Data quality review program: the Society of Thoracic Surgeons Adult Cardiac National Database

In summary, the National Database Committee's Audit and Validation Subcommittee is working to maximize the data completeness and quality of the STS National Database. Toward this end, we welcome your suggestions for improvement.     

On histocompatibility barriers, Th1 to Th2 immune deviation, and the nature of the allograft responses

In the present study, we have sought to determine the basis for the frequent failure of Th1 to Th2 immune deviation to blunt the severity of allograft rejection, as such immune deviation has proven highly effective in the treatment of several T cell-dependent autoimmune states. Our study demonstrates that treating islet allograft recipient mice with anti-IL-12 mAb is highly effective in producing Th1 to Th2 immune deviation in several model systems (i.e., fully MHC, partially MHC, or multiple minor Ag barriers). Nevertheless, anti-IL-12 failed to prolong the engraftment of fully MHC-mismatched islet allografts. However, anti-IL-12-treated recipients carrying MHC-matched but multiple minor Ag-mismatched allografts experienced prolonged engraftment; allograft tolerance was frequently achieved in the DBA/2J (H-2d) to BALB/c (H-2d) strain combination. In another model, in which the host response was dominated by CD4+ T cells responding to donor allopeptides presented upon host APCs in the context of self MHC class II molecules, anti-IL-12 treatment proved to be extremely potent. Thus, Th1 to Th2 immune deviation produces prolonged engraftment as compared with recipients of MHC-mismatched allografts when rejection is dependent upon indirectly presented allogeneic peptides and a reduced mass of responding alloreactive T cells.     

Investigations of the problems of assessing aflatoxin levels in peanuts

In this study, a number of probability distributions that have been used to model the occurrence of aflatoxin in peanuts are compared. Two distributions, the compound gamma and the negative binomial, are shown to have special appeal in that both can be justified by reasoning from the fundamental biological and stochastic processes that generate the aflatoxin. Since method of moments and maximum likelihood give consistent estimates of parameters in both models, practical considerations suggest using the former. One hundred twenty data sets, each consisting of fifty observations, were not sufficient to provide goodness-of-fit tests to establish either as superior to the other as a model. Both models fit the data well, appreciably better than other models examined. An attractive aspect of the compound gamma and the negative binomial distributions is that, as a consequence of their theoretical underpinnings, both involve parameters that have meaningful interpretations. In the compound gamma, the alpha parameter reflects the shape of the kernel-to-kernel aflatoxin content distribution, the lambda parameter reflects the number (or frequency) of contaminated kernels in the sample, and the beta parameter is a scale parameter. In the negative binomial, the two parameters can be used as measures of mean or location and shape.     

Effect of anticoagulant therapy on the hypercoagulable state in patients carrying the factor V Arg506Gln mutation

The National Practitioner Data Bank (NPDB), created by the 1986 Health Care Quality Improvement Act, has been in operation since 1990. Hospitals and other credentialing bodies must query the NPDB when granting and renewing privileges. The NPDB receives about 25,000 reports of adverse actions against health practitioners each year. The NPDB was designed to be a flagging system providing information to licensing or credentialing authorities who would further examine practitioner records. Its purpose is to ensure that decision makers have information that might not otherwise be readily available, especially in the case of incompetent practitioners who move from hospital to hospital or state to state. Access to NPDB information is a concern for consumers and providers alike. Only 2% of matched reports to the NPDB made a difference in hospital privileging decisions. A limitation of NPDB information is that malpractice payments recorded in the NPDB do not necessarily constitute a comprehensive and definitive reflection of actual health care incompetence. All health care providers need to be aware of the NPDB, its mission, potential impact on their ability to be credentialed, and proposed additional uses of its information.     

Transient current in amorphous, porous semiconductor-crystalline semiconductor structures

The time-of-flight technique in the weak signal mode (i.e., under conditions of small charge drift in the sample) is used to study the transient photocurrent in amorphous (porous) semiconductor-crystalline semiconductor structures. Amorphous Se-As materials, porous Si, and crystalline Si and CdSe were incorporated in the structures. The carrier drift mobilities in the amorphous and porous layers of the structures were determined. The appearance of a cusp on the curves of the transient current is shown to be caused by acceleration of carriers passing through the interface between the amorphous (porous) layer and the crystal. It is established that the carrier acceleration influences the drift mobility and the dispersion parameters. Fiz. Tekh. Poluprovodn. 32, 187–191 (February 1998)     

Phosphorylation events mediated by protein kinase C alpha and epsilon participate in regulation of tau steady-state levels and generation of certain "Alzheimer-like" phospho-epitopes

Hyperactivation of protein kinase C (PKC) in intact neuroblastoma cells by several methods increases site-specific tau phosphorylation as shown by increases in paired helical filament-I (PHF-I) and ALZ-50 but not AT-8 immunoreactivity. In the present study, the influence of PKC on tau metabolism was further examined by isoform-specific antisense oligonucleotide-mediated PKC downregulation in human SH-SY-5Y neuroblastoma cells and by generation of stably-transfected subclones expressing isoform-specific anti-PKC mRNA sequences. Downregulation of PKC epsilon by both of these methods reduced PHF-I and ALZ-50 immunoreactivity, suggesting that this PKC isoform, perhaps via downstream kinase cascades, regulated tau phosphorylation events that normally generate these epitopes. By contrast, downregulation of either PKC epsilon or PKC alpha reduced immunoreactivity towards the phosphate-independent anti-tau antibodies 5E2 and JM, suggesting that both of these isoforms participated in regulation of tau steady-state levels. Downregulation of PKC beta did not affect any of the above changes. The above roles were apparently unique for PKC epsilon and PKC alpha, since activation of multiple PKC isoforms by phorbol ester treatment and/or other calcium-dependent kinase(s) by ionophore-mediated calcium influx could not compensate for downregulation of PKC alpha or PKC epsilon in maintaining tau steady-state levels or PHF-I/ALZ-50 immunoreactivity, respectively. These findings suggest that hyperactivation of signal transduction pathways, including those regulated by PKC, could evoke changes in neuronal cells reminiscent of those seen in affected neurons in Alzheimer's disease.