Recent reports have suggested that periodontal disease is a risk factor for coronary heart disease (CHD). However, little is known about the relationship between periodontal disease and CHD in the very elderly. Therefore, we evaluated the association between tooth loss and abnormal ECG findings in octogenarians. Of the 1,282 octogenarians in Fukuoka Prefecture, Japan, 697 participated. Oral examinations--including a tooth count and an assessment of the Community Periodontal Index--and a 12-lead ECG were performed. Logistic regression analysis revealed that individuals with < 20 teeth had increased prevalence of ST segment depression, and T-wave abnormalities, after we adjusted for gender, smoking, serum cholesterol and glucose, blood pressure, and body mass index. Compared with individuals with > or = 20 teeth, edentulous individuals had an increased prevalence of T-wave abnormalities and arrhythmias after adjustment for coronary risk factors. We conclude that tooth loss may be an independent predictor of abnormal ECG findings in octogenarians.

Porphyromonas gingivalis, a bacterium implicated in periodontal pathogenesis, has a growth requirement for iron protoporphyrin IX. By complementation with a P. gingivalis 381 chromosomal DNA library, we were able to isolate a clone that enhanced the poor growth of a hemG mutant of Escherichia coli. The DNA sequence analysis of this clone revealed three open reading frames (ORFs). ORF3 encoded a protein of 466 amino acids with a calculated molecular weight of 51 695 Da. The deduced amino acid sequence of the ORF3 gene had significant similarity to sequences of protoporphyrinogen oxidase (PPO) from Myxococcus xanthus (30% identical residues). When the ORF3 gene was overexpressed in E. coli, the extract had much higher PPO activity than a control extract, and this activity was inhibited by acifluorfen, a specific inhibitor of PPO. Thus, ORF3 was named PgHemG. Furthermore, several porphyrin-related genes, including hemD, hemN and hemH, were identified in the data bases on the websites available on-line. We postulated that a porphyrin biosynthetic pathway to heme from preuroporphyrin may be conserved in P. gingivalis.

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