Comparison of outcomes in patients with and without neurologic diseases undergoing holmium laser enucleation of the prostate

INTRODUCTION

We aimed to compare holmium laser enucleation of the prostate (HoLEP) outcomes in patients with and without neurologic diseases (ND).

METHODS

A prospectively maintained database of patients undergoing HoLEP from January 2021 to April 2022 was reviewed. The following NDs were included: diabetes-related neuropathy/neurogenic bladder, Parkinson's disease, dementia, cerebrovascular accident, multiple sclerosis, traumatic brain injury, transient ischemic attack, brain/spinal tumors, myasthenia gravis, spinal cord injury, and other. Statistical analysis was performed using t-tests, Chi-squared, and binomial tests (p<0.05).

RESULTS

A total of 118 ND patients were identified with 135 different neurologic diseases. ND patients were more likely to have indwelling catheters (57% vs. 39%, p=0.012) and urinary tract infections (UTIs) preoperatively (32% vs. 19%, p=0.002). Postoperatively, ND patients were more likely to fail initial trial of void (20% vs. 8.1%, p<0.001) and experience an episode of acute urinary retention (16% vs. 8.5%, p=0.024). Within 90 days postoperative, the overall complication rate was higher in the ND group (26% vs. 13%, p=0.001). Within the ND group, 30/118 (25%) had ≥1 UTI within 90 days preoperative, which decreased to 10/118 (8.7%) 90 days postoperative (p<0.001). At last followup (mean 6.7 months [ND] vs. 5.4 months [non-ND], p=0.03), four patients (4.4%) in the ND group required persistent catheter/clean intermittent catheterization compared to none in the non-ND group (p=0.002).

CONCLUSIONS

Patients with ND undergoing HoLEP are more likely to experience postoperative retention and higher complication rates compared to non-ND patients. While UTI rates are higher in this population, HoLEP significantly reduced three-month UTI and catheterization rates.

Intradetrusor OnabotulinumtoxinA Injections at the Time of Holmium Laser Enucleation of the Prostate for Men with Severe Storage Symptoms

Introduction: Intradetrusor onabotulinumtoxinA (OTA) injection is a well-established treatment option for refractory overactive bladder; however, its use at the time of holmium laser enucleation of the prostate (HoLEP) for men with bladder outlet obstruction (BOO) and severe storage symptoms has not been previously reported. Materials and Methods: We retrospectively identified men with BOO and severe storage symptoms who underwent treatment with 200 U of intradetrusor OTA (Botox®) at the time of HoLEP. Patients were propensity score matched to a cohort of HoLEP-only patients based on age, Michigan Incontinence Symptom Index (M-ISI) score, preoperative urinary retention, urge incontinence, and prostate size. Perioperative, postoperative, and patient-reported outcomes were examined between groups. Results: We identified 82 men who underwent HoLEP, including 41 patients in the OTA group and 41 patients in the control group. There was no difference in operative times (59 minutes OTA vs 55 minutes control, p = 0.2), rates of same-day trial of void (TOV) (92% OTA vs 94% control, p = 0.7), or rates of same-day discharge (88% OTA vs 85% control, p = 0.6) between groups. There was no difference in temporary postoperative urinary retention (7% OTA vs 2% control, p = 0.3) between groups. Patients who received OTA injections had a significant reduction in their incontinence scores at 3-month follow-up (M-ISI -8, interquartile range [IQR]: -13 to 0, p < 0.001), whereas control patients did not (M-ISI -5, IQR: -8 to -1, p = 0.2). There was no difference in rates of 90-day complications between groups (OTA 10% vs control 5%, p = 0.7). Conclusions: Intradetrusor OTA at the time of HoLEP is safe and is associated with improved urinary incontinence scores and AUA Symptom Score. Rates of same-day discharge and same-day TOV after HoLEP were not affected by OTA. These findings support the role of OTA as an adjunct to surgical intervention in men with incontinence in the presence of BOO.

Using Competing Risk of Mortality to Inform the Transition from Prostate Cancer Active Surveillance to Watchful Waiting

BACKGROUND

For men on active surveillance (AS) for prostate cancer (PCa), disease progression and age-related changes in health may influence decisions about pursuing curative treatment.

OBJECTIVE

To evaluate the predicted PCa and non-PCa mortality at the time of reclassification among men on AS, to identify clinical criteria for considering a transition from AS to watchful waiting (WW).

DESIGN, SETTING, AND PARTICIPANTS

Patients enrolled in a large AS program who experienced biopsy grade reclassification (Gleason grade increase) were retrospectively examined. All patients who had complete documentation of medical comorbidities at reclassification were included.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

A validated model was used to assess 10- and 15-yr untreated PCa and non-PCa mortalities based on patient comorbidities and PCa clinical characteristics. We compared the ratio of predicted PCa mortality with predicted non-PCa mortality ("predicted mortality ratio") and divided patients into four risk tiers based on this ratio: (1) tier 1 (ratio: >0.33), (2) tier 2 (ratio 0.33-0.20), (3) tier 3 (ratio 0.20-0.10), and (4) tier 4 (ratio <0.10).

RESULTS AND LIMITATIONS

Of the 344 men who were reclassified, 98 (28%) were in risk tier 1, 85 (25%) in tier 2, 93 (27%) in tier 3, and 68 (20%) in tier 4 for 10-yr mortality. Fifteen-year risk tiers were distributed similarly. The 23 (6.7%) men who met the "transition triad" (age >75 yr, Charlson Comorbidity Index >3, and grade group ≤2) had a 14-fold higher non-PCa mortality risk and a lower predicted mortality ratio than those who did not (0.07 vs 0.23, p < 0.001). The primary limitations of our study included its retrospective nature and the use of predicted mortalities.

CONCLUSIONS

At reclassification, nearly half of patients had a more than five-fold and one in five patients had a more than ten-fold higher risk of non-PCa death than patients having a risk of untreated PCa death. Despite a more significant cancer diagnosis, a transition to WW for older men with multiple comorbidities and grade group <3 PCa should be considered.

PATIENT SUMMARY

Men with favorable-risk prostate cancer and life expectancy of >10 yr are often enrolled in active surveillance, which entails delay of curative treatment until there is evidence of more aggressive disease. We examined a group of men on active surveillance who developed more aggressive disease, and found, nevertheless, that the majority of these men continued to have a dramatically higher risk of death from non-prostate cancer causes than from prostate cancer based on a risk prediction tool. For men older than 75 yr, who have multiple medical conditions and who do not have higher-grade cancer, it may be reasonable to reconsider the need for curative treatment given the low risk of death from prostate cancer compared with the risk of death from other causes.

Patient and in-hospital predictors of post-discharge opioid utilization: Individualizing prescribing after radical prostatectomy based on the ORIOLES initiative

OBJECTIVE

Judicious opioid stewardship would match each patient's prescription to their true medical necessity. However, most prescribing paradigms apply preset quantities and clinical judgment without objective data to predict individual use. We evaluated individual patient and in-hospital parameters as predictors of post-discharge opioid utilization after radical prostatectomy (RP) to provide evidence-based guidance for individualized prescribing.

METHODS

A prospective cohort of patients who underwent open or robotic RP were followed in the Opioid Reduction Intervention for Open, Laparoscopic, and Endoscopic Surgery (ORIOLES) initiative. Baseline demographics, in-hospital parameters, and inpatient and post-discharge pain medication utilization were tabulated. Opioid medications were converted to oral morphine equivalents (OMEQ). Predictive factors for post-discharge opioid utilization were analyzed by univariable and multivariable linear regression, adjusting for opioid reduction interventions performed in ORIOLES.

RESULTS

Of 443 patients, 102 underwent open and 341 underwent robotic RP. The factors most strongly associated with post-discharge opioid utilization included inpatient opioid utilization in the final 12 hours before discharge (+39.6 post-discharge OMEQ if inpatient OMEQ was >15 vs. 0), maximum patient-reported pain score (range 0-10) in the 12 hours before discharge (+27.6 OMEQ for pain score ≥6 vs. ≤1), preoperative opioid use (+76.2 OMEQ), and body mass index (BMI; +1.4 OMEQ per 1 kg/m²). A final predictive calculator to guide post-discharge opioid prescribing was constructed.

CONCLUSIONS

Following RP, inpatient opioid use, patient-reported pain scores, prior opioid use, and BMI are correlated with post-discharge opioid utilization. These data can help guide individualized opioid prescribing to reduce risks of both overprescribing and underprescribing.

Volume-outcome relationships for kidney cancer may be driven by disparities and patient risk

PURPOSE

Provider and hospital factors influence healthcare quality, but data are lacking to assess their impact on renal cancer surgery. We aimed to assess factors related to surgeon and hospital volume and study their impact on 30-day outcomes after radical nephrectomy.

MATERIALS AND METHODS

Renal surgery data were abstracted from Maryland's Health Service Cost Review Commission from 2000 to 2018. Patients ≤18 years old, without a diagnosis of renal cancer, and concurrently receiving another major surgery were excluded. Volume categories were derived from the mean annual cases distribution. Multivariable logistic and linear regression models assessed the association of volume on length of stay, intensive care days, cost, 30-day mortality, readmission, and complications.

RESULTS

7,950 surgeries, completed by 573 surgeons at 48 hospitals, were included. Demographic, surgical, and admission characteristics differed between groups. Radical nephrectomies performed by low volume surgeons demonstrated increased post-operative complication frequency, mortality frequency, length of stay, and days spent in intensive care relative to other groups. However, after logistic regression adjusting for clinical risk and socioeconomic factors, only increased length of stay and ICU days remained associated with lower surgeon volume. Similarly, after adjusted logistic regression, hospital volume was not associated with the studied outcomes.

CONCLUSIONS

Surgeons and hospitals differ in regards to patient demographic and clinical factors. Barriers exist regarding access to high-volume care, and thus some volume-outcome trends may be driven predominantly by disparities and case mix.

A micro-costing analysis of outpatient flexible cystoscopy: implications for adoption of single-use flexible cystoscopes

PURPOSE

To evaluate the total cost of outpatient flexible cystoscopy associated with reusable device purchase, maintenance, and reprocessing, and to assess potential cost benefits of single-use flexible cystoscopes.

METHODS

Cost data regarding the purchasing, maintaining, and reprocessing of reusable flexible cystoscopes were collected using a micro-costing approach at a high-volume outpatient urology clinic. We estimated the costs to facilities with a range of annual procedure volumes (1000-3000) performed with a fleet of cystoscopes ranging from 10 to 25. We also compared the total cost per double-J ureteral stent removal procedure performed using single-use flexible cystoscopes versus reusable devices.

RESULTS

The cost associated with reusable flexible cystoscopes ranged from $105 to $224 per procedure depending on the annual procedure volume and cystoscopes available. As a practice became more efficient by increasing the ratio of procedures performed to cystoscopes in the fleet, the proportion of the total cost due to cystoscope reprocessing increased from 22 to 46%. For ureteral stent removal procedures, the total cost per procedure using reusable cystoscopes (range $165-$1469) was higher than that using single-use devices ($244-$420), unless the annual procedure volume was sufficiently high relative to the number of reusable cystoscopes in the fleet (≥ 350 for a practice with ten reusable cystoscopes, ≥ 700 for one with 20 devices).

CONCLUSION

The cost of reprocessing reusable cystoscopes represents a large fraction of the total cost per procedure, especially for high-volume facilities. It may be economical to adopt single-use cystoscopes specifically for stent removal procedures, especially for lower-volume facilities.

Systematic Evaluation of Smartphone Applications for the Medical Management of Nephrolithiasis

Objective: The aim of this study was to comprehensively evaluate the quality of patient-oriented, mobile health applications (apps) available for medical management of kidney stone disease (KSD). Materials and Methods: A systematic search was performed to identify apps from the Apple and Google Play app stores. Eligible apps were divided into two categories: (1) fluid apps and (2) dietary apps. Descriptive characteristics were summarized and app quality was independently evaluated on the basis of technical quality, usability, clinical value, and privacy/security. The validated Mobile App Rating Scale (MARS) was the backbone for the evaluation framework. Results: In total, 31 apps (18 fluid apps and 13 dietary apps) were included. Fluid apps outscore dietary apps in all dimensions of MARS quality. All but one fluid app exceeded the minimum acceptable MARS score of 3.0 vs 46% of dietary management apps. Dietary apps feature less functionality and most are limited to noninteractive informational content. While most data-capturing apps provide a privacy policy and ensure that security measures are taken to protect user identity, only 36% offer users choice or consent for secondary use of their data after data have already been collected. Overall, only one app has undergone any form of real-world clinical investigation. Conclusions: Fluid management apps outperform dietary apps in technical quality, usability, and clinical value at the cost of greater privacy/security risks. Despite not being targeted to patients with KSD, they are higher in most quality measures and offer greater functionality to support long-term disease management compared with dietary apps.

Assessing quality of care in the diagnosis and treatment of early-stage testicular cancer: A critical review and summary

OBJECTIVE

To review the current literature on quality of care in the diagnosis and management of early-stage testicular cancer.

METHODS

PubMed, Embase, and the Cochrane Central Register of Controlled Trials were searched for studies on quality of care in testicular cancer diagnosis and management from January 1980 to August 2018. Major overlapping themes related to quality of care in the diagnosis and management of TGCT were identified and evidence related to these themes were abstracted.

EVIDENCE

62 studies were included in the review. A number of themes were identified including (1) trends in survival and outcomes, (2) management patterns, (3) adherence to evidence-based clinical guidelines, (4) delays in care, (5) treatment complications and toxicities, (6) sociodemographic factors, (7) volume of patients treated, (8) gaps in provider knowledge and medical errors, and (9) multidisciplinary approaches to care.

EVIDENCE SUMMARY

As survival for patients with testicular cancer improves, there has been a greater emphasis on other components of quality of care, such as reducing treatment toxicity and minimizing delays in diagnosis. Efforts to meet these goals include encouragement of adherence to evidence-based guidelines, greater utilization of surveillance, and promotion of multidisciplinary team-based care. Although outcomes have improved, social determinants of health, such as insurance status, race, and geographical residence all may influence survival and cancer-related outcomes. Additionally, qualitative review indicates patients who receive care at high-volume institutions appear to experience better outcomes than those treated at smaller centers.

CONCLUSIONS

As outcomes and survival improve for patients with testicular cancer, quality of care has become an important consideration. Future avenues of research on this topic include identifying an appropriate balance between centralization of care and expanding access to underserved areas, minimizing delays in care, ensuring greater adherence to clinical guidelines, and addressing sociodemographic and racial disparities in outcomes.

Contemporary Assessment of the Most Cited Clinical, Basic Science, and Guidelines Papers in Urology: A Reference for Urology Journal Club

OBJECTIVE

To perform bibliometric analysis of the top cited articles in urology as a guide for journal club article selection.

METHODS

Bibliometric citation analysis was performed using Scopus. Tables illustrating the top cited clinical, basic science, and guidelines/position statements papers were constructed. Linear regression was used to determine association between h-index and number of citations.

RESULTS

A total of 3,188,861 publications from 1788 to 2020 were analyzed. The top 100 cited clinical papers from 1788 to 2020, top 100 cited contemporary clinical papers from 2000 to 2020, top 25 cited basic science papers, and the top 25 cited guidelines/position statement papers were reported. Median number of citations in the top 100 cited clinical papers was 1463 (interquartile range 1186-1821). Memorial Sloan Kettering Cancer Center (12), Johns Hopkins University (6), and Harvard University (6) contributed the most top cited clinical papers in urology. Urologic oncology was the most represented subspecialty in both clinical (75%) and basic science (96%) papers. First author and last author h-index were found to correlate with the number paper citations in the top 100 cited clinical papers from 1788 to 2020 (first author β:5.3, P= .003, last author β:4.5, P= .03). Only 7% of the most cited clinical papers in urology were from female first authors, which was not statistically significantly different from those reported in prior publications published in 2009 and 2013.

CONCLUSION

Contemporary citation analysis of indexed manuscripts in urology may serve as a valuable educational tool for urologists and trainees.

Testis-sparing Surgery: A Single Institution Experience

OBJECTIVE

To demonstrate the safety and efficacy of testis-sparing surgery (TSS) in 2 specific circumstances: small, nonpalpable masses suspected to be benign and masses suspicious for germ cell tumor in a solitary or functionally solitary testicle or bilateral disease.

METHODS

Our institutional review board-approved testicular cancer registry was reviewed for men who underwent inguinal exploration with intent for TSS (2013-2020). The attempted TSS and completed TSS groups were evaluated for differences using Student's t test for normally-distributed variables, chi-squared and Fisher's exact tests for proportions, and Wilcoxon rank-sum test for nonparametric variables.

RESULTS

TSS was attempted in 28 patients and completed in 14. TSS was completed only if intraoperative frozen section demonstrated benign disease, except for 1 patient with stage I seminoma and solitary testicle. Sensitivity and specificity of frozen section analysis was 100% and 93%, respectively. There were no significant differences in demographics between attempted vs completed TSS cohorts. Median tumor size was significantly smaller in the completed TSS cohort (1.0 cm vs 1.7 cm, P = .03). In patients with unilateral masses without history of testis cancer, the testis was successfully spared in 9 of 22 cases (41%). In patients with bilateral disease or germ cell tumor in solitary testis, the testis was spared in 5 of 6 cases (83%). At a median follow up of 12.2 months, all patients were alive, and 27 of 28 had no evidence of disease (96%).

CONCLUSION

TSS is safe and effective for small, benign masses and in the setting of bilateral disease or tumor in a solitary testis.

Evidence-based quality and accuracy of YouTube videos about nephrolithiasis

OBJECTIVE

To assess the quality and accuracy of online videos about the medical management of nephrolithiasis.

MATERIALS AND METHODS

To evaluate trends in online interest, we first examined the frequency of worldwide YouTube searches for 'kidney stones' from 2015 to 2020. We then queried YouTube with terms related to symptoms and treatment of kidney stones and analysed English-language videos with >5000 views. Quality was assessed using the validated DISCERN instrument. Evidence-based content analysis of video content and viewer comments was performed.

RESULTS

Online searches for videos about kidney stones doubled between 2015 and 2019 (P < 0.001). We analysed 102 videos with a median (range) number of views of 46 539 (5024-3 631 322). The mean (sd) DISCERN score was 3.0 (1.4) out of 5, indicating 'moderate' quality; scores were significantly higher for the 21 videos (21%) authored by academic hospitals (mean 3.7 vs 2.8, P = 0.02). Inaccurate or non-evidence-based claims were identified in 23 videos (23%); none of the videos authored by academic institutions contained inaccurate claims. Videos with inaccurate statements had more than double the viewer engagement (viewer-generated comments, 'thumbs up' and 'thumbs down' ratings) compared to videos without inaccuracies (P < 0.001). Among viewer comments, 43 videos (43%) included comments with inaccurate or non-evidence-based claims, and a large majority (82 videos, 80%) had 'chatbot' recommendations.

CONCLUSIONS

Interest in YouTube videos about nephrolithiasis has doubled since 2015. While highly viewed videos vary widely in quality and accuracy, videos produced by academic hospitals have significantly fewer inaccurate claims. Given the high prevalence of stone disease and poor-quality videos, patients should be directed to evidence-based content online.

A Comparative Analysis of Surgical Scar Cosmesis Based on Operative Approach for Radical Prostatectomy

Objective: Recent developments in minimally invasive approaches to radical prostatectomy (RP) for localized prostate cancer have improved oncological outcomes, but may also affect surgical scar cosmesis, an important component of survivorship and patient quality of life. Our aim was to evaluate surgical scar appearance based on operative approach to RP using a validated tool for evaluating psychosocial impact of scar appearance. Methods: Men between the ages of 45 and 80 were surveyed on an online crowdsourcing platform. Well-healed surgical scars after open, multiport (MP) robotic (transperitoneal and extraperitoneal), and single-port (SP) robotic RP were digitally rendered on stock photos to control for patient appearance. Respondents evaluated images using the SCAR-Q© psychosocial impact domain. Additionally, different RP scars were ranked by appearance and assigned 10-point appearance scores. Results: Two hundred thirty-four surveys were included for analysis (completion rate 84.2%). The median age was 54 (IQR: 49-61) and 35% (85/234) had previous abdominal surgery, of which 45% (38/85) was robotic or laparoscopic. SP scars had better psychosocial impact scores (median 100 out of 100 vs 69 and 58) than MP and open, respectively (both p < 0.001). SP scars were consistently ranked higher by appearance (median rank 1, IQR: 1-1) than MP (2, IQR: 2-3) and open (3, IQR: 3-4) (p < 0.001). SP without assistant port had the highest appearance score (median 9, IQR: 7-9) among all scars (p < 0.001). Conclusion: SP scars scored highest on psychosocial impact and were consistently ranked highest in appearance. These findings may be informative for optimizing both cosmetic appearance and quality of life for patients undergoing RP.

A prospective comparative study of routine versus deferred pelvic drain placement after radical prostatectomy: impact on complications and opioid use

PURPOSE

To evaluate the association of post-RP drain placement with post-operative complications and opioid use at a high-volume institution.

METHODS

A prospective, comparative cohort study of patients undergoing robot-assisted or open RP was conducted. Patients for two surgeons did not routinely receive pelvic drains ("No Drain" arm), while the remainder routinely placed drains ("Drain" arm). Outcomes were evaluated at 30 days including Clavien-Dindo complications and opioid use. Intention-to-treat primary analysis and additional secondary analyses were performed using appropriate statistical tests and logistic regression.

RESULTS

Of 498 total patients, 144 (28.9%) were in the No Drain arm (all robot-assisted) and 354 (71.1%) in the Drain arm. In the No Drain arm, 19 (13.2%) intraoperatively were chosen to receive drains. There was no difference in overall or major (Clavien ≥ 3) complications between groups (p = 0.2 and 0.4, respectively). Drain deferral did not predict complications on multivariable analysis adjusted for age, BMI, comorbidities, clinical risk, surgical approach, operating time, lymphadenectomy, and number of nodes removed [OR 0.61, 95% CI 0.34-1.11, p = 0.10]; nor did it predict symptomatic fluid collection, adjusting for lymphadenectomy and nodes removed [OR 1.14, 95% CI 0.43-3.60, p = 0.8]. Drain deferral did not decrease opioid use (p = 0.5). Per protocol analysis and restriction to robot-assisted cases demonstrated similar results.

CONCLUSION

There was no difference in adverse events, complications, symptomatic collections, or opioid use with deferral of routine drain placement after RP. Experienced surgeons may safely defer drain placement in the majority of robot-assisted RP cases.

Comparison of Perioperative and Pathologic Outcomes Between Single-port and Standard Robot-assisted Radical Prostatectomy: An Analysis of a High-volume Center and the Pooled World Experience

OBJECTIVE

To perform an early comparative study of outcomes between single-port and robot-assisted laparoscopic radical prostatectomy (SP-RALRP) and standard RALRP at our institution and pooled analysis of series to date.

PATIENTS AND METHODS

Patients with organ-confined prostate cancer undergoing SP-RALRP at a high-volume institution were identified retrospectively along with reported SP-RALRP series to date. Data were compared to a contemporary prospective cohort of men undergoing standard RALRP. Patient demographics, perioperative and postoperative data, and complications categorized by the Clavien-Dindo system were compared for the institutional and pooled SP-RALRP cohorts to standard RALRP.

RESULTS

A total of 208 SP-RALRP cases were identified (26 from our institution) and compared to 376 standard RALRP cases. In the institutional analysis, there was no difference in operative time, length of stay, overall complications (15.4% vs 17.3%, P= 1.0), major (Clavien ≥III) complications (3.8% vs 3.7%, P = .6), inpatient opioid use, or patient-reported pain scores; median estimated blood loss (100 mL vs 150 mL, P = .02) and number of lymph nodes removed (5.5 vs 9, P = .002) were lower for SP-RALRP. In the pooled analysis, 208 patients receiving SP-RALRP had similar estimated blood loss and complication rates but fewer lymph nodes removed (P = .02) and marginally longer operating time (+16 minutes, P = .01) compared to standard RALRP. The difference in rate of positive surgical margins was not statistically significant (31.3% vs 24.5%, P = .08).

CONCLUSION

Based on an early experience with SP-RALRP at a high-volume center and a pooled analysis of SP series to date, perioperative and pathologic outcomes appear nearly equivalent compared to standard RALRP.

Complications after open and robot-assisted radical prostatectomy and association with postoperative opioid use: an analysis of data from the PREVENTER trial

OBJECTIVE

To evaluate perioperative complications for open radical prostatectomy (ORP) and robot-assisted RP (RARP) for patients enrolled in the PREvention of VENous ThromboEmbolism Following Radical Prostatectomy (PREVENTER; ClinicalTrials.gov Identifier: NCT03006562) trial, to determine predictors and impact on opioid consumption.

PATIENTS AND METHODS

A prospective cohort of 500 patients undergoing ORP and RARP was followed to determine rates of complications and opioid use. Complications were classified 30 days after RP using the Clavien-Dindo system. Patient characteristics and outcomes were compared using appropriate statistical tests. Logistic and linear regressions were performed to identify predictors of complications and evaluate the relationship between complications and postoperative opioid use.

RESULTS

A total of 124 (24.8%) men underwent ORP and 376 (75.2%) RARP, with 418 (83.6%) receiving pelvic lymph node dissection (PLND). While 83 patients (16.6%) had complications, only 19 (3.8%) were major (Clavien-Dindo Grade ≥III), with no differences by surgical approach. PLND (odds ratio [OR] 2.96, 95% confidence interval [CI] 1.25-8.71; P = 0.03) and Stage pT3b (OR 2.76, 95% CI 1.23-6.00;P = 0.01) were the only predictors of complications after controlling for potential confounders. Patients who had complications had greater inpatient (P = 0.02) and outpatient (P = 0.005) opioid use, which persisted after controlling for patient-reported pain, attending surgeon variation, surgical approach, and undergoing PLND (inpatient β:77.2, 95% CI 17.9-136.5,P = 0.03; and outpatient β:21.9, 95% CI 4.7-39.1,P = 0.01).

CONCLUSION

In an analysis of prospectively collected data, overall and major complications rates did not differ by surgical approach. Patients receiving PLND and with Stage pT3b disease had more complications. Complications were independently associated with higher inpatient and outpatient postoperative opioid use.

Evaluating Urology Residency Applications: What Matters Most and What Comes Next?

PURPOSE OF REVIEW

In light of the announcement that the United States Medical Licensing Examination Step 1 exam will transition to pass/fail reporting, we reviewed recent literature on evaluating residency applicants with a focus on identifying objective measurements of applicant potential.

RECENT FINDINGS

References from attending urologists, Step 1 scores, overall academic performance, and research publications are among the most important criteria used to assess applicants. There has been a substantial increase in the average number of applications submitted per applicant, with both applicants and residency directors indicating support for a cap on the number of applications that may be submitted. Additionally, there are increasing efforts to promote diversity with the goal of improving care and representation in urology. Despite progress in standardizing interview protocols, inappropriate questioning remains an issue. Opportunities to improve residency application include promoting diversity, enforcing prohibitions of illegal practices, limiting application numbers, and finding more transparent and equitable screening measures to replace Step 1.

Detection of a Meckel's diverticulum on PSMA PET/CT: A case report

Meckel's diverticulum is the most common congenital malformation of the gastrointestinal tract. In this report, we present a patient with a Meckel's diverticulum that was incidentally discovered on prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) imaging performed for prostate cancer staging. We discuss hypotheses for why the Meckel's diverticulum showed high uptake of PSMA-targeted radiotracer and the clinical implications of this finding.

Evaluation of Apparent Diffusion Coefficient as a Predictor of Grade Reclassification in Men on Active Surveillance for Prostate Cancer

OBJECTIVE

To evaluate the association between apparent diffusion coefficient (ADC) on initial multiparametric MRI (mpMRI) and biopsy grade reclassification (GR) to grade group (GG) ≥2 prostate cancer (CaP) in men on active surveillance (AS) with GG 1 CaP.

METHODS

We retrospectively identified 242 AS patients with reported ADC values on their initial mpMRI. ADC value from the index lesion was assessed as an independent predictor of GR using a Cox model. To ease clinical interpretation, we used a log-rank test to establish an ADC cutoff of 1128 × 10^-6 mm²/s for Kaplan-Meier analysis.

RESULTS

Of the 242 men, 70 underwent GR following initial mpMRI, of which 26 (37%) had GR at the index lesion. There was no significant difference in the median interval between biopsies for men with and without GR (P >.9). Men with GR had significantly lower median ADC than those without GR (P = .01). In multivariable analysis adjusting for age, prostate-specific antigen density, and National Comprehensive Cancer Network risk group, a 100-unit decrease in ADC was associated with a 12% increase in the risk of GR (HR = 1.12, 95% CI: 1.01-1.22, P = .03). Two- and 4-year rates of freedom from GR were significantly lower for men with ADC <1128 × 10^-6 mm²/s vs ADC ≥1128 × 10^-6 mm²/s (62% and 42% vs 78% and 68%, respectively; P <.001).

CONCLUSION

For AS patients, lower ADC on initial mpMRI index lesion is associated with increased risk of GR to GG ≥2 CaP and would be a useful component of multivariable risk prediction tools.

Identification of small molecule inhibitors of beta-amyloid cytotoxicity through a cell-based high-throughput screening platform

Calpain activation is hypothesized to be an early occurrence in the sequence of events resulting in neurodegeneration, as well as in the signaling pathways linking extracellular accumulation of beta-amyloid (Abeta) peptides and intracellular formation of neurofibrillary tangles. In an effort to identify small molecules that prevent neurodegeneration in Alzheimer's disease by early intervention in the cell death cascade, a cell-based assay in differentiated Sh-SY5Y cells was developed using calpain activity as a read-out for the early stages of death in cells exposed to extracellular Abeta. This assay was optimized for high-throughput screening, and a library of approximately 120,000 compounds was tested. It was expected that the compounds identified as calpain inhibitors would include those that act directly on the enzyme and those that prevented calpain activation by blocking an upstream step in the pathway. In fact, of the compounds that inhibited calpain activation by Abeta with IC(50) values of <10 microM and showed little or no toxicity at concentrations up to 30 microM, none inhibit the calpain enzyme directly.

Disruption of Caenorhabditis elegans muscle structure and function caused by mutation of troponin I

Caenorhabditis elegans strains mutant for the unc-27 gene show abnormal locomotion and muscle structure. Experiments revealed that unc-27 is one of four C. elegans troponin I genes and that three mutant alleles truncate the protein: recessive and presumed null allele e155 terminates after nine codons; semidominant su142sd eliminates the inhibitory and C-terminal regions; and semidominant su195sd abbreviates the extreme C-terminus. Assays of in vivo muscular performance at high and low loads indicated that su142sd is most deleterious, with e155 least and su195sd intermediate. Microscopy revealed in mutant muscle a prevalent disorder of dense body positioning and a less well defined sarcomeric structure, with small islands of thin filaments interspersed within the overlap region of A bands and even within the H zone. The mutants' rigid paralysis and sarcomeric disarray are consistent with unregulated contraction of the sarcomeres, in which small portions of each myofibril shorten irregularly and independently of one another, thereby distorting the disposition of filaments. The exacerbated deficits of su142sd worms are compatible with involvement in vivo of the N-terminal portion of troponin I in enhancing force production, and the severe impairment associated with su195sd highlights importance of the extreme C-terminus in the protein's inhibitory function.

Expression of human Wiskott-Aldrich syndrome protein in patients' cells leads to partial correction of a phenotypic abnormality of cell surface glycoproteins

The Wiskott-Aldrich syndrome (WAS) is an uncommon X-linked recessive disease characterized by thrombocytopenia, eczema and immunodeficiency. The biochemical defect of this disorder primarily affects cells derived from bone marrow. To understand better the molecular mechanisms underlying this disease and to evaluate the possibility of correcting the genetic defects in hematopoietic cells, a Moloney murine leukemia virus (MoMLV)- based retroviral vector carrying a functional Wiskott-Aldrich syndrome protein (WASp) cDNA driven by an SV40 promoter (LNS-WASp) was constructed. A packaging cell line containing this vector produced a stable level of WAS protein and maintained a high titer of viral output. Epstein-Barr virus (EBV)-transformed B lymphoblastoid cell lines (B-LCL) from WAS patients, which lack expression of the WAS protein, were transduced by the LNS-WASp retroviral vector and showed expression of WASp by Western blot. Analysis of the O-glycan pattern on cell surface glycoproteins from WAS patients' B-LCL showed an altered glycosylation pattern, due to increased activity of beta-1, 6-N-acetylglucosaminyltransferase (C2GnT). Transduction by the retroviral vector carrying the functional WASp cDNA partially restored the abnormal glycosylation pattern, and was accompanied by a decreasing C2GnT activity. These findings imply a functional linkage between the WAS protein and the expression of the glycosyltransferase involved in the O-glycosylation, and also suggest a potential gene therapy via transferring a functional WASp cDNA into hematopoietic cells for Wiskott-Aldrich syndrome. Gene Therapy (2000) 7, 314-320.

Retrovirus-mediated transfer of the human alpha-L-iduronidase cDNA into human hematopoietic progenitor cells leads to correction in trans of Hurler fibroblasts

Hurler syndrome (mucopolysaccharidosis IH or MPS IH) is a congenital mucopolysaccharide storage disorder resulting from a genetic deficiency of alpha-L-iduronidase (IDUA), which is required for lysosomal degradation of glycosaminoglycans heparan sulfate and dermatan sulfate. Even though histocompatible bone marrow transplantation has been applied for the treatment of Hurler syndrome, gene therapy via autologous bone marrow transplantation (BMT) may be more beneficial for this disease. Two retroviral vectors containing a full-length human IDUA cDNA were constructed using Moloney murine leukemia virus (MoMLV)-based vector backbones. High-titer vector-producing clones containing the L-HuID-SN and MFG-HuID retroviral vectors were established. The efficiency of gene transfer into primitive human CD34+ hematopoietic cells using both retroviral vectors is in the range of 18-23%. The level of enzyme expression in transduced primary bone marrow cells was increased 40- to 50-fold compared with that of sham-transduced cells. Enzyme produced by the progeny of the transduced human CD34+ cells carrying IDUA cDNA corrected Hurler fibroblasts via mannose-6-phosphate receptors. These findings suggest that genetically modified hematopoietic progenitor cells can potentially be useful for gene therapy of Hurler syndrome.

Individual variation in recombination among human males

Studies of recombination between the markers D6S291 and D6S109 in individuals by sperm typing provide direct evidence for significant variation in recombination among humans. A statistically significant difference in the recombination fraction (range 5.1%-11.2%) was detected among five donors. This variation could reflect polymorphisms in genes affecting recombination or in chromosome structure. Ignoring this variability in studies designed to examine the relationship between physical and genetic distances could lead to incorrect inferences. Individual variation in recombination makes it difficult to predict the recombination fraction for an interval in any particular individual. This could be important in certain genetic counseling situations.

Talin requires beta-integrin, but not vinculin, for its assembly into focal adhesion-like structures in the nematode Caenorhabditis elegans

In cultured cells, the 230-kDa protein talin is found at discrete plasma membrane foci known as focal adhesions, sites that anchor the intracellular actin cytoskeleton to the extracellular matrix. The regulated assembly of focal adhesions influences the direction of cell migrations or the reorientation of cell shapes. Biochemical studies of talin have shown that it binds to the proteins integrin, vinculin, and actin in vitro. To understand the function of talin in vivo and to correlate its in vitro and in vivo biochemical properties, various genetic approaches have been adopted. With the intention of using genetics in the study of talin, we identified a homologue to mouse talin in a genetic model system, the nematode Caenorhabditis elegans. C. elegans talin is 39% identical and 59% similar to mouse talin. In wild-type adult C. elegans, talin colocalizes with integrin, vinculin, and alpha-actinin in the focal adhesion-like structures found in the body-wall muscle. By examining the organization of talin in two different C. elegans mutant strains that do not make either beta-integrin or vinculin, we were able to determine that talin does not require vinculin for its initial organization at the membrane, but that it depends critically on the presence of integrin for its initial assembly at membrane foci.

New HLA-DPB1 alleles generated by interallelic gene conversion detected by analysis of sperm

The rate at which allelic diversity at the HLA loci evolves has been the subject of considerable controversy. The patchwork pattern of sequence polymorphism within the second exon of the HLA class II loci, particularly in the DPB1 locus, may have been generated by segmental exchange (gene conversion). We have analysed the frequency of variant DPB1 sequences that have been created by interallelic gene conversion in the germline by screening pools of sperm using PCR amplification and oligonucleotide probe typing. Our results indicate that about 1/10,000 sperm represents a new DPB1 sequence generated by short tracts of segmental exchange (gene conversion) within the second exon, suggesting that interallelic gene conversion may have an important role in generating the extensive allelic diversity at the HLA loci.

Analysis of mutational changes at the HLA locus in single human sperm

Using a simple and efficient single sperm PCR and direct sequencing method, we screened for HLA-DPB1 gene mutations that may give rise to new alleles at this highly polymorphic locus. More than 800 single sperm were studied from a heterozygous individual whose two alleles carried 16 nucleotide sequence differences clustered in six polymorphic regions. A potential microgene conversion event was detected. Unrepaired heteroduplex DNA similar to that which gives rise to postmeiotic segregation events in yeast was observed in three cases. Control experiments also revealed unusual sperm from DPB1 homozygous individuals. The data may help explain allelic diversity in the MHC and suggest that a possible source of human mosaicism may be incomplete DNA mismatch repair during gametogenesis.

Substitutions and deletions in the cytoplasmic domain of the phagocytic receptor Fc gamma RIIA: effect on receptor tyrosine phosphorylation and phagocytosis

Fc gamma RIIA in the absence of other Fc receptors or receptor subunits induces the ingestion of IgG-coated cells. The cytoplasmic domain of Fc gamma RIIA contains two Y-x-x-L sequences similar to those in other Ig gene family receptors plus an additional tyrosine residue not in a Y-x-x-L motif. Upon cross-linking, Fc gamma RIIA is phosphorylated on tyrosine and the cytoplasmic tyrosines, Y275 (Y1), Y282 (Y2), and Y298 (Y3), may be important for its phagocytic activity. Because COS-1 cells can serve as a model for examining molecular structures involved in phagocytosis, substitutions and deletions were introduced into the cytoplasmic domain of Fc gamma RIIA and examined in COS-1 cell transfectants for their effects on phagocytosis and tyrosine phosphorylation. Disruption of a single cytoplasmic Y-x-x-L motif by substitution of tyrosine Y2 or Y3 by phenylalanine or by removing the threonine and leucine residues within the motif inhibited phagocytosis 50% to 65%. Tyrosine phosphorylation of Fc gamma RIIA also was inhibited, although to a greater extent by the substitution of Y3 than of Y2. Replacement of the N-terminal first cytoplasmic domain tyrosine, Y1, which is not within a typical Y-x-x-L, by itself did not inhibit phagocytosis, but replacement of Y1 in mutants lacking Y2 or Y3 virtually eliminated phagocytic activity and receptor tyrosine phosphorylation. Thus, at least two cytoplasmic tyrosines, including at least one typical single Y-x-x-L motif, are required for phagocytosis by Fc gamma RIIA. The data suggest that there is a close but not a simple relationship between phosphorylation of the Fc gamma RIIA cytoplasmic tyrosines and Fc gamma RIIA-mediated phagocytosis. Y3 appears to be particularly important because its removal by truncation or replacement with phenylalanine inhibits both tyrosine phosphorylation and phagocytosis in parallel. Alterations in the 12 residue proline-containing sequence between the two Y-x-x-L motifs also reduced phagocytic activity and tyrosine phosphorylation. Thus, the specific structure of the Fc gamma RIIA cytoplasmic domain accounts for its ability to stimulate phagocytosis in the absence of other subunits.

The high affinity Fc gamma receptor (CD64) induces phagocytosis in the absence of its cytoplasmic domain: the gamma subunit of Fc gamma RIIIA imparts phagocytic function to Fc gamma RI

The high affinity Fc gamma receptor, Fc gamma RI, is unique among the three classes of macrophage Fc gamma receptors not only in its affinity for IgG, but also in the structure of its cytoplasmic domain. Fc gamma RIIA and the gamma subunit of Fc gamma RIIIA have tyrosine-containing motifs within their cytoplasmic domains that are phosphorylated when crosslinked and that are required for phagocytosis by COS-1 cell transfectants. In contrast to these other Fc gamma receptors, Fc gamma RI does not contain cytoplasmic tyrosines and does not induce phagocytosis in COS-1 transfectants. We transfected wild-type (WT) and mutant (MT) Fc gamma RI lacking the cytoplasmic domain into COS-1 cells and murine macrophages and assessed phagocytosis using IgG-coated red blood cells (RBCs) and RBCs conjugated with Fab anti-human Fc gamma RI monoclonal antibody (mAb). Fc gamma RI, in contrast to Fc gamma RIIA, did not induce phagocytosis in COS cells. However, both WT and MT Fc gamma RI induced phagocytosis in murine macrophages, and phagocytosis was inhibited by the tyrosine kinase inhibitor tyrphostin 23. Human monocytes also phagocytosed Fc gamma RI-targeted RBCs, and activation of Fc gamma RI on monocytes with Fab anti-Fc gamma RI induced phosphorylation of Fc gamma RII on tyrosine residues. However, Fc gamma RI activation of Fc gamma RI-Fc gamma RIIA COS-1 cotransfectants did not induce tyrosine phosphorylation of Fc gamma RIIA, and coexpression of Fc gamma RI and Fc gamma RIIA in COS cells did not confer Fc gamma RI phagocytic capability. In contrast, coexpression in COS-1 cells of Fc gamma RI with the gamma subunit of Fc gamma RIIIA conferred phagocytic function to both Fc gamma RI and the MT Fc gamma RI lacking the cytoplasmic domain. Thus, Fc gamma RI does not require its cytoplasmic domain to mediate a phagocytic signal and interacts with the gamma subunit of Fc gamma RIIIA to induce phagocytosis.

Insertion of cytoplasmic tyrosine sequences into the nonphagocytic receptor Fc gamma RIIB establishes phagocytic function

Receptors for the Fc domain of IgG on cells of hematopoietic lineage perform important functions, including stimulation of the ingestion of IgG-coated cells. In examining the function of Fc gamma receptor isoforms by transfection into COS-1 cells, we have observed that Fc gamma RIIA induces the binding and phagocytosis of IgG-sensitized RBCs (EA) and that transfected COS-1 cells can serve as a model for examining the molecular structures involved in mediating a phagocytic signal. We now report that COS-1 cell transfectants expressing the isoforms Fc gamma RIIB1 and Fc gamma RIIB2 and a Fc gamma RIIA mutant without a cytoplasmic tail efficiently bind EA but do not mediate their phagocytosis. Furthermore, wild-type Fc gamma RIIA, but not Fc gamma RIIB1 or Fc gamma RBII2, was phosphorylated on tyrosine upon receptor activation. Tyrphostin 23, which alters tyrosine kinase activity, inhibited the phagocytosis of EA and reduced the phosphorylation of Fc gamma RIIA on tyrosine. Fc gamma RIIB1 and Fc gamma RIIB2 contain one copy of the cytoplasmic sequence YXXL/I implicated in signal transduction, whereas Fc gamma RIIA contains two copies. We therefore inserted YXXL/I sequences at different sites in Fc gamma RIIB2. Low levels of phagocytosis were observed in a Fc gamma RIIB2 mutant bearing the Fc gamma RIIA sequence YMTL and higher levels of phagocytosis were observed in a second Fc gamma RIIB2 mutant that contained both the upstream YMTL and an additional downstream tyrosine-containing motif. Activation of this mutant receptor also induced receptor tyrosine phosphorylation. Thus, these studies indicate that both the number and placement of YXXL sequences in the cytoplasmic domain of the Fc gamma RII receptor family affect both receptor tyrosine phosphorylation and phagocytic competence.

Fc gamma RIIA-mediated phagocytosis and receptor phosphorylation in cells deficient in the protein tyrosine kinase Src

In the absence of other Fc receptors, stimulation of Fc gamma RIIA induces receptor phosphorylation and phagocytosis of immunoglobulin G (IgG)-coated cells. In vitro, Fc gamma RIIA is phosphorylated by the Src-related tyrosine kinase (SRTK) Src. Therefore, we investigated whether fibroblasts transfected with Fc gamma RIIA mediate phagocytosis of IgG-coated cells and whether Src is required for Fc gamma RIIA phosphorylation and for phagocytosis in vivo. Activation of Fc gamma RIIA in a fibroblast cell line deficient in Src kinase resulted in phosphorylation of the receptor on tyrosine. In addition, Fc gamma RIIA-mediated phagocytosis was observed in these fibroblasts in both the presence and absence of Src. In the presence of Src, however, phagocytosis of IgG-coated cells was more efficient. The data indicate that the SRTK Src is not required for Fc gamma RIIA phosphorylation or for Fc gamma RIIA-mediated phagocytosis in these cells. In vitro kinase assays demonstrated that the SRTK Fyn also is able to phosphorylate Fc gamma RIIA. Thus, Fc gamma RIIA can be phosphorylated by more than one tyrosine kinase in vitro. The data suggest that there may be shared functions among some intracellular kinases in receptor phosphorylation.

Adhesive ligand binding to integrin alpha IIb beta 3 stimulates tyrosine phosphorylation of novel protein substrates before phosphorylation of pp125FAK

Tyrosine phosphorylation of multiple platelet proteins is stimulated by thrombin and other agonists that cause platelet aggregation and secretion. The phosphorylation of a subset of these proteins, including a protein tyrosine kinase, pp125FAK, is dependent on the platelet aggregation that follows fibrinogen binding to integrin alpha IIb beta 3. In this report, we examined whether fibrinogen binding, per se, triggers a process of tyrosine phosphorylation in the absence of exogenous agonists. Binding of soluble fibrinogen was induced with Fab fragments of an anti-beta 3 antibody (anti-LIBS6) that directly exposes the fibrinogen binding site in alpha IIb beta3. Proteins of 50-68 KD and 140 kD became phosphorylated on tyrosine residues in a fibrinogen-dependent manner. This response did not require prostaglandin synthesis, an increase in cytosolic free calcium, platelet aggregation or granule secretion, nor was it associated with tyrosine phosphorylation of pp125FAK. Tyrosine phosphorylation of the 50-68-kD and 140-kD proteins was also observed when (a) fibrinogen binding was stimulated by agonists such as epinephrine, ADP, or thrombin instead of by anti-LIBS6; (b) fragment X, a dimeric plasmin-derived fragment of fibrinogen was used instead of fibrinogen; or (c) alpha IIb beta 3 complexes were cross-linked by antibodies, even in the absence of fibrinogen. In contrast, no tyrosine phosphorylation was observed when the ligand consisted of monomeric cell recognition peptides derived from fibrinogen (RGDS or gamma 400-411). Fibrinogen-dependent tyrosine phosphorylation was inhibited by cytochalasin D. These studies demonstrate that fibrinogen binding to alpha IIb beta 3 initiates a process of tyrosine phosphorylation that precedes platelet aggregation and the phosphorylation of pp125FAK. This reaction may depend on the oligomerization of integrin receptors and on the state of actin polymerization, organizational processes that may juxtapose tyrosine kinases with their substrates.

Extension of base mispairs by Taq DNA polymerase: implications for single nucleotide discrimination in PCR

Thermus aquaticus (Taq) DNA polymerase was used to measure the extension efficiency for all configurations of matched and mismatched base pairs at template-primer 3'-termini. The transition mispairs, A(primer).C, C.A, G.T, and T.G were extended 10(-3) to 10(-4)-fold less efficiently than their correctly paired counterparts. Relative efficiencies for extending transversion mispairs were 10(-4) to 10(-5) for T.C and T.T, about 10(-6) for A.A, and less than 10(-6) for G.A, A.G, G.G and C.C. The transversion mispair C(primer).T was extended with high efficiency, about 10(-2) compared to a correct A.T basepair. The unexpected ease of extending the C.T mismatch was not likely to have been caused by primer-template misalignment. Taq polymerase was observed to bind with similar affinities to each of the correctly paired and mispaired primer-template 3'-ends. Thus, the failure of Taq polymerase to extend mismatches efficiently appears to be an intrinsic property of the enzyme and not due to an inability to bind to 3'-terminal mispairs. For almost all of the mispairs, C.T being the exception, Taq polymerase exhibits about 100 to 1000-fold greater discrimination against mismatch extension compared to avian myeloblastosis reverse transcriptase and HIV-1 reverse transcriptase which extend most mismatched basepairs permissively. Relative mismatch extension efficiencies for Taq polymerase were measured at 45 degrees C, 55 degrees C and 70 degrees C and found to be independent of temperature. The mispair extension data should be important in designing experiments using PCR to distinguish between sequences that vary by a single nucleotide.

Activation of Fc gamma RII induces tyrosine phosphorylation of multiple proteins including Fc gamma RII

Platelets provide a useful system for studying Fc gamma receptor-mediated signaling events because these cells express only a single class of Fc gamma receptors and because platelet aggregation and secretion can be activated through Fc gamma receptor stimulation. We report here that stimulation of platelets by cross-linking antibodies to Fc gamma RII or by treatment with an anti-CD9 monoclonal antibody, which acts through Fc gamma RII, causes an induction of tyrosine phosphorylation of multiple platelet proteins. Although the profile of tyrosine-phosphorylated proteins induced by stimulation of this Fc receptor was similar to that induced by thrombin, an additional 40-kDa phosphorylated protein was also detected. This protein co-migrated with Fc gamma RII and was immunoprecipitated with a monoclonal antibody to Fc gamma RII. In addition, after the cross-linking of Fc gamma RII in HEL cells or in COS-1 cells transfected with Fc gamma RII cDNA, the 40-kDa protein immunoprecipitated with anti-Fc gamma RII was also phosphorylated on tyrosine. These data strongly suggest that Fc gamma RII itself is a substrate for a tyrosine kinase(s) activated when Fc gamma RII is stimulated. Fc gamma RII was phosphorylated by the Src protein in vitro, suggesting that this kinase may be responsible for phosphorylation of Fc gamma RII in vivo. These studies establish that activation of platelets and human erythroleukemia cells through Fc gamma RII and CD9 involves an induction of tyrosine phosphorylation of multiple proteins including Fc gamma RII itself and suggest that these phosphorylation events may be involved in Fc gamma RII-mediated cell signaling.

Base mispair extension kinetics. Binding of avian myeloblastosis reverse transcriptase to matched and mismatched base pair termini

We investigate the enzymatic basis for the inefficient extension of single base mismatches by DNA polymerase compared with the extension of correct base pairs. Inefficient mismatch extension could result from either a reduced binding of the enzyme to mispaired versus correctly paired DNA template-primer termini, or from a lowered intrinsic rate of extension of mispairs by a bound enzyme, or from a combination of both factors. Avian myeloblastosis reverse transcriptase is used to measure the affinities (equilibrium dissociation constants) for the four matched and twelve mismatched base pair configurations situated at a primer 3'-terminus. The binding affinities are analyzed by two different assays employing polyacrylamide gels. The first assay uses steady-state kinetics to measure the efficiency of elongating correct and incorrect base pairs and to evaluate the enzyme's dissociation constants for matched and mismatched termini. The estimated KD values obtained in the steady-state analysis fall within a range of approximately 0.1-20 nM. The efficiencies of extending two of the mispairs, G.G and C.C, are too low to allow a determination of KD by the kinetics method. The second assay uses equilibrium binding to measure the ratio of polymerase bound to matched compared with mismatched termini, KDright/KDwrong. The affinity ratios, including values for G.G and C.C mispairs, are in the range of about 0.4-4.2. While around 1 order of magnitude difference is observed in the relative binding affinities of the polymerase for matched and mismatched primer termini, the relative extension efficiencies vary over more than 5 orders of magnitude. Therefore, it appears that inefficient mismatch extension is caused primarily by a kinetic block inhibiting elongation from mispaired primer 3'-termini rather than to a difference in binding.

Membrane glycoprotein IV (CD36) is physically associated with the Fyn, Lyn, and Yes protein-tyrosine kinases in human platelets

Activation of platelets with thrombin and other agonists causes a rapid increase in the phosphorylation of multiple proteins on tyrosine. To identify candidate protein-tyrosine kinases (PTKs; EC 2.7.1.112) that may be responsible for these phosphorylation events, we analyzed the expression of seven Src-family PTKs and examined the association of these kinases with known platelet membrane glycoproteins. Five Src-related PTKs were detected in platelets: pp60SRC, pp60FYN, pp62YES, pp61HCK, and two LYN products of Mr 54,000 and 58,000. The Fgr and Lck PTKs were not detected. Although strict comparative quantification of protein levels was not possible, pp60SRC was detected at higher levels than any of the other kinases. In addition, glycoprotein IV (GPIV, CD36), one of the major platelet membrane glycoproteins, was associated in a complex with the Fyn, Yes, and Lyn proteins in platelet lysates. Similar complexes were also found in two GPIV-expressing cell lines, C32 melanoma cells and HEL cells. Since PTKs appear to be involved in stimulus-response coupling at the plasma membrane, these results suggest that ligand interaction with GPIV may activate signaling pathways that are triggered by tyrosine phosphorylation.

The adenovirus early region 4 open reading frame 6/7 protein regulates the DNA binding activity of the cellular transcription factor, E2F, through a direct complex

Nuclear factor E2F is a cellular protein that binds to the adenovirus E2 promoter and E1A enhancer regions and to the cellular c-myc P2 promoter region. The DNA binding activity of E2F, detected in vitro using nuclear extracts prepared from HeLa cells, is increased by adenovirus infection (termed E2F induction). We demonstrate here that a 19.5-kD protein, encoded by adenovirus early region 4 (E4) open reading frame (ORF) 6/7, is primarily responsible for the induction of E2F DNA binding activity to the E2 promoter region. Viral mutants that contain frame-shift mutations in E4 ORF 6/7 failed to induce E2F binding activity; a virus that carries an E4 ORF 6/7 cDNA in place of the E4-coding sequences induced E2F efficiently. Using gel mobility shift assays, we demonstrate that the E4 ORF 6/7 product induces the binding of E2F to the E2 promoter via a direct complex. The addition of a peptide-specific antiserum, directed against the E4 ORF 6/7 protein, to an in vitro E2F-binding reaction resulted in the formation of a DNA-protein complex with reduced gel mobility compared to the normal, adenovirus-induced E2F-E2 promoter complex. The formation of the E2F-E2 promoter-antibody complex was blocked by the addition of the cognate peptide used to generate the antiserum but not by a nonspecific peptide. Nuclear extracts prepared from adenovirus-infected HeLa cells were cleared of E2F binding activity using the ORF 6/7 peptide-specific serum, but not the preimmune serum, suggesting that E2F and the E4 ORF 6/7 product form a protein-protein complex in solution. The adenovirus E1A proteins are not absolutely required for the induction of E2F binding activity because the infection of HeLa cells with an E1A mutant, dl312, at high multiplicity resulted in E2F induction. Under these conditions of infection, the E4 ORF 6/7 product was synthesized. E2F binding activity was induced, but inefficiently, in cells infected with E4 ORF 6/7 mutants, indicating that an additional pathway may lead to E2F induction.

Adenovirus early region 4 encodes two gene products with redundant effects in lytic infection

In order to assign specific functions to individual gene products encoded by adenovirus type 5 early region 4 (E4), we have constructed and analyzed a set of mutant viruses that express individual E4 open reading frames or combinations of open reading frames. The results of these analyses demonstrate that the gene products of E4 open reading frames 3 and 6 have redundant effects in viral lytic infection. These E4 products independently augment viral DNA replication, viral late protein synthesis, the shutoff of host cell protein synthesis, and the production of infectious virus. The product of open reading frame 6 is more efficient in the regulation of these processes than is the product of open reading frame 3. The regulation of viral DNA replication and the control of viral and cellular protein synthesis appear to be separable functions associated with both E4 gene products. The role of early region 4 in adeno-associated virus helper function, however, is mediated only by the product of open reading frame 6. Finally, we demonstrate that E4 mutant viruses display a multiplicity-leakiness phenotype which is consistent with the regulatory role that this region plays in viral infection.

Partitioning and extraction of glucose regulates cerebral glucose utilization in newborn dogs

We investigated the amount of fasting steady-state systemic glucose production utilized by the neonatal canine cerebral cortex. The relationship of systemic glucose production and cerebral glucose utilization were analyzed as functions of cerebral blood flow, cerebral oxygen uptake, and indirect measures of alternate fuel utilization. Fasting arterial blood glucose was 3.36 mM and glucose production was 49.6 mumol/kg/min. Average cerebral blood flow was 0.83 ml/g/min, and cerebral glucose uptake was 0.60 +/- 0.15 mumol/g/min. 36.6% of systemic glucose production was utilized by the cerebral cortex. There were no correlations between systemic glucose production, cerebral blood flow, or cerebral glucose uptake with blood glucose concentration. Furthermore, total cerebral glucose uptake was static across a wide range of glucose levels. Nonetheless, the percent of glucose production used by the brain was an inverse function of systemic glucose production (r = -0.71, p less than 0.001). The cerebral extraction of glucose (27.6 +/- 4.1%) decreased as a function of increasing blood glucose levels (r = -0.51, p less than 0.05), while brain uptake index correlated with increasing systemic glucose production (r = 0.61, p less than 0.02). We can conclude that the canine neonatal cerebral cortex may utilize only 37% of systemic glucose production. At low rates of glucose turnover, a larger proportion of systemic glucose production is allotted to the brain. Mechanisms that may regulate total cerebral glucose influx may be glucose permeability, or the increased extraction of glucose at lower blood glucose levels.

Allocation of systemic glucose output to cerebral utilization as a function of fetal canine growth

To determine whether the neonatal canine brain consumes a major proportion of the systemic glucose production, we investigated the cerebral glucose requirement and hepatic glucose production in beagle pups. Sixteen pups received D-[6-3H]-glucose to determine systemic glucose production. Cerebral blood flow was measured by [N-methyl-14C]antipyrine, and the brain uptake index (BUI) of glucose was determined using 2-[14C]deoxy-D-glucose. Glucose production was 49.6 +/- 11.0 mumol.kg-1.min-1. Cerebral blood flow was 0.83 ml.g-1.min-1; cerebral uptake of glucose was 0.60 +/- 0.15 mumol.g-1.min-1. Of the total glucose production 36.6 +/- 7.9% was accounted for by the cerebral uptake of glucose. Brain-to-body weight and brain-to-liver weight ratios were the greatest in the smallest pups, suggesting brain sparing. The effect of growth status on cerebral substrate availability could not be correlated with cerebral uptake of glucose or oxygen or with systemic glucose production. However, the percentage of systemic glucose production allotted to the cerebral cortex increased with increasing body weight (r = 0.50, P less than 0.05). Cerebral glucose entry measured by BUI was demonstrated to be 0.108 +/- 0.014; BUI inversely correlated with canine birth weight (r = -0.832, P less than 0.001). We conclude that the percentage of glucose production utilized by the neonatal canine brain is not proportionately larger in the smaller pups despite a proportionately larger brain. Because the absolute cerebral glucose utilization may be static, we speculate that BUI (glucose entry) may be less of a rate-limiting factor for cerebral glucose entry in the smallest pups.