Biological responses of dog prostate and adjacent structures after meso-tetra-(m-hydroxyphenyl) chlorin and aluminum disulfonated phthalocyanine based photodynamic therapy.

Further to our work on the feasibility of application of photodynamic therapy (PDT) to the canine prostate, this study evaluates the biological responses of the prostate and adjacent vital structures with meso-tetra-(m-hydroxylphenyl) chlorin (mTHPC) or aluminum disulfonated phthalocyanine (AlS2Pc) based PDT as a preparatory step for clinical trials. Skin photosensitivity was not particularly problematic if light protection could be implemented properly for 2 weeks following sensitization. Prostate PDT was well tolerated by the experimental animals with only minor physical distress. mTHPC was more powerful than AlS2Pc in terms of prostate lesions induced. A large portion of prostate tissue could be destroyed by PDT with 4 punctures. Physical distress was probably caused by severe urethral irritation and aching from acute swelling of the prostate. Although the voiding condition normalized within 10 days, regeneration of urethral epithelium was not complete until 3-4 weeks after PDT. Improper placement of laser fiber caused extensive ecchymosis of the retroperitoneal organs. The biological significance of PDT induced hyperemia in the periprostatic structures remains poorly defined. Neither periprostatic nerve damage nor rectal lesions were seen in dogs receiving either mTHPC or AlS2Pc. Glandular atrophy with papillary cystic regeneration of the prostate was the most prominent finding 90 days after PDT. The glandular architecture was well preserved because the interlobular collagens were less affected than the cellular components of the glands. Our study suggests that PDT with mTHPC and AlS2Pc is safe and promising for necrosing a substantial amount of prostate tissue. The completeness of treatment and long-term therapeutic effectiveness for prostate cancer, however, remains to be determined through further investigation.

Effect of teicoplanin on isolation of Staphylococcus aureus from blood culture media.

Intraoperative bacteraemia has been used as an indicator of the efficacy of prophylactic antibiotics. Two clinical isolates of Staphylococcus aureus in nutrient broth, with or without human serum, were exposed to teicoplanin (50 mg/L) and, either immediately or after 30 min, inoculated into blood culture bottles. Bottles with and without resin were used and the experiment was repeated five times with one strain. In the absence of teicoplanin, an inoculum of 10 cfu/mL produced growth in both resin and non-resin bottles. In the presence of teicoplanin, an inoculum of at least 10(5) cfu/mL was required in non-resin bottles to obtain growth, but this was reduced to 10(2)-10(3) cfu/mL for resin bottles. Intraoperative blood cultures overestimate the efficacy of bacterial killing by prophylactic antibiotics during surgery.