Twigged streptavidin polymer as a scaffold for protein assembly

Protein assemblies are an emerging tool that is finding many biological and bioengineering applications. We here propose a method for the site-specific assembly of proteins on a twigged streptavidin (SA) polymer using streptavidin as a functional scaffold. SA was genetically appended with a G tag (sortase A recognition sequence) and a Y tag (HRP recognition sequence) on its N- and C-termini, respectively, to provide G-SA-Y. G-SA-Y was polymerized using HPR-mediated tyrosine coupling, then fluorescent proteins were immobilized on the polymer by biotin-SA affinity and sortase A-mediated ligation. Fluorescence measurements showed that the proteins were immobilized in close proximity to each other. Hydrolyzing enzymes were also functionally assembled on the G-SA-Y polymer. The site-specific assembly of proteins on twigged SA polymer may find new applications in various biological and bioengineering fields.

Recurrence of sigmoid colon carcinoma in the residual urethra after cystectomy

INTRODUCTION

We report a case of recurrence of sigmoid colon cancer in the residual urethra after cysto-prostato-sigmoidectomy.

METHODS/RESULTS

The patient successfully underwent urethrectomy and is currently tumor-free. To our knowledge, this is the first case of recurrence of a non-urothelial malignant tumor in the residual urethra.

[Prevalence of upper urinary tract stones in Tajima, north Hyogo, Japan]

Toyooka Hospital is a central hospital in Tajima, a rural area in the northern part of Hyogo Prefecture. Because we possess the sole lithotripter in this area, almost all urolithiasis patients requiring treatment have been referred to our department. Based on the number of urolithiasis patients treated in our institution, we estimated the annual prevalence and incidence of upper urinary tract stones in the Tajima area. The mean annual prevalence of urolithiasis and incidence during the 1991-1993 period were 141 and 93 per 100,000, respectively. The male to female ratio was 2.0 to 1 in prevalence and 2.2 to 1.0 in incidence. Prevalence was highest in the sixties (245) and fifties (235), followed by the forties (205), seventies (162) and thirties (160). The incidence was highest in the fifties (169), followed by the forties (147), sixties (145) and thirties (118). In consideration of sex, the incidence was highest in males in the fifties and the forties. Of the patients with upper urinary calculi, 23.1% were treated by extracorporeal shock wave lithotripsy, while in 23.8% stones passed spontaneously and 50.9% were followed up without treatment. On stone analysis, calcium oxalate and/or calcium phosphate was present in 75.6%, uric acid in 16.4%, struvite and/or carbonate apatite in 5.6% and cystine in 1.4%. In summary, the prevalence and incidence of upper urinary tract calculi in the Tajima area were considerably higher than those in the nationwide survey on urolithiasis in Japan conducted in 1985.

A case of hydronephrosis caused by arteriosclerotic compression of the renal pelvis

We present the case of a 65-year-old woman with vascular compression of the renal pelvis, causing calyectasis. The diagnosis was a subtype of Fraley's syndrome. The cause of compression was concluded to be arteriosclerotic change of both the renal artery and the abdominal aorta.

[Two cases of delayed ureteral fistulas following rectal amputation]

We report two rare cases of delayed ureteral fistulas which occurred one month following rectal amputation. Case 1 was a 52-year-old male who underwent abdominal perineal resection of the rectum. One month after surgery, the patient had a paralytic ileus. Computed tomographic (CT) scan and drip infusion pyelography showed left ureteral fistula and a large pelvic urinoma. Because retrograde placement of a double-J stent was unsuccessful, antegrade placement of the double-J stent was performed. The fistula and urinoma healed soon after the placement of the double J stent. Case 2 was a 43-year-old male who underwent abdominal sacral resection of the rectum. One month after surgery, a large amount of urine began to drain from the perineal wound. CT scan and retrograde pyelography showed a right ureteral fistula and a large pelvic urinoma. There had been temporary improvement in the discharge without the treatment of the ureteral fistula, only for it to return more profusely. Because placement of a double-J stent was unsuccessful, right percutaneous nephrostomy was performed, after which, a right ureterocysto-neostomy (Boari flap method) was performed. We advocate the initial use of the double-J stent or percutaneous nephrostomy in ureteral fistula. This approach is simple and may cure the fistula. If unsuccessful, it will not hinder subsequent open surgery.

[Comparison of treatment results of prostatic cancer between radical prostatectomy and radiation therapy]

Between 1982 and 1990, 55 patients with prostate cancer (clinical stage A2-C) underwent pelvic lymphadenectomy at the Public Toyooka Hospital. The patients were subsequently treated either by radical prostatectomy (36 cases) or external radiation therapy (19 cases). The age of the patients varied from 56 to 85 (Mean 73.1). The outcome of the 46 patients with negative lymph node (prostatectomy 31, radiation 15) were compared. The 10-year disease-specific survival rates were 100% for the patients treated by prostatectomy and 78% for those treated by radiation (P = 0.035). The 5-year progression-free survival rates for the prostatectomy group and radiation group were 97% and 56%, respectively (P = 0.013). Among the radiation groups, patients with well differentiated carcinoma showed a lower progression rate as compared to those with moderately or poorly differentiated carcinoma (5-year progression-free survival, 81 vs 20%, P = 0.094). The outcome of the 9 patients with positive lymph node (prostatectomy 5, radiation 4) was not satisfactory because of the high progression rates in the two groups (5 year progression-free survival, 30% in prostatectomy and 25% in radiation group).

[A case of prostatic cyst]

A 45-year-old man visited our hospital for further examinations because an abnormal echogram of the bladder had been noted at a medical checkup. Transrectal echography and magnetic resonance imaging (MRI) showed a cystic mass in the bladder neck. Endoscopically it was situated in the anterior aspect of the vesical neck at about the position of 12 o'clock on the dial of a clock. Transurethral resection of the cyst wall was performed under the diagnosis of prostatic cyst. Histopathologically the cyst wall was lined by flattened epithelium and this case was supposed to be classified as retention cysts. This was thought to be the 23rd case of prostatic cysts in the Japanese literature. The characteristics, diagnostic problems and treatments of prostatic cysts are discussed.

[Clinical and statistical studies on prostatic cancer: prognostic value of clinical stage, Gleason score and age]

We assessed the outcome of 200 patients with prostatic cancer treated at the Public Toyooka Hospital from 1980 to 1989. The patient's age varied from 53 to 94 years (mean 76.8). Overall actuarial survival rate at 5 and 10 years were 52% and 25%, respectively. The 5-year survival according to clinical stage was 69% for stage A, 66% for stage B, 43% for stage C and 32% for stage D disease. A significant difference was noted between the survival of patients with stage A or B and those with stage C or D. Patients with Gleason score of less than 7 showed significantly better survival as compared to those with Gleason score of 7 or more (5-year survival, 64% vs 33%). No significant difference was observed between the survival of patients under the age of 75 and those 75 or older.

[Assessment of treatment outcome and prognostic factors of renal cell cancer]

We assessed the treatment outcome of 71 patients (45 men and 26 women) with renal cell cancer treated at the Public Toyooka Hospital from 1969 to 1992. The patient's age varied from 15 to 85 (mean 64). The overall actuarial and disease specific survival rates at 5 years were 55% and 67%, respectively. Statistical analysis of various parameters associated with prognosis was performed. The parameters achieving statistical significance were pT, PV, distant metastasis, grade, histological architecture, cell type, tumor size and erythrocyte sedimentation rate.

[Application of urethral stent under metal bougie guidance]

We reviewed our experience in the application of a urethral spiral stent under metal bougie guidance for 10 patients from March 1992 to May 1992. Five cases had urinary retention that required indwelling catheters and 5 cases had an obstructive symptom. The patients ranged from 52 to 89 (mean 80.2) years old. Urethral stents were used since the patients were either unfit for or refused operations for benign prostatic hyperplasia, inoperable advanced prostatic cancer with urinary retention or neurogenic bladder. The urethral stent in these cases was a spiral coil type, made of gold-plated stainless steel. Under local anesthesia, it could be easily and safely inserted using a 9 Fr. metal bougie (Dittel type). The urethral stent was placed under fluoroscopic guidance. In all cases, the urethral stent was inserted and successfully moved into place. Eight patients could void by themselves immediately after insertion and their quality of life seemed to be significantly improved. We concluded that the insertion of a spiral coil intraurethral stent under a metal bougie guidance is a new, easy and non-invasive treatment for elderly patients with lower urinary tract obstruction.