James C. Boyd

p53, bcl-2 AND RETINOBLASTOMA PROTEINS AS LONG-TERM PROGNOSTIC MARKERS IN LOCALIZED CARCINOMA OF THE PROSTATE

PURPOSE The accumulation of p53 and bcl-2 gene products as well as the loss of the retinoblastoma (Rb) gene product have been associated with prostate cancer progression. We assessed whether the levels of immunoreactivity for p53, Rb and bcl-2 are better long-term predictors of disease specific survival than conventional pathological parameters of the primary tumor, such as Gleason score, capsular penetration, seminal vesicle invasion and percent tumor in the specimen, in patients with clinically localized prostate cancer treated with radical prostatectomy. MATERIALS AND METHODS A total of 71 patients with clinical stages A1 to B2 adenocarcinoma of the prostate underwent radical prostatectomy after a negative metastatic evaluation. No neoadjuvant or adjuvant treatments were given and causes of death were recorded. Prostatectomy specimens were analyzed to determine the conventional pathological parameters, and p53, Rb and bcl-2 immunohistochemical staining. Univariate and multivariate analyses were done to determine the independent contributions of p53, Rb and bcl-2 in predicting survival. RESULTS On multivariate analysis the independent factors predicting disease specific survival were p53 staining score (p < 0.001) and Rb staining score (p < 0.001). In patients with p53 immunoreactive tumors the 15-year disease specific survival was 38% compared to 87% for those with less immunoreactivity. Analysis of Rb immunoreactivity for 15-year disease specific survival yielded 92 and 66% high and low staining levels, respectively. Best subset analysis revealed that the combination of p53 score and Rb score yielded the best predictive value for disease specific survival. CONCLUSIONS p53 and Rb immunohistochemical staining scores were independent predictors of disease specific survival and were superior to conventional pathological prognostic factors of the primary tumor. These findings lay the groundwork for the prospective study of these markers in patients treated with radical prostatectomy.

Tight Glucose Control in the Intensive Care Unit: Are Glucose Meters up to the Task?

Many institutions use tight glycemic control (TGC)1 protocols in their intensive care units (ICUs). TGC protocols became standard of care after the initial, very promising, studies demonstrating that it improved patient outcomes (1). For instance, Van den Berghe et al. (1) demonstrated that TGC reduced mortality by one-third in surgical intensive care patients. Other early studies of TGC also demonstrated marked and significant benefits in infection rates and mortality. Typical TGC protocols consist of placing postoperative and critically ill patients on a continuous intravenous insulin infusion, checking their blood glucose concentrations on an hourly basis (or other schedule), and giving a bolus of insulin and/or changing the infusion rate of insulin based on the glucose concentration, with a goal of maintaining glucose between 4.4 and 6.7 mmol/L (80 and 120 mg/dL). Of the numerous variations in protocols regarding timing and frequency of glucose measurements, insulin infusion rates, and target glucose values, all have a goal of maintaining tight glycemic control in critically ill patients. A new metaanalysis has suggested that TGC protocols offer limited if any benefits in critically ill adults and revealed that these protocols resulted in a 3- to 5-fold increased risk of hypoglycemia (2). The metaanalysis examined 29 randomized controlled trials that met predefined inclusion criteria. Of the 27 trials that examined mortality as an endpoint, 16 favored TGC and 11 favored usual care, but the reductions in relative risk were statistically significant (95% confidence) in only 2 of the 16 favoring TGC and in none of the 11 favoring usual care. The only outcome for which TGC demonstrated a significantly reduced risk was the development of septicemia; this was seen in surgical intensive care patients but not in medical ICU patients. The metaanalysis concluded that TGC may not be as beneficial as predicted from some …

Three distinct regions of allelic loss at 13q14, 13q21-22, and 13q33 in prostate cancer.

Chromosome 13 is one of the most frequently altered chromosomes in cancer, including carcinoma of the prostate. Two known tumor suppressor genes, RB1 and BRCA2, map to chromosome 13; however, recent reports suggest that unknown genes on 13q are more likely to be involved in the development of prostate cancer. In order more fully to define the genetic changes on chromosome 13 in prostate neoplasms, we analyzed 27 polymorphic microsatellite markers spanning the q arm for loss of heterozygosity in 40 primary tumors and in metastases from 11 other patients who died of prostate cancer. Of the 40 primary tumors, 23 (58%) showed LOH for at least one marker. Three distinct regions at q14, q21‐22, and q33, defined by markers D13S267 → D13S153, D13S166 → D13S1225, and D13S259 → D13S274, showed the most frequent LOH, suggesting their involvement in the development of prostate cancer. For the 12 patients whose tumors showed LOH at these markers, the average age at diagnosis was 58 years, which was younger than that (63 years, P < 0.05) for the 28 patients whose tumors lacked LOH. Ten of the 11 (91%) metastases showed LOH with one or more markers. Two of the three most frequently deleted regions (i.e., q14 and q21‐22) in the primary tumors and markers linked to the RB1, BRCA2, and EDNRB genes showed high frequencies (56–71%) of LOH in metastases. These results demonstrate that allelic loss on chromosome 13 at q14, q21‐22, and q33 occurs in a subset of primary prostate tumors and is a frequent event in metastatic lesions of prostate cancer. Genes Chromosomes Cancer 25:108–114, 1999.

Comparison of Diagnostic Accuracies in Outpatients and Hospitalized Patients of D-Dimer Testing for the Evaluation of Suspected Pulmonary Embolism

BACKGROUND The ability of various D-dimer assays to exclude the diagnosis of thromboembolic diseases is controversial. We examined the diagnostic accuracy of two D-dimer methods in hospitalized patients and outpatients. METHODS We studied consecutive patients for whom D-dimer testing was ordered for investigation of suspected pulmonary embolism. We measured D-dimer by an ELISA (VIDAS D-dimer) and an enhanced microlatex immunoassay method (Diagnostica Stago STA Liatest D-di). Patient diagnoses were based on imaging studies or, when these were not performed, on follow-up by review of medical records 3 months later. RESULTS We examined 233 hospitalized patients and 234 outpatients with a mean age of 58 years (range, 1-92 years) and a female-to-male ratio of 1.4 to 1. Thromboembolism was present in 8% of outpatients and 12% of hospitalized patients. In outpatients, the negative predictive values were 98% [95% confidence interval (CI), 93-100%] and 99% (94-100%) for the microlatex and ELISA methods, respectively, at the recommended cutoffs. Areas under the ROC curves were similar for the two methods [0.77 (95% CI, 0.67-0.87) and 0.81 (0.73-0.89), respectively]. By contrast, in hospitalized patients, the confidence intervals for the areas under the ROC curves included 0.5 [0.60 (95% CI, 0.50-0.71) and 0.56 (0.44-0.67)]. CONCLUSIONS For hospitalized patients, in contrast to outpatients, the diagnostic accuracy of D-dimer testing for pulmonary embolism is poor in a tertiary care setting, presumably reflecting thrombosis and comorbidities, other than pulmonary embolism, that increase the D-dimer concentrations in these patients. The patient population studied appears more important than assay method in studies of the diagnostic accuracy of D-dimer testing.

Aberrant Localization of the Neuronal Class III b-Tubulin in Astrocytomas A Marker for Anaplastic Potential

c Background.—The class III b-tubulin isotype (bIII) is widely regarded as a neuronal marker in development and neoplasia. In previous work, we have shown that the expression of bIII in neuronal/neuroblastic tumors is differentiation dependent. In contrast, the aberrant localization of this isotype in certain nonneuronal neoplasms, such as epithelial neuroendocrine lung tumors, is associated with anaplastic potential. Objective.—To test the generality of this observation, we investigated the immunoreactivity profile of bIII in astrocytomas. Design.—Sixty archival, surgically excised astrocytomas (8 pilocytic astrocytomas, WHO grade 1; 18 diffuse fibrillary astrocytomas, WHO grade 2; 4 anaplastic astrocytomas, WHO grade 3; and 30 glioblastomas, WHO grade 4), were studied by immunohistochemistry using anti-bIII monoclonal (TuJ1) and polyclonal antibodies. A monoclonal antibody to Ki-67 nuclear antigen (NC-MM1) was used as a marker for cell proliferation. Antibodies to glial fibrillary acidic protein (GFAP) and BM89 synaptic vesicle antigen/synaptophysin were used as glial and neuronal markers, respectively. Results.—The bIII immunoreactivity was significantly greater in high-grade astrocytomas (anaplastic astrocytomas and glioblastomas; median labeling index [MLI], 35%; interquartile range [IQR], 20%‐47%) as compared with diffuse fibrillary astrocytomas (MLI, 4%; IQR, 0.2%‐21%) (P , .0001) and was rarely detectable in pilocytic astrocytomas (MLI, 0%; IQR, 0%‐0.5%) (P , .0001 vs high-grade astrocytomas; P , .01 vs diffuse fibrillary astrocytomas). A highly significant, grade-dependent relationship was observed between bIII and Ki-67 labeling and malignancy, but this association was stronger for Ki-67 than for bIII (bIII, P , .006; Ki-67, P , .0001). There was co-localization of bIII and GFAP in neoplastic astrocytes, but no BM89 synaptic vesicle antigen/synaptophysin staining was detected. Conclusions.—In the context of astrocytic gliomas, bIII immunoreactivity is associated with an ascending gradient of malignancy and thus may be a useful ancillary diagnostic marker. However, the significance of bIII-positive phenotypes in diffuse fibrillary astrocytomas with respect to prognostic and predictive value requires further evaluation. Under certain neoplastic conditions, bIII expression is not neuron specific, calling for a cautious interpretation of bIII-positive phenotypes in brain tumors. (Arch Pathol Lab Med. 2001;125:613‐624)

The use of urinary dipstick tests to exclude urinary tract infection: a systematic review of the literature.

Several systematic reviews have examined the use of dipstick tests to diagnose or rule in urinary tract infection (UTI). We examined the evidence relating to the use of urine leukocyte esterase and nitrite tests in adults to exclude or rule out UTI. A search of the literature from 1966 to 2003 revealed 30 studies as containing relevant and suitable information and 23 of these, which used a cut-off of 108 colony-forming units per liter, were combined in a meta-analysis. The leukocyte esterase or nitrite test combination, with one or the other test positive, was used in 14 studies, showed the highest sensitivity and the lowest negative likelihood ratio. While there was significant heterogeneity between the studies, 7 of 14 demonstrated significant decreases in pretest to posttest probability with a pooled posttest probability of 5% for the negative result. In certain circumstances, there is evidence for the use of urinalysis as a rule-out test for UTI.

Aggressive Papillary Tumor of Middle Ear/temporal Bone and Adnexal Papillary Cystadenoma Manifestations of von Hippel-lindau Disease

The occurrence of an aggressive papillary middle ear/temporal bone tumor (APMET) and a benign adnexal papillary tumor of probable mesonephric origin (APMO) in a patient with von Hippel-Lindau disease (VHL) is reported. Histologically, both tumors were identical to papillary cystadenomas of the epididymis and broad ligament of probable mesonephric derivation. A comprehensive literature review showed that including the current case, seven of 46 (15%) documented cases of APMET and four of four (100%) cases of APMO arose in patients with VHL. Given an estimated minimum birth incidence of 1/36,000, a one-sample test of binomial proportion using the exact method establishes that the association of APMET and APMO with VHL is highly significant (p = 1.4 x 10(-24) and 1 x 10(-18), respectively). The data indicate that APMET and APMO may represent major visceral manifestations of VHL. Accordingly, in the presence of one of these tumors strong consideration should be given to the diagnosis of VHL, given either the presence of another major component of VHL or documentation of VHL in at least one consanguineous relative.

Glucose Meter Performance Criteria for Tight Glycemic Control Estimated by Simulation Modeling

BACKGROUND Glucose meter analytical performance criteria required for safe and effective management of patients on tight glycemic control (TGC) are not currently defined. We used simulation modeling to relate glucose meter performance characteristics to insulin dosing errors during TGC. METHODS We used 29,920 glucose values from patients on TGC at 1 institution to represent the expected distribution of glucose values during TGC, and we used 2 different simulation models to relate glucose meter analytical performance to insulin dosing error using these 29,920 initial glucose values and assuming 10%, 15%, or 20% total allowable error (TEa) criteria. RESULTS One-category insulin dosing errors were common under all error conditions. Two-category insulin dosing errors occurred more frequently when either 20% or 15% TEa was assumed compared with 10% total error. Dosing errors of 3 or more categories, those most likely to result in hypoglycemia and thus patient harm, occurred infrequently under all error conditions with the exception of 20% TEa. CONCLUSIONS Glucose meter technologies that operate within a 15% total allowable error tolerance are unlikely to produce large (>or=3-category) insulin dosing errors during TGC. Increasing performance to 10% TEa should reduce the frequency of 2-category insulin dosing errors, although additional studies are necessary to determine the clinical impact of such errors during TGC. Current criteria that allow 20% total allowable error in glucose meters may not be optimal for patient management during TGC.

Mathematical tools for demonstrating the clinical usefulness of biochemical markers.

Various approaches have been proposed for evaluating the diagnostic value of biochemical markers. Careful design of experimental protocol is key in carrying out any evaluation of clinical diagnostic value. A prospective cohort study is the best clinical trial design and should include an appropriate reference (gold) standard applied in every patient, the results of which are assessed blindly. The spectrum of patients evaluated should reflect the population in which the test will be used, be appropriately broad to avoid bias, and include both symptomatic and asymptomatic patients. The handling of indeterminate results and the eligibility criteria for inclusion in the study should be carefully defined. Although sensitivity, specificity, and predictive value have long been used as indices of test accuracy, newer methods such as receiver operating characteristic curve (ROC) analysis, logistic regression analysis and likelihood ratios are more robust indicators that overcome many limitations of the traditional indices. The area under the ROC curve (AUC) is the best global indicator of test accuracy, but comparisons of AUC for different tests must take correlation between the tests into account if they have been performed in the same patients. Logistic regression analysis allows the diagnostic information from several tests to be evaluated multivariately, provides a probability estimate for a given outcome, and requires few assumptions regarding the underlying distributions of test data. Logistic regression also provides a straightforward method for calculating likelihood ratios. Likelihood ratios are useful for interpreting test results in the individual patient because they provide a convenient means to directly determine predictive value without having to calculate sensitivity and specificity for a given decision limit. Application of these methods is demonstrated using specific examples.

An appraisal of statistical procedures used in derivation of reference intervals

Abstract When conducting studies to derive reference intervals (RIs), various statistical procedures are commonly applied at each step, from the planning stages to final computation of RIs. Determination of the necessary sample size is an important consideration, and evaluation of at least 400 individuals in each subgroup has been recommended to establish reliable common RIs in multicenter studies. Multiple regression analysis allows identification of the most important factors contributing to variation in test results, while accounting for possible confounding relationships among these factors. Of the various approaches proposed for judging the necessity of partitioning reference values, nested analysis of variance (ANOVA) is the likely method of choice owing to its ability to handle multiple groups and being able to adjust for multiple factors. Box-Cox power transformation often has been used to transform data to a Gaussian distribution for parametric computation of RIs. However, this transformation occasionally fails. Therefore, the non-parametric method based on determination of the 2.5 and 97.5 percentiles following sorting of the data, has been recommended for general use. The performance of the Box-Cox transformation can be improved by introducing an additional parameter representing the origin of transformation. In simulations, the confidence intervals (CIs) of reference limits (RLs) calculated by the parametric method were narrower than those calculated by the non-parametric approach. However, the margin of difference was rather small owing to additional variability in parametrically-determined RLs introduced by estimation of parameters for the Box-Cox transformation. The parametric calculation method may have an advantage over the non-parametric method in allowing identification and exclusion of extreme values during RI computation. Clin Chem Lab Med 2010;48:1537–51.