Evaluation of Asymptomatic Microscopic Hematuria by Renal Ultrasound to Detect Upper Tract Malignancy: A 20-Year Experience in a Community Hospital.

OBJECTIVE: To evaluate the sensitivity of ultrasound imaging in detecting upper urinary tract malignancy in patients with asymptomatic microscopic hematuria (AMH) in an outpatient community setting. MATERIALS AND METHODS: A list of all patients who received renal ultrasound for hematuria in our health care system between January 1, 1997 and July 1, 2015 was obtained, and electronic health records were retrospectively reviewed. Patients were excluded for age (<18 years), <3 years follow-up, prior upper tract malignancy, recent urinary tract catheterization, inpatient status, pregnancy, insufficient data, or gross hematuria. The initial ultrasound was considered positive if suspicious findings led to a subsequent diagnosis of an upper tract malignancy. False negatives were determined by electronic medical record follow-up for at least 3 years. RESULTS: Of the 2138 patients with AMH who met inclusion criteria, ultrasound imaging detected suspicious findings in 9 of 9 patients with renal cell carcinoma and 3 of 3 patients with upper tract urothelial cancer, indicating a sensitivity of 100% and 100%, respectively. Four additional malignancies were diagnosed more than 3 years after the initial evaluation for an incidence rate of 1.6 cases of upper tract malignancy per 10,000 person-years. CONCLUSION: The prevalence of upper urinary tract malignancy was low in patients with AMH. Ultrasonography is an appropriate modality for upper tract imaging in the initial evaluation of patients with AMH. Practice guidelines should be updated to reflect the high sensitivity of ultrasound and low risk of upper tract malignancy in patients with AMH.

A Variant PfCRT Isoform Can Contribute to Plasmodium falciparum Resistance to the First-Line Partner Drug Piperaquine.

Current efforts to reduce the global burden of malaria are threatened by the rapid spread throughout Asia of Plasmodium falciparum resistance to artemisinin-based combination therapies, which includes increasing rates of clinical failure with dihydroartemisinin plus piperaquine (PPQ) in Cambodia. Using zinc finger nuclease-based gene editing, we report that addition of the C101F mutation to the chloroquine (CQ) resistance-conferring PfCRT Dd2 isoform common to Asia can confer PPQ resistance to cultured parasites. Resistance was demonstrated as significantly higher PPQ concentrations causing 90% inhibition of parasite growth (IC90) or 50% parasite killing (50% lethal dose [LD50]). This mutation also reversed Dd2-mediated CQ resistance, sensitized parasites to amodiaquine, quinine, and artemisinin, and conferred amantadine and blasticidin resistance. Using heme fractionation assays, we demonstrate that PPQ causes a buildup of reactive free heme and inhibits the formation of chemically inert hemozoin crystals. Our data evoke inhibition of heme detoxification in the parasite's acidic digestive vacuole as the primary mode of both the bis-aminoquinoline PPQ and the related 4-aminoquinoline CQ. Both drugs also inhibit hemoglobin proteolysis at elevated concentrations, suggesting an additional mode of action. Isogenic lines differing in their pfmdr1 copy number showed equivalent PPQ susceptibilities. We propose that mutations in PfCRT could contribute to a multifactorial basis of PPQ resistance in field isolates.IMPORTANCE The global agenda to eliminate malaria depends on the continued success of artemisinin-based combination therapies (ACTs), which target the asexual blood stages of the intracellular parasite Plasmodium Partial resistance to artemisinin, however, is now established in Southeast Asia, exposing the partner drugs to increased selective pressure. Plasmodium falciparum resistance to the first-line partner piperaquine (PPQ) is now spreading rapidly in Cambodia, resulting in clinical treatment failures. Here, we report that a variant form of the Plasmodium falciparum chloroquine resistance transporter, harboring a C101F mutation edited into the chloroquine (CQ)-resistant Dd2 isoform prevalent in Asia, can confer PPQ resistance in cultured parasites. This was accompanied by a loss of CQ resistance. Biochemical assays showed that PPQ, like CQ, inhibits the detoxification of reactive heme that is formed by parasite-mediated catabolism of host hemoglobin. We propose that novel PfCRT variants emerging in the field could contribute to a multigenic basis of PPQ resistance.