Polymerase chain reaction based method for the detection of BCG retention after intravesical instillation in guinea pig bladders.

OBJECTIVE: In intravesical Bacille bilié de Calmette-Guérin (BCG) immunotherapy of superficial bladder cancer, a T cell mediated immunological reaction is associated with the antitumor activity. To gain insight into the approximate number of BCG bacteria retained in the normal, noninjured, urinary bladder after intravesical application responsible for induction of the immune reaction, the utility of a sensitive polymerase chain reaction (PCR) based assay was investigated in a guinea pig model. METHODS: After one single or six subsequent weekly instillations with 1x10(7) CFU of BCG, the bladders were resected and processed for BCG determination with PCR. The bladders were resected 24 h after instillation, aiming at (semi)quantifying the number of BCG organisms able to resist the natural voiding washout of the bladder. The PCR was based on amplification of a 249 base pair fragment of the insertion element IS6110 and is specific for bacteria belonging to the Mycobacterium tuberculosis complex which includes Mycobacterium bovis BCG. RESULTS: After one single instillation no detectable BCG retention was found. However, after six weekly instillations, BCG bacteria could be demonstrated in 2 out of 5 guinea pig bladders, indicating that the number of adhering BCG organisms was around the detection limit of the assay (600-1,000 BCG bacteria per bladder). CONCLUSIONS: The data suggest that after six instillations, the retention of BCG in the guinea pig bladder is enhanced as compared with one single instillation. This finding is suggestive of a role of the inflammatory process that is, besides immune system mediated reactions, associated with intravesical BCG instillations. The nature of the molecules involved in enhanced BCG retention after repeated instillations remains to be investigated.

Strategies for gene cloning.

Cancer, including genitourinary malignancy, is a consequence of accumulated genetic aberrations in genes involved in crucial regulatory pathways. The result is a deregulation of cellular behaviour, leading to neoplastic transformation, uncontrolled cell proliferation and acquisition of metastatic ability. The development and perfection of techniques in the field of recombinant DNA technology, gene cloning, (differential) analysis of gene expression, and sequencing of genes and proteins have provided a wealth of information about the genetic aberrations associated with cancer development. This "recombinant DNA and gene cloning" technology and the recently developed DNA chip technology may provide new molecular diagnostic tools. Furthermore, the technology of gene cloning in combination with the progress in in vivo gene delivery techniques offers new treatment modalities, like gene therapy, additional to conventional therapies. This review is intended to provide a general introduction to the fundamentals or strategies of recombinant DNA and gene cloning techniques as a basis for understanding the rapidly expanding range of new diagnostic and therapeutic opportunities. Some illustrative examples are provided, addressing basic and biomedical research and possible clinical applications in genitourinary oncology.