Barrier Gel Research Articles

Stability of NT-proBNP in serum specimens collected in Becton Dickinson Vacutainer (SST) tubes.

Atrial natriuretic peptides, B-type natriuretic peptide (BNP), and C-type peptides play important roles in the cardiovascular system (1)(2)(3). ProBNP is a 108-amino acid peptide that is secreted by the ventricle and is cleaved to physiologically active BNP (amino acids 77–108) and N-terminal fragment NT-proBNP (amino acids 1–76) (3). NT-proBNP is a useful marker for heart failure, including congestive heart failure (4)(5)(6). Recently, Roche Diagnostics marketed an automated NT-proBNP assay on the Elecsys analyzer. The assay uses polyclonal antibodies against NT-proBNP. The concentration of NT-proBNP in healthy individuals depends on both age and gender, with females and elderly patients having higher concentrations. The clinical sensitivity and specificity of NT-proBNP at a cutoff of 125 ng/L for male patients younger than 75 years are 81.6–91.7% (sensitivity) and 86.7–95.7% (specificity), depending on age. The corresponding sensitivity and specificity for female patients are 86.7–94.3% (sensitivity) and 57.8–84.9% (specificity), respectively. The negative predictive value of this test is almost 100% at a clinical threshold of 125 ng/L, according to the package insert (NT-proBNP; Roche Diagnostics). A common practice in clinical laboratories is to draw blood in serum-separator tubes because of the advantage of the barrier gel, which facilitates rapid separation of serum from cellular constituents of blood and prevents hemolysis during prolonged storage. However, measured concentrations of certain drugs, such as phenytoin, phenobarbital, carbamazepine, quinidine, and lidocaine, can be reduced if specimens are stored in Becton Dickinson SSTTM tubes (7). Bush et al.(8) reported reductions in estradiol concentrations when specimens were stored in SST tubes. The purpose of the current study was to determine the stability of NT-proBNP in specimens stored in …

Lumbar microdiscectomy with and without prophylaxis of perineural scar formation using ADCON-L barrier gel – 2-year results

A retrospective study investigated the advantages of the intraoperative application of the anti-adhesion barrier gel ADCON-L after lumbar microdiscectomy. For the study 92 patients were recruited. Following the operation 46 patients (study group) received ADCON-L application. In another 46 patients (control group), wounds were closed without ADCON-L application. Median follow-up was 32 (26–33) months in the study group and 37 (32–41) months in the control group postoperation. All patients were examined clinically and spinal MRIs carried out on 12 randomly selected patients in each group. According to the score of the Low Back Pain Committee of the Japanese Orthopedic Association, no significant clinical difference could be established between the two groups. Subjective evaluation of operation results (score according to Weber) was not significant. Peridural scarring in the postoperative MRI of 24 patients did not differ significantly. A significant effect on clinical results after ADCON-L application could not be found.

Antifibrotic gels versus a barrier sheet in the prevention of epidural fibrosis postlaminectomy

Antifibrotic gels versus a barrier sheet in the prevention of epidural fibrosis postlaminectomy

Comparison of BD Vacutainer SST™ Plus Tubes with BD SST™ II Plus Tubes for common analytes

Serum separator tubes were introduced 25 years ago and are widely used in the clinical laboratory today for routine collection of blood. These tubes have gained widespread acceptance due to the advantage of the barrier gel that facilitates rapid separation of serum from cellular constituents of blood and thus reduces hemolysis. However, there are some limitations associated with gel tubes (i.e., gel stability and analyte incompatibilities). The serum separator BD SST tubes manufactured by BD are widely used in clinical laboratories. Recently, BD has developed a new barrier gel, which is superior to the existing gel. We studied the stability of common analytes when serum specimens were stored in the new BD SST II tubes by comparing the performance with the existing BD SST tubes. We did not observe any significant reduction in concentrations of 42 commonly ordered analytes using the new BD SST II tubes. Significant differences were noted at low serum volumes for estradiol in both tube types over time. We conclude that the new BD SST II tubes are suitable for collection of blood and storage of serum for commonly ordered laboratory tests.

Suitability of collection tubes with separator gels for collecting and storing blood samples for therapeutic drug monitoring (TDM).

In this study, we present significant changes occurring in serum drug concentrations while using blood collection tubes that contain a barrier gel. This report also contains results with antidepressant drugs, which have not been studied before with human samples. The drug concentrations were measured either with high performance liquid chromatography (HPLC) or fluorescence polarization immunoassay (FPIA). The results show that gel tubes are suitable for blood collection for antiepileptic, antibiotic, asthma and cardioactive drug measurements, since only slight adsorption was seen (0-5%). However, the studied tubes are not suitable for blood collection of antidepressants nor benzodiazepines, because the adsorption can be 5-30%. The adsorption was even higher (up to 40%) when samples were stored for 24 h after centrifugation in gel tubes. When the centrifugation step was performed after storage the effect of the barrier gel was lower (only 0-13%). Antidepressant drug measurements performed from patient specimens collected in the studied gel tubes and stored for 3 h showed <10% adsorption of the studied drugs. After 24 h storage time, concentrations of all analysed drugs decreased even more: adsorbed amount of drugs were about 5-20%. The studied gel tubes are proposed to be satisfactory for blood collection for antidepressant drug measurements if separation step is performed within 3 h after blood clotting. With the spiked samples the adsorption to barrier gel was higher, so it seems that adsorption is faster when drugs are not highly bound to serum proteins.

Inhibition of epidural fibrosis with ADCONê-L: Effect on clinical outcome one year following re-operation for recurrent lumbar radiculopathy

In a prospective multicenter studYI 20 patients underwent re-operation for recurrent radiculopathy after lumbo-sacral discectomYI and were treated with AOCONê-L (Adhesion Control in a Barrier Gel) to inhibit epidural fibrosis following secondary surgery. Outcomes after re-operation were assessed at six and 12 months using: Visual Analog Scales to measure radicular and back painl straight leg raising examsl and selfassessment of activity-related radicular pain. Each parameter was compared to baseline valuesl obtained immediately prior to the re-operation. The long term clinical results at 12 months after re-operation (summarized below) demonstrate a significant improvement of all clinical parametersl and correlated with the results seen at six months. Radicular painl measured when most severel was reduced from an average pre-operative score of 8.1-3.7 (p < 0.005). The straight leg raising angle increased from an average preoperative value of 41°-67° (p < 0.005). Activity-related pain mean score was 4.61 VS. 17.0 pre-operatively (p < 0.005). Low back painl measured when most severel was reduced from an average pre-operative score of 6.1 to 3.1 (p < 0.012). These clinical findings compare very favorably with data reported in the literature. There were no adverse events or complications related to the use of AOCONê-L. [Neural Res 1999; 21 Suppl 1: S51-S60]

MR evaluation of epidural fibrosis: Proposed grading system with intra- and inter-observer variability

The purpose of this study is to present a grading system for the Magnetic Resonance (MR) appearance of epidural fibrosis, and to present the inter- and intra-observer variability of the system. The study population was from a randomized, double blind, controlled multicenter clinical trial evaluating the safety and effectiveness of AOCOê-L anti-adhesion barrier gel, in preventing epidural fibrosis and dural adhesions following single-level unilateral laminectomy/discectomy for lumbar disc herniations. MRI of the lumbar spine was obtained, without and with gadolinium enhancement, pre-operatively and at six months postoperatively. Patients having extensive epidural scar have been shown to be 3.2 times more likely to experience recurrent radicular pain than those patients with less extensive epidural scarring. New agents have appeared in the marketplace and in clinical trials that may be used intra-operatively to modulate the presence or absence of epidural scar tissue. Given these factors, the need to accurately describe the location and amount of epidural scar tissue has assumed more pressing importance. Two readers, blinded to clinical findings and to the other reader, independently evaluated the MR examinations in 50 postoperative lumbar spine surgery patients using the previously defined categorization of epidural scar for five levels in each patient, four quadrants per level. In addition, 114 examinations were separately evaluated by the same reader for evaluation of intra-observer variability. For the purposes of epidural fibrosis identification, only the axial T1-weighted images with and without contrast were utilized. The amount of epidural fibrosis was graded on a scale of 0-4 for each quadrant at each imaging slice encompassing the operative level: 0= no/trace scar; 1= > 0% and ≤ 25% of quadrant filled with scar; 2= > 25% and ≤ 50% of quadrant filled with scar; 3 = > 50% and ≤ 75% of quadrant filled with scar; 4 = > 75% and ≤ 100% of quadrant filled with scar. Each reader evaluated a total of 1000 epidural quadrants for the interobserver assessment. The estimated Kw index is 0.68 with 95% confidence interval (CI) of [0.64, 0.71]; this is substantial agreement. There were a total of 2,280 quadrants evaluated overall for the intra-observer assessment. The estimated Kw index is 0.94 with 95% CI of [0.93, 0.95]; this is almost perfect agreement. Substantial intra-observer and near perfect ,inter-observer agreement was achieved for evaluation of epidural scar using a relatively simple, semi-quantitative approach to the T1-weighted axial MR images. A standard grading system for epidural scar is proposed. [Neural Res 1999; 21 Suppl 1: 523-526]

Disruption of Barrier Function in Neonatal Skin Associated With Adhesive Removal

Objective Patients in the neonatal intensive care unit require life support and monitoringequipment that must be securely attached to the skin; removal or replacement often causes skin trauma. In this study, we compared the effects of application and removal of three different adhesives on the skin barrier function of premature neonates. The effects were measured by transepidermal water loss (TEWL), colorimetric measurements, and visual inspection. Design Thirty neonates, between 26 and 40 weeks of gestational age and with birth weights ranging from 690 to 3000 gm, were enrolled in the study during the first week of life. Pieces of plastic tape (1 cm 2 ), pectin barrier, and hydrophilic gel were applied to previously undisturbed sites on the back. A fourth site was used as a control. We measured TEWL, colorimetric readings, and visual inspection scores of skin irritation and stripping at each of the four sites serially: before adhesive application, 30 minutes after adhesive removal, and 24 hours later. Results Thirty minutes after adhesive removal, TEWL, colorimetric measurements, and visual inspection scores were all significantly higher at the sites of plastic tape and pectin barrier removal than at the control and gel adhesive sites (p

Cost effectiveness of lumbar disc surgery and of a preventive treatment for peridural fibrosis.

This study used a retrospective modeling approach to predict the sequelae, treatment patterns, and economic outcomes that patients treated or not treated with ADCON-L Anti-Adhesion Barrier Gel can experience over a 1-year period following first-time surgery for herniated lumbar disc. The study was designed for and carried out in the Netherlands. The study was carried out to investigate the economic impact of ADCON-L application in lumbar disc surgery. Patients with a poor outcome following primary lumbar disc surgery represent a medical challenge to physicians and an economic concern, as they often experience long-term sequelae. Patients who have failed to benefit adequately from primary surgery tend to be very expensive patients, receiving a costly array of conservative therapies, diagnostic measures and, sometimes, repeat surgery. A Markov model was constructed to integrate the retrospectively assessed treatment patterns, economic outcomes, and costs of Dutch lumbar disc patients with the analysis of the benefits of ADCON-L as shown in a clinical study population derived from the preliminary results of a multicenter, randomized clinical trial of ADCON-L in Europe. Use of ADCON-L can recoup 20% of its proposed initial cost of NLG 1000 in direct health care savings during the first year after primary surgery. When indirect/societal as well as direct costs are considered, for every Dutch guilder invested in ADCON-L treatment, savings of NLG 1.8 are achieved. In patients treated with ADCON-L during lumbar discectomy, the quality of surgical outcome improves while cost per successful outcome is reduced.

ADCON�-L: a review of its development, mechanism of action, and preclinical data

ADCON-L Anti-Adhesion Barrier Gel is a resorbable gel that is placed into the site of a laminectomy before surgical closure and acts as a barrier to scar and surgical adhesions. The scientific rationale for ADCON products is based on certain properties of glial cells and the nature and role of the basal lamina. ADCON-L was evaluated in laminectomy models using rats and rabbits and a discectomy model in dogs. In all studies, ADCON-L was an effective barrier to peridural scar and surgical adhesions.

Comparison of Plastic vs. Glass Evacuated Serum-Separator (SSTTM) Blood-Drawing Tubes for Common Clinical Chemistry Determinations

We evaluated a plastic evacuated blood-drawing tube containing an integral serum-separating barrier gel, by direct comparison with a glass counterpart. The plastic tube demonstrated no differences when compared for common clinical chemistry analytes with multiple types of instruments and systems. A total of 260 such different combinations were studied with emphasis on tests sensitive to drawing and handling indexes such as lactate dehydrogenase and potassium. A total of six separate blood drawings were tested with no significant differences noted in these tests. The total study included subjective evaluations of the plastic tube's use as a blood-drawing device and objective studies based on quantitative test results from normal and hospitalized patients and use of the primary sampling tubes (both plastic and glass) for 48-h storage.