The effect of component placement on knee kinetics after arthroplasty with an unconstrained prosthesis

The mechanical success of a total knee replacement demands stable patellar tracking without subluxation and, stable tracking, in turn, can depend largely on the medial-lateral forces restraining the patella. Patellar button medialization has been advocated as a means of reducing subluxation, and experimental evidence has shown femoral component rotation also affects medial-lateral forces. Surgeons have choices in femoral component rotation and patellar button medialization and must frequently make intra-operative decisions concerning component placement because of anatomical variations among patients. Thus, in seeking to minimize medial-lateral patellar force, we examined the effects of patellar button medialization and external femoral component rotation. The study used an unconstrained total knee system implanted in nine cadaveric specimens tested on a knee simulator operating through flexion angles up to 100 degrees. Tests included all combinations of external femoral component rotation of 0 degree, 2.5 degrees, and 5 degrees and patellar placement at the geometric center and at 3.75 mm medial to the geometric center. A video-based motion analysis system tracked patellar and tibial kinematics while a six-component load cell measured patellofemoral loads. Repeated measures analysis of variance revealed a statistically significant decrease in the average medial-lateral force with button medialization but no significant change with femoral component rotation. Neither femoral component rotation nor patellar button medialization had an effect on the normal component of the patellar reaction force. External femoral component rotation did cause significant increases in lateral patellar tilt, in tibial varus angle, and in external tibial rotation. Button medialization caused significant increases in lateral patellar tracking, lateral patellar tilt and external tibial rotation. The results in medial-lateral patellar forces quantify the benefit of patellar button medialization and discount any benefit of femoral rotation. The change in tibial kinematics with patellar button medialization and femoral component rotation cannot be measured in vivo with current technology, and the precise clinical implications are unknown.

Prediction of prostate carcinoma stage by quantitative biopsy pathology

BACKGROUND

Considerable evidence has shown that the use of computational algorithms to combine pretreatment clinical and pathology results can enhance predictions of patient outcome. The aim of this study was to prove that the application of such methods to predict patient-specific likelihoods of organ-confined (OC) prostate carcinoma (PCA) may be helpful to patients and physicians when they are choosing an optimal treatment for carcinoma of the prostate.

METHODS

The authors used clinical and quantitative pathology results from the biopsy specimens of 817 PCA patients who had been evaluated at a large national pathology reference laboratory. The pathology parameters that were measured included the number of positive cores, Gleason grades and score, percentage of tumor involvement, and the tumor location. The pathologic stage of these cases, as determined by results from radical prostatectomy, lymphadenectomy, or bone scan, categorized the PCA as either OC, non-OC due to capsular penetration only (NOC-CP) or advanced disease with metastasis (NOC-Mets), i.e., seminal vesicle and/or lymph-node positive or bone-scan positive. There were a total of 481 OC cases, 185 NOC-CP cases, and 151 NOC-Mets cases. Patient-specific prediction models were trained by ordinal logistic regression (OLOGIT) and genetically engineered neural networks (GENNs), and the resulting trained models were validated by biopsy information from an independent set of 116 PCA patients.

RESULTS

When the authors applied a cutoff of >or= 35% for the n = 817 training set of OC, NOC-CP, and NOC-Mets predictive probabilities, the OLOGIT model predicted OC PCA with an accuracy of 91%, whereas the GENN model predicted the same with an accuracy of 95%. When the authors employed the n = 116 validation set (76 OCs, 31 NOC-CPs, and 9 NOC-Mets), the OLOGIT and GENN models correctly identified OC PCA with 91% and 97% accuracy, respectively.

CONCLUSIONS

The value of combining patient pretreatment diagnostic pathology parameters to make predictions concerning the postoperative extent of pathology was illustrated clearly in this study. This finding further confirms the need to pursue such approaches for PCA disease management in the future, especially with the increasing prevalence of clinical T1c (American Joint Committee on Cancer, 1977) disease.

Contemporary use of complexed PSA and calculated percent free PSA for early detection of prostate cancer: impact of changing disease demographics

OBJECTIVES

To assess the diagnostic performance of complexed prostate-specific antigen (cPSA), total PSA (tPSA), and calculated free/total PSA (f/t PSA) ratios in the differentiation of benign disease from prostate cancer (CaP) using a contemporary patient cohort.

METHODS

The cPSA, tPSA, and calculated fPSA values were determined using the Bayer Immuno-1 system. To validate our calculated f/t PSA ratio, we also retrospectively measured fPSA using the Abbott AxSYM immunoassay system in archival pretreatment sera obtained between 1990 and 1997 from 362 men with clinically and biopsy-confirmed benign prostatic hyperplasia (n = 179) or CaP (n = 183). The diagnostic utility of tPSA, cPSA, and the calculated f/t PSA ratio was assessed using a contemporary test population consisting of sera prospectively collected between June 1999 and June 2000 from 3006 men who had recently undergone a systematic biopsy by urologists in clinical practices throughout the United States. This contemporary patient sample had biopsy diagnoses of either no evidence of malignancy (n = 1857) or CaP (n = 1149). All serum samples had tPSA values between 2.0 and 20.0 ng/mL.

RESULTS

The measured versus calculated f/t PSA ratios had a Pearson's correlation coefficient of 0.9130 in the retrospectively studied population of 362 men. The areas under the receiver operating characteristic curves (ROC-AUCs) for the measured and calculated f/t PSA ratios were indistinguishable (69.6% versus 69.2%, respectively). In the contemporary population (n = 3006), the ROC-AUC for tPSA, cPSA, and the calculated f/t PSA ratio was 52.2%, 53.9%, and 58.4%, respectively. We also compared the diagnostic performance using published cutoffs for tPSA (greater than 4.0 ng/mL), cPSA (greater than 3.8 ng/mL), and the f/t PSA ratio (greater than 15% and greater than 25%) in tPSA reflex ranges of 2 to 20 ng/mL and 2 to 10 ng/mL. We found that both cPSA and the f/t PSA ratio (greater than 25% cutoff) outperformed tPSA and yielded similar results in terms of biopsies spared and cancers missed.

CONCLUSIONS

The calculated f/t PSA ratio and cPSA perform equally well in terms of the improvement of specificity in the discrimination of benign disease and CaP. The f/t PSA ratio and cPSA provide clinical benefits over the use of tPSA alone, such as an increased sparing of unnecessary biopsies performed with a manageable degree of risk of delayed cancer detection.

Personality disorders

Some general recommendations can be made, collected from these subjective descriptions of personality types. Because determining an accurate psychiatric diagnosis is not the internist's aim, it is better for him or her to have a stance that generalizes to all patients, which can be refined as personality characteristics emerge. Tolerate the patient's affect (such as anger or anxiety), being firm and kind, rather than punitive or overinvested. Accept dependency and vulnerability. Accept and respect the underlying coping style. Understand that the patient's personality style is the best (and usually only) way he or she knows to have a relationship, including a relationship with the physician. Understand that personality traits additionally may have a function (e.g., to guard against anxiety or depression). Recognize that personality traits do not come in pure form. One personality trait is likely to blend into or overlap with other traits. Identify and treat any underlying symptom disorder, such as anxiety, depression, irritability, or thought disorder. Educate the patient clearly (and without patronizing) about medical illness. Document what was explained to the patient and how the patient responded, including dispassionate observations about behavior and emotional expression. Appreciate the patient's possible attachment to medical symptoms. Avoid arguments with patients who make unreasonable demands. Make timely judgments about whether or not to accede to a demand. When in doubt about a patient's honesty, give the patient the benefit of the doubt. Do not worry about being used because all patients use their physicians to some extent. Go to the limits of your tolerance for a patient's personality, but know your limits and refer to a colleague when you cannot work with the patient. Terminate an interaction and get help if there is a risk (or fear) of violence. Given the time it takes to manage the relationship and the psychiatric elements of treatment, a referral to a psychiatrist or other mental health professional often is wise if the patient will accept it. Include the mental health professional as part of the medical team. Although these various recommendations have been emphasized in connection with certain personality types, one can be flexible about their application in a variety of patients. It is important also to reiterate the limits of subjective descriptions. It is rare to find any of the aforementioned subjective descriptions in unmodified form; characteristics of more than one personality type usually appear in the same person. The descriptions are composites that provide a starting point for the physician. The physician should edit the composites based on experience with real patients. This article has described human characteristics and rough guidelines for helpful human responses and possible pharmacologic interventions. So equipped, the primary care physician may find it less troubling and more interesting to face the wide variation in human character.

Standardization, analytical validation, and quality control of intermediate endpoint biomarkers

Standardized processes should be used in the identification and development of intermediate endpoint biomarkers (IEB) for the prediction of patient-specific disease outcomes. Using our own experiences, we outline some of our standardized processes. Using computer-assisted image analysis, we developed a new biomarker of genetic instability, termed quantitative nuclear grade (QNG). The QNG biomarker is derived using nuclear images analyzed from the tumor areas of Feulgen-stained 5-microm biopsy or radical prostatectomy tissue sections. From the variances of 41 to 60 different nuclear size, shape, and chromatin organization features, a QNG solution is computed using either logistic regression or artificial neural networks. QNG can then be used as an input for models that solve for a patient-specific probability to accurately predict disease outcomes. Preoperatively, QNG predicted both the pathologic stage and progression of prostate cancer using biopsies (P <0.0001). Postoperatively, QNG proved extremely valuable in the prediction of biochemical progression using radical prostatectomy specimens with more than 10 years of follow-up (P <0.0001). We also demonstrate the identification of novel, differentially expressed, prostate cancer genes using RNA fingerprinting methods and the clinical utility of testing for these genes in both blood and tissue samples. Also illustrated is the improvement of serum biomarker performance by combining molecular forms of PSA with new biomarkers. In conclusion, the development of new IEBs requires planning based upon an understanding of the molecular pathogenesis of disease. IEB selection and clinical evaluation should employ standardized methods of testing and validation, followed by publication. QNG is 1 example of a new, highly predictive, IEB for prostate cancer that has been developed using these processes.

Genetic variability in susceptibility and response to toxicants

Everyone has a unique combination of polymorphic traits that modify susceptibility and response to drugs, chemicals and carcinogenic exposures. The metabolism of exogenous and endogenous chemical toxins may be modified by inherited and induced variation in CYP (P450), acetyltransferase (NAT) and glutathione S-transferase (GST) genes. We observe that specific 'at risk' genotypes for GSTM1 and NAT1/2 increase risk for bladder cancer among smokers. Genotypic and phenotypic variation in DNA repair may affect risk of somatic mutation and cancer. Variants of base excision and nucleotide excision repair genes (XRCC1 and XPD) appear to modify exposure-induced damage from cigarette smoke and radiation. We are currently engaged in discovering genetic variation in environmental response genes and determining if this variation has any effect on gene function or if it is associated with disease risk. These and other results are discussed in the context of evaluating inherited or acquired susceptibility risk factors for environmentally caused disease.

Apoptotic cell death induced by baccatin III, a precursor of paclitaxel, may occur without G(2)/M arrest

PURPOSE

Paclitaxel has been demonstrated to possess significant cell-killing activity in a variety of tumor cells by induction of apoptosis, but the mechanism by which paclitaxel leads to cell death and its relationship with mitotic arrest is not entirely clear. In this study, baccatin III, a synthetic precursor of paclitaxel, was used to analyze whether paclitaxel-induced apoptosis can be a separate event from microtubule bundling and G(2)/M arrest.

METHODS

Several different methods including DNA fragmentation, flow cytometric analyses, TdT-mediated dUTP nick end labeling (TUNEL) and time-lapse video microscopy were used to analyze apoptotic cell death induced by baccatin III and its possible correlation with cell cycle distribution.

RESULTS

Our results demonstrated that baccatin III could also cause apoptotic cell death in both BCap37 (a human breast cancer cell line) and KB cells (derived from human epidermoid carcinoma), but had less effect on microtubule bundling and G(2)/M arrest. Furthermore, we demonstrated that most apoptotic events induced by baccatin III were not coupled with G(2)/M arrest. Instead, these apoptotic events occurred predominantly in the cells in other phases of the cell cycle.

CONCLUSION

Baccatin III, which contains the core taxane ring, is the fundamental piece of paclitaxel structure. The finding of baccatin III-induced apoptosis independent of cell cycle arrest, on the one hand, implies that the core taxane ring may play a critical role in inducing cell death and, on the other hand, suggests that paclitaxel might induce apoptosis from other phases of the cell cycle by a similar mechanism.

Correlation of antepartum uterine activity and cervical change in twin gestation

OBJECTIVE

To determine the correlation between quantitative measurements of antepartum uterine activity and cervical change twin gestations.

METHODS

Forty women from our Twin Clinic constituted the study group. Participants had a cervical examination each week between 20 and 37 weeks gestation and a cervical score (CS) was calculated as follows: CS = cervical length (cms)-cervical dilation (cms) at the internal os. The women also performed blinded home uterine activity monitoring (HUAM) for a mean of 7.0 + 3.0 hrs/wk (+SD). Uterine activity was expressed as mean number of contractions/hour/week gestation based on the average of three independent reviewers. CS was determined by a single clinician unaware of the HUAM recordings. A significant change in the CS was defined as a reduction of at least 0.5 from the preceding week. Correlation coefficients were used to determine the association between uterine activity and change in the cervical score.

RESULTS

Twin pregnancy was characterized by a rise from 0.2 + .03 contractions/hr at 20 weeks to 3.2 + 2.4 contractions/hr at 37 weeks gestation. CS fell from a mean of 2.6 + 0.2 at 20 weeks to -2.1 + 0.9 at 37 weeks gestation. There was a significant negative correlation (-0.317, p < .0001) between increasing uterine activity and decreasing CS. There were significantly more (p < .002) contractions during the 7 days preceding a significant reduction in CS (3.3 + 3.5 contractions/hr) than when the CS was unchanged (1.6 +/- 1.5 contractions/hr).

CONCLUSIONS

In twin gestations, an increasing frequency of uterine contractions is strongly correlated with quantifiable cervical change between 20-37 weeks gestation. Persistent daytime contraction frequencies of > 3/hr represent a risk factor for cervical dilation and/or effacement.

Relationship between amine-carboxyboranes and TNF alpha for the regulation of cell growth in different tumor cell lines

The amine-carboxyboranes were shown to be synergistic with tumor necrosis factor alpha (TNF alpha) in cytotoxicity and inhibition of DNA synthesis in select types of cancer cells depending on the presence of a TNF alpha high affinity receptor on the membrane of the cell. Initially both TNF alpha and the amine-carboxyboranes reduce the influx of calcium but later cause a significant increase intracellularly. This influx is not linked with the amine-carboxyborane activating the calcitonin receptor in the tumor cells. Neither the agents nor TNF alpha directly inhibits DNA topoisomerase II activity but both did cause decreased phosphorylation of the enzyme by protein kinase C (PKC). The two agents caused synergistic inhibition. This event correlated with increased DNA protein linked breaks, DNA fragmentation and cell death. These protein linked breaks are additive with etoposide's effects but the latter agent's mechanism is different than phosphorylation of topoisomerase II. There was no evidence that the DNA fragmentation was caused by a calcium induced endonuclease enzyme in these cancer cells. The low-molecular weight amine-carboxyboranes appear to play an identical function as TNF alpha in its role to cause DNA breaks and fragmentation to cause apoptosis.

Superficial urothelial (umbrella) cells. A potential cause of abnormal DNA ploidy results in urine specimens

OBJECTIVE

To determine the DNA ploidy distribution in urothelial superficial (umbrella) cells and to assess the value of the image analysis operator's experience.

STUDY DESIGN

DNA ploidy was assessed in 12 cytologically negative bladder washes stained with Feulgen stain. All 12 cases were evaluated independently by three operators with different levels of cytopathology experience and different goals. Operator 1 (experienced) selected only nuclei of urothelial cells, avoiding nuclei of superficial cells; operator 2 (experienced) selected only nuclei of superficial cells; operator 3 (inexperienced) selected the largest and most-atypical-looking nuclei. Each operator measured a total of 100 nuclei per case.

RESULTS

Operator 1 found all cases to be diploid (97% of nuclei on average). Operators 2 and 3 showed a wide range of results. Almost half the nuclei (47%) analyzed by operator 2 were in the diploid region, a third (35%) were in the tetraploid region, and the remaining (18%) ones had a DNA index (DI) in the range of 1.2-1.8 or > 2.5. Operator 3 obtained the most abnormal results. Only 9% of the nuclei were diploid, while 37% were in the tetraploid region, 18% were in the hyperploid region, and 35% had a DI in the range of 1.2-1.8. Differences among results obtained by each operator were statistically significant.

CONCLUSION

The nuclei of superficial (umbrella) cells often have abnormal DNA content, which may cause abnormal DNA ploidy results in cytomorphologically normal bladder washes. Consequently, the nuclei of superficial cells should be avoided in the evaluation of urine samples. DNA analysis of urine specimens requires selection of nuclei only of deep urothelial cells by an experienced operator.

The Tetrahymena p80/p95 complex is required for proper telomere length maintenance and micronuclear genome stability

The telomerase enzyme adds simple sequence repeats to chromosome ends. Telomerases share two essential subunits, telomerase RNA and telomerase reverse transcriptase, that associate with species-specific proteins of predominantly unknown functions. The Tetrahymena p80/p95 complex can coimmunopurify active telomerase from cell extract, and recombinant p80/p95 can interact directly with telomerase RNA and single-stranded telomeric DNA in vitro. Here, we test the functions of p80/p95 in vivo. Surprisingly, telomerase RNA accumulation and telomerase activity in cell extract are unaffected by loss of the genes encoding p80/p95. However, in the absence of p80/p95, telomeres become elongated in both macronuclei and micronuclei. Micronuclear chromosome maintenance is also compromised. These findings suggest that p80/p95 functions to maintain appropriate telomere length and micronuclear genomic stability but does so in a manner different than previously anticipated.

Template definition by Tetrahymena telomerase reverse transcriptase

The ribonucleoprotein enzyme telomerase extends chromosome ends by copying a specific template sequence within its integral RNA component. An active recombinant telomerase RNP is minimally composed of this RNA and the telomerase reverse transcriptase (TERT) protein, which contains sequence motifs conserved among viral reverse transcriptases (RTs), flanked by N- and C-terminal extensions specific to TERTs. We have used site-directed mutagenesis to explore the roles of Tetrahymena TERT in determining features of telomerase activity in general and in establishing the boundaries and use of an internal RNA template in specific. We identify a new ciliate-specific motif in the TERT N-terminus required for template definition. Moreover, several residues in reverse transcriptase motifs 1, 2, A and D are critical for specific aspects of internal template use. Our results indicate that the unique specificity of telomerase activity is conferred to a reverse transcriptase active site by TERT residues both within and beyond the RT motif region.

Influence of season on the incidence of DNA hypodiploidy in urinary cytology

OBJECTIVE

This study was conducted to determine if an incidence of hypodiploidy in urinary specimens is related to seasonal temperature changes.

MATERIALS AND METHODS

DNA ploidy was evaluated on 10,846 urinary specimens fixed in buffered alcohol (MOPSO/NaCl + ETOH) and received over a one year period from numerous sites throughout the United States. The percentage of hypodiploid (DNA index < 0.8) cases was evaluated in each month. As a control, DNA ploidy results from 3, 755 prostate biopsies, fixed in 10% neutral buffered formalin, received during the winter and summer months of the same year, were evaluated.

RESULTS

The average percentage of hypodiploidy in cytologic specimens during the summer months was 19.6% compared to 5. 4% in the winter and early spring months (range: 20.6-4.8%). The average percentage of hypodiploid cells in histologic specimens was 0.8% for both the summer and winter months (range: 1.73-0.36%).

CONCLUSIONS

The rate of hypodiploidy in urinary cytology seems to be temperature related. The hypodiploidy rate of histologic specimens fixed in formalin shows no fluctuation with the seasons.

Children's exposure to magnetic fields produced by U.S. television sets used for viewing programs and playing video games

Two epidemiologic studies have reported increased risk of childhood leukemia associated with the length of time children watched television (TV) programs or played video games connected to TV sets. To evaluate magnetic field exposures resulting from these activities, the static, ELF, and VLF magnetic fields produced by 72 TV sets used by children to watch TV programs and 34 TV sets used to play video games were characterized in a field study conducted in Washington DC and its Maryland suburbs. The resulting TV-specific magnetic field data were combined with information collected through questionnaires to estimate the magnetic field exposure levels associated with TV watching and video game playing. The geometric means of the ELF and VLF exposure levels so calculated were 0.0091 and 0.0016 microT, respectively, for children watching TV programs and 0.023 and 0.0038 microT, respectively, for children playing video games. Geometric means of ambient ELF and VLF levels with TV sets turned off were 0.10 and 0.0027 microT, respectively. Summed over the ELF frequency range (6-3066 Hz), the exposure levels were small compared to ambient levels. However, in restricted ELF frequency ranges (120 Hz and 606-3066 Hz) and in the VLF band, TV exposure levels were comparable to or larger than normal ambient levels. Even so, the strengths of the 120 Hz or 606-3066 Hz components of TV fields were small relative to the overall ambient levels. Consequently, our results provide little support for a linkage between childhood leukemia and exposure to the ELF magnetic fields produced by TV sets. Our results do suggest that any future research on possible health effects of magnetic fields from television sets might focus on the VLF electric and magnetic fields produced by TV sets because of their enhanced ability relative to ELF fields to induce electric currents.

Analysis of repeated biopsy results within 1 year after a noncancer diagnosis

OBJECTIVES

A prostate biopsy data base derived from patients referred to private practice urologists was analyzed for the cancer diagnosis rates of the "initial" biopsy and the repeated biopsy performed within 1 year for those patients with a noncancer diagnosis.

METHODS

A retrospective analysis assessed 132,426 prostate biopsies received and processed by a single pathology laboratory between March 1994 and September 1998; none had had a previous biopsy processed at this laboratory. Prostate cancer was diagnosed in 50,521 of the patients (38.2%). The remaining 81,905 patients (61.8%) had a noncancer diagnosis of either no evidence of malignancy (NEM), high-grade prostatic intraepithelial neoplasia (HGPIN), small acinar glands suspicious for cancer (suspicious), or suspicious with HGPIN (Susp-HGPIN). We identified 6380 (7.8%) of these "noncancer" patients who underwent a repeated biopsy within 1 year.

RESULTS

The incidence of NEM, HGPIN, suspicious, and Susp-HGPIN biopsy diagnoses in the "noncancer" patients (81,905) was 55.3%, 3.7%, 2.5%, and 0.3%, respectively. The rate at which these "noncancer" patients (81,905) underwent a repeated biopsy was 4.8% for patients with a diagnosis of NEM, 26.6% for HGPIN, 40.4% for suspicious, and 47.5% for Susp-HGPIN. The overall cancer diagnosis rate in the repeated biopsy patient sample (6380) was 25.7%. When stratified by the initial biopsy diagnosis, the cancer diagnosis rate for the repeated biopsies was 19.8%, 22.6%, 40.0%, and 53.1%, for the patients with NEM, HGPIN, suspicious, and Susp-HGPIN, respectively. The repeated biopsy diagnosis rates did not vary dramatically when analyzed at 3-month intervals during the 1-year period. Also, a strong correlation (79%) was observed between the number of tissue samples obtained at the initial and repeated biopsy procedures. In a subset of patients with free and total prostate-specific antigen (PSA) results obtained before the repeated biopsy (n = 813), we were able to construct a multivariate logistic regression algorithm using the patients' age, initial biopsy diagnosis, total PSA, and free/total PSA ratio that could predict the likelihood of cancer on the repeated biopsy with an accuracy of 70%.

CONCLUSIONS

Men who have an initial noncancerous biopsy diagnosis remain at risk of prostate cancer, especially if the initial diagnosis was suspicious or Susp-HGPIN. These data suggest that the initial biopsy strategy needs to be improved and/or expanded to increase the overall cancer detection rate in the primary biopsy. In addition, combining factors such as the initial biopsy diagnosis, family history, digital rectal examination results, prostate gland volume, age, total PSA, and free/total PSA ratio could provide valuable information for predicting the likelihood of cancer.

EMG responses resulting from transient and steady-state dynamic isometric loading of the human biceps can be distinguished

In order to determine if differences in human muscle EMG response to steady-state (STD) dynamic load and transient (TRN) load could be detected, two distinct sinusoidal loads having identical amplitude and frequency were applied to the forearm, which was held in a fixed posture. The first condition used application of a constant amplitude, constant frequency, STD sinusoid, and the second condition used application of a single sinusoid of identical amplitude and frequency as the STD load. Time-domain parameters of Half-Mass, Dispersion Moments, Asymmetry Moments, Peak Ratio (ratio of cycle peak RMS EMG to cycle mean RMS EMG) and Time-to-Peak Ratio (ratio of cycle time to reach peak RMS EMG to cycle time duration) were used to quantify responses in the time domain. A single frequency-domain parameter, Dispersion Moments, was used to quantify responses in the frequency domain. Individual ANOVA's of the time domain parameter results revealed that p = 0.689 for Dispersion Moments, p = 0.111 for Half-Mass, p = 0.007 for Asymmetry Moments, p = 0.001 for Peak Ratio, and p = 0.001 for Time-to-Peak Ratio. The time-domain MANOVA and frequency-domain ANOVA revealed that EMG responses resulting from STD and TRN applied loads were statistically different in the time domain (p = 0.001), but not in the frequency domain (p = 0.810). Thus, use of Asymmetry Moments, Peak Ratio, and Time-to-Peak Ratio parameters can distinguish EMG responses to STD and TRN loads.

Genetically engineered neural networks for predicting prostate cancer progression after radical prostatectomy

OBJECTIVES

To use pathologic, morphometric, DNA ploidy, and clinical data to develop and test a genetically engineered neural network (GENN) for the prediction of biochemical (prostate-specific antigen [PSA]) progression after radical prostatectomy in a select group of men with clinically localized prostate cancer.

METHODS

Two hundred fourteen men who underwent anatomic radical retropubic prostatectomy for clinically localized prostate cancer were selected on the basis of adequate follow-up, pathologic criteria indicating an intermediate risk of progression, and availability of archival tissue. The median age was 58.9 years (range 40 to 87). Men with Gleason score 5 to 7 and clinical Stage T1b-T2c tumors were included. Follow-up was a median of 9.5 years. Three GENNs were developed using pathologic findings (Gleason score, extraprostatic extension, surgical margin status), age, quantitative nuclear grade (QNG), and DNA ploidy. These networks were developed using three randomly selected training (n = 136) and testing (n = 35) sets. Different variable subsets were compared for the ability to maximize prediction of progression. Both standard logistic regression and Cox regression analyses were used concurrently to calculate progression risk.

RESULTS

Biochemical (PSA) progression occurred in 84 men (40%), with a median time to progression of 48 months (range 1 to 168). GENN models were trained using inputs consisting of (a) pathologic features and patient age; (b) QNG and DNA ploidy; and (c) all variables combined. These GENN models achieved an average accuracy of 74.4%, 63.1 %, and 73.5%, respectively, for the prediction of progression in the training sets. In the testing sets, the three GENN models had an accuracy of 74.3%, 80.0%, and 78.1%, respectively.

CONCLUSIONS

The GENN models developed show promise in predicting progression in select groups of men after radical prostatectomy. Neural networks using QNG and DNA ploidy as input variables performed as well as networks using Gleason score and staging information. All GENN models were superior to logistic regression modeling and to Cox regression analysis in prediction of PSA progression. The development of models using improved input variables and imaging systems in larger, well-characterized patient groups with long-term follow-up is ongoing.

Free/total PSA ratio improves differentiation of benign and malignant disease of the prostate: critical analysis of two different test populations

OBJECTIVES

To evaluate the ability of free PSA (fPSA), total PSA (tPSA), and the free/total PSA (f/t PSA) ratio to differentiate between benign prostate disease (benign prostatic hyperplasia [BPH] and no evidence of malignancy [NEM]) and prostate cancer (CaP) using two different testing populations, and to compare predictive probabilities for the two test populations.

METHODS

One test population consisted of sera from 531 men with clinically well-defined and biopsy-confirmed BPH (n = 255) or CaP (n = 276), with tPSA values ranging from 2 to 20 ng/mL. All of these serum samples were retrospective and obtained from patients evaluated in academic settings before any treatment. A second test population consisted of a prospective analysis of sera obtained from 4870 men, collected by urologists throughout the United States and processed at a single pathology laboratory. All these patients had a systematic biopsy evaluated and diagnosed at the same pathology laboratory, with the diagnosis categorized as either NEM (n = 2961) or CaP (n = 1909). No additional information on concurrent disease or pre- or current treatment status was known for this test population. For both populations, two tPSA reflex range groups, 2 to 10 and 2 to 20 ng/mL, were evaluated.

RESULTS

Both test populations benefited from the application of either fPSA alone or the f/t PSA ratio to differentiate benign from malignant disease (t test P value less than 0.001). The receiver operating characteristic (ROC) curve for the f/t PSA ratio had an area under the curve (AUC) of 72% for n = 531 versus 63% for n = 4870, irrespective of the tPSA reflex range. Average fPSA values demonstrated a linear correlation to a range of tPSA concentrations for both test populations. Predictive probabilities (adjusted for established cancer prevalence rates in the academic population [n = 531]) calculated using f/t PSA ratios also demonstrated their value in contrasting the performance characteristics in the two test populations.

CONCLUSIONS

The fPSA and f/t PSA ratio improved the differentiation of benign disease and CaP in two different patient samples. The f/t PSA ratio demonstrated an increased sensitivity and specificity when applied to differentiate clinically well-defined BPH and CaP (n = 531). The differences in the results between the two test samples are probably attributable to the variability of the patient's disease and treatment status in the larger, less refined, community-based population. The use of predictive probabilities provides the opportunity to provide patient-specific cancer probabilities instead of using population-based specific single cutoffs.

Interleukin-8 serum levels in patients with benign prostatic hyperplasia and prostate cancer

OBJECTIVES

Using arbitrarily primed polymerase chain reaction (AP-PCR) ribonucleic acid (RNA) fingerprinting, we discovered a messenger RNA (mRNA) that encoded the cytokine interleukin-8 (IL-8) that was up-regulated in the peripheral blood leukocytes (PBLs) of patients with metastatic prostate cancer (CaP) compared with similar cells from healthy individuals. We compared the total prostate-specific antigen (PSA) levels, the free/total (f/t) PSA ratios, and the immunoreactive IL-8 serum concentrations in patients with either biopsy-confirmed benign prostatic hyperplasia (BPH) or CaP.

METHODS

The sera from 35 apparently healthy normal volunteers and 146 patients with biopsy-confirmed BPH and CaP obtained from two academic centers were retrospectively examined to determine the serum levels of IL-8, total PSA (tPSA), and the f/t PSA ratio. Logistic regression and trend analysis statistical methods were used to assess the results.

RESULTS

Normals (n = 35), BPH patients (n = 53), patients with clinical Stages A to C CaP (n = 81), and patients with metastatic CaP (n = 1 2) had mean levels of IL-8 of 6.8, 6.5, 15.6, and 27.8 pg/mL, respectively. The IL-8 serum concentrations correlated with increasing CaP stage and also differentiated BPH from clinical Stages A, B, C, or D CaP better than tPSA and performed similarly to the f/t PSA ratio. The combination of the IL-8 levels and f/t PSA ratios using multivariate logistic regression analysis distinguished BPH from Stages A, B, C, or D CaP or only Stages A and B with a receiver operating characteristic area under the curve of 89.8% and 87.5%, respectively (P <0.0001).

CONCLUSIONS

The IL-8 serum concentration in our clinically well-defined patient sample was independent of the f/t PSA ratio as a predictor of CaP. When test samples are controlled for extraneous clinical origin of inflammation or infection, the combination of the IL-8 and f/t PSA assay results may offer an improved approach for distinguishing BPH from CaP.