Effects of aging on the dimensional stability of custom-made mouthguards.

OBJECTIVE: The purpose of this investigation was to assess the effects of aging on the dimensional stability of vacuum-formed, pressure-formed, and pressure-laminated custom-made mouthguards. METHOD AND MATERIALS: A master model representing the dental arch was fabricated in acrylic resin. Two ethylene vinyl acetate thermoplastic materials were tested: Essix (regular) and Proform (prelaminated). The model was benchmarked in five places along the curvature of the arch. The model was used to fabricate 10 specimens for each of the following groups: 1 = vacuum-formed (3-mm) Essix; 2 = vacuum-formed (4-mm) Proform; 3 = pressure-formed (3-mm) Essix; 4 = pressure-formed (4-mm) Proform; 5 = pressure-laminated (3-mm + 2-mm) Essix; 6 = pressure-laminated (3-mm + 3-mm) Essix. Die stone was poured into the newly made specimens and measured. Aging of the specimens was simulated by reproducing cleaning cycles (48 hours' soaking in water at 60 degrees F and brushing 100 times with a soft denture brush in soapy water at 140 degrees F for 20 minutes). Die stone was poured into the aged specimens and measured. Initial and postaging measurements were compared. RESULTS: All specimens showed dimensional changes post-aging, mainly decreases. Pressure-laminated specimens showed the best dimensional stability. CONCLUSION: Aging induced various dimensional changes in mouthguards, depending on the materials and processing techniques used. Most of the dimensional change for all mouthguards occurred at the central incisor region, the most important area for the protection of the anterior teeth and the premaxilla. Pressure-laminated mouthguard specimens showed the smallest range of changes at the central incisor region, suggesting potentially improved fit, comfort, and protection.     

Pneumocystis carinii pneumonia in AIDS patients. Aspects of clinical evolution in 37 cases

This study concerns 37 cases of Pneumocystis carinii pneumonia in AIDS patients. The time elapsed between human immunodeficiency virus (HIV) seropositivity and the onset of pneumocystosis has been established. Three clinical types are individualized. In cases with normal X-ray films of the chest, measurement of carbon dioxide transfer capacity, always reduced, has led to a bronchoalveolar lavage which provided an early diagnosis. In spite of good response to treatment, the prognosis of pneumocystosis is poor owing to the frequency of associated diseases.     

Variability of anti-αGal antibodies in human serum and their relation to serum cytotoxicity against pig cells

Abstract: One of the major obstacles in pig-to-human xenografting is hyperacute rejection (HAR) of pig cells caused by preformed anti-pig antibodies and complement. In 1991 we suggested that anti-αGal antibodies play a major role in the HAR of pig cells. Anti-αGal antibodies recognize terminal α-galactose-containing epitopes on glycoproteins and glycolipids. They are present in humans, apes, and Old World monkeys, but not in lower mammals such as pigs. However, pigs, unlike humans, express terminal α-galactose epitopes on vascular endothelium which represent targets for human anti-αGal antibodies. Despite increasing recognition that anti-αGal antibodies are an important factor, many questions related to their precise role in HAR remain to be answered.
In this study, we analyzed 75 human AB sera in terms of (i) cytotoxic activity against cultured pig (PK-15) cells, (ii) anti-αGal titers, (iii) immunoglobulin-binding to pig cells, and (iv) immunoglobulin concentrations. The results demonstrated considerable variability in cytotoxicity, anti-αGal titers, and immunoglobulin binding to pig cells, whereas the serum immunoglobulin concentrations were less variable. Positive correlations were found between cytotoxicity and binding of IgG and IgM to the surface of pig cells. The surface-bound IgG and IgM also correlated with the serum anti-αGal IgG and IgM titers. Anti-αGal IgA, however, did not show any relation with cytotoxicity or cell binding. Concentrations of serum total immunoglobulins correlated with neither I cytotoxic activity nor cell binding.     

Cataract surgery after injection of silicone]

Thirty eyes were studied retrospectively, after cataract surgery following intraocular silicone oil injection. Cataract surgery took place before silicone oil removal in 9 eyes, at the same time as silicone oil removal in 2 eyes, and after silicone oil removal in 19 eyes. Extracapsular extraction was performed in 27 eyes, and intracapsular extraction was performed in 3 eyes. A posterior chamber intraocular lens was placed in 14 cases, and an anterior chamber intraocular lens in one case. Capsular fibrosis was observed in 19 cases, and it was treated with YAG laser in 10 eyes during follow-up. Twenty five eyes had a postoperative follow up of 3 to 37 months. Total retinal detachment occurred in 2 eyes.