A Comparison of Commercially Available Polymethylmethacrylate-Based Soft Tissue Fillers

BACKGROUND The rapid market expansion of filler treatment options requires physicians and health care providers to fully understand differences among comparable products.
OBJECTIVE The objective was to compare commercially available polymethylmethacrylate (PMMA)-based soft tissue fillers to determine if there are meaningful variations in these products that could result in significantly different therapeutic profiles, especially with respect to safety.
METHODS AND MATERIALS PMMA particles were evaluated for size and morphology using scanning electron microscopy (SEM) techniques. PMMA microsphere soft tissue filler products from the United States, Europe, Brazil, and Canada were compared with respect to size, homogeneity/irregularity, surface smoothness/roughness, and the presence or absence of sediment and particulate debris.
RESULTS Marked differences with respect to PMMA particle morphology and related particle characteristics from a variety of products were found. Of note, some products demonstrated potentially concerning significant variability in particle size and irregular morphology.
CONCLUSION It is anticipated that the variability detected in these products, based on the literature, could result in different therapeutic profiles, especially with respect to safety. Physicians and health care providers should be aware that "comparable" products that at a glance appear similar may not be equal.     

A Proposed Model of Relapse Prevention for Adolescents Who Abuse Alcohol

Adolescents who abuse alcohol are being admitted to treatment centers in increasing numbers. However, relapse prevention, a critical aspect of recovery, rarely is addressed in this high-risk population. This article briefly reviews adolescent development, the current literature on adolescent drinking patterns and relapse, and analyzes current models of relapse prevention in adults. This information is then used to propose a relapse prevention model for adolescents.     

Does Atrial Fibrillation Beget Ventricular Fibrillation in Patients with Acute Myocardial Infarction?

Background: Atrial fibrillation (AF) is associated with increased mortality and a higher complication rate postmyocardial infarction (MI), but the exact mechanisms are unknown. We investigated whether AF predisposes to ventricular arrhythmia in postmyocardial infarct patients, thereby accounting for increased mortality. Methods: Five hundred consecutive patients admitted to our coronary care unit with acute MI were monitored for in‐hospital arrhythmias. Detailed information was also compiled on past history, co‐morbidities, electrolyte disturbances, drug therapies, and ejection fraction. Mortality data were collected for an average of 5.5 years. Results: The results have shown that the incidence of ventricular fibrillation (VF) is much greater in patients presenting with AF (P = 0.03) and multivariate analysis has shown that AF is independently associated with the development of VF. This association occurs principally in patients who are admitted with AF (P = 0.01) rather than those who develop it during their admission, although these patients are also at mildly increased risk. The increased incidence of VF does account for increased mortality in the AF patients but does not explain all of their excess risk. There was no association between AF and ventricular tachycardia (VT); P = 0.50. Conclusions: In conclusion, AF on admission to the hospital with acute MI is associated with an increased risk of VF and subsequent mortality.     

The Effect of Renal Transplantation with a Minimal Steroid Regime on Uraemic Hypertriglyceridaemia

We have studied the lipid and associated biochemical indicesin 18 renal transplant patients maintained on an alternate dayprednisolone regime. At an average 27 months following transplantationserum lipids were not significantly different from normals despitesome renal impairment in the transplant recipients. In additionthe blood sugar and plasma immunoreactive insulin levels wereelevated in transplanted patients. The intravenous fat tolerancetest (IVFTT) was not found to be different from that of normals.In some patients IVFTT was performed before and after transplantationand it was shown that K₂ (fractional removal rate of Intralipid®)improved from abnormal to normal values. Thus, it has been demonstratedthat previously abnormal lipid levels can return to normal aftertransplantation and this may be related to alternate day steroidregimes. Impaired removal of triglyceride seen in chronic renalfailure is improved by transplantation.     

In vivo relevance for platelet glycoprotein Ibα residue Tyr276 in thrombus formation

Summary.  Background:  Platelet glycoprotein (GP) Ib-IX-V supports platelet adhesion on damaged vascular walls by binding to von Willebrand factor (VWF). For several decades it has been recognized that the α-subunit of GP (GPIbα) also binds thrombin but the physiological relevance, if any, of this interaction was unknown. Previous studies have shown that a sulfated tyrosine 276 (Tyr276) is essential for thrombin binding to GPIbα. Objectives:  This study investigated the in vivo relevance of GPIbα residue Tyr276 in hemostasis and thrombosis. Methods:  Transgenic mouse colonies expressing the normal human GPIbα subunit or a mutant human GPIbα containing a Phe substitution for Tyr276 (hTg^Y276F) were generated. Both colonies were bred to mice devoid of murine GPIbα. Results:  Surface-expressed GPIbα levels and platelet counts were similar in both colonies. hTg^Y276F platelets were significantly impaired in binding α-thrombin but displayed normal binding to type I fibrillar collagen and human VWF in the presence of ristocetin. In vivo thrombus formation as a result of chemical damage (FeCl₃) demonstrated that hTg^Y276F mice have a delayed time to occlusion followed by unstable blood flow indicative of embolization. In models of laser-induced injury, thrombi developing in hTg^Y276F animals were also less stable. Conclusions:  The results demonstrate that GPIbα residue Tyr276 is physiologically important, supporting stable thrombus formation in vivo .