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Oak Ridge National Laboratory (ORNL) has been engaged in the development and testing of a computational system that would use a grid of activation foil detectors to provide postdetonation forensic information from a nuclear device detonation. ORNL has developed a high-performance, three-dimensional (3-D) deterministic radiation transport code called Denovo. Denovo solves the multigroup discrete ordinates (S^) equations and can output 3-D data in a platform-independent format that can be efficiently analyzed using parallel, high-performance visualization tools. To evaluate the sensitivities and uncertainties associated with the deterministic computational method numerics, a numerical study on the New York City Times Square model was conducted using Denovo. In particular, the sensitivities and uncertainties associated with various components of the calculational method were systematically investigated, including (a) the Legendre polynomial ex- pansion order of the scattering cross sections, (b) the angular quadrature, (c) multigroup energy binning, (d) spatial mesh sizes, (e) the material compositions of the building models, (f) the composition of the foundations upon which the buildings rest (e.g., ground, concrete, or asphalt), and (g) the amount of detail included in the building models. Although Denovo may calculate the idealized model well, there may be uncertainty in the results because of slight departures of the above-named parameters from those used in the idealized calculations. Fluxes and activities at selected locations from perturbed calculations are compared with corresponding values from the idealized or base case to determine the sensitivities associated with specified parameter changes. Results indicate that uncertainties related to numerics can be controlled by using higher fidelity models, but more work is needed to control the uncertainties related to the model. [ABSTRACT FROM AUTHOR]

Background: Changes in cardiac output may occur during insufflation for laparoscopic procedures. However, there are limited data regarding its potential effects on cerebral oxygenation. Materials and Methods: Cerebral oxygenation (ScO2), end tidal CO2, heart rate, blood pressure and oxygen saturation by pulse oximetry were recorded every 5 minutes prior to insufflation, during insufflation and after desufflation. Minute ventilation was increased to maintain normocapnia and the depth of anesthesia was adjusted or fluids/phenylephrine administered to maintain the blood pressure within 20% of the baseline. Results: The cohort for the study included 70 adults for laparoscopic herniorrhaphy, gastric bypass or cholecystectomy. A total of 1004 ScO2 values were obtained during laparoscopy. The ScO2 decreased from the baseline in 758 of the1004 data points. The ScO2 was 0–9 less than the baseline in 47.8% of the values, 10–19 less than the baseline in 24.9% of the values and 20–29 less than the baseline in 26 values (2.6%). Eighty-two (8.2%) of the values were less than 80% of the baseline value, while 25 values (2.5%) were less than 75% of the baseline value. Twelve patients had at least one ScO2 value that was less than 80% of the baseline and 6 had at least one ScO2 value that was less than 75% of the baseline. Four patients of the cohort had ScO2 values less than 80% of the baseline for more than 50% of the laparoscopic procedure. Conclusions: Although relatively uncommon, significant changes in cerebral oxygenation do occur in some patients during insufflation for laparoscopic surgery. [ABSTRACT FROM AUTHOR]

Introduction The electrocardiogram (ECG) is one of the most important tools in diagnosing cardiac abnormalities, particularly arrhythmias and myocardial infarction. It is one of the certifiable competencies for final-year medical undergraduate students. We determined virtual reality's effectiveness in acquiring and retaining ECG interpretation skills among medical students compared to traditional teaching. Methods One hundred and forty students were randomized into two groups. Seventy-one students (immersion group) were trained using virtual reality simulation to acquire and retain interpretation skills of normal and abnormal ECG. Sixty-nine students (traditional group) were trained in the classroom using chalk and board. The primary outcome of change in acquiring knowledge of the interpretation of ECG was determined by comparing pre and post-test scores. The secondary outcome of retention of knowledge was determined by comparing pre-test and second post-test scores conducted after eight weeks of intervention. The p-value of <0.05 was considered significant. Results Out of 140 students, 50 (35.7%) were males and 90 (64.3%) were female. The mean age of the students was 22.1 (SD 1.1), with 69.3% of them between the ages of 21 and 22 years. Mean pre-test scores for the interpretation of normal ECG among immersion and traditional groups were 9.8 (SD 8.4) and 8.3 (SD 7.5), respectively, and post-test scores for the acquisition of knowledge were 24.3 (SD 5.5) and 24.8 (SD 6.3), respectively. The post-test scores for retention skills were 25.3 (SD 5.6) and 20.7 (SD 6.9) respectively (p<0.001). The mean pre-test scores for the interpretation of abnormal ECG of both groups were 7.0 (SD 6) and 8.3 (SD 6.6), respectively. Mean post-test scores for acquiring knowledge to interpret abnormal ECG were 23.5 (SD 6.2) and 17.7 (SD 9), respectively (p<0.001), and mean post-test scores for retention of interpretation skills of abnormal ECG were 19.2 (SD - 6.9) and 13.3 (SD 10.2) respectively (p=0.001). The pairwise comparison of the immersion group indicates that all the combinations that changed in score from the pre to post-intervention time points, from pre-to-retention time, and from the post-to-retention time were significant (p<0.001). Conclusion Virtual reality teaching had a better impact on acquiring and retaining the skill for interpreting normal and abnormal electrocardiograms., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Institute Ethics Committee of Pondicherry Institute of Medical Sciences issued approval sd. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Iqbal et al.)

Background: Patients with severe obesity (body mass index (BMI) greater than 35 kg x m(-2)) present difficulties for end-tidal carbon dioxide (FE'(CO(2))) monitoring. Previous studies suggest that transcutaneous (TC) carbon dioxide measurements could be valuable, so we compared FE' and TC measures with Pa(CO(2)) in severely obese patients during anaesthesia., Methods: We studied patients with severe obesity (BMI >or=40 kg x m(-2)) undergoing gastric bypass surgery. Carbon dioxide was measured with both FE' and TC devices. The difference between each measure (FE'(CO(2)) and TC-CO(2)) and the Pa(CO(2)) was averaged for each patient to provide one value, and data compared with a non-paired, two-way t-test, Fisher's exact test., Results: We studied 30 adults (aged 18-54 yr, mean 41, SD 8.0 yr; weight: 115-267 kg, mean 162, SD 35 kg). The absolute difference between the TC-CO(2) and Pa(CO(2)) was 0.2 (0.2) (mean, SD) kPa while the absolute difference between the FE'(CO(2)) and Pa(CO(2)) was 0.7 (0.4) kPa (P<0.0001). The bias and precision were +0.1 (0.3) kPa for TC vs arterial carbon dioxide and -0.7 (0.4) kPa for FE' vs arterial carbon dioxide., Conclusions: Transcutaneous carbon dioxide monitoring provides a better estimate of Pa(CO(2)) than FE'(CO(2)) in patients with severe obesity.

Purpose: To determine the impact of the neuromuscular blocking agent given for intubation on the duration of effect of multiple maintenance doses of pancuronium and rocuronium., Methods: Seventy-eight subjects were randomly assigned to receive one of four dosing combinations for intubation and neuromuscular maintenance: rocuronium for intubation and maintenance, rocuronium for intubation and pancuronium for maintenance, pancuronium for intubation and rocuronium for maintenance, or pancuronium for both. Each time that the first twitch response returned to 25% of the baseline value, the duration of the dose was determined and another maintenance dose was administered. The duration of action of the maintenance doses was compared between the groups., Results: Twitch suppression from the first maintenance dose was shorter for subjects who received rocuronium for both doses (Group RR) compared with that for subjects that received pancuronium (Groups PR & PP) as their intubation dose (17.6 vs 34 & 59.8 min, respectively, P < 0.05). Subjects who received rocuronium followed by pancuronium (Group RP) showed a shorter duration of twitch suppression after the first maintenance dose than the group that received pancuronium for both doses (Group PP) (21.3 vs 59.8 min, P < 0.05). By the third maintenance dose, the influence of the intubating dose on the maintenance dose duration had essentially diminished., Conclusions: For combinations of rocuronium and pancuronium, the duration of twitch suppression after a maintenance dose is only dependent on the first agent given for the first two maintenance doses administered.

Children with Duchenne's muscular dystrophy should not be exposed to succinylcholine because of the risk of hyperkalemic cardiac arrest and rhabdomyolysis. This report describes the response to rapacuronium bromide in two patients with Duchenne's muscular dystrophy. Both patients had a recovery index 2 times longer than that reported in children with normal neuromuscular function.

Prostate cancer remains one of the most significant challenges in clinical oncology, yet present therapies provide incomplete treatment in many cases. Innovative and practical gene therapy-based approaches will prove invaluable in filling the gaps that now exist in the treatment of localized and distant disease. Although multiple potential strategies have been developed, early clinical trials in prostate cancer gene therapy are now in the phase I/II stage of development. Novel preclinical and early clinical data should be considered optimistically, yet cautiously, as this field emerges from its infancy.

Background: Laparoscopic approach for hiatal hernia repair is relatively new. Information on the learning curve is limited., Methods: From January 1994 to September 1996, 280 patients underwent antireflux surgery at our institution. A laparoscopic repair was attempted in 60 patients (21.4%). There were 38 men and 22 women. Median age was 49 years (range 21 to 78 years). Indications for operation were gastroesophageal reflux in 59 patients and a large paraesophageal hernia in one. A Nissen fundoplication was performed in all patients; 53 (88.3%) had concomitant hiatal hernia repair., Results: In eight patients (13.3%) the operation was converted to an open procedure. Median operative time for the 52 patients who had laparoscopic repair was 215 minutes (range 104 to 320 minutes). There were no deaths. Complications occurred in five patients (9.6%). Median hospitalization was 2 days (range 1 to 5 days). Median operative time and median hospitalization were significantly longer in the first 26 patients than in the subsequent 25 patients (248 vs 203 minutes and 2 days vs 1 day, respectively; p = 0.03). Seven of the first 30 patients (23.3%) required laparotomy as compared with two of the second 30 (6.7%) (p = 0.07). Follow-up in the 51 patients who had laparoscopic fundoplication for reflux was complete in 50 (98.0%) and ranged from 7 to 38 months (median 13 months). Functional results were classified as excellent in 34 patients (68.0%), good in 6 (12.0%), fair in 7 (14.0%), and poor in 3 (6.0%). Three patients were reoperated on for recurrent reflux symptoms at 5, 5, and 11 months., Conclusions: We conclude that laparoscopic Nissen fundoplication can be performed safely. The operative time, hospitalization, and conversion rate to laparotomy are higher during the early part of the experience, but all are reduced after the learning curve.

In this paper, we investigate the ability of fuzzy to adapt the parameters of a pharmacokinetic and pharmacodynamic model-based controller for the delivery of the muscle relaxant pancuronium. The system uses the model to control the rate of drug delivery and uses feedback from a sensor which measures muscle relaxation level to adapt the model using fuzzy logic. The control strategy administers mini-bolus doses of pancuronium and modulates the magnitude and time interval between the bolus doses to maintain a patient's muscle relaxation within an allowable range specified by the user. Before each new dose is given, the fuzzy logic adaptation scheme uses the error between the predicted patient response and the measured response to adapt the model. The system was tested using computer simulation by varying the parameters of the model by 50% from their nominal values. It was also evaluated in a clinical trial of five patients undergoing surgical procedures lasting 5 h or longer.

Unlabelled: This study examined the concentration-related effects of sevoflurane and isoflurane on cerebral physiology and plasma inorganic fluoride concentrations. Middle cerebral artery flow velocity (Vmca), intracranial pressure (ICP), electroencephalogram (EEG) activity, and jugular bulb venous oxygen saturation were measured, and cerebral perfusion pressure (CPP) and estimated cerebral vascular resistance (CVRe) were calculated at baseline and at 0.5, 1.0, and 1.5 minimum alveolar anesthetic concentration (MAC) sevoflurane (n = 8) or isoflurane (n = 6). Mannitol 0.5-0.75 g/kg was given before dural incision, and blood was sampled for plasma inorganic fluoride during surgery and for up to 72 h postoperatively. Both sevoflurane and isoflurane decreased Vmca (to 31 +/- 12 - 36 +/- 14 cm/s, mean +/- SD), did not significantly alter ICP (13 +/- 9 - 15 +/- 11 mm Hg), and did not cause epileptiform EEG activity. With sevoflurane, decreased Vmca was accompanied by decreased CPP and unchanged CVRe at 0.5 MAC, and unchanged CPP and increased CVRe at 1.0 and 1.5 MAC. Plasma inorganic fluoride was 39.0 +/- 12.9 microM at the end of anesthesia (3.2 +/- 2.0 MAC hours) with sevoflurane, similar to the value (36.2 +/- 3.9 microM) for 3.7 +/- 0.1 MAC hours sevoflurane in patients not receiving mannitol. Decreased Vmca during sevoflurane presumably results from decreased cerebral metabolic rate, with CVRe changing secondarily in accord with CPP. Plasma inorganic fluoride does not seem to be altered by mannitol-induced diuresis., Implications: In neurosurgical patients, sevoflurane decreased middle cerebral artery flow velocity and caused no epileptiform electroencephalogram activity and no increase of intracranial pressure or plasma inorganic fluoride. These effects are suitable for neurosurgery. Two other possible effects of sevoflurane, i.e., increased cerebrospinal fluid volume and/or intracranial elastance, may not be suitable for neurosurgery and warrant further study.

Study Objectives: To compare the flexor hallucis brevis, which is responsible for flexion of the great toe, to the adductor pollicis as a site for monitoring the onset and recovery from neuromuscular block after an intubating dose of mivacurium chloride., Design: Prospective patient-controlled study., Setting: University teaching hospital., Patients: 10 ASA physical status I and II adults (age 18 to 55 years, 6 women, 4 men) scheduled for elective procedures requiring muscle relaxation for tracheal intubation., Measurements and Main Results: Patients were monitored at the adductor pollicis and the flexor hallucis brevis during the onset and recovery of neuromuscular block, which was administered to facilitate tracheal intubation. All subjects were given mivacurium 0.2 mg/kg over 30 seconds. Their train-of-four (TOF) response was continually monitored at both sites until the patient recovered from the intubating dose to a TOF ratio of 0.75. The time to onset of neuromuscular block, recovery of the first TOF response, and recovery to a TOF ratio of 0.75 were compared between the two monitoring sites using the Wilcoxon signed rank test. Following administration of the intubating dose of mivacurium, the loss of all twitch response occurred 1.2 minutes sooner at the adductor pollicis than at the flexor hallucis brevis (p < 0.02). Reappearance of the first twitch occurred 0.49 minutes slower at the adductor pollicis, although this difference was not statistically significant. The time to recovery to a TOF ratio of 0.75 at the adductor pollicis was slower by 2.83 minutes (p = 0.046)., Conclusions: Due to its lag behind the adductor pollicis, the flexor hallucis brevis is not a good indicator of when to intubate the trachea during the onset of neuromuscular block; however, its faster recovery may make it useful for monitoring deep neuromuscular block intraoperatively or during recovery when the adductor pollicis TOF response still shows complete blockade.

From January 1960 to June 1995, 185 patients underwent reoperation without esophageal resection for symptoms of recurrent gastroesophageal reflux disease. There were 102 men and 83 women. Median age was 58 years (range 20 to 84 years). A single previous antireflux operation had been performed in 147 patients, two in 33, and three in 5. The median interval between the reoperation and the previous operation was 36 months (range 1 to 291 months). Indications for reoperation were symptoms in 184 patients and a large paraesophageal hernia in one patients. The surgical approach was by means of a thoracotomy in 133 patients (71.9%), laparotomy in 27 (14.6%), and a thoracoabdominal incision in 25 (13.5%). A Nissen fundoplication was performed in 107 patients (57.8%), Belsey fundoplication in 47 (25.4%), truncal vagotomy and antrectomy with Roux-en-Y reconstruction in 17 (9.2%), anatomic hernia repair in 12 (6.5%), and Hill gastropexy in 2 (1.1%). A Collis gastroplasty was added to the fundoplication in 116 patients (62.7%), and a pyloroplasty was performed in 17 (9.2%). There was one operative death (0.5%). Complications occurred in 47 patients (25.4%). Median postoperative hospitalization was 9 days (range 5 to 58 days). Follow-up was complete in 156 patients (84.3%) and ranged from 3 to 283 months (median 44 months). Improvement occurred in 137 patients (87.8%). Functional results were classified as excellent in 65 patients (41.6%), good in 29 (18.6%), fair in 43 (27.6%), and poor in 19 (12.2%). No single operative approach or procedure proved to be functionally superior. We conclude that reoperation with esophageal preservation after a failed antireflux procedure will result in significant functional benefit and can be performed with low mortality and acceptable morbidity. The type of repair should be tailored to the individual patient.

Objective: We studied the accuracy and repeatability of train-of-four (TOF) ratio measurements made from a dynamic piezoelectric sensor that records movement of the thumb in response to ulnar nerve stimulation compared with an isometric mechanomyogram that measures force of contraction of the adductor pollicis., Methods: The study involved 10 patients whose level of neuromuscular block was held constant with an intravenous (IV) infusion of vecuronium bromide (0.4 to 1.0 micrograms/kg/min) (Organon, West Orange, NJ). The sensors were attached to opposite arms of each patient and simultaneous measurements of TOF ratio were taken at stimulation current levels of 50, 30, and 20 mA., Results: In comparison to the TOF ratio measured at the maximal stimulation current (50 mA), the TOF ratio from the piezo sensor showed a bias and standard deviation of -0.13 +/- 0.24 when the stimulation current was reduced to 30 mA. At 20 mA, the bias and standard deviation was -0.24 +/- 0.28. The TOF ratio from the mechanomyogram showed a bias and standard deviation of 0.01 +/- 0.07 at 30 mA and 0.0 +/- 0.20 at 20 mA when compared with measurements made when the stimulation current was 50 mA., Conclusions: Both sensors showed diminished repeatability in TOF measurement with decreasing stimulation current. The data indicate that neither sensor is reliable for general monitoring of neuromuscular block at submaximal current levels. However, the individual patient results showed that some patients could be monitored accurately with both sensors, even at the lowest stimulation current levels.

We have developed an easy-to-use, noninvasive piezoelectric sensor for quantitative monitoring of neuromuscular block. In a clinical evaluation with 23 patients, the piezo sensor was objectively compared to a mechanomyogram (MMG) for its ability to measure train-of-four (TOF) ratio from the adductor pollicis. After administration of succinylcholine (120-200 mg intravenously [i.v.]) to facilitate intubation, neuromuscular block was maintained with vecuronium by either boluses (1-2 mg i.v.) or an infusion (0.4-1.0 micrograms.kg-1.min-1 i.v.). Paired measurements were made of the TOF ratio from both sensors over a complete range of block levels (8%-100%). The difference in the TOF ratio measurement between the sensors showed a bias of 0.018. The SD of the difference between the sensors was +/- 0.129. The limits of agreement, which define the range in which 95% of the differences between the sensor measurements lie, were from -0.24 to 0.275. The sensitivity of the piezo sensor for detecting recovery based on a TOF ratio greater than 0.70 was shown to be 0.74 with specificity of 0.91. Under the conditions tested, the piezo sensor was not as accurate as the MMG. However, it was able to predict recovery of neuromuscular block with better accuracy than shown previously by manual evaluation of the TOF ratio, making it a reasonable, convenient alternative for quantitative monitoring of recovery from neuromuscular block.

Purpose: The authors performed percutaneous biliary ductal shave biopsy through an existing transhepatic biliary drainage tract with use of the Simpson atherectomy catheter. The technical feasibility, sensitivity, and complications of this endoluminal biopsy method were studied when used for diagnosis of biliary ductal and pancreatic neoplasm., Patients and Methods: Nineteen bile duct shave biopsies were performed in 18 patients with symptomatic biliary obstruction by using a 9-F Simpson directional atherectomy catheter. Seven of the 18 patients underwent nine negative percutaneous needle biopsies prior to undergoing percutaneous biliary drainage. Results of previous transcatheter brush biopsies performed through the transhepatic tract were negative in all patients., Results: A histologic diagnosis was obtained in 15 of the 19 procedures (sensitivity, 0.79) and included cholangiocarcinoma (n = 7), pancreatic carcinoma (n = 5), metastatic carcinoma (n = 2), and primary sclerosing cholangitis (n = 1). Two complications occurred in the 19 procedures (10.5%), both transient but significant hemorrhage, one of which necessitated transfusion., Conclusions: Percutaneous biliary ductal shave biopsy with the Simpson atherectomy catheter can be performed successfully through the transhepatic approach and is a sensitive endoluminal biopsy technique, particularly in patients with tumors of the biliary tree that are not diagnosed by means of percutaneous needle biopsy or endoscopic methods. Disadvantages of this method include the high cost of the device and risk of hemorrhage. Atherectomy shave biopsy should be used cautiously and only after more conventional biopsy methods have been employed.

To determine whether endotracheal tube cuff pressure increases significantly with surgical retraction and cervical spine distraction during anterior cervical spine surgery with Caspar instrumentation, we prospectively studied 10 patients undergoing this procedure. The tracheas of all patients were intubated with a Mallinckrodt Hi-Lo endotracheal tube. Tracheal tube cuff pressures measured with a transducer system were 42.4 mm Hg +/- 7.0 mm Hg (SEM) after intubation and cuff inflation. Air was removed from the endotracheal tube cuff until the trachea was just barely sealed at a cuff pressure of 15.2 mm Hg +/- 1.6 mm Hg. The endotracheal tube cuff pressure was readjusted to "just-seal" pressure before the surgeons introduced the Caspar instrumentation. The cuff pressure with traction and distraction was 43.2 mm Hg +/- 5.0 mm Hg. This pressure was significantly increased from the "just-seal" pressure, and from the cuff pressure after instrumentation was discontinued (9.8 mm Hg +/- 2.3 mm Hg). We conclude that anterior cervical spine surgery with Caspar instrumentation is associated with a significant increase in endotracheal tube cuff pressure.

After a relatively mild course of uncontrollable shocks, two distinct groups of rats can be defined in terms of their performance in learning to escape from a controllable stressor. Response-deficient (RD) rats do not learn to terminate the controllable stressor, whereas nondeficient (ND) rats learn this response as readily as do untreated control rats. The current studies were designed to determine the neurochemical correlates of the behavioral differences between these groups of rats. The major findings concerned postsynaptic beta-adrenergic effects in the hippocampus of RD rats. These included an up-regulation of beta-adrenergic receptors and, in parallel experiments, an increase in the sensitivity of adenylyl cyclase to stimulation by norepinephrine. There was no difference in brain levels of catecholamines between the three groups of rats. A statistically significant increase in levels of 5-hydroxytryptamine was noted in the hippocampus and hypothalamus of RD rats as compared to levels in ND rats, but no significant differences were measured between groups of rats in terms of S1 or S2 serotonergic receptor binding. These results implicate both beta-adrenergic and serotonergic mechanisms in the behavioral deficit caused by uncontrollable shock.

Distinguishing seminomatous from nonseminomatous testicular neoplasms preoperatively is useful because treatment of these two tumors types is different. We evaluated whether the distinction could be made with MR imaging in six patients with seminomatous and nine patients with nonseminomatous testicular tumors (including teratoma, teratocarcinoma, embryonal cell, and choriocarcinoma). The MR diagnoses, which were obtained from the formal reports of the MR studies done and interpreted before orchiectomy, were compared with the pathologic diagnosis. The distinction between the two tumor types on MR images was based on the signal intensity and heterogeneity of the lesion. We also retrospectively compared the MR findings with tissue histology. MR scans in nonseminomatous tumors showed a marked heterogeneous mix of signals, with some regions less intense and others more intense than normal testicular tissue on both proton-density and T2-weighted images. The typical background signal was nearly equal to normal testicular tissue. The tumors also had a dark band at their periphery that correlated with a fibrous tumor capsule on histologic examination. In contradistinction, seminomatous tumors were isointense with testis on proton-density images and consistently hypointense and relatively homogeneous on T2-weighted images. These tumors typically lacked a capsule on MR images. One lesion, only 3 mm in diameter, could not be characterized on MR images because of limitations in spatial and contrast resolution. In 13 of the 14 lesions that could be characterized, the histologic type was predicted correctly on the basis of the MR appearance. The one error occurred in a patient with pure seminoma. Although the MR appearance of the lesion was otherwise similar to the other seminomas, the lesion had a single focus of bright signal that was due to hemorrhage. This focus was interpreted incorrectly as a nonseminomatous element. Our findings in this small series of patients suggest that MR imaging can be used to distinguish seminomatous from nonseminomatous testicular tumors.