No abstract

We have investigated the levels of several antioxidant enzymes and the level of oxidative DNA base damage in lymphocytes of children with acute lymphoblastic leukemia (ALL) and in disease-free children. Children with ALL had just been diagnosed with the disease and had received no therapy prior to obtaining blood samples. A multitude of typical hydroxyl radical-induced base lesions in lymphocyte DNA of children were identified and quantified by gas chromatography-isotope dilution mass spectrometry. Higher levels of DNA base lesions were observed in patients with ALL than in children without the disease. The levels of the antioxidant enzymes glutathione peroxidase, catalase and Superoxide dismutase in lymphocytes of ALL patients were lower than in lymphocytes of controls. These findings are in agreement with earlier observations in various types of adulthood cancer. Some of the identified DNA base lesions are known to possess premutagenic properties and may play a role in carcinogenesis. The results may indicate a possible link between decreased activities of antioxidant enzymes and increased levels of DNA base lesions due to oxidative damage, and support the notion that free radical reactions may be increased in malignant cells.

Thalassemia major continues to be a significant health problem for Mediterranean, Afro-Arabic countries, India and South Easth Asia. It was generally assumed that the β-thalassemia heterozygotes do not bear significant medical risks except a mild microcytic anemia. Nonetheless, increasing number of reports associate β-thalassemia trait with autoimmune conditions, nephritis, diabetes, arthritis, fibromyalgia and asthma. Available sparse data indicate reduced incidence of systemic lupus erythematosus (SLE) in β-thalassemia heterozygotes; yet, if two conditions coexist, the SLE manifestations occur much severer. These associations make sense when considering that the hemoglobin β-chain locus at 11p15.5 resides in close proximity to eight genes with profound roles in immune regulation: STIM1, CD151, TC21/RRAS2, SIGIRR/TOLL/IL1R8, pp52/LSP1 (lymphocyte specific protein), TRIM21, toll interacting protein (TOLLIP) and SLEN3. β-Thalassemia trait accompaniment to autoimmune disease may be the result of haplotypal associations between the close proximity genes. An alternative explanation to thalassemia heterozygosity: autoimmune disease association may be the changed concentrations of hemorphins. Hemorphins are endogenous opioid peptides derived via proteolytical cleavage of hemoglobin. They are shown to bind diverse opioid receptors and act anti-inflammatory. Their reduced expression in thalassemia heterozygosity may explain a proinflammatory stage and autoimmunity vulnerability.

In this study, blood samples were taken from 200 patients with childhood acute leukaemias, including acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia (AML), and from 100 healthy volunteers (controls). The frequency of the human leucocyte antigen (HLA)-DRB1*04 allele was significantly higher, and the frequencies of the HLA-A23 and HLA-B7 antigens were significantly lower, in patients with ALL compared with controls. Among patients with AML, the frequency of the HLA-B49 antigen and the HLA-DRB1*15 allele were significantly higher, whereas the frequencies of the HLA-A11 and HLA-B38 antigens were significantly lower compared with controls. The frequency of the HLA-DRB1*04 allele was also significantly higher in male patients with ALL and AML, whereas the HLA-DRB1*13 allele was found significantly less frequently in male AML and female ALL patients than in controls. To date, this is the only study to evaluate the associations between HLA molecules and leukaemia in a Turkish population with acute childhood leukaemia.

Infection remains the major cause of morbidity and mortality in immunocompromised children with malignancy. In addition, the economic impact of antibiotic treatment should always be evaluated, especially in developing countries. In our center between January 1998 and January 1999, 73 children with hematological malignancies [acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML)]; 9 children with solid tumors (rhabdomyosarcoma, neuroblastoma) had 87 febrile neutropenic episodes (related to chemotherapy). These children were randomized prospectively into three treatment groups. The first group (n: 28) received cefepime plus netilmicin, while the second group (n: 29) was treated with ceftazidime plus amikacin and the third (n: 30) with meropenem as monotherapy. The aim of the study was to compare the success rates and cost of fourth generation cephalosporin plus aminoglycoside and monotherapy of meropenem with ceftazidime plus amikacin, which is the standard therapy for febrile neutropenia. Microbiologically documented infections were 29.9%, clinically documented infections were 9.2% and 60.9% of the febrile neutropenic episodes were considered to be FUO. Gram-positive microorganisms were the most commonly isolated agents from blood cultures [MRSA (Methicillin Resistant Staphylococcus aureus) in 6 patients and MSSA (Methicillin Sensitive Staphylococcus aureus) in 4 patients]. The success rates were 78.5%, 79.3% and 73.3 % for the 1st, 2nd and 3rd groups respectively. In 4 patients (4.5%) fever responded only to amphotericin-B therapy. There was no statistically significant difference between the three treatment regimens with respect to efficacy, safety and tolerance (chi2 test, p>0.05), but while the third and fourth generation cephalosporins + aminoglycosides were comparable for cost, the monotherapy regimen was the most expensive. The main determining factors for the choice of treatment of febrile neutropenic children, especially in a developing country, are cost, presence of indwelling catheter and the bacterial flora of the unit, as well as efficacy.