ABSTRACT: It is well known that light transmission through blood is the most widely utilized method for the study of erythrocyte aggregation. The curves obtained had been considered empirically as exponential functions. In consequence, the process becomes characterized by an only parameter that varies with all the process factors without discrimination. In the present paper a mathematical model for RBC aggregation process is deduced in accordance with von Smoluchowski's theory about the kinetics of colloidal particles agglomeration. The equation fitted the experimental pattern of the RBC suspension optical transmittance closely and contained two parameters that estimate the most important characteristics of the aggregation process separately, i.e., (1) average size of rouleaux at equilibrium and (2) aggregation rate. The evaluation of the method was assessed by some factors affecting erythrocyte aggregation, such as temperature, plasma dilutions, Dextran 500, Dextran 70 and PVP 360, at different media concent rations, cellular membrane alteration by the alkylating agent TCEA, and decrease of medium osmolarity. Results were interpreted considering the process characteristics estimated by the parameters, and there were also compared with similar studies carried out by other authors with other methods. This analysis allowed us to conclude that the equation proposed is reliable and useful to study erythrocyte aggregation.    © 1999 Academic Press

Keywords: Erythrocyte aggregation, kinetics, hemorheology, aggregogram.

Reprint requests to: M. Rasia, Catedra de Biofísica, Fac. de Ciencias Médicas, Universidad Nac. de Rosario, Santa Fe 3100, 2000-Rosario, Santa Fe, REP. ARGENTINA, fax: 5441-4484761, e-mail: mgbysmb@cablenet.com; mrasia@mailcity.com.

Abstract: The discovery of the C282Y and H63D point mutations in the hereditary hemochromatosis-associated HFE gene allows us to study the molecular basis of congenital and acquired iron overload disorders. In hereditary hemochromatosis an increased frequency of the C282Y and, to a lesser extent, of the H63D mutations has been established, but their role in other conditions associated with iron overload and their prevalence in the normal population are still under investigation. We sought to determine the presence of such mutations, and their possible involvement in the multi-step neoplastic transformation of the hepatocytes, in patients diagnosed with hepatocellular carcinoma, a frequent complication of iron-induced liver cirrhosis occurring in untreated hereditary hemochromatosis subjects. The frequency of the C282Y and H63D mutations was determined in DNA from 12 patients with hepatocellular carcinoma and with no clinical signs of hereditary hemochromatosis. The frequency of the mutations was also determin ed in 130 normal subjects. A germline C282Y mutation was found in none of the hepatocellular carcinoma patients; the frequency of the H63D mutation was not increased, compared to the 130 controls. The allele frequencies of the C282Y and H63D mutations in the normal population were 0.042 and 0.185, respectively. In conclusion, we suggest that the hereditary hemochromatosis-related mutations of the HFE gene do not play a significant role in the pathogenesis of hepatocellular carcinoma.   © 1999 Academic Press

Keywords: Hereditary hemochromatosis, HFE, C282Y, H63D, iron overload, hepatocellular carcinoma.

Reprint requests to: Dr. Anna Maria Ferraris, Ematologia Oncologica, IST, Largo Rosanna Benzi, 10, 16132 Genoa, Italy, fax: +39 010 509052, e-mail: gaetani@mbox.ulisse.it.

Abstract: Two amino acid variants in the HFE gene, C282Y and H63D, have been reported in most cases of hereditary hemochromatosis. A recently discovered novel amino acid variant of HFE, namely S65C, has been implicated to be responsible for a mild form of iron overload. We determined genotypes of the HFE S65C variant in 230 voluntary blood donors with a transferrin saturation > 45%, who did not carry the HFE C282Y variant. The control group consisted of 248 first time blood donors who had a transferrin saturation < 45%. We also determined genotypes of the HFE H63D variant in the two groups. For the HFE S65C variant, the frequency of the HFE C65 allele was 1.7% and 2.2% in the high and low transferrin saturation groups, respectively (p = 0.65). In contrast, for the HFE H63D variant, the frequency of the HFE D63 allele was 24.8% and 14.7% in the high and low transferrin saturation groups, respectively (p = 0.0009). This study demonstrates no association of the HFE C65 allele with the phenotype of high transferrin saturation. The results do not support the use of DNA genotyping for the HFE S65C mutation in population screening studies for hemochromatosis.    © 1999 Academic Press

Reprint requests to: Dr. Paul C. Adams, Department of Medicine, London Health Sciences Centre, 339 Windermere Road, London, Ontario N6A 5A5, CANADA, fax: 519-663-3232, e-mail: padams@julian.uwo.ca.