The protease inhibitor ritonavir inhibits the functional activity of the multidrug resistance related-protein 1 (MRP-1)

BACKGROUND: Efflux pumps situated on the plasma membrane, such as P-glycoprotein (Pgp) and the multidrug resistance related-protein 1 (MRP-1), have been shown to extrude HIV protease inhibitors from the cell. MRP-1 is present on many barrier sites throughout the body, such as the blood-brain and blood-testis interfaces and could reduce the concentration of protease inhibitors in these sanctuary sites for HIV-1 replication. Factors that modulate efflux pump function in vivo are poorly defined. OBJECTIVE: To analyze the inhibitory potential of the anti-retroviral drugs indinavir, amprenavir, ritonavir, lamivudine or zidovudine to modulate MRP-1 function. METHODS: Effect of anti-HIV drugs on the efflux pump activity of MRP-1 was evaluated in the presence of increasing concentrations of human plasma, using UMCC-1/VP cells which stably over-express MRP-1. MRP-1 activity was abrogated by probenecid. The potential of blocking MRP-1 function for an extended (3 day) time period, was also examined in MRP-1 over-expressing cells cultured with either probenecid or the anti-retroviral drugs and a cytotoxic compound (etoposide) that is transported by MRP-1. RESULTS: Ritonavir inhibited the functional activity of MRP-1 similarly to probenecid, as demonstrated by re-sensitization of MRP-1 over-expressing cells to cytotoxic effects of etoposide. Inhibition by ritonavir was inversely related to the concentration of human plasma added to the cells (r2 = 0.89). Other anti-HIV drugs didn't affect the MRP-1 mediated efflux of etoposide. CONCLUSIONS: These data may be exploitable to further improve sanctuary site concentrations of anti-HIV or anti-cancer drugs by using ritonavir as a lead compound to develop more potent MRP-1 inhibitors.     

Effects of heparin and protamine on left ventricular performance in the dog.

The effects of protamine on left ventricular (LV) function were measured under conditions of controlled heart rate and proximal aortic pressure in eight anaesthetized, heparinised dogs. Protamine 3 mg.kg-1 produced a 21% decrease in LV dP/dt max, a 43% decrease in cardiac output, a 47% decrease in stroke work and decreases in systolic and diastolic pressures (-16%, -19% respectively). Protamine 6 mg.kg-1 resulted in a 17% decrease in LV dP/dt max, a 26% decrease in cardiac output, a 50% decrease in LV stroke work and 25 and 30% decreases in systolic and diastolic pressures. These results show that an impairment of LV function plays an important part in the circulatory depression produced by protamine.     

Diagnostic accuracy of a rapid urine-screening test (Multistix8SG) in cirrhotic patients with spontaneous bacterial peritonitis

OBJECTIVE: To assess the diagnostic accuracy of a rapid urine-screening test (Multistix8SG) for spontaneous bacterial peritonitis (SBP) in cirrhotic patients. METHODS: Seventy-two consecutive patients (44 males, 28 females; mean age 61.6 years) with cirrhosis and ascites were included in the study. A diagnostic paracentesis was performed on hospital admission in all patients and 2 days after antibiotic treatment in the case of SBP (polymorphonuclear [PMN] count over 250/mm in ascitic fluid). Each fresh sample of ascitic fluid was also tested using the Multistix8SG urine test, and the results were scored as negative, trace or positive. RESULTS: Nine of the 72 patients had SBP and the Multistix8SG urine test was positive. After 48 h of antibiotic therapy, the PMN count of three of these nine patients was still above 250/mm and the Multistix8SG test remained positive. In three other patients with SBP, the PMN count dropped below 250/mm and the Multistix8SG test result had become negative. Two of the nine SBP patients died before 48 h, and paracentesis was not performed in the ninth case. In the other 63 patients, the PMN count in ascitic fluid was below 250/mm; the Multistix8SG test revealed 17 trace results and 46 negative results. At the threshold of 250 PMN/mm in ascitic fluid, this test had a sensitivity and a specificity of 100%. CONCLUSION: A positive Multistix8SG urine test result in ascitic fluid appears to be an indication for antibiotic treatment.     

Human immunodeficiency virus type 1 and other viral co-infections among young heterosexual men and women in Argentina

Infections with hepatitis C virus, (HCV), hepatitis B virus (HBV), and human T lymphotropic type I/II (HTLV-I/II) virus are commonly found in patients infected with human immunodeficiency virus type 1 (HIV-1). We conducted a seroepidemiologic study among 174 HIV-positive heterosexuals in Buenos Aires, Argentina in 1999. Evidence of exposure to HCV, HBV, and HTLV-I/II was found in 32%, 17%, and 5%, respectively. A higher prevalence of HBV infection was observed among males (33%) compared with females (12%; P < 0.05). Among women, a prior history of a sexually transmitted infection, injecting drug use (IDU), having had more than five lifetime sex partners, and having exchanged sex-for-goods were significantly associated with HCV infection, whereas an IDU history, syringe sharing, and having exchanged sex-for-goods were found to be associated with HBV infection. Among men, an IDU history and syringe/needle sharing were significantly associated with HCV infection. The IDU-related and sexual transmission of hepatitis viruses constitute a significant problem among young, HIV-infected, heterosexuals in Argentina.     

Analysis of the Pediatric Health Information System Database as a Surveillance Tool for Travel-Associated Infectious Diseases

The Pediatric Health Information System (PHIS) database collects admission, diagnostic, and treatment data among 44 children''s hospitals across the United States (U.S.) and presents an opportunity for travel-associated infectious disease (TAID) surveillance. We calculated cumulative incidence rates among children admitted to 16 PHIS hospitals for dengue, malaria, and typhoid, and pooled TAID using discharge codes from 1999 to 2012. We compared incidence rates before, during, and after the 2007–2009 economic recession. Among 16 PHIS hospitals during the study period (1999–2012), incidence of dengue and pooled TAID (malaria, dengue, typhoid fever) increased significantly, and rates of malaria and typhoid trended upward. Admissions for dengue and pooled TAIDs increased significantly among 16 children''s hospitals across the United States from 1999 to 2012. The PHIS database may provide a useful surveillance tool for TAIDs among children in the United States.International travel to other countries has increased 5% in the United States and 48% worldwide in the last decade, and more travelers visit low- and middle-income countries (LMICs) than ever before.¹ As many as 8% of U.S. travelers seek medical care, and many more suffer from milder illness while abroad.^2–4 A significant proportion of the 62 million annual U.S. international travelers develops illness after returning to the United States with infections that may be unfamiliar to local health-care providers.^5–7 Estimating incidence rates of non-endemic diseases may help public health officials direct educational resources and raise awareness among local practitioners.Currently, surveillance systems for travel-associated infectious diseases (TAIDs) in the United States are limited. Many TAIDs are reportable to state health departments, but reporting is often unreliable.⁸ The GeoSentinel Surveillance Network (GSSN) is a system of 57 travel disease clinics worldwide, including 15 clinics in the United States. Although the GSSN obtains robust clinical and diagnostic information, it surveys only those seeking care at specialty travel clinics, and only 7% of GSSN patients are children.¹The Pediatric Health Information System (PHIS) database was established to collect administrative and financial data from pediatric hospitals across the Unites States. More recently, the database has been augmented (PHIS+) to also collect clinical, laboratory, treatment, and outcome data at multiple health-care settings (inpatient, outpatient, and emergency departments [EDs]) among 44 freestanding children''s hospitals across the United States.^9,10 It offers an opportunity for objective hospitalized TAID surveillance among the greater than 5 million children hospitalized annually at these institutions.¹¹ We evaluated the PHIS database as a potential TAID surveillance tool by determining cumulative incidence rates of three TAIDs (malaria, dengue, and typhoid fever) among PHIS hospitals over a 14-year period.A total of 16 PHIS hospitals from geographically diverse metropolitan areas (median population 426,001 people, interquartile range 247,026–757,907 people)¹² had non-missing data available during the study period (1999–2012). The metropolitan areas include San Diego, CA; Norfolk, VA; St. Petersberg, FL; Orange County, CA; Corpus Christi, TX; Miami, FL; Denver, CO; Memphis, TN; Chicago, IL; Akron, OH; Little Rock, AR; Columbus, OH; Fort Worth, TX; Omaha, NE; Milwaukee, WI; and St. Louis, MO. All inpatient discharges from these sites with a principal discharge diagnosis (International Classification of Diseases 9 [ICD-9]) code¹³ for malaria (0840, 0841, 0842, 0843, 0846, 0849), typhoid (0020), and dengue (061) were identified within the PHIS database. Readmissions for the same ICD-9 diagnosis were excluded from the analysis. Cumulative incidence rates of malaria, typhoid, and dengue as well as pooled TAID incidence rates for all three diseases were determined by dividing hospitalized cases by total hospital discharges per year. Individual disease and pooled incidence rates were compared over the study period (1999–2012). We hypothesized that TAID incidence rates may have decreased during the 2007–2009 economic recession due to decreased international travel, and thus, rates for before (1999–2006), during (2007–2009), and after the U.S. economic recession were compared.^7,14,15 Categorical variables were compared using χ² with Fisher''s exact testing when appropriate.The 16 PHIS hospitals represented 2,203,063 pediatric hospital admissions during the study period. Individual and pooled cumulative TAID incidence trended upward from 1999 to 2012, though the trend did not achieve statistical significance (r² = 0.158). When comparing cumulative incidence rates from before (1999–2006), during, and after (2010–2012) the 2007–2009 economic recession, there was a significant change in incidence rates for dengue (P = 0.016) and pooled TAID (p = 0.009), though all diseases studied showed a similar trend with decreases during the recession and highest rates after (Figure 1 ).Open in a separate windowFigure 1.Comparison of pooled and individual travel-associated infectious diseases (TAIDs) in the Pediatric Health Information System (PHIS) database, 1999–2012.

Table 1

Hospital admission incidence rates of travel-associated infectious diseases (TAIDs) in children before, during, and after the 2007–2009 economic recession.

Phenotype-Genotype Correlations and Estimated Carrier Frequencies of Primary Hyperoxaluria

Primary hyperoxaluria (PH) is a rare autosomal recessive disease characterized by oxalate accumulation in the kidneys and other organs. Three loci have been identified: AGXT (PH1), GRHPR (PH2), and HOGA1 (PH3). Here, we compared genotype to phenotype in 355 patients in the Rare Kidney Stone Consortium PH registry and calculated prevalence using publicly available whole-exome data. PH1 (68.4% of families) was the most severe PH type, whereas PH3 (11.0% of families) showed the slowest decline in renal function but the earliest symptoms. A group of patients with disease progression similar to that of PH3, but for whom no mutation was detected (11.3% of families), suggested further genetic heterogeneity. We confirmed that the AGXT p.G170R mistargeting allele resulted in a milder PH1 phenotype; however, other potential AGXT mistargeting alleles caused more severe (fully penetrant) disease. We identified the first PH3 patient with ESRD; a homozygote for two linked, novel missense mutations. Population analysis suggested that PH is an order of magnitude more common than determined from clinical cohorts (prevalence, approximately 1:58,000; carrier frequency, approximately 1:70). We estimated PH to be approximately three times less prevalent among African Americans than among European Americans because of a limited number of common European origin alleles. PH3 was predicted to be as prevalent as PH1 and twice as common as PH2, indicating that PH3 (and PH2) cases are underdiagnosed and/or incompletely penetrant. These results highlight a role for molecular analyses in PH diagnostics and prognostics and suggest that wider analysis of the idiopathic stone-forming population may be beneficial.     

Purging of acute myeloid leukemic cells by ether lipids and hyperthermia

Ether lipids (EL) and hyperthermia have been shown to possess a relatively selective cytotoxicity to leukemic cells. In this study, the combined effects of EL (ET-18-OCH3, ET-16-NHCOCH3, or BM 41.440) and hyperthermia on the growth of hematopoietic progenitors, myeloid leukemic cell lines, and leukemic cells obtained from patients with acute myeloid leukemia (AML) were examined to determine if this combination resulted in a greater selective killing of leukemic cells than that achieved by either EL or heat alone. When the cells were treated simultaneously with EL (50 micrograms/mL) and hyperthermia (42 degrees C) for one hour, the killing of leukemic cell line cells was enhanced considerably. Among the three EL, however, the combination of ET-18-OCH3 and heat seemed to be the most cytotoxic to leukemic cell line cells with no effect on the growth of hematopoietic progenitors. An increase in the duration of treatment with ET-18-OCH3 to four hours with heat added during the last hour resulted in a further reduction of leukemic cell line cells while sparing 50% of hematopoietic progenitors after cryopreservation. The combined treatment with ET-18-OCH3 and heat also inhibited the growth of leukemic progenitors obtained from AML patients by 97% to 100%. These data indicate that the combined treatment with EL and hyperthermia might offer an efficient means to eliminate myeloid leukemic cells in vitro.