Yan Yan - Academia.edu (original) (raw)

Papers by Yan Yan

Journal of Urology, 2002

Purpose: Laparoscopic radical nephrectomy has been shown to be less morbid than traditional open ... more Purpose: Laparoscopic radical nephrectomy has been shown to be less morbid than traditional open radical nephrectomy. The long-term oncological effectiveness of laparoscopic radical nephrectomy remains to be established.

Journal of Urology, 2003

Laparoscopic pyeloplasty has become a viable option for the treatment of select patients with pri... more Laparoscopic pyeloplasty has become a viable option for the treatment of select patients with primary ureteropelvic junction obstruction with success rates similar to those of open surgery. However, little has been written on the application of this technique for secondary ureteropelvic junction obstruction. We report the largest series of secondary ureteropelvic junction obstruction managed by laparoscopic pyeloplasty. Between March 1994 and March 2001, 36 patients underwent laparoscopic transperitoneal pyeloplasty for secondary ureteropelvic junction obstruction. The patients had undergone an average of 1.3 ureteropelvic junction procedures (range 1 to 4) prior to presentation, including cutting balloon retrograde endopyelotomy in 28, antegrade endoscopic endopyelotomy in 7, retrograde endoscopic endopyelotomy in 4, retrograde balloon dilation in 4 and open pyeloplasty in 3. A preoperative diagnosis of recurrent obstruction was confirmed by renal scan in 31 cases, retrograde pyelography in 2 and computerized tomography in 3. Of the 31 patients who underwent spiral computerized tomography angiogram 87% had crossing vessels. Laparoscopic repair comprised dismembered pyeloplasty in 31 cases, Fengerplasty in 3 and flap repair in 2. Postoperative renal scan or excretory urography objective followup was available for all patients at a mean of 10 months (range 3 to 40). Postoperative subjective patient well-being was assessed using an analog pain scale at a mean followup of 21.8 months (range 3 to 85). Average operative time was 6.2 hours (range 2.7 to 10). Average hospital stay was 2.9 days (range 1 to 7). One intraoperative complication occurred, that is bleeding necessitating conversion to an open procedure. Postoperative complications occurred in 8 cases, including anastomotic leakage in 4, and urinary tract infection, pneumonia, atelectasis, fever, bilateral upper extremity weakness and stone formation 2 months postoperatively in 1 each. On excretory urography, furosemide renal scan or the Whitaker test 32 of 36 patients (89%) had a widely patent ureteropelvic junction. Two patients (5.5%) had equivocal radiographic studies but were asymptomatic. In 2 patients the ureteropelvic junction was obstructed by renal scan. One patient had an indwelling stent for renal function deterioration and 1 was asymptomatic. Hence, 34 of the 36 patients (94%) had a reasonable objective response. Overall a 50% or greater decrease in pain was seen in 32 of 36 patients (89%). In the 4 patients with a less than 50% decrease in pain objective renal scans showed an open ureteropelvic junction. As such, the overall success rate of a greater than 50% decrease in pain, a patent ureteropelvic junction and stable or improved function of the affected renal unit was 83% (30 of 36 patients). For secondary ureteropelvic junction obstruction, laparoscopic pyeloplasty can be performed safely with a success rate comparable to that of standard open pyeloplasty. The patient benefits of laparoscopic ureteropelvic junction repair of secondary ureteropelvic junction obstruction are similar to the benefits of laparoscopic repair of primary ureteropelvic junction obstruction.

Journal of Endourology, 2000

Stent morbidity appears to be secondary to lower urinary tract irritation. In an effort to decrea... more Stent morbidity appears to be secondary to lower urinary tract irritation. In an effort to decrease stent morbidity, a &amp;quot;one size fits all&amp;quot; Tail stent (Microvasive [Boston Scientific] Natick, MA) was developed with a 7F proximal pigtail and 7F shaft which tapers to a lumenless straight 3F tail. We randomized 60 patients in a single-blind fashion to a 7F tail stent or 7F double-pigtail Percuflex stent. Patients were evaluated at the time of stent removal and 2 weeks later with a standardized questionnaire assessing: irritative lower tract symptoms individually and on a total scale of 0 (no symptoms) to 30 (worst symptoms), obstructive lower tract symptoms (on a total scale of 0-20), and upper tract irritative symptoms (on a total scale of 0-10). Patient age, weight, and height were similar in the two groups. Complications, including fever, urinary tract infections, emergency room visits, and the need for antispasmodics and pain medication, also demonstrated no significant difference. At the time of stent removal, patients who received a tail stent had significantly less urinary frequency and a statistically significant (21%) decrease in overall irritative voiding symptoms (12.2 v 15.4; p = 0.048). Two weeks after stent removal, the total irritative voiding symptoms was markedly decreased in both groups (7.1 in the Tail v 5.3 in the double-pigtail group; p = 0.15). Obstructive bladder and flank symptoms were not significantly different in the two stent groups, either at the time of stent removal or at 2 weeks after removal. In this randomized, single-blind study, the 7F Tail stent produced significantly less irritative symptoms than did the standard 7F double-pigtail stent. Obstructive symptoms tended to be less with the new stent, while flank symptoms were similar.

Journal of Integral Equations and Applications, 1988

The existence-uniqueness of the solution and its behaviour for one-dimensional integral equations... more The existence-uniqueness of the solution and its behaviour for one-dimensional integral equations of the first kind with logarithmic kernels are investigated. The analysis is based on the transfinite diameter or logarithmic capacity and spaces deriving from Fourier series. The uniqueness results apply to any closed bounded subset of the plane. The other results apply to open arcs, polygons and other regions with piecewise-smooth boundaries.

Cancer, 2000

BACKGROUND. There is limited information on outcomes of prostate carcinoma treatments given to sc... more BACKGROUND. There is limited information on outcomes of prostate carcinoma treatments given to screened patient populations for whom cancer is usually detected at an earlier stage.

Urology, 2002

Objectives. To evaluate the pathologic characteristics of clinical Stage T1c (nonpalpable, prosta... more Objectives. To evaluate the pathologic characteristics of clinical Stage T1c (nonpalpable, prostate-specific antigen [PSA]-detected) prostate cancers detected in the 2.6 to 4.0-ng/mL PSA range and compare them with Stage T1c cancers concurrently detected in the 4.1 to 10.0-ng/mL PSA range. All cancers were detected in a prostate cancer screening study. Methods. We studied 94 patients with clinical Stage T1c prostate cancer diagnosed by four or six-sector ultrasound-guided needle biopsy who underwent radical prostatectomy between June 1995 and December 1996. We included all men whose prostatectomy specimens were processed with complete embedding of all prostatic tissue. Of these, 42 had a PSA level of 2.6 to 4.0 ng/mL and 52 a PSA level 4.1 to 10.0 ng/mL at the time of cancer detection. We determined the tumor volume by complete embedding and grid morphometry, pathologic stage, Gleason sum, and surgical margin status and compared the cancer volume and pathologic tumor stages for each group. Results. Men with cancer detected at the 2.6 to 4.0 ng/mL PSA range had significantly smaller cancer volumes (1.1 Ϯ 1.1 cm 3 versus 1.8 Ϯ 1.5 cm 3 , P ϭ 0.02); however, no difference was found in the proportion (11.9% versus 11.5%, P ϭ 0.9, and 23.8% versus 26.9%, P ϭ 0.7, respectively) of tumors that met previously published criteria of "clinically insignificant" (organ confined, less than 0.2 cm 3 tumor volume, Gleason sum 6 or less) or "clinically unimportant" (organ confined, less than 0.5 cm 3 tumor volume, and Gleason sum 6 or less) tumors. Using the lower PSA cutoff point resulted in the detection of a significantly higher percentage of organ-confined tumors (88% versus 63%, P ϭ 0.01). Conclusions. The use of a 2.6-ng/mL PSA threshold for screening resulted in the more frequent detection of small, organ-confined tumors without overdetecting possibly clinically insignificant ones. UROLOGY 60: 469-474, 2002.