Stress nuclear myocardial perfusion imaging versus stress echocardiography: prognostic comparisons

The use of noninvasive stress cardiac imaging for stratifying risk in patients with known or suspected coronary artery disease is growing as a tool for identification of the subgroup most likely to benefit from the expense and risk of more invasive procedures, including cardiac catheterization and coronary revascularization. In this setting, it is especially important that a test be able to identify patients with sufficiently low risk that clinicians are comfortable in deferring such interventions, especially in those with other markers of increased risk. Previous data have shown that cardiac risk is most closely related to the presence and extent of jeopardized viable myocardium on noninvasive stress cardiac imaging. Although stress echocardiography may have comparable ability to detect coronary artery disease, current data suggest that stress echocardiography detects significantly less jeopardized viable myocardium than stress nuclear myocardial perfusion imaging and consequently fewer patients at risk for cardiac events. Stress nuclear myocardial perfusion imaging may therefore have important advantages for risk stratification and the direction of future care of patients with known or suspected coronary artery disease.

Circulating rotavirus-specific antibody-secreting cells (ASCs) predict the presence of rotavirus-specific ASCs in the human small intestinal lamina propria

Rotaviruses are the most important cause of infectious diarrhea in children throughout the world. Protection is most likely mediated by small-intestinal virus-specific IgA. However, neither fecal nor serum virus-specific IgA clearly correlates with protection against challenge. The capacity of rotavirus-specific antibodies and rotavirus-specific antibody-secreting cells (ASCs) in the circulation to predict the presence of ASCs in the intestines of children was evaluated. Mononuclear cells from intestinal biopsy samples and blood from 21 children were enriched for CD38, a marker of terminally differentiated B cells, and evaluated for the presence of virus-specific and total IgA- and IgG-secreting cells, by ELISPOT assay. Serum virus-specific IgA and IgG levels were determined by ELISA. The ratio of virus-specific to total IgA-secreting cells in the blood correlated with that found in the small, but not large, intestine. In contrast, serum rotavirus-specific IgA correlated less well with the presence of virus-specific ASCs in the small intestine.

Purification, characterization, cDNA cloning and expression of a novel ketoreductase from Zygosaccharomyces rouxii

A novel ketoreductase isolated from Zygosaccharomyces rouxii catalyzes the asymmetric reduction of selected ketone substrates of commercial importance. The 37.8-kDa ketoreductase was purified more than 300-fold to > 95% homogeneity from whole cells with a 30% activity yield. The ketoreductase functions as a monomer with an apparent Km for 3,4-methylenedioxyphenyl acetone of 2.9 mM and a Km for NADPH of 23.5 microM. The enzyme is able to effectively reduce alpha-ketolactones, alpha-ketolactams, and diketones. Inhibition is observed in the presence of diethyl pyrocarbonate, suggesting that a histidine is crucial for catalysis. The 1.0-kb ketoreductase gene was cloned and sequenced from a Z. rouxii cDNA library using a degenerate primer to the N-terminal sequence of the purified protein. Furthermore, it was expressed in both Escherichia coli and Pichia pastoris and shown to be active. Substrate specificity, lack of a catalytic metal, and extent of protein sequence identity to known reductases suggests that the enzyme falls into the carbonyl reductase enzyme class.

Bitemarks in chocolate: a case report

Police investigating a theft from a chocolate factory recovered three pieces of chocolate with irregular fractured surfaces displaying a pattern of marks made by human teeth. A highly accuracy dental impression material was used to prepare casts of these marks which were examined and photomicrographed, confirming that they had in fact been produced by human teeth. Casts and photomicrographs of the suspect's teeth were made in order to record the fine details of the casts of the dentition. Unique characteristics evident on these casts included a small notch on the incisal edge of the upper right lateral incisor, wear facets on the incisal edges of the upper central incisors and on the lower right lateral incisor and a space of approximately 1.5 mm between the upper left central incisor and lateral incisor which was rotated about 20 degrees distally. Both direct and photomicrographic comparisons between the casts of the chocolates and of the suspect's dentition revealed correspondence between their unique characteristics.

Flow cytometric analysis of different adhesion molecules expression on circulating CD14- and CD64- human dendritic cell precursors

Blood dendritic cell precursors (DCps) are identified as mononuclear leukocytes expressing HLA-DR but lacking the characteristic antigens associated with T cells (CD3), NK cells (CD16 and CD56) and B cells (CD 19). Dendritic cell precursors are distinguished from monocytes by their lack of expression of CD64 rather than of CD14. This study investigated whether CD14- DCps differed from CD64-DCps, which were predominantly CD14+, in their expression of five well-characterised adhesion molecules. There were significantly fewer cells expressing CD11b, CD18 and CD29 in the CD64-DCp population compared with CD14- DCps, and this CD64- DCp subpopulation also had a lower expression of CD11b and CD18. Our results suggest that the two DC precursor subpopulations may differ from one another in their binding characteristics to blood vessel walls and to other leukocytes.

Liver transplantation

Survival after liver transplantation has steadily improved, in part because of newer immunosuppression, which may offer decreased long-term side effects. Reduction of steroids early in the course of transplant continues to be a goal, with satisfactory results in terms of both risk of rejection and reduction of side effects. Dominating the literature and the press in 1999 was the controversy surrounding the way in which livers are allocated. Regulation by the federal government was proposed to change the way the United Network of Organ Sharing distributes and allocates livers. Prompted by the shortage of organs, living-donor liver transplantation has blossomed. Continued experience in pediatric patients has shown excellent survival rate and quality of life. In adults, further experience is being gained with respect to the use of right lobes for transplantation. Early data suggest that this is a potential alternative to cadaveric transplantation in adults, with acceptable risk to the donor. Despite advances made in improving the technical aspects of transplantation, recurrent disease remains a significant issue. Lamivudine appears to be a potent inhibitor of hepatitis B virus DNA replication after liver transplantation, although resistance remains a significant problem. Further review of transplantation for hepatitis C virus is encouraging, with excellent five-year survival rate. However, studies evaluating the evolution of fibrosis in these patients throw caution on those results, showing increased progression to cirrhosis over time. Further follow-up of these patients is needed to more accurately assess long-term impact of hepatitis C on morbidity and mortality rates after liver transplantation.

Chemical and physiological characterization of fluo-4 Ca(2+)-indicator dyes

We have developed fluo-4, a new fluorescent dye for quantifying cellular Ca2+ concentrations in the 100 nM to 1 microM range. Fluo-4 is similar in structure and spectral properties to the widely used fluorescent Ca(2+)-indicator dye, fluo-3, but it has certain advantages over fluo-3. Due to its greater absorption near 488 nm, fluo-4 offers substantially brighter fluorescence emission when used with excitation by argon-ion laser or other sources in conjunction with the standard fluorescein filter set. In vitro, fluo-4 exhibited high fluorescence emission, a high rate of cell permeation, and a large dynamic range for reporting [Ca2+] around a Kd(Ca2+) of 345 nM. We have also developed several Ca(2+)-indicators related to fluo-4 having lower affinities for Ca2+ that are useful in cellular studies requiring quantification of higher [Ca2+]. In a variety of physiological studies of live cells, fluo-4 labeled cells more brightly than did fluo-3, when challenged with procedures designed to elevate calcium levels. Fluo-4 is well suited for photometric and imaging applications that make use of confocal laser scanning microscopy, flow cytometry, or spectrofluorometry, or in fluorometric high-throughput microplate screening assays. Because of its higher fluorescence emission intensity, fluo-4 can be used at lower intracellular concentrations, making its use a less invasive practice.

Evaluating the effects of functional communication training in the presence and absence of establishing operations

We conducted functional analyses of aberrant behavior with 4 children with developmental disabilities. We then implemented functional communication training (FCT) by using different mands across two contexts, one in which the establishing operation (EO) that was relevant to the function of aberrant behavior was present and one in which the EO that was relevant to the function of aberrant behavior was absent. The mand used in the EO-present context served the same function as aberrant behavior, and the mand used in the EO-absent context served a different function than the one identified via the functional analysis. In addition, a free-play (control) condition was conducted for all children. Increases in relevant manding were observed in the EO-present context for 3 of the 4 participants. Decreases in aberrant behavior were achieved by the end of the treatment analysis for all 4 participants. Irrelevant mands were rarely observed in the EO-absent context for 3 of the 4 participants. Evaluating the effectiveness of FCT across different contexts allowed a further analysis of manding when the establishing operations were present or absent. The contributions of this study to the understanding of functional equivalence are also discussed.

Correlations among p53, Her-2/neu, and ras overexpression and aneuploidy by multiparameter flow cytometry in human breast cancer: evidence for a common phenotypic evolutionary pattern in infiltrating ductal carcinomas

Human solid tumors develop multiple genetic abnormalities that accumulate progressively in individual cells during the course of tumor evolution. We sought to determine whether there are specific sequences of occurrence of these progressive evolutionary changes in human breast cancers by performing correlated cell-by-cell measurements of cell DNA content, p53 protein, Her-2/neu protein, and ras protein by multiparameter flow cytometry in 56 primary tumor samples obtained at surgery. In addition, p53 allelic loss and Her-2/neu gene amplification were determined by fluorescence in situ hybridization in cells from the same samples. We reasoned that if there is a specific order in which genetic changes occur, the same early changes would be found consistently in the cells with the fewest abnormalities. We reasoned further that late-developing abnormalities would not occur alone in individual cells but would almost always be found together with the early changes inherited by the same cells. By these criteria, abnormalities involving p53 generally occurred early in the course of development of invasive breast cancers, whereas ras protein overexpression was found to be a late-occurring phenomenon. Within individual tumors, cellular p53 overexpression was often observed alone in individual cells, whereas ras protein overexpression was rarely observed in the absence of p53 overexpression and/or Her-2/neu overexpression in the same cells. Furthermore, the intracellular level of each abnormally expressed protein was found to increase progressively as new abnormalities were acquired. Infiltrating ductal carcinomas exhibited characteristic phenotypic patterns in which p53 allelic loss and/or p53 protein overexpression, Her-2/neu amplification and/or overexpression, aneuploidy, and ras overexpression accumulated within individual cells. However, this pattern was not a prominent feature of lobular breast cancers. All six lobular breast cancers studied were diploid. p53 allelic loss and/or early p53 overexpression, and late ras cooverexpression in the same cells were less common in lobular breast cancers than in infiltrating ductal carcinomas. Although Her-21neu overexpression was a common finding in lobular breast cancers, Her-2/neu amplification was not observed in these tumors.

Early dipyridamole (99m)Tc-sestamibi single photon emission computed tomographic imaging 2 to 4 days after acute myocardial infarction predicts in-hospital and postdischarge cardiac events: comparison with submaximal exercise imaging

BACKGROUND

Because of its brief hemodynamic effects and minor effect on determinants of myocardial oxygen demand, vasodilator stress myocardial perfusion imaging (MPI) can be applied very early after acute myocardial infarction (AMI) for risk stratification, allowing management decisions to be made earlier and thus potentially shortening hospitalization stays, reducing costs, and preventing early cardiac events. This multicenter randomized trial compared the prognostic value of early dipyridamole MPI and standard predischarge submaximal exercise MPI in patients who presented with AMI.

METHODS AND RESULTS

Patients who presented with their first AMI (n=451) were randomized in a 3:1 ratio to undergo either both an early (day 2 to 4) dipyridamole (99m)Tc-sestamibi MPI study and a predischarge (day 6 to 12) submaximal exercise (99m)Tc-sestamibi MPI study or only the predischarge study. Multivariate predictors of in-hospital cardiac events included nuclear imaging summed stress and summed reversibility scores and peak creatine kinase. For postdischarge cardiac events, multivariate predictors in patients undergoing dipyridamole MPI included only the summed stress, reversibility, and rest imaging scores and anterior MI. For a given summed stress score, the interaction of reversibility score further improved the predictive value. Dipyridamole MPI showed better risk stratification than submaximal exercise MPI.

CONCLUSIONS

Dipyridamole MPI very early after MI predicts early and late cardiac events, with superior prognostic value compared with submaximal exercise imaging. The extent and severity of the stress defect and reversibility of the defect were the most important predictors of cardiac death and recurrent MI. This technique can allow management decisions to be made earlier with regard to AMI patients and could have important economic impact if applied widely.

Conservation of a CD1 multigene family in the guinea pig

CD1 is a family of cell-surface molecules capable of presenting microbial lipid Ags to specific T cells. Here we describe the CD1 gene family of the guinea pig (Cavia porcellus). Eight distinct cDNA clones corresponding to CD1 transcripts were isolated from a guinea pig thymocyte cDNA library and completely sequenced. The guinea pig CD1 proteins predicted by translation of the cDNAs included four that can be classified as homologues of human CD1b, three that were homologues of human CD1c, and a single CD1e homologue. These guinea pig CD1 protein sequences contain conserved amino acid residues and hydrophobic domains within the putative Ag binding pocket. A mAb specific for human CD1b cross-reacted with multiple guinea pig CD1 isoforms, thus allowing direct analysis of the structure and expression of at least a subset of guinea pig CD1 proteins. Cell-surface expression of CD1 was detected on cortical thymocytes, dermal dendritic cells in the skin, follicular dendritic cells of lymph nodes, and in the B cell regions within the lymph nodes and spleen. CD1 proteins were also detected on a subset of PBMCs consistent with expression on circulating B cells. This distribution of CD1 staining in guinea pig tissues was thus similar to that seen in other mammals. These data provide the foundation for the development of the guinea pig as an animal model to study the in vivo function of CD1.

Tissue quantification of hepatitis C virus RNA with morphologic correlation in the diagnosis of recurrent hepatitis C virus in human liver transplants

BACKGROUND

Histologic findings and liver enzymes in liver transplants are often non-diagnostic of recurrent hepatitis C virus (HCV) disease. In addition, the relationship between HCV replication and the presence of recurrent HCV hepatitis after liver transplantation remains unclear. We studied liver transplant recipients to determine if quantitation of HCV RNA in liver tissue by reverse transcriptase-polymerase chain reaction (RT-PCR) correlates with histopathologic disease and/or liver enzymes.

METHODS

Twenty-six patients who received liver transplants for HCV infection were evaluated. Four sequential biopsies were analyzed for each patient. HCV RNA was extracted and quantified using the Amplicor HCV Monitor Test. Histologic examination and RNA quantitation were blinded. All available liver enzymes on the day of liver biopsy were analyzed.

RESULTS

HCV RNA quantity in liver tissue was significantly increased at the time of clinically-suspected recurrence (P < .0001). HCV RNA levels were highest in biopsies with lobular hepatitis and nonspecific inflammation, followed by biopsies with cytomegalovirus infection, chronic hepatitis, and acute cellular rejection. HCV RNA quantity had a significant correlation with increasing portal inflammation (P = .0002), decreasing amount of interface hepatitis (P = .0333), and presence of acidophilic bodies (P = .0316). Increasing HCV RNA levels significantly correlated with decreasing number of episodes of treated rejection. HCV RNA quantity did not correlate with other histologic features or liver enzymes.

CONCLUSIONS

HCV RNA levels are highest at the time of active hepatocellular destruction. Elevated HCV RNA indicates recurrence. HCV RNA quantitation may be a useful diagnostic test for determining recurrent disease and distinguishing it from other causes of inflammation, such as rejection.

Liver transplantation

The growing disparity between available organs for liver transplantation and the number of waiting recipients has prompted significant debate over organ allocation and distribution. In light of this debate, recipient selection and prediction of factors relating to outcome have become increasingly important. Current immunosuppressive regimens provide excellent short-and long-term survival for patients and grafts. Increasingly, efforts are being made to decrease or withdraw immunosuppression late after transplantation to minimize long-term side effects. Viral disease, particularly cytomegalovirus infection, results in significant morbidity and mortality in patients. However, strategies for targeting high-risk patients with prophylactic antiviral therapy have been successful in reducing the incidence of cytomegalovirus disease. Recurrent viral hepatitis following liver transplantation may limit long-term graft success. Lamivudine appears to limit recurrent infection with hepatitis B virus in a significant number of patients who develop this condition following liver transplantation and may represent a cost savings over hepatitis B immunoglobulin. Although the overall survival of patients with chronic hepatitis C virus infection after orthotopic liver transplantation is excellent, significant morbidity and mortality occur in the subset of patients with severe recurrent disease. Interferon may delay the onset of disease in patients infected with hepatitis C virus following orthotopic liver transplantation, and investigation continues into antiviral therapy in this group of patients.

Correlates of missed appointments in orofacial injury patients

OBJECTIVE

The purposes of this study were to compare the sociodemographic and health-related characteristics of orofacial injury patients who miss appointments with those of patients who do not and to determine which patient characteristics best predict missed-appointment behaviors (e.g., the number of missed clinic visits).

STUDY DESIGN

A total of 190 patients (134 African American and 56 Hispanic) treated for mandible fractures at the King/Drew Medical Center, Los Angeles, participated in a prospective study involving structured interviews at 4 points (denoted recalls 1-4) over a 6-month period. To be included in the study, patients were required to have attended recall 1. Most patients in the study sample were male, more than 32 years of age, unmarried, and unemployed; most had completed high school; and most had sustained their injuries as a result of assault.

RESULTS

Only 22% of the patients attended all 4 recall clinic appointments. However, 42% completed 3 recall visits, and 69% completed 2 recall visits. Patients who missed appointments were more likely to be African American than Hispanic and more likely to be unemployed than employed. There was a significant negative association between perceived social support and missed appointments (r = -0.18, P = .01). Patients who missed more appointments perceived themselves to have less social support than those who missed fewer or no appointments. The data revealed no associations between missed appointment behavior and age, gender, marital status, or education. None of the health-related variables investigated were associated with missed appointments. Multiple regression analysis confirmed that race, unemployment, and perceived social support were the best predictors of missed appointments.

CONCLUSIONS

Social variables have a greater impact than health variables in predicting missed-appointment behavior. Unemployed African American patients are at the greatest risk for missing recall clinic appointments; however, this finding is independent of health insurance. Accessing and enlisting patients' social networks to support follow-up medical care has potential for improving appointment-keeping behavior and should be further examined.