Influence of bismuth oxide concentration on the pH level and biocompatibility of white Portland cement

Objectives

To investigate if there is a relation between the increase of bismuth oxide and the decrease of pH levels and an intensification of toxicity in the Portland cement.

Material and Methods

White Portland cement (WPC) was mixed with 0, 15, 20, 30 and 50% bismuth oxide, in weight. For the pH level test, polyethylene tubes were filled with the cements and immersed in Milli-Q water for 15, 30 and 60 days. After each period, the increase of the pH level was assessed. For the biocompatibility, two polyethylene tubes filled with the cements were implanted in ninety albino rats (n=6). The analysis of the intensity of the inflammatory infiltrate was performed after 15, 30 and 60 days. The statistical analysis was performed using the Kruskal-Wallis, Dunn and Friedman tests for the pH level and the Kruskal-Wallis and Dunn tests for the biological analysis (p<0.05).

Results

The results showed an increase of the pH level after 15 days, followed by a slight increase after 30 days and a decrease after 60 days. There were no significant statistical differences among the groups (p>0.05). For the inflammatory infiltrates, no significant statistical differences were found among the groups in each period (p>0.05). The 15% WPC showed a significant decrease of the inflammatory infiltrate from 15 to 30 and 60 days (p<0.05).

Conclusions

The addition of bismuth oxide into Portland cement did not affect the pH level and the biological response. The concentration of 15% of bismuth oxide resulted in significant reduction in inflammatory response in comparison with the other concentrations evaluated.     

Thrombocytopenia following acute acetaminophen

An unusual case of severe thrombocytopenia following acetaminophen overdose is pre sented along with a retrospective review of 174 patients with hospital admissions for acute acetaminophen toxicity. Thrombocytopenla occurred in 3.4% of these patients and strongly correlated with the degree of hepatotoxicity (as measured by peak AST values) but did not correlate with serum acetaminophen levels. The mechanism appears to be a transient direct toxic effect on platelets or megakaryocytes, and the finding of thrombocytopenia early in the course of acetaminophen overdose may identify a subset of patients at risk for significant hepatotoxicity. © 1994 Wiley-Liss, Inc.     

Diagnostic and Therapeutic Implications of Type 2 Myocardial Infarction: Review and Commentary

The Task Force for the Universal Definition of Myocardial Infarction recently published updated guidelines for the clinical and research diagnosis of myocardial infarction under a variety of circumstances and in a variety of categories. A type 1 myocardial infarction (MI) is usually the result of atherosclerotic coronary artery disease with thrombotic coronary arterial obstruction secondary to atherosclerotic plaque rupture, ulceration, fissuring, or dissection, causing coronary arterial obstruction with resultant myocardial ischemia and necrosis. Patients with a type 2 MI do not have atherosclerotic plaque rupture. In this latter group of patients, myocardial necrosis occurs because of an increase in myocardial oxygen demand or a decrease in myocardial blood flow. Type 2 MI has been the subject of considerable clinical discussion and confusion. This review by knowledgeable members of the Task Force seeks to help clinicians resolve the confusion surrounding type 2 MI.     

The pathology of posttransplant lymphoproliferative disorders occurring in the setting of cyclosporine A-prednisone immunosuppression.

Posttransplant lymphoproliferative disorders (PTLDs) were diagnosed in 43 patients from the Pittsburgh-Denver series between June 1980 and March 1987. This constitutes a detection rate of 1.7%. Major categories of clinical presentation included a mononucleosislike syndrome, gastrointestinal/abdominal disease, and solid organ disease. The median time of onset in patients initially immunosuppressed with cyclosporine-A (CsA)-containing regimens was 4.4 months after transplant, regardless of tumor clonality. A strong association of PTLD with Epstein-Barr virus (EBV) was observed. A histologic spectrum of lesions from polymorphic to monomorphic was observed. Whereas polymorphic lesions could be either clonal or nonclonal, monomorphic lesions appeared to be clonal in composition. The presence of large atypical cells (atypical immunoblasts) or necrosis did not appreciably worsen the prognosis. Twelve patients had clonal, 13 had nonclonal, and five had both clonal and nonclonal tumors. Clonality was indeterminate in 13 cases. Most patients were treated with a regimen based on reduced immunosuppression and supportive surgery. Almost all nonclonal and about half of the clonal lesions respond to this conservative therapy, indicating that it is an appropriate first line of treatment. This behavior suggests that a spectrum of lesions ranging from infectious mononucleosis to malignant lymphoma constitutes the entity known as PTLD. Some monoclonal tumors can undergo regression, however, apparently in response to host immune control mechanisms. Because of its short latency and strong association with EBV, PTLD is an important model for the study of virus-associated tumor progression in humans.     

Degradation of Soluble Immunoglobulin Aggregates in Vitro by Monocytes from Normal Subjects and from Patients with Systemic Lupus Erythematosus

The capacity of human peripheral monocytes to degrade soluble immunoglobulin (IgG) aggregates (AIgG) was studied in vitro. Under serum-free conditions peripheral monocytes from normal donors were able to degrade soluble AIgG in a linear and time-dependent fashion. Addition of fresh human or fresh guinea-pig serum to the incubation mixtures caused a marked increase in degradation of the amount of soluble AIgG available. The stimulatory effect of fresh serum was complement-mediated, because it was abolished by heat treatment of the serum and was not seen when C4- or C3-deficient sera were tested. Functional inactivation of C3 receptors on the phagocytes by trypsin also abolished the complement-mediated stimulation, suggesting cooperation between Fc and C3 receptor in degradation of soluble AIgG. No significant differences were found between monocytes from normal donors and those from patients with systemic lupus erythematosus, as far as degradation is concerned in the presence of complement.     

Changes in fetal rhesus monkey plasma dehydroepiandrosterone sulfate: relationship to gestational age, adrenal weight and preterm delivery

These studies were performed to assess the concentrations of dehydroepiandrosterone sulfate (DHAS) in the rhesus monkey fetal circulation from midgestation through the neonatal period, to determine the relation between changes in fetal adrenal size and DHAS levels both during gestation and after surgical stress, and to explore possible relations between changes in the concentration of DHAS in the fetal circulation and the initiation of labor. When plasma DHAS was quantified in cord blood and in serial samples from chronically catheterized rhesus monkey fetuses, a significant increase in plasma DHAS concentration occurred after 150 days gestational age (404 +/- 37 vs. 1093 +/- 159 ng/ml), and an additional increase was found after 159 days (2246 +/- 712 ng/ml). A diurnal change in fetal plasma DHAS occurred in chronically catheterized fetuses, with evening samples having higher values than morning samples. Further, there was an increase in plasma DHAS concentrations in the 4-5 days after fetal surgery. A significant increase in fetal plasma DHAS concentration occurred in the newborn rhesus monkey. Although plasma DHAS concentrations remained significantly higher than in the late gestation fetus, they decreased by approximately half within the first 2 weeks of life. A close correlation existed between fetal plasma DHAS and fetal adrenal weight in control fetuses delivered by hysterotomy and fetuses that were delivered 5 days after fetal surgery. Adrenal weights in the latter were significantly higher than those in comparably aged fetuses delivered by hysterotomy that had not undergone the stress of fetal surgery. The possible relationship between the increase in plasma DHAS and the initiation of labor was studied by monitoring the changes in daily morning DHAS concentrations in long term catheterized fetuses and comparing these values to the mean cross-sectional DHAS values corresponding to that gestational age. In all but one case, the values of DHAS, although they increased preceding delivery, were still within the range found in fetuses of the same gestational age that were not in labor. These data indicate that increases in DHAS are intimately related to parallel increases in fetal adrenal weight, that there are striking increases in DHAS levels near the end of gestation, that an increase in DHAS is a component of the fetal response to surgical stress, and that there is no immediately apparent, direct relationship between fetal DHAS and preterm delivery.     

Concordance of creatine kinase-MB activity and mass

The recent availability of monoclonal antibodies that are highly specific for creatine kinase (CK; EC 2.7.3.2) MB isoenzyme should allow for the development of rapid, sensitive, and specific assays of CK-MB mass and activity. However, the relationship between the mass concentration of CK-MB and its activity in plasma has previously been thought by some to be variable. To determine the extent to which discrepancies of potential clinical significance might arise between measurements of activity and mass in plasma, we compared CK-MB activity and concentration in 1298 samples obtained from 226 patients admitted to the cardiac-care unit. CK-MB activity concentration was determined with an immunoadsorption assay, and mass concentration was measured by an automated "sandwich" assay (Magic Lite; Ciba Corning Diagnostics). Both of these assays are based on specific monoclonal antibodies for CK-MB. Values obtained with these assays correlated well (r = 0.94). Normal and abnormal values with the two assays were concordant in 96% of the samples. In all but three instances, differences occurred late after myocardial infarction and were characterized by minimal increases as determined by one method vs values at the upper limit of normal as determined with the other. Thus, measurements of CK-MB mass and activity concentrations in plasma with assays based on these specific monoclonal antibodies are comparable for the detection or exclusion of acute myocardial infarction.