Efficient multi-keV X-ray sources from Ti-doped aerogel targets

We have measured the production of hnu approximately 4.7 keV x rays from low-density Ti-doped aerogel (rho approximately 3 mg/cc) targets at the OMEGA laser facility (University of Rochester), with the goal of maximizing x-ray output. Forty OMEGA beams (lambda(L)=0.351 microm) illuminated the two cylindrical faces of the target with a total power that ranged from 7 to 14 TW. The laser fully ionizes the target (n(e)/n(crit)</=0.1), and a laser-bleaching wave excites, supersonically, the high-Z emitter ions in the sample. Ti K-shell x-ray emission was spectrally resolved with a two-channel crystal spectrometer and also with a set of filtered aluminum x-ray diodes; both instruments provide absolute measurement of the multi-keV x-ray emission. We find between 40 and 260 J of output with 4.67</=hnu</=5.0 keV.

Magnetic fields produced by hand held hair dryers, stereo headsets, home sewing machines, and electric clocks

A recent epidemiologic study reported associations between leukemia risk in children and their personal use of television (TV) sets, hair dryers, and stereo headsets, and the prenatal use by their mothers of sewing machines. To provide exposure data to aid in the interpretation of these findings, extremely and very low frequency (ELF and VLF) magnetic fields produced by a sample of each type of appliance were characterized in a field study of volunteers conducted in Washington DC and its Maryland suburbs. Questionnaire data regarding children's or mothers' patterns of usage of each type of appliance were also collected. ELF magnetic fields measured 10 cm from the nozzles of hair dryers were elevated over the ambient by a mean factor of 17 when these devices were in use. Fields near headsets being used to listen to music were not distinguishable from ambient levels except at frequencies below and well above 60 Hz and, even then, field levels were < 0.01 microT. Home sewing machines produced ELF magnetic fields that were elevated by a factor of 2.8 over ambient levels at the front surfaces of the lower abdomens of mothers. Estimated mean daily times of usage of hair dryers, stereo headsets, and sewing machines were 2.6, 19, and 17 minutes, respectively. These data and previously published data on TV sets, do not provide a consistent picture of increased (or decreased) leukemia risk in relation to increasing peak or time weighted average (TWA) ELF magnetic field exposure. The data could, however, conceivably be compatible with some more complex biophysical model with unknown properties. Overall, the results of this study provide little evidence supporting the hypothesis that peak or TWA ELF magnetic fields produced by appliances are causally related to the risk of childhood leukemia in children.

Efficient multi-keV underdense laser-produced plasma radiators

Novel, efficient x-ray sources have been created by supersonically heating a large volume of Xe gas. A laser-induced bleaching wave quickly ionizes the high- Z gas, and the resulting plasma emits x rays. This method significantly improves the production of hard x rays because less energy is lost to kinetic energy and sub-keV x rays. The conversion efficiency of laser energy into L-shell radiation between 4-7 keV is measured at approximately 10%, an order of magnitude higher than efficiencies measured from solid disk targets. This higher flux enables material testing and backlighting in new regimes and scales well to future high-powered lasers.

Structural mechanisms of QacR induction and multidrug recognition

The Staphylococcus aureus multidrug binding protein QacR represses transcription of the qacA multidrug transporter gene and is induced by structurally diverse cationic lipophilic drugs. Here, we report the crystal structures of six QacR-drug complexes. Compared to the DNA bound structure, drug binding elicits a coil-to-helix transition that causes induction and creates an expansive multidrug-binding pocket, containing four glutamates and multiple aromatic and polar residues. These structures indicate the presence of separate but linked drug-binding sites within a single protein. This multisite drug-binding mechanism is consonant with studies on multidrug resistance transporters.

Optimizing femoral component rotation in total knee arthroplasty

Femoral component rotation is important in total knee arthroplasty to optimize patellofemoral and tibiofemoral kinematics. More recently, the epicondylar axis has been cited as the definitive landmark for femoral component rotation. However, there are few studies to support the validity of this rotational landmark and its effect on the patellofemoral and tibiofemoral articulations. In the current study, a total knee arthroplasty was done in 11 knees from cadavers. The knees were tested with various femoral component rotations from 5 degrees internal rotation to 5 degrees external rotation referenced to the epicondylar axis and to the posterior femoral condyles. Each knee acted as its own internal control. The knees were actively ranged from 0 degrees to 100 degrees by a force on the quadriceps tendon in an Oxford knee simulator. Three-dimensional kinematics of all three components were measured whereas a multiaxial transducer imbedded in the patella measured patellofemoral forces. Femoral component rotation parallel to the epicondylar axis resulted in the most normal patellar tracking and minimized patellofemoral shear forces early in flexion. This optimal rotation also minimized tibiofemoral wear motions. These beneficial effects of femoral rotation were less reproducibly related to the posterior condyles. Rotating the femoral component either internal or external to the epicondylar axis worsened knee function by increasing tibiofemoral wear motion and significantly worsening patellar tracking with increased shear forces early in flexion. Based on the current study, the femoral component should be rotationally aligned parallel to the epicondylar axis to avoid patellofemoral and tibiofemoral complications.

Quantitative nuclear grade (QNG): a new image analysis-based biomarker of clinically relevant nuclear structure alterations

This review addresses the potential clinical value of using quantitative nuclear morphometry information derived from computer-assisted image analysis for cancer detection and predicting outcomes such as tumor stage, recurrence, and progression. Today's imaging technology uses sophisticated hardware platforms coupled with powerful and user-friendly software packages that are commercially available as complete image analysis systems. There are many different mathematically derived nuclear morphometric descriptors (NMD's) (i.e. texture features) that can be calculated by these image analysis systems, but for the most part, these NMD's quantify nuclear size, shape, DNA content (ploidy), and chromatin organization (i.e. texture, both Markovian and non-Markovian) parameters. We have utilized commercially available image analysis systems and the NMD's calculated by these systems to create a mathematical solution, termed quantitative nuclear grade (QNG), for making clinical, diagnostic, and prognostic outcome predictions in both prostate and bladder cancer. A separate computational model is calculated for each outcome of interest using well-characterized and robust training, testing, and validation patient sample sets that adequately represent the selected population and clinical dilemma. A specific QNG solution may be calculated either by non-parametric statistical methods or non-linear mathematics employed by artificial neural networks (ANNs). The QNG solution, a measure of genomic instability, provides a unique independent variable to be used alone or to be included in an algorithm to assess a specific clinical outcome. This approach of customization of the nuclear morphometric descriptor (NMD) information through the calculation of a QNG solution mathematically adjusts for redundancy of features and reduces the complexity of the inputs used to create decision support tools for patient disease management. J. Cell. Biochem. Suppl. 35:151-157, 2000.

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.