Organic compounds in water extracts of coal: links to Balkan endemic nephropathy.

The Pliocene lignite hypothesis is an environmental hypothesis that has been proposed to explain the etiology of Balkan endemic nephropathy (BEN). Aqueous leaching experiments were conducted on a variety of coal samples in order to simulate groundwater leaching of organic compounds, and to further test the role of the Pliocene lignite hypothesis in the etiology of BEN. Experiments were performed on lignite coal samples from endemic BEN areas in Romania and Serbia, and lignite and bituminous coals from nonendemic regions in Romania and the USA. Room temperature, hot water bath, and Soxhlet aqueous extraction experiments were conducted between 25 and 80 °C, and from 5 to 128 days in duration. A greater number of organic compounds and in higher concentrations were present in all three types of leaching experiments involving endemic area Pliocene lignite samples compared to all other coals examined. A BEN causing molecule or molecules may be among phenols, PAHs, benzenes, and/or lignin degradation compounds. The proposed transport pathway of the Pliocene lignite hypothesis for organic compound exposure from endemic area Pliocene lignite coals to well and spring drinking water, is likely. Aromatic compounds leached by groundwater from Pliocene lignite deposits in the vicinity of endemic BEN areas may play a role in the etiology of the disease. A better understanding of organic compounds leached by groundwater from Pliocene lignite deposits may potentially lead to the identification and implementation of effective strategies for the prevention of exposure to the causative agent(s) for BEN, and in turn, prevention of the disease.

The etiology of Balkan endemic nephropathy: still more questions than answers.

Balkan endemic nephropathy (BEN) has attracted increasing attention as a possible environmental disease, and a significant amount of research from complementary scientific fields has been dedicated to its etiology. There are two actual competing theories attempting to explain the cause of this kidney disease: 1) the mycotoxin hypothesis, which considers that BEN is produced by ochratoxin A ingested intermittently in small amounts by the individuals in the endemic regions, and 2) the Pliocene lignite hypothesis, which proposes that the disease is caused by long-term exposure to polycyclic aromatic hydrocarbons and other toxic organic compounds leaching into the well drinking water from low rank coals underlying or proximal to the endemic settlements. We outline the current developments and future prospects in the study of BEN and differentiate possible factors and cofactors in disease etiology.

Balkan endemic nephropathy, the haematopoietic system and the environmental connection.

We previously reported the detection of an increased subpopulation of cytotoxic T lymphocytes in patients with Balkan (endemic) nephropathy (BEN) and in area controls (individuals free of clinical syndrome but born in a BEN endemic area and having a family history of BEN). Extending the flow-cytometric analyses to other populations of peripheral blood leucocytes, we found a decrease in the proportion of B lymphocyte subset and an increased proportion of eosinophils in BEN patients and in area controls. Although these numerical alterations cannot be categorically linked to the aetiopathogeny of the disease, it is presumed that they can be induced by the same factor(s) causing the kidney damage, through a direct haemato- and lymphotoxic effect.

Immunologic tolerance: self-nonself discrimination versus costimulatory factors and second signals.

An attempt is made to assess the total number of the theoretically possible antigenic epitopes, the number of lymphocyte clones and the number of epitopes on cell surface antibody of a clone may be able to recognize. We suggest that the structures of recognizing antibody sites of a human are far from random and derived from a limited number of structures adapted to the recognition of pathogenic agents. The probability of recognition for a random epitope-like structure is likely to be very small. Discriminative power of BCR and TCR binding sites, together with T-helper control, should be sufficient for prevention of peripheral autoimmune response, but second-signal-type controls should not be neglected as supplementary mechanisms to prevent such response.

P-glycoprotein mediated multidrug resistance assessment by flow-cytometry in malignant hemopathies.

A relatively common and frequent form of multidrug resistance(MDR) in cancer cells is due to membrane overexpression of P-glycoprotein. Mdr phenotype was investigated by flow-cytometry in several types of malignant hemopathies -chronic lymphocytic leukemia, non-Hodgkin lymphomas, acute lymphoblastic and myeloblastic leukemias. We used daunomycin and fluo-3 as fluorochromes, and verapamil as reversor agent. The method is lacking unitary clinical parametrization and in order to improve it, we tried to establish an optimal concentration of verapamil, which was shown to be 14.92 micrograms/ml. The reliability of results obtained with fluo-3 in culture media containing Ca2+ is questionable, as low variations in the intracellular level of this ion dramatically influences light emission by the fluorochrome and possibly the function of P-gp. To avoid such fluorescence intensity variations, Ca(2+)-free cell culture medium for fluo-3-based flow-cytometric assay is suggested to be used.

Molecular aspects concerning antigen oligopeptide selection by MHC class I molecules.

T cells can recognize the antigen only if it is associated with self MHC molecules on the surface of antigen presenting cells (APC). There are several characteristic parameters defining interaction of MHC molecule with antigenic peptides giving circumstances for specific antigen presentation and an individualized immune response. Here are assessed some size and conformational parameters of the peptides presented by MHC class I molecules-lengths, widths, van der Waals volumes and surfaces-using COSMIC 2.0 software. The peptides derived from HIV gp 160 are obtained from literature and are known to be active and inactive in a cytotoxicity assay. An increased tendency for beta- or beta-like structures and volumes close to those of the MHC binding site are encountered in the case of active peptides.

DNA topology and V(D)J recombination: a tentative connection.

Gene recombination is the fundamental basis of immunoglobulin (Ig) and T cell receptor (TCR) diversity. Although several specific and nonspecific enzymatic equipments were revealed to be necessary for Ig and TcR gene assembly, almost nothing is known about the developmental and tissue specific control of recombination and the individual functions of the heptameric and nonameric signals and 12/23 spacers in this process. According to certain conformational and functional respects, we consider the nonamer a DNA insertion site to the nuclear scaffold, in relation with its structural homology to the satellite (5'-ACAAACC-3') and microsatellite repetitions, involved in DNA-nucleoskeleton impact. A topological control for V(D)J recombination is proposed, through different accessibilities of the substrates in the catalytic site, defined by a specific nonamer-mediated insertion to the nuclear scaffold. Recognition of heptamer and nonamer sequences by RAG proteins is followed by the assembly of an asymmetric recombinant complex. Even more important in this assembly may be the role of nonamer which, through DNA flexibilization and bending, could participate at the formation of the enzyme core. This core with the attached DNA could have a nucleosome-like geometry, a motif present in certain DNA processing enzymatic systems. Such an assumption emerges from the close homology of the nonamers with the DNA mobilization intergenic sequences (CA5-6T), found in many eukaryotic organisms.