Comparison of Heated Electrospray Ionization and Nanoelectrospray Ionization Sources Coupled to Ultra-High-Resolution Mass Spectrometry for Analysis of Highly Complex Atmospheric Aerosol Samples.

Direct infusion analysis using soft ionization techniques coupled to ultra-high-resolution mass spectrometers (UHRMS) allows screening of thousands of organic species in complex samples. Despite the high analytical throughput of direct infusion, this technique is known to be prone to matrix effects caused by changes in the ionization efficiency of an analyte, ion suppression, or enhancement due to the presence of certain compounds and inorganic salts in the sample. In this study we compared two soft ionization sources, that is, heated electrospray ionization (HESI) and nano-ESI for the analysis of atmospheric aerosol samples in the negative ionization mode. In-source fragmentation tests were conducted and experiments involving sample desalting through solid-phase extraction (SPE) with a reversed phase functionalized polymeric sorbent and spiking samples with inorganic salt were performed. Both ionization sources showed specific advantages and disadvantages for the direct infusion analysis of atmospheric aerosol extracts. The mass spectra of aerosol samples analyzed using HESI contained a large number of high molecular weight homologues containing sulfur and nitrogen, suggesting that this source is prone to formation of salt adducts and noncovalent compounds in samples enriched with inorganic salts. Data from the same aerosol sample extracts analyzed using nanoelectrospray ionization (nano-ESI) show less adduct formation; however, a decrease in the number of homologues was observed, as well as loss of molecules at higher mass range, indicating that the nano-ESI source is more prone to ion suppression. Irrespective of ionization source, SPE pretreatment significantly improved ion recoveries for organic species with nonpolar and moderately polar functional groups, but lower recoveries were obtained for highly oxygenated molecules. Therefore, while SPE reduced in-source adduct formation, it also limited the range of compounds identified through a single analysis.

Application of the Chinese version of the International Prostate Symptom Score for the management of lower urinary tract symptoms in a primary health care setting.

OBJECTIVES: To determine whether the Chinese version of the International Prostate Symptom Score can differentiate surgically treatable conditions from functional disorders among patients with lower urinary tract symptoms. DESIGN: Retrospective cross-sectional study. SETTING: Community hospital, Hong Kong. PATIENTS: A cohort of 121 adult males with lower urinary tract symptoms referred to a specialty clinic from July 2006 to February 2007. MAIN OUTCOME MEASURES: Scores were obtained following self-administration of the Chinese version of the International Prostate Symptom questionnaire. A combination of uroflowmetry and urethrocystoscopy were applied as the gold-standard diagnostic tests for surgically treatable conditions. The effectiveness of the instrument was explored in terms of sensitivity, specificity, and positive and negative predictive values. RESULTS: A total of 121 records were reviewed, among which 58 patients with lower urinary tract symptoms had completed both the questionnaire and gone through the relevant diagnostic tests. The receiver operating characteristics curve was constructed; the area under curve was 0.68. Using the receiver operating characteristics analysis, the optimal cut-off value for the Chinese version of the International Prostate Symptom Score was 24. The respective sensitivity and specificity values were 62% and 84%. The positive predictive value was 68% and negative predictive value was 79%. CONCLUSION: The Chinese version of International Prostate Symptom Score is not a sensitive instrument for diagnosing surgically treatable conditions and it is not a suitable medical test to exclude patients from referrals to secondary health care services. An acceptable specificity with a score of 24 was advantageous for triaging patients to receive early specialist attention.

Limitation of the atrial extrastimulus technique for assessment of the His-Purkinje system in patients with right bundle branch block.

A prospective study of the usefulness of the atrial extrastimulus technique for assessment of the His-Purkinje system was undertaken in 19 consecutive patients with complete RBBB and an abnormal or indeterminate frontal QRS axis. A total of 59 basic cycle lengths (BCLs) could be analyzed in detail. The most common patterns of His-Purkinje conduction seen were simple linear (V1V2 vs H1H2, N = 49) or flat (H2V2 vs H1H2, N = 44) curves. This finding is related to the limitation imposed by interposition of the slowly conducting AV node between the site of the extrastimulus and the His-Purkinje system. One or more refractory periods could be measured in only 27% of BCLs (10 Effective Refractory Periods of the remaining intact His-Purkinje system plus 16 Functional Refractory Periods and 19 Relative Refractory Periods). No refractory periods of the His-Purkinje system could be determined in 8 of 19 patients (42%), the major limitation being slowed AV node conduction. The results suggest limited likelihood that additional clinically useful information about His-Purkinje system conduction can be obtained by the atrial extrastimulus technique, as used in this study, although it may be helpful in assessing other parts of the conduction system.

Baroreceptor influence on a spinal cardiovascular reflex.

A stretch of the walls of the thoracic aorta, performed in vagotomized cats without obstructing aortic flow, induces increases in heart rate, myocardial contractility, and arterial pressure. These reflex responses are still present after high spinal section. Cats under chloralose-urethane anesthesia were vagotomized and one carotid sinus was isolated and perfused with arterial blood at constant flow. The contralateral carotid sinus nerve and both aortic nerves were sectioned. A stretch of the walls of the thoracic aorta between the 7th and 10th intercostal arteries induced a reflex increase in mean arterial pressure 29 +/- 2 mmHg (mean +/- SE). Stepwise increases of carotid sinus pressure (CSP) or electrical stimulation of the carotid sinus nerve induced stepwise decreases of this reflex response. At maximal baroreceptor stimulation (CSP 212 +/- 9 mmHg) the reflex response to aortic stretch was reduced by 42%. These experiments show that this spinal cardiovascular reflex is at least partially under the inhibitory control of the baroreceptor input.

Reflex effects of thoracic aorta wall stretch on regional vascular resistance.

In anesthetized, vagotomized cats with both carotid arteries occluded, a stretch of the walls of the thoracic aorta, performed without obstructing aortic flow, induced a significant reflex increase in arterial pressure (35 +/- 2-26 +/- 1 mmHg; systolic-diastolic). This pressure increase was accompanied by significant increases in peripheral resistance in the superior mesenteric (+30%), renal (+23%), and external iliac (+23%) vascular beds. The increase in iliac resistance observed in the skinned leg was comparable with that observed in the contralateral intact limb. All these vascular responses were drastically reduced by the administration of phenoxybenzamine. After alpha-adrenergic blockade no signs of reflex vasodilatation could be detected during aortic stretch in any of the vascular beds examined.

Inhibition by atropine, phenoxybenzamine and propranolol of the autonomic nervous system of the domestic fowl.

Because of the paucity and inconsistency of information on blockage of the chicken autonomic nervous system for extended periods, the effects of atropine, phenoxybenzamine and propranolol in the anesthetized hen were examined. It was found that cholinergic blockade by atropine was very short lived. For effective (80%) parasympathetic blockage a priming dose of 0.25 mg./kg;, followed by an infusion at the rate of 17.5 microgram/kg./min., was required. Similarly, inhibition of the beta-sympathetic system required propranolol in a priming dose of 0.25 mg./kg. and an infusion of 5 microgram/kg./min. The alpha-sympathetic inhibitor, phenoxybenzamine, was effective when given as a single dose of 5 mg./kg. Using these levels of inhibitor it was possible to ensure blockade in all cases for periods of two hours or more.