A comparison of measured and estimated glomerular filtration rate in successfully treated HIV-patients with preserved renal function

BACKGROUND

Monitoring of renal function becomes increasingly important in the aging population of HIV-1 infected patients. We compared Cockroft & Gault (C&G), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), Modification of Diet in Renal Disease (MDRD), Cystatin C- and 24 h urine-based estimated GFR (eGFR) with the gold standard, measured GFR (mGFR) using [125I]-iothalamate.

METHODS

Substudy within a randomized, multinational trial comparing continuing zidovudine/ lamivudine with switching to tenofovir/ emtricitabine in patients with suppressed HIV-1 infection. Accuracy (defined as the mean difference between eGFR and mGFR) and precision (defined as standard deviation (SD) of the mean difference between eGFR and mGFR) of the eGFRs were calculated using linear regression and Bland & Altman analysis.

RESULTS

We included 19 patients, 18 men, 15 Caucasian, mean (SD) age 46.0 y (± 8.9) and BMI 23.9 kg/m2 (± 3.0). Mean (SD) mGFR was 102 ml/min/1.73 m2 (± 19), 4 patients had mild renal dysfunction. All eGFRs tended to underestimate true GFR, with best accuracy for C&G (-1 ml/min/1.73 m2), CKD-EPI (-1 ml/min/1.73 m2), 24 hcreatinine clearance (-2 ml/min/1.73 m2) and MDRD-6 (0 ml/min/1.73 m2), and worst for cystatin C-based (-9 ml/min/1.73 m2) and MDRD-4 estimations (-10 ml/min/1.73 m2). Accuracy worsened at higher mGFR, but was not significantly influenced by age. C&G tended to overestimate at higher BMI. Precision was comparable for all GFR estimations.

CONCLUSIONS

In this limited number of patients with preserved renal function and suppressed HIV-infection C&G and CKD-EPI appeared to be the best reflection of real GFR and most practical tool for monitoring GFR.

Transient lowering of the viral set point after temporary antiretroviral therapy of primary HIV type 1 infection

Whether temporary antiretroviral treatment during primary HIV infection (PHI) lowers the viral set point or affects the subsequent CD4 count decline remains unclear. The objectives of this study were to analyze the clinical, viral, and immunological effects of temporary early HAART during PHI. This is a cohort study of patients with laboratory evidence of PHI. Independent predictors of early HAART and the viral set point were analyzed using multiple regression analysis. Plasma HIV-1 RNA (pVL) and CD4 trajectories were analyzed using linear mixed models. A total of 332 patients were included in the analysis. Sixty-four patients started HAART within 180 days of seroconversion. A higher baseline pVL was independently predictive of the start of early HAART (OR: 2.69/log10pVL, p = 0.001). Thirty-two patients who interrupted early HAART were compared with 250 patients who remained untreated for more than 180 days after seroconversion. Temporary early HAART was not significantly associated with a longer AIDS-free survival but did result in an initial, but transient lowering of the viral set point. The viral set point was initially 0.6 log copies/ml lower after interruption of early HAART (p < 0.001) and remained lower during 83 weeks of follow-up. No significant difference in the slopes of CD4 decline was detected between the groups. Temporary HAART in PHI is started more frequently in patients with a higher pVL and can transiently lower the viral set point compared to never treated patients.

ortho-substituted PCB95 alters intracellular calcium signaling and causes cellular acidification in PC12 cells by an immunophilin-dependent mechanism

ortho-Substituted PCBs mobilize Ca2+ from isolated brain microsomes by interaction with FKBP12/RyR complexes. Investigation into the cellular importance of this mechanism was undertaken using PC12 cells by fluoroimaging the actions of specific PCB congeners on [Ca2+]i and pH. RyR and IP3R share a common intracellular Ca2+ store in PC12 cells. Perfusion of nM to low microM PCB95 caused a transient rise of [Ca2+]i that was not completely dependent on extracellular Ca2+. Pre-incubation of the cells with ryanodine or FK506 completely eliminated PCB95 responses, suggesting a primary action on the FKPP12/RyR-sensitive store. PCB95, but not PCB126, induced a gradual decrease in cytosolic pH that could be completely eliminated by FK506 pre-incubation of the cells. Direct respiration measurement using isolated brain mitochondria demonstrated that neither of the PCBs directly altered any stage of mitochondrial respiration. These results revealed that PCB95 disrupts intracellular Ca2+ signaling in PC12 cells by interaction with the FKBP12/RyR complex that in turn accelerated cellular metabolism, possibly affecting signaling between ER and mitochondria. Since ortho-substituted PCBs have been shown to be neurotoxic and may affect neurodevelopment, studies on the molecular mechanism by which they alter cellular signaling may provide valuable information on the physiological roles of FKPB12 and RyR on neuronal functions.

Liver Cell Estrogen Receptor Binding in Prespawning Female LargemouthBass, Micropterus salmoides, Environmentally Exposed toPolychlorinated Biphenyls

Estrogen-receptor-like binding was partiallycharacterized in liver tissue of prespawning female largemouth bass,Micropterus salmoides (LMB). Saturation and Scatchard analysesexhibited estrogen binding activity with high affinity (Kd in the10(-9) M range) and limited capacity (nuclear = 37.4fmol/g tissue; cytosol = 234 fmol/g tissue). Androgens, progestins,and cortisol competed poorly for binding in competition studies. Thus, LMBliver estrogen binding activity possesses similar properties to estrogenreceptors (ER) described in other vertebrates.In a study of prespawning female LMB from Lake Hartwell, SC/GA, a reservoir contaminated bypolychlorinated biphenyls (PCBs), individuals environmentally exposed to highlevels of PCBs had significantly lower ER binding capacity (Bmax) and highernonspecific binding (NS) than fish from a relatively uncontaminated referencelocation. Fish obtained at a site with intermediate levels of PCBs did notexhibit the expected decrease in Bmax. The lower Bmax observed in fish fromthe location with high PCB contamination is consistent with the reportedbehavior of liver ER in fish experimentally exposed to PCBs. Increased NS inthe ER assays could be related to elevations in albumin associated with thePCB exposure.

Acquired epileptic aphasia: neuropsychologic follow-up of 12 patients

A study of specific neuropsychologic, neurolinguistic, and behavioral features of acquired epileptic aphasia or Landau-Kleffner syndrome was conducted in a group of 12 patients followed-up for 2-15 years (mean: 8 yr). Seventy-five percent had exhibited some language disturbance prior to acquired epileptic aphasia. Even when 9 patients had normal electroencephalographic findings in the long-term course of the disease, only 3 achieved normal language. No patient with persisting electroencephalographic abnormalities recovered normal or near normal language. The need to perform detailed neurolinguistic and neuropsychologic evaluations in the work-up and follow-up of children with acquired epileptic aphasia is stressed. An adapted neuropsychologic profile battery proved to be practical and objective for the follow-up of these patients.