Features in short guanine-rich sequences that stimulate DNA polymerization in vitro.

We have discovered that short guanine-rich oligonucleotides are able to self-associate into higher order structures that stimulate DNA synthesis in vitro without the addition of a conventional template [Ying, J., Bradley, R. K., Jones, L. B., Reddy, M. S., Colbert, D. T., Smalley, R. E., and Hardin, S. H. (1999) Biochemistry 38, 16461-16468]. Our initial analysis indicated the importance of the presence of three contiguous guanines (G) in an oligonucleotide that stimulates DNA polymerization. To gain insight into and to refine sequence requirements for the unexpected DNA synthesis, we analyzed a 231-member guanine-rich octamer library in a fluorescent nucleotide polymerization assay. We observe that, in addition to three contiguous Gs, the presence of a secondary G cluster within the octamer is essential. Furthermore, the location of the primary G cluster in the center of the molecule is most stimulatory. The majority of the octamers that form extended DNA products have a single non-G base separating the primary and secondary G clusters, the identity of which is predominantly thymine (T). Further, a T 5' or 3' of the primary G cluster positively influences the stimulatory function of the oligonucleotide. Overall, the occurrence of bases in the octamer is in the descending order of G > T > A > C. Our studies demonstrate that structures stabilized by noncanonical base pairings are recognized by a DNA polymerase in vitro, and these findings may have relevance within the cell. In particular, the features of these G-rich stimulatory sequences show striking similarities to telomeric sequences that form diverse G-quartet structures in vitro.

A technique for resection of small bladder tumors using a flexible cystoscope on an outpatient basis: bladder tumor resection with newly designed hot cup forceps.

PURPOSE: We describe a technique for resecting small papillary superficial bladder tumors using a new device and flexible cystoscope. MATERIALS AND METHODS: In a 79-year-old man 3 small recurrent papillary bladder tumors were resected transurethrally on an outpatient basis. The procedure was performed using a flexible cystoscope and a newly designed type of cup forceps with the patient under topical anesthesia. No urethral catheter remained indwelling after surgery and the patient was discharged home the same day. RESULTS: Bladder tumor resection using this technique was tolerable to the patient and postoperative bladder hemorrhage was not noted. Resected specimens were adequate for pathological tumor evaluation, which revealed grade 1 stage Ta superficial transitional cell carcinoma of the bladder. CONCLUSIONS: This easy technique seems to be tolerated well by the patient. Resected specimens should be adequate for evaluating the pathological grade and depth of stage Ta or T1 superficial bladder cancer. This technique may be an alternative to standard transurethral resection for removing small recurrent bladder lesions in select patients who prefer outpatient management of bladder tumors.

[The vanishing testis: diagnosis and histological findings].

PURPOSE: Controversy exists on how to diagnose the vanishing testis and the degree of investigation required. In this series, we reviewed anatomical and histological findings in vanishing testes and investigated the effectiveness of diagnostic laparoscopy and imaging studies. MATERIALS AND METHODS: Between 1974 and March 1999, 107 boys with nonpalpable testis underwent surgery. Of the total, 52 had spermatic vessels, vas deferens, and/or nubbin, and as a result the diagnosis of vanishing testis was made. RESULTS: The affected side of vanishing testis was left 41, right 9 and bilateral 2.35 nubbins were found and the lengths of 24 nubbins were 5 mm or less. Histological examinations were performed in 43 cases including 27 nubbins. From that total, 31 had vas deferens and 11 had epididymis. Only two nubbins had seminiferous tubules but they included no germ cells. The two nubbins were greater than 5 mm long. Laparoscopic surgery was undertaken in 12 separate cases of the vanishing testis and as a result hypoplastic spermatic vessels were present in 7 of the 12 cases. CONCLUSION: The incidence of viable testicular tissue in vanishing testes was 4.7% in our series and it ranges from 0-16% in other series. We submit that one can diagnose the inguinal vanishing testis with preoperative imaging and laparoscopy, and that the nubbin seldom contains testicular tissue. Our results do not support the necessity to remove nubbins.