ELECTRICAL REMODELLING OF CHRONIC ATRIAL FIBRILLATION

1. It is now recognized that atrial fibrillation (AF) is not a benign condition, as it is associated with a 40% increase in mortality and a doubling of the risk of stroke. 2. The development of AF leads to mechanical, electrophysiological and cellular changes in the atria that tend to sustain AF. This process is known as atrial remodelling. 3. The three electrophysiological elements in the atria that initiate and sustain AF are: (i) shortening of the refractory period and an increase in dispersion; (ii) slowing of conduction velocity; and (iii) the presence of triggerin. foci. 4. As AF is a heterogeneous disorder, therapeutic strategies include the use of devices (pacemakers and atrial defibrillators), radiofrequency ablation (focal ablation or the creation of linear lines) and drug therapy that may reverse a remodelle. atrium.     

Low-density lipoprotein subfraction profiles in dialysis patients

Summary: Uraemic dyslipidaemia is a major risk factor for cardiovascular disease in end-stage renal failure patients. In patients without renal failure, high levels and qualitative abnormalities of low-density lipoprotein (LDL) are known to be atherogenic. Recently, LDL subfraction analysis has associated premature coronary artery disease with a high prevalence of small, dense LDL particles characterizing the LDL subclass phenotype B. We therefore examined the lipid profiles, LDL subfraction distribution and phenotypes in our population of haemodialysis (HD; n = 30) and peritoneal dialysis patients (PD; n = 17), and compared them to 40 asymptomatic, non-uraemic volunteers. Dialysis patients had significantly higher triglyceride and VLDL cholesterol concentrations and lower HDL cholesterol and smaller LDL peak particle diameters. PD patients had significantly higher total cholesterol, glycated haemoglobin and fasting blood glucose levels with smaller LDL peak particle diameters (24.4 [0.1] vs 24.8 [0.1 nm] than HD. Both groups showed significant negative correlations between plasma triglyceride and LDL peak particle diameter, and positive correlations between HDL cholesterol and LDL peak particle diameter. All the PD patients expressed the B phenotype (LDL peak diameter ± 25.5 nm) compared to 73% of HD patients. This study demonstrates that HD and especially PD patients have atherogenic lipid profiles which are associated with a predominance of small dense LDL particles and the highly atherogenic LDL subclass phenotype B.     

An evaluation of numerical integration algorithms for the estimation of the area under the curve (AUC) in pharmacokinetic studies

Six numerical integration algorithms based on linear and log trapezoidal methods as well as four cubic-spline methods were proposed for estimation of area under the curve (AUC). These six different algorithms were implemented using IMSL/IDL^TM command language and evaluated using data simulated under five different dosing conditions and two different sampling conditions. Comparisons between AUC estimations using these six different algorithms and the theoretical results were made in terms of both overall AUC values and the superimposability of the concentration-time profiles. In well designed studies with ample data points, the algorithm based on IMSL/IDL^TM function CSSHAPE with concavity preservation gave the best performance. In contrast, when the frequency of blood collection was limited, the algorithm based on the log trapezoidal rule proved to be stable with reasonable accuracy, and is recommended as the practical method for numerical interpolation and integration in pharmacokinetic studies. Algorithms based on the combination of the log trapezoidal rule and cubic-spline methods using IMSL/IDL^TM function CSSHAPE can be developed to enhance overall performance.     

Appendicitis in the era of ultrasound: Are plain radiographs still useful?

We reviewed plain radiographs of 215 pediatric patients with surgically proven appendicitis to study the value of plain radiography for diagnosis.     

Complications associated with maxillary nerve block anaesthesia via the greater palatine canal

This paper documents the type, frequency and duration of complications associated with regional anaesthesia of the maxillary nerve via the greater palatine canal in a series of 101 patients treated in the Oral Surgery Department, United Dental Hospital of Sydney.     

Horner syndrome

Horner syndrome is an uncommon but important clinical entity, representing interruption of the sympathetic pathway to the eye and face. Horner syndrome is almost always diagnosed clinically, though pharmacological testing can be used to confirm the diagnosis. Imaging modalities such as PET, CT and MRI are important components of work‐up for patients presenting with acquired Horner syndrome. Our patient’s presentation with Horner syndrome unmasked the causative superior sulcus squamous cell carcinoma and a coincidental lower lobe adenocarcinoma. Successful radical treatment of these cancers resulted in complete resolution of the syndrome and disease‐free survival at 18 months. We review the anatomy and pathophysiology underlying this and other causes of Horner syndrome.     

Disposition of a silicon-containing amide, an inhibitor of acyl-CoA: cholesterol acyltransferase, in dog and rat

The pharmacokinetics of 3-(decyldimethylsilyl)-N-[2-(4-methylphenyl)-1-phenylethyl]propanamide (DMPP), an inhibitor of acyl-CoA:cholesterol acyltransferase, have been studied in the dog and the rat using 14C and 3H dual-labelled drug. In both species, gastrointestinal absorption of DMPP was slow and incomplete, amounting to approximately 20 per cent of the oral dose given in corn oil. In the rat, use of PEG-400, Tween 80, ethanol, and aqueous CMC as vehicles resulted in similar or lower absorption than corn oil. Absorbed DMPP was rapidly and extensively distributed to body tissues. Data from the rat showed highest concentrations of radioactivity in the liver and spleen, while concentrations in the adrenals and lung also markedly exceeded circulating radioactivity levels. In both dog and rat. DMPP was completely metabolized prior to excretion. The routes of biotransformation involved hydrolysis of the amide bond, oxidation of the phenyl ring, and degradation of the decyldimethylsilyl propanoyl moiety. The metabolites of DMPP were excreted slowly, predominantly in the faeces. The elimination half-life of 14C was 105 h in the dog and 83 h in the rat, while that of 3H was approximately 32 h in both species.