Sister chromatid exchange frequencies in patients with scleroderma and their relatives

The alteration of sister chromatid exchange frequencies in Behçet's disease with and without HLA-B51

BACKGROUND

The analysis of sister chromatid exchange (SCE) is a cytogenetic technique used to show DNA damage as a result of an exchange of DNA fragments between sister chromatids. It is known that there is an increased SCE frequency in Behçet's disease (BD).

OBJECTIVE

To investigate whether human leucocyte antigen (HLA)-B51-positive patients with Behçet's disease exhibit higher SCE frequencies than those without HLA-B51.

METHODS

Lymphocytes from 75 patients (38 women, 37 men) and from 50 controls (28 women, 22 men) were cultured in darkness for 72 h in the presence of bromodeoxyuridine. Metaphase chromosomes were stained with a fluorescence plus Giemsa technique after a standard harvest procedure. For HLA-B51 typing, DNA was extracted from ethylenediaminetetraacetic acid blood samples and HLA-B5 allele genotyping was performed by the polymerase chain reaction (PCR)-sequence specific primer method.

RESULTS

Thirty-nine of 75 patients with BD (52%) and 15 of 50 controls (30%) were found HLA-B51-positive. The SCE frequencies in HLA-B51-positive patients were higher than in HLA-B51-negative ones (P < 0.001), whereas no difference was detected in the control group.

CONCLUSION

This study revealed that there was a significant association between elevated SCE frequencies and existence of HLA-B51 patients with BD.

Evaluation of DNA damage using the comet assay in children on long-term benzathine penicillin for secondary prophylaxis of rheumatic fever

BACKGROUND

Benzathine penicillin is the most widely used antibiotic in the prophylaxis of children with rheumatic fever. The aim of the present study was to evaluate the DNA damage in children receiving one dose of 1.2 million units benzathine penicillin every 4 weeks over a long period to prevent recurrences of rheumatic fever.

METHODS

Thirty-five children with confirmed rheumatic fever under benzathine penicillin prophylaxis were enrolled in the study and 35 healthy children with similar ages and socioeconomic backgrounds served as controls. To detect any DNA damage, the comet assay was performed on circulating lymphocytes from the study subjects.

RESULTS

Damaged (limited and extensive migration) cells in children on prophylactic therapy were higher than those in controls (P<0.001).

CONCLUSIONS

It has been suggested that differences in the comet scores were induced by the administration of benzathine penicillin over a long period of time and further investigations are needed to confirm this toxic effect.

Sister-chromatid exchange analysis on long-term benzathine penicillin for secondary prophylaxis of rheumatic fever

A single intra-muscular injection of 1.2 millions units of benzathine penicillin every 4 weeks is the most widely used method for the antibiotic prophylaxis of rheumatic fever. The aim of this study is to evaluate the effect of long-term benzathine penicillin on DNA in patients with rheumatic fever. Thirty children with confirmed rheumatic fever who were on the benzathine penicillin prophylaxis were enrolled in the study, and 30 similar normal children served as a control group. To detect any DNA damage, SCE analysis were performed in circulating lymphocytes of the subjects. A statistically significant increased frequency of SCE was observed in children on the benzathine penicillin prophylaxis (no = 30, mean SCEs/cell +/- SD 7.54 +/- 1.81) as compared to a control group (no = 30, mean SCEs/cell +/- SD 5.82 +/- 1.40). It has been suggested that the difference in the SCE frequencies was induced by the administration of the benzathine penicillin for a long time, and further investigations are needed to confirm this toxic effect.

Chromosome abnormalities in peripheral lymphocytes from patients with progressive systemic sclerosis

Chromosomal abnormalities in cultured peripheral lymphocytes from 14 progressive systemic sclerosis (PSS) patients and 15 normal subjects were examined. No increase was observed in the frequency of chromosome aberrations in PSS patients who had not received any medical treatment. Those who had received medication showed an increased frequency of dicentrics (0.3%) although the frequency was not significantly higher than that for normal subjects. It is not clear, however, whether the increase was due to the hypersensitivity of PSS patients to agents used for therapeutic purposes.

Familial clustering of scleroderma spectrum disease

This is the second case report of familial scleroderma (systemic sclerosis) in South Carolina. The family includes two cases of scleroderma meeting American Rheumatism Association criteria, one of systemic sclerosis sine scleroderma, and two other cases of undifferentiated connective tissue disease with features of scleroderma spectrum disorders; there are also two cases of Raynaud's phenomenon (one associated with rheumatoid arthritis), for a total of seven affected relatives. Evidence of scleroderma spectrum disorders was sought in six siblings of the two co-index cases and in 23 of the 35 offspring. Laboratory studies included antinuclear antibody determinations and typing for the following genetic markers: HLA (A, B, C, DR), complotypes, Gm and Km allotypes, and alpha-1 antitrypsin phenotypes. No common genetic markers restricted to affected members of this family were found, and no environmental exposures were detected that could explain this familial clustering of cases. This report should, however, add to the slowly accumulating information on the genetic characteristics of families at unusually high risk for scleroderma spectrum disorders. Positive antinuclear antibody tests at a titer of 1/40 or higher were present in 57 percent of the first-degree relatives of the affected cases.