Tissue characterization and calcification potential of commercial bioprosthetic heart valves.

BACKGROUND: Tissue properties may contribute to intrinsic calcification of bioprosthetic heart valves. Phospholipids have been proposed as potential nucleation sites for calcification. Other tissue properties might also be important in calcification. METHODS: Commercial and control bioprosthetic valve tissues were characterized by shrinkage temperature, moisture content, free amine content, phospholipid content, and calcification level after 90-day rat subcutaneous implantation as described. RESULTS: Shrinkage temperature, moisture content, and free amine content were typical for glutaraldehyde-cross-linked tissues. Phospholipid and calcium levels varied considerably among valve types. There was a significant correlation between phospholipid levels and calcification (r = 0.63, p = 0.04). Sulzer Carbomedics Mitroflow and Toronto SPV valve tissues had significantly more calcification than other commercial bioprostheses in this study (p < 0.01). Carpentier-Edwards Duraflex, CE SAV, and CE PERIMOUNT valve tissues had significantly less calcification than Medtronic Mosaic in this animal model (p < 0.02). CONCLUSIONS: Processes that reduce phospholipid levels are associated with reduced calcification in the rat subcutaneous model. Significant differences in calcification level were found among commercially available valves. The clinical significance of these results is unknown.

Benefit of screening mammography in women aged 40-49: a new meta-analysis of randomized controlled trials.

Eight randomized controlled trials (RCTs) of screening mammography have been conducted involving women aged 40-49 at entry. Current data are now available from these trials at 10.5 to 18 years of follow-up (average follow-up time: 12.7 years). Meta-analysis has been performed using a Mantel-Haenszel estimator method to combine current follow-up data from the eight RCTs of mammography that included women aged 40-49 at entry, including new follow-up data presented at the NIH Consensus Development Conference held January 21-23, 1997. Combining the most recent follow-up data on women aged 40-49 at entry into all eight RCTs yields a statistically significant 18% mortality reduction among women invited to screening mammography (relative risk: 0.82; 95% confidence interval: 0.71-0.95). Combining all current follow-up data on women aged 40-49 at entry into the five Swedish RCTs yields a statistically significantly 29% mortality reduction among women invited to screening (relative risk: 0.71; 95% confidence interval: 0.57-0.89). Meta-analysis including the most recent follow-up data from all eight RCTs involving women aged 40-49 at entry demonstrates for the first time a statistically significant mortality reduction due to regular screening mammography in women of this age group.

Predictors of thought rebound.

Individual differences in the paradoxical thought rebound effect (increased thought expression following attempted thought suppression) were examined in two studies. In these two studies, the majority of Ss did not evidence thought rebound and, in both studies, it was found that a measure of thought rebound was correlated with other variables. In Study 1, a four-factor regression model predicted thought rebound (R2 = 0.1477). The significant predictors were: (1) ACT Composite (higher ACT predicted more rebound); (2) gender, (3) thought intrusion frequency during suppression; and (4) the interaction of gender and thought intrusion frequency (for male Ss only, more thought intrusions during suppression predicted more rebound). In Study 2, a replication regression model (R2 = 0.1408) cross-validated the ACT effect observed in Study 1. A Study 2 extension model (R2 = 0.2154) found the following significant predictors of thought rebound: (1) obsessionality (less obsessionality predicted more rebound); (2) trait anxiety (less anxiety predicted more rebound); (3) race (whites rebounded more than blacks); (4) gender; (5) 16 PF independence; and (6) the interaction of gender and 16 PF independence (for male Ss only, more independence predicted more rebound). The implications of these results for thought rebound theory are discussed.

Heritability of inhibitory gating of the P50 auditory-evoked potential in monozygotic and dizygotic twins.

Most normal subjects suppress the P50 evoked response to repeated auditory stimulus when paired stimuli are presented, 500 ms apart. The ratio of the amplitude of the response to the second stimulus to that of the first forms a quantitative measure of the activity of a central inhibitory sensory gating mechanism. The variance of this measure in a group of monozygotic and dizygotic twin pairs was determined. The calculation of heritability (h2) indicates that a significant portion of the variance (0.44 or greater) is due to heritable factors. This study supports the use of the inhibitory gating of the P50 response as a phenotype for genetic studies of schizophrenia in which a P50 gating abnormality has been identified.

Longitudinal measurement of anticardiolipin antibodies during normal pregnancy: a prospective study.

We have previously shown that elevation of anticardiolipin antibodies (aCL) at the first prenatal visit is associated with increased fetal loss in normal pregnancy. The variation in aCL levels during normal pregnancy has not been established. To examine this question we measured IgG, IgM and IgA aCL levels five times during pregnancy at weeks 5-15, 16-25, 26-35, 36-37 and at delivery. Data were analyzed to determine: (a) the within and between subject variability of aCL during pregnancy; (2) the temporal trend of aCL; and (3) the relation of serial measures of aCL with maternal complications of pregnancy. We divided our cohort of 354 subjects into two groups. Group A included those subjects with consistently normal levels of aCL and group B those subjects with at least one elevated level of aCL. In group A the within subject variability was relatively low (28-34%). In group B we found wide fluctuations in aCL levels and a within subject variability of 88-91%. Subjects in group B had no increase in maternal complications of pregnancy. The present data suggest that aCL may fluctuate significantly during normal pregnancy and there is little clinical value in measuring aCL on a serial basis during pregnancy.

Benefit of mammography screening in women ages 40 to 49 years. Current evidence from randomized controlled trials.

BACKGROUND: Eight randomized controlled trials (RCTs) of screening mammography were conducted involving women ages 40 to 49 years at entry. Current data gathered for periods ranging from 7 to 18 years of follow-up are available from these trials. METHODS: Meta-analyses were performed using a Mantel-Haenszel estimator method to combine current follow-up data from the eight RCTs of mammography that included women ages 40 to 49 years. RESULTS: Combining all current data on women ages 40 to 49 years at entry into the trials yielded a 16% [corrected] benefit from screening mammography, without statistical significance at the 95% confidence level. Combining all data on women ages 40 to 49 years at entry, excluding results from the Canadian National Breast Screening Study, yielded a 24% [corrected] benefit to women invited for screening, with statistical significance at the 95% confidence level. CONCLUSIONS: These results suggest that screening mammography in women ages 40 to 49 years at entry can reduce mortality from breast cancer when combined with adequate follow-up.

Simple isolation of antimycin A1 and some of its toxicological properties.

An unidentified actinomycete, RTI 246, was found to produce antimycin A(1) in high yield on a high protein cereal medium. The antibiotic compound was extracted from the cells and isolated in pure form by crystallization. It was identified by ultraviolet, infrared, nuclear magnetic resonance, and mass spectroscopy and by alkaline hydrolysis to antimycic acid and a neutral lactone. The intravenous LD(50) was 1.0 mg/kg in white mice, whereas the intraperitoneal LD(50) was 1.50 +/- 0.19 mg/kg. Animals receiving an intraperitoneal injection displayed an incoordination of the hind limbs and impaired reflexes before showing signs of respiratory distress. These findings indicated that antimycin A(1) possesses a neurotoxic property separate from its well-documented property as a respiratory poison.