Heparan sulfate and fibronectin improve the capacity of collagen barriers to prevent apical migration of the junctional epithelium.

The objective of the present study was to assess the effect of bilayered/collagen barriers enriched with fibronectin and heparan sulfate on the prevention of apical migration of the epithelium during the initial stage of periodontal wound healing. Experimental osseous defects were produced on the labial aspect of maxillary canines in dogs. Experimental sites were treated with either bilayered enriched collagen barriers or with non-enriched bilayered collagen barriers, using the guided tissue regeneration technique. Control sites were treated with monolayered collagen barriers that were not enriched with fibronectin and heparan sulfate. Histologic and histomorphometric examinations performed on specimens obtained 20 days post-operative indicate the formation of a short junctional epithelium in the experimental sites treated with enriched collagen barriers. In this group, 95% of the occlusal-apical length of the defects was repopulated by connective tissue cells. In the other 2 groups, a long junctional epithelium developed with only 65% of the occlusal-apical length of the defects being repopulated by connective tissue cells. These findings suggest that the enrichment of collagen barriers with fibronectin and heparan sulfate may be important to enhance the repopulation of exposed root surfaces by connective tissue cells and prevent the apical migration of the epithelium during the initial stages of periodontal wound healing.     

Comparative analysis of various platelet glycoprotein IIb/IIIa antagonists on shear-induced platelet activation and adhesion

Platelet accretion into arterial thrombus in stenotic arterial vessels involves shear-induced platelet activation and adhesion. The Cone and Plate(let) Analyzer (CPA) is designed to simulate such conditions in vitro under a rotating high shear rate in whole blood. In the present study, we evaluated various experimental conditions (including aspirin, temperature, and calcium concentration) and investigated the effects of small molecules along with peptide glycoprotein IIb/IIIa antagonists on platelet adhesion using the CPA system. Concentration-dependent effect of glycoprotein IIb/IIIa antagonists on shear-induced platelet adhesion showed marked differences in potencies: IC50 = 34, 35, 91, 438, and 606 nM for DPC802 (a specific glycoprotein IIb/IIIa antagonist), roxifiban, sibrafiban, lotrafiban, and orbofiban (free acid forms), respectively, and IC50 values of 43, 430, and 5781 nM for abciximab, tirofiban, and eptifibatide, respectively. Parallel study was also conducted to evaluate the effect of glycoprotein IIb/IIIa inhibitors using optical aggregometry. The potency of fibans in blocking shear-induced platelet adhesion correlated well with their binding affinity to the resting and activated glycoprotein IIb/IIIa receptors, as well as their "off-rates". Nevertheless, none of these fibans was able to effectively block shear-induced platelet adhesion at targeted clinical dosing regimens except for abciximab. These data suggest that glycoprotein IIb/IIIa antagonists that show similar efficacy in the inhibition of platelet aggregation in a static in vitro assay may differ substantially in a shear-based system of platelet adhesion. The clinical significance of this phenomenon awaits further investigation.     

Relationship of pleural effusions to increased permeability pulmonary edema in anesthetized sheep.

We studied anesthetized sheep to determine the relationship between increased permeability pulmonary edema and the development and mechanism of pleural effusion formation. In 12 sheep with intact, closed thoraces, we studied the time course of pleural liquid formation after 0.12 ml/kg i.v. oleic acid. After 1 h, there were no pleural effusions, even though extravascular lung water increased 50% to 6.0 +/- 0.7 g/g dry lung. By 3 h pleural effusions had formed, they reached a maximum at 5 h (48.5 +/- 16.9 ml/thorax), and at 8 h there was no additional accumulation of pleural liquid (45.5 +/- 16.9 ml). Morphologic studies by light and electron microscopy demonstrated subpleural edema but no detectable injury to the visceral pleura, suggesting that the pleural liquid originated from the lung and not the pleura. In nine sheep, we quantified the rate of formation of pleural liquid by enclosing one lung in a plastic bag. By comparing in the same sheep the volume of pleural liquid collected from the enclosed lung to the volume found in the opposite intact chest, we estimated the rate of liquid absorption from the intact chest to be 0.32 ml/(kg.h); we had previously reported a liquid absorption rate of 0.28 ml/(kg.h) in normal sheep. These studies also supported the conclusion that the majority of the pleural liquid originated from the lung because we could account for all of the pleural liquid that was formed and cleared. The volume of pleural liquid collected from the enclosed lungs was equal to 21% of the excess lung liquid that formed after oleic acid-induced lung injury. Thus, the pleural space and parietal pleural lymphatic pathways are important pathways for the clearance of pulmonary edema liquid after experimentally induced increased permeability pulmonary edema.     

Metastatic basal cell carcinoma of the posterior neck: case report and review of the literature

Although primary basal cell carcinoma (BCC) represents an extremely common malignancy, metastases derived from BCC are exceedingly rare. The prognosis for metastatic BCC is poor, and little consensus exists regarding predictive factors or optimal treatment strategies. Here, we present the case of a 63-year-old man with BCC of the neck who subsequently developed multiple metastases to subcutaneous tissue, lymph nodes, and the parotid gland. Risk factors and clinical features of metastatic BCC are reviewed, as is the relationship of histopathologic subtype to metastatic behavior. Current chemotherapeutic and targeted therapies also are discussed in the context of recent advances in molecular biology.     

Coating conditions matter to collagen matrix formation regarding von Willebrand factor and platelet binding

Introduction

Von Willebrand factor (VWF) and platelet binding needs a uniform collagen matrix therefore we aimed to find an optimal condition for the preparation of human type-I and type-III collagen matrices.

Method

The effects of pH, salt and ligand concentration and binding time were tested when collagen matrices were prepared by adsorption. Surface-bound collagen and collagen-bound VWF measured by specific antibodies. Platelet adhesion was tested under flow conditions at a shear rate of 1800 s^− 1 for 2 min. Matrices and platelets were visualized by atomic force and scanning electron microscope.

Results

The extent of human collagens type-I and III binding to the surface was 10 and 4 times greater and binding was maximal under 8-16 hours, when coated from physiological buffer solution versus acid solution. Collagen fibrils were more developed and platelet adhesion was higher, with more organized and denser aggregates. VWF binding was parallel to the surface bound collagen in both collagen types.

Conclusion

Collagen coating of surfaces for VWF binding and platelet adhesion studies is very variable from acid solution. Our experiments provide evidences that neutralizing the acid and adding NaCl in physiological concentration, thereby facilitating formation of collagen fibril molecules in solution, results in efficient coating of human type-I and type III collagens, which then bind normal VWF equally well.     

Body composition changes during the first two years of university

Objective

Changes in body weight, composition, and shape were investigated in male and female college students between the freshman and sophomore years.

Methods

Changes in weight, body mass index (BMI), percent and absolute body fat and fat-free mass (via bioelectrical impedance), and waist circumference (via body scans) were assessed over the freshman and sophomore years (2007-2009) among 120 students attending a Southern public university.

Results

Weight (2.5 and 1.7 lbs) and BMI gains (0.3 and 0.3 kg/m²) did not significantly differ between the freshman and sophomore years, respectively. Significantly more percent body fat and fat mass were gained during the freshman (1.9% and 3.3 lbs, respectively) than the sophomore year (0.0% and 0.6 lbs, respectively). Females lost significantly more fat-free mass during the freshman (−0.8 lb) than during the sophomore year (1.0 lb). Changes in waist circumference and weight were significantly correlated. Increases in the percentages of females classified as overweight and with unhealthy body fat amounts and waist circumferences were observed.

Conclusion

While the sophomore year was characterized by slightly healthier body composition changes than the freshman year, the gains in weight, fat mass, and waist circumference measurements suggest increased health risks for many college females.     

Effect of Maternal Immunopotentiation on Apoptosis-Associated Molecules Expression in Teratogen-Treated Embryos

Problem  Potentiation of the maternal immune system was shown by us to affect the embryonic response to teratogenic insults. In order to understand better the mechanisms underlying that phenomenon, we explored the effect of maternal immunopotentiation by rat splenocytes on the early stages of the embryonic response to cyclophosphamide (CP).
Method of study  Immunopotentiated CP-treated embryos were analysed for cell cycle changes by flow cytometry, while cell proliferation and apoptosis were assessed by 5'-bromo-2'-deoxyuridine (BrdU) incorporation and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick-end labeling (TUNEL) respectively. The expression of the p65 subunit of NF-κB, IκBα, Bax, bcl-2 and p53 was assessed by flow cytometry.
Results  Exposure to CP resulted in significant growth retardation and in the appearance of cellular damage, a reduction in cell proliferation and the appearance of apoptotic cells, which were all found to be delayed in immunopotentiated embryos. In parallel, CP-treated embryos demonstrated a reduction in the percentage of p65- or IκBα-positive cells, while the percentage of bcl-2- or p53-positive cells increased initially and decreased later. Those changes were normalized by maternal immunopotentiation when tested at 24 hrs after exposure to the teratogen.
Conclusion  Our data implicate maternal immunopotentiation to protect the embryo against teratogenic insults, possibly through its effect on the expression of p65, bcl-2 or p53.