effects of checklists, little is known about the process of introducing this tool into the health care environment. In 2008, a pre-induction checklist was implemented in our anaesthetic department; in this study, we explored the nurses' and physicians' acceptance and experiences with this checklist.</p> <p>Method</p> <p>Focus group interviews were conducted with a purposeful sample of checklist users (nurses and physicians) from the Department of Anaesthesia and Intensive Care in a tertiary teaching hospital. The interviews were analysed qualitatively using systematic text condensation.</p> <p>Results</p> <p>Users reported that checklist use could divert attention away from the patient and that it influenced workflow and doctor-nurse cooperation. They described senior consultants as both sceptical and supportive; a head physician with a positive attitude was considered crucial for successful implementation. The checklist improved confidence in unfamiliar contexts and was used in some situations for which it was not intended. It also revealed insufficient equipment standardisation.</p> <p>Conclusion</p> <p>Our findings suggest several issues and actions that may be important to consider during checklist use and implementation.</p

A change in the optical polarization associated with a gamma-ray flare in the blazar 3C 279

It is widely accepted that strong and variable radiation detected over all accessible energy bands in a number of active galaxies arises from a relativistic, Doppler-boosted jet pointing close to our line of sight. The size of the emitting zone and the location of this region relative to the central supermassive black hole are, however, poorly known, with estimates ranging from light-hours to a light-year or more. Here we report the coincidence of a gamma-ray flare with a dramatic change of optical polarization angle. This provides evidence for co-spatiality of optical and gamma-ray emission regions and indicates a highly ordered jet magnetic field. The results also require a non-axisymmetric structure of the emission zone, implying a curved trajectory for the emitting material within the jet, with the dissipation region located at a considerable distance from the black hole, at about 10^5 gravitational radii.Comment: Published in Nature issued on 18 February 2010. Corresponding authors: Masaaki Hayashida and Greg Madejsk

Assessing the efficiency and significance of Methylated DNA Immunoprecipitation (MeDIP) assays in using in vitro methylated genomic DNA

<p>Abstract</p> <p>Background</p> <p>DNA methylation contributes to the regulation of gene expression during development and cellular differentiation. The recently developed Methylated DNA ImmunoPrecipitation (MeDIP) assay allows a comprehensive analysis of this epigenetic mark at the genomic level in normal and disease-derived cells. However, estimating the efficiency of the MeDIP technique is difficult without previous knowledge of the methylation status of a given cell population. Attempts to circumvent this problem have involved the use of <it>in vitro </it>methylated DNA in parallel to the investigated samples. Taking advantage of this stratagem, we sought to improve the sensitivity of the approach and to assess potential biases resulting from DNA amplification and hybridization procedures using MeDIP samples.</p> <p>Findings</p> <p>We performed MeDIP assays using <it>in vitro </it>methylated DNA, with or without previous DNA amplification, and hybridization to a human promoter array. We observed that CpG content at gene promoters indeed correlates strongly with the MeDIP signal obtained using <it>in vitro </it>methylated DNA, even when lowering significantly the amount of starting material. In analyzing MeDIP products that were subjected to whole genome amplification (WGA), we also revealed a strong bias against CpG-rich promoters during this amplification procedure, which may potentially affect the significance of the resulting data.</p> <p>Conclusion</p> <p>We illustrate the use of <it>in vitro </it>methylated DNA to assess the efficiency and accuracy of MeDIP procedures. We report that efficient and reproducible genome-wide data can be obtained via MeDIP experiments using relatively low amount of starting genomic DNA; and emphasize for the precaution that must be taken in data analysis when an additional DNA amplification step is required.</p