Standard 12-core prostate biopsies should continue to be performed in men despite the absence of suspicious prostate lesions on magnetic resonance imaging (MRI) scans, investigators reported at the Society of Urologic Oncology 17th annual meeting in San Antonio, Texas. In a study, they found that prostate MRI missed 13% of high-grade prostate tumors that were revealed by subsequent standard template transrectal ultrasound (TRUS) 12-core biopsy. “There is no doubt that MRI targeted biopsy is better than a random TRUS biopsy, but it is imperfect,” lead investigator Eric Kim, MD, told Renal & Urology News. “Currently, optimal cancer detection requires both targeted and systematic biopsy. As MRI interpretation and other imaging modalities, such as PET [positron emission tomography], improve, systematic biopsy may not be needed.” Dr Kim and his colleagues at Washington University School of Medicine in St. Louis defined the negative predictive value (NPV) of prostate MRI at their institution and the characteristics of men with clinically significant cancer (Gleason 7 or higher PCa) but a negative MRI. They studied 84 men with negative prostate MRI who subsequently underwent standard template transrectal ultrasound-guided prostate biopsy. The group consisted of 39 biopsy-naïve patients, 30 patients who had a previous negative biopsy, and 15 patients on active surveillance (AS). All of the AS patients had been diagnosed with Gleason 6 cancer. The researchers calculated the NPV of prostate MRI as the number of TRUS biopsies divided by the sum of negative and positive TRUS biopsies. Results showed that MRI had an NPV of 87% for Gleason 7 or higher PCa, which the investigators said is in line previously published studies. The only predictor of Gleason 7 or higher cancer among negative MRI patients was an increasing Prostate Cancer Prevention Trial risk calculator estimate for high-grade PCa. Dr Kim's group reported finding no significant differences in NPV between patients based on prior biopsy status.
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New research reveals fresh clues on the infection-fighting properties of cranberries. Researchers in Canada showed how cranberry extract rich in a particular type of compound successfully disrupted cell-to-cell communication in bacteria responsible for hard-to-treat infections. The team - from McGill University in Montreal and INRS-Institut Armand-Frappier in Laval, both in Canada - reports the discovery in the journal Scientific Reports. Previous studies have already shown that cranberries contain proanthocyanidins (PACs), a class of compound that fends off illness through various antibacterial properties. For example, they can stop certain bacteria from sticking onto the wall of the bladder and causing a urinary tract infection. However, the team behind the new study also wanted to find out if cranberry compounds can control the virulence of bacteria, and therefore reduce the severity of an infection. They suggest their findings not only give fresh clues on how PACs in cranberries fight bacteria, but they could also lead to new approaches to infection control. Cranberry compounds disrupt bacterial cell communication For their study, the team used fruit flies - a useful model for studying human infections at the level of cells and molecules. They found severity of bacterial infection was reduced in fruit flies fed on cranberry extract rich in PACs, compared with cranberry-free fruit flies. The cranberry-fed flies also lived longer. Further investigation revealed the cranberry PACs disrupt a cell communication process called "quorum sensing" that forms an essential link in a chain of events involved in the spread and severity of chronic bacterial infections. The research focuses on a bacterium called Pseudomonas aeruginosa, which can cause infections in hospital patients and people with weak immune systems. Patients on breathing machines, fitted with catheters, or with burns or surgical wounds are potentially at risk for serious, life-threatening infections. Implications for antibiotic resistance Pseudomonas infections are generally treated with antibiotics. However, because of increasing antibiotic resistance, these and other hospital-acquired bacterial infections are becoming harder to treat. In the United States, there are an estimated 51,000 healthcare-associated P. aeruginosa infections every year. Of these, around 13 percent are multi-drug resistant, and about 400 deaths are due to these infections. In their paper, the researchers discuss the relevance of their findings to the problem of drug resistance. They found that while the cranberry PACs disrupted bacterial quorum sensing, this did not kill the cells - it just disrupted their communication and spread. They suggest this could be important because one reason conventional antibiotics lead to drug resistance is because they kill bacteria - which they note poses "strong selective pressure in any environment." However, the authors also point out it would be "naive to presume" that by disrupting quorum sensing one would not be placing any selective pressures that might lead to resistance against drugs that work using this mechanism. Nonetheless, the findings are still useful in that they "expand our strategies for combating pathogen resistance by identifying novel anti-microbial and anti-virulence agents," they conclude. The study was funded by the Natural Sciences and Engineering Research Council of Canada, the Wisconsin Cranberry Board, and the Cranberry Institute. |
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