Effects of nitric oxide on gentamicin toxicity in isolated perfused rat kidneys

BACKGROUND: There have been many studies in recent years concerning the role of nitric oxide (NO) in acute renal failure (ARF). In this study, the effects of the inhibition or the induction of NO synthase (NOS) on gentamicin-induced ARF was investigated in isolated perfused rat kidneys. METHODS: Kidneys from male Sprague-Dawley rats were perfused in situ for 90 min. Perfusion was conducted in the presence of inulin (60 mg/dL in perfusion buffer) as a glomerular filtration rate (GFR) marker. Six groups (total: 42 rats) were studied: group 1, controls with no treatment; group 2, L-arginine (2 mM in perfusate); group 3, L-nitro-arginine-methyl ester (L-NAME, 0.1 mM in perfusate); group 4, gentamicin (GM, 0.5 mg/mL in perfusate); group 5, GM + L-arginine (same dose as groups 2 and 4) and; group 6, GM + L-NAME (same dose as groups 3 and 4). Cell injury was assessed by measuring N-acetyl-beta-D-glucosaminidase (NAG), lactate dehydrogenase (LDH) and alkaline phosphatase (ALP) activity in urine. RESULTS: L-arginine prevented, whereas L-NAME enhanced, GM-induced enzyme release and GFR reduction. Histological studies showed that GM-treated kidneys had clear signs of tubular damage and this damage was increased by simultaneous L-NAME and GM administration. CONCLUSION: This study suggests that NO formation could prevent the GM-induced nephrotoxicity in this ARF model.     

HIV care and treatment for children in resource-limited settings

Although efforts to combat the HIV epidemic have focused on the perinatal reduction of HIV transmission, many children are still being infected with HIV in resource-limited settings. Access to HIV care, cotrimoxazole and antiretroviral therapy (ART) for HIV-infected children has greatly improved in recent years, and has proven to be very effective in reducing mortality in all age categories. Many challenges remain to be resolved, such as the retention in care of children born to HIV-infected mothers, the lack of pharmacokinetic data on ART in malnourished children, optimum timing of ART, treatment and diagnosis of concomitant tuberculosis, and the effects of ART and HIV on the child's development. In the long term, treatment success might be negated due to lower rates of viral suppression in children and the accumulation of resistance mutations. Evidenced-based comprehensive care models should allow for decentralizing care up to the level of the community, allowing larger numbers of children to receive HIV care.     

Pediatric HIV infection: the state of antiretroviral therapy

Pediatric HIV/AIDS has become less of a problem in resource-rich countries as the number of perinatal infections has reduced dramatically since the advent of antiretrovirals, resulting in the effective prevention of mother-to-child transmission. In resource-limited settings, however, pediatric HIV infection remains a colossal problem; a separate review in this same issue of Expert Review of Anti-Infective Therapy examines the international aspects of pediatric HIV/AIDS. Treatment of HIV infection in children differs from that in adults in the use of immunologic markers and owing to drug pharmacokinetics and age-related adherence issues. This review, geared for the general pediatrician or family practitioner who may see the HIV-positive child in the clinic or the hospital, summarizes the most recent pediatric data and guidelines for the testing and treatment of HIV, including the US NIH guidelines released in February 2008. Treatment-experienced patients, who should be cared for by pediatric HIV specialists, are not addressed here specifically. Adolescents, infected either perinatally or sexually, with their own unique issues, deserve a separate review.     

Novel Βeta (β)-Thalassemia Mutation in Turkish Children

Beta (β)-thalassemia is the most frequently observed hereditary blood disorder in the world. It is characterized by deficiency of hemoglobin β-globin gene and is also a profoundly heterogeneous both at the molecular and clinical level. In the case of β-thalassemia, there is reduced (β⁺ type) or absent (β^o type) synthesis of the beta chains of hemoglobin. β-Thalassemia clinically occurs in three main forms: major, intermedia and minor according to requirement of transfusion. The objective of this study was to evaluate β-thalassemia mutations in 89 patients ranging from 2 months to 16 years of age, who enrolled to Medical School Research and Training Hospital, Gaziantep University. The direct DNA sequence analysis was performed for mutation scanning of β-globin gene. 89 children with β-Thalassemia including all types were analyzed, 16 different β-thalassemia mutations were detected. We have also identified a novel mutation (HBB.c.-80delT, rs397509430) in the promoter region (−30 TATA box) of β-globin gene, and clinical data of patient having novel mutation was given. The β-Thalassemia mutations were determined as β-Thalassemia major type in 42 patients (47.19 %), β-Thalassemia intermedia in 4 (4.49 %), β-Thalassemia minor in 43, (48.31 %) patients. The most frequent mutation was IVS I-110 G>A, followed by IVS I-1 G>A, IVS I-6 T>C, IVS II-1 G>A, respectively.     

Glomerular filtration rate-based cystatin C compared to microalbuminuria to detect early stage of diabetic nephropathy in children with type 1 diabetes mellitus

Microalbuminuria is a sensitive marker to detect early nephropathy in diabetes mellitus. Cystatin C correlates better than serum creatinine with microalbuminuria in type 1 diabetes mellitus (T1D). We evaluated the correlation between microalbuminuria, serum cystatin C (Cyc-C), and serum creatinine (SCr) in diabetic children. A hundred patients with stable T1D and 66 sex-matched healthy children were entered in the study between September 2008 and February 2011. Fasting blood sample was drawn for HbA₁C, creatinine, and cystatin C. A. 24-h urine aliquot was collected to measure microalbumin, creatinine, and volume. Glomerular filtration rate estimated based on creatinine (eGFR_cr), cystatin C (eGFR_{Cyst C}), and creatinine + cystatin C (eGFR_{Cyst C + Cr}). Binary logistic regression analysis, chi-square, ANOVA, Student’s t test, and nonparametric median tests were used to analyze data. P < 0.05 was considered significant. Medians serum creatinine and cystatin C of T1D group were significantly different from controls (P < 0.05). Overall, medians eGFR_{Cyst C} were higher than eGFR_cr, or eGFR_{Cyst C + Cr}. Thirty-six children with T1D had microalbuminuria. There was a correlation between microalbuminuria and eGFR_{Cyst C} (<60 and >130 ml/min/1.73 m²) (P < 0.05). Medians eGFR_cr were significantly lower than medians eGFR_{Cyst C} in T1D, regardless of microalbuminuria (P < 0.05). Chronic kidney disease classification according to eGFR_cr and eGFR_{Cyst C} were not matched (P < 0.05). GFR in healthy children was overestimated by eGFR_{Cyst C} and underestimated by eGFR_cr. There was higher correlation between abnormal eGFR_{Cyst C} and microalbuminuria in diabetic children. eGFR_Cr detected higher rate of GFR less than 60 ml/min/1.73 m².

     

Copper Complexation Screen Reveals Compounds with Potent Antibiotic Properties against Methicillin-Resistant Staphylococcus aureus

Macrophages take advantage of the antibacterial properties of copper ions in the killing of bacterial intruders. However, despite the importance of copper for innate immune functions, coordinated efforts to exploit copper ions for therapeutic interventions against bacterial infections are not yet in place. Here we report a novel high-throughput screening platform specifically developed for the discovery and characterization of compounds with copper-dependent antibacterial properties toward methicillin-resistant Staphylococcus aureus (MRSA). We detail how one of the identified compounds, glyoxal-bis(N4-methylthiosemicarbazone) (GTSM), exerts its potent strictly copper-dependent antibacterial properties on MRSA. Our data indicate that the activity of the GTSM-copper complex goes beyond the general antibacterial effects of accumulated copper ions and suggest that, in contrast to prevailing opinion, copper complexes can indeed exhibit species- and target-specific activities. Based on experimental evidence, we propose that copper ions impose structural changes upon binding to the otherwise inactive GTSM ligand and transfer antibacterial properties to the chelate. In turn, GTSM determines target specificity and utilizes a redox-sensitive release mechanism through which copper ions are deployed at or in close proximity to a putative target. According to our proof-of-concept screen, copper activation is not a rare event and even extends to already established drugs. Thus, copper-activated compounds could define a novel class of anti-MRSA agents that amplify copper-dependent innate immune functions of the host. To this end, we provide a blueprint for a high-throughput drug screening campaign which considers the antibacterial properties of copper ions at the host-pathogen interface.