Search results for "block"

Performance of different C18 columns in reversed-phase liquid chromatography with hydro-organic and micellar-organic mobile phases

2014

Column selection in reversed-phase liquid chromatography (RPLC) can become a challenge if the target compounds interact with the silica-based packing. One of such interactions is the attraction of cationic solutes to the free silanols in silica-based columns, which is a slow sorption-desorption interaction process that gives rise to tailed and broad peaks. The effect of silanols is minimised by the addition of a competing agent in the mobile phase, such as the anionic surfactant sodium dodecyl sulphate (SDS). In micellar-organic RPLC, the adsorption of an approximately fixed amount of SDS monomers gives rise to a stable modified stationary phase, with properties remarkably different from th…

Peak half-width plots to study the effect of organic solvents on the peak performance of basic drugs in micellar liquid chromatography.

2009

The addition of the anionic surfactant sodium dodecyl sulphate (SDS) to hydro-organic mixtures of methanol, ethanol, propanol or acetonitrile with water yielded enhanced peak shape (i.e. increased efficiencies and symmetrical peaks) for a group of basic drugs (β-blockers) chromatographed with a Kromasil C18 column. The effect can be explained by the thin layer of surfactant associated to the hydrocarbon chain on the stationary phase in the presence of the organic solvents, which covers the free silanols on the siliceous support avoiding their interaction with the cationic basic drugs. These instead interact with the anionic head of the surfactant increasing their retention and allowing a mo…

Anxiety and pain perception in patients undergoing mandibular autogenous block bone surgery

2020

Background The aim of the present study was to investigate pain perception and anxiety within the context of surgery for the placement of mandibular block bone and to evaluate the causality effect between theses variables. Material and methods A total of 13 patients were recruited for the study and were submitted to mandibular autogenous block bone surgery. Demographic data were collected and the anxiety level was determined using the State-Trait Anxiety Inventory (STAI). The STAI was administered on the day of surgery and on the 14th postoperative day. Pain was determined using the visual analogue scale (VAS) and limitation of daily activities and postoperative symptoms were also reported.…

P and R Wave Detection in Complete Congenital Atrioventricular Block

2009

Complete atrioventricular block (type III AVB) is characterized by an absence of P wave transmission to ventricles. This implies that QRS complexes are generated in an autonomous way and are not coordinated with P waves. This work introduces a new algorithm for the detection of P waves for this type of pathology using non-invasive electrocardiographic surface leads. The proposed algorithm is divided into three stages. In the first stage, the R waves located by a QRS detector are used to generate the RR series and time references for the other stages of the algorithm. In the second stage, the ventricular activity (QT segment) is removed by using an adaptive filter that obtains an averaged pa…

Syncope in pediatric patients: role of arrhythmias

2009

Outpatient management of proctologic disease. Which techniques for local anesthesia? The experience of a single center

2019

Introduction. Since 1899 outpatient management of surgical patients had been increasing, becoming the best option when possible. In 1988 was described the first experience of outpatient management of proctologic disease. Advances in local anesthesia techniques have improved the outpatient approach to surgical disease, particularly in patients with proctological diseases. Methods. From 2010 to 2016, 1160 patients who needed surgery for proctologic disease have been recruited: 239 hemorrhoidectomies using the variant of Milligan Morgan technique described by Phillips, 45 trans-anal hemorrhoidal DE-arterialization (THD), 315 sphincterotomies, 12 anal polypectomies, 230 loop seton positions, 65…

Safety of anti-tumor necrosis factor-alpha therapy in patients with rheumatoid arthritis and chronic hepatitis C virus infection.

2008

The prevalence of concurrent rheumatoid arthritis (RA) and hepatitis C virus (HCV) infection is probably underestimated because of the increasing spread of this virus worldwide, especially in developing countries. In these patients, anti-tumor necrosis factor-alpha (anti-TNF-alpha) therapy may aggravate hepatitis and increase viremia. We evaluated the safety of these treatments, which remain controversial.Thirty-one HCV-positive patients (23 women, 8 men, mean age 59+/-13 yrs, mean disease duration 13+/-11.5 SD yrs) with active RA [Disease Activity Score 28 (DAS28)3.2] unresponsive to conventional therapies were treated with TNF-alpha blockers (infliximab 11, etanercept 17, adalimumab 3) at…

Wall motion characteristic of the right pulmonary artery in the suprasternal echocardiogram

1980

This study describes the motion pattern of the right pulmonary artery (RPA) as it can be assessed from the suprasternal echocardiogram. The motion characteristic of the RPA is dependent on hemodynamic factors within the lumen of the RPA and those within the left atrium and the aortic arch. During atrial contraction the superior wall of the left atrium separates from the inferior wall of the RPA (IWRPA) and produces an "a" dip in the wall motion of the IWRPA. During isovolumic contraction the RPA is shifted upward (IC point). The incisura in the pulmonary artery pressure curve reflecting pulmonic valve closure can be seen by a sudden decrease in the diameter of the RPA (PC point). In conditi…

Influence of digoxin on sinus node function after pharmacologic autonomic blockade.

1983

The effect of iv digoxin on normal sinus node function was studied after pharmacologic autonomic blockade (AB) in ten patients. Sinus cycle length (SCL), sinus node recovery time (SNRT) and sinoatrial conduction time (SACT) were determined before and after AB with propranolol (0.2 mg/kg body weight) and atropine sulfate (0.04 mg/kg body weight) iv, and 15 min, 30 min, and 45 min after 1 mg iv digoxin. AB resulted in a significant decrease (P less than 0.01) in SCL (916 +/- 158 to 716 +/- 120 ms), in SNRT (1,229 +/- 221 to 871 +/- 190 ms), and in SACT (79 +/- 34 to 44 +/- 10 ms). Fifteen minutes after iv digoxin there was no significant change observed in SCL (716 +/- 120 to 708 +/- 92 ms), …

The influence of penbutolol and placebo on blood sugar levels and insulin consumption in the glucose-controlled insulin infusion system ("artificial …

1990

The aim of the study was to investigate the influence of 40 mg of the beta-blocker penbutolol (Betapressin TM; Hoechst Ltd., Frankfurt/Main) in comparison to placebo on the insulin consumption on the blood sugar profile in twelve insulin-dependent diabetes (IDDM) patients. The patients were treated with penbutolol and placebo for a period of three days, and then were examined with the help of the glucose-controlled insulin infusion system. The blood sugar profile and insulin consumption over a 24 hour period was not affected by either penbutolol or placebo, nor could any changes be measured in these parameters when measured after food intake. After a submaximal exercise load on the bicycle …