Quantitative detection of Streptococcus mutans and bacteria of dental caries and no caries groups in permanent teeth from a north China population / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Streptococcus mutans (S. mutans) is the prime pathogen of dental caries. There are few reports that studied the relationship between S. mutans, bacteria and dental caries in permanent teeth when compared to those in primary teeth. This study aimed to detect S. mutans and bacteria of dental caries and non-caries groups in permanent teeth from a north China population by real-time polymerase chain reaction (PCR) and compare the relationship between the number of these bacteria and the prevalence of dental caries in permanent teeth.</p><p><b>METHODS</b>Human saliva samples were collected from 142 subjects with permanent teeth. According to their dental tooth (DT), 142 subjects were divided into a dental caries group (DT ≥ 1) and a non-caries group (DT = 0). With specific primers for S. mutans and 16S rRNA, the total number of S. mutans and total bacteria of 142 saliva samples were detected by real-time PCR and statistically analyzed.</p><p><b>RESULTS</b>There was no significant difference between the detection rates of S. mutans (P = 0.118) and medians of S. mutans (P = 0.115). The ratio of S. mutans to total bacteria in people with dental caries was significantly higher than in those without caries (P < 0.001), but the total number of bacteria in people with dental caries was significantly lower than in those without caries (P < 0.001).</p><p><b>CONCLUSIONS</b>S. mutans had different effects on caries in the permanent teeth of several individuals from a north China population. The ratios of S. mutans to total bacteria in saliva detected by real-time PCR with Sm479F/R and 16S RNA primers were closely associated with the prevalence of dental caries in the same population. These assays may be useful for the assessment of an individual's risk of dental caries.</p>

Molecular regulation of telomerase activity in aging

The process of aging is mitigated by the maintenance and repair of chromosome ends (telomeres), resulting in extended lifespan. This review examines the molecular mechanisms underlying the actions and regulation of the enzyme telomerase reverse transcriptase (TERT), which functions as the primary mechanism of telomere maintenance and regulates cellular life expectancy. Underpinning increased cell proliferation, telomerase is also a key factor in facilitating cancer cell immortalization. The review focuses on aspects of hormonal regulations of telomerase, and the intracellular pathways that converge to regulate telomerase activity with an emphasis on molecular interactions at protein and gene levels. In addition, the basic structure and function of two key telomerase enzyme components-the catalytic subunit TERT and the template RNA (TERC) are discussed briefly.

Quantitative detection of Streptococcus mutans in different people with dental caries by real-time polymerase chain reaction / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To establish a quantity detection method of Streptococcus mutans (Sm) and bacteria and compare the relationship between the number of these bacteria and the prevalence of dental caries in different people.</p><p><b>METHODS</b>With specific primers for a unique sequence in a 14 kb HaeIII restriction fragment consistently presenting during detecting Sm by chromosomal DNA fingerprints, the total number of Sm and bacteria of 99 saliva samples were detected by real-time polymerase chain reaction (PCR) and statistically analyzed.</p><p><b>RESULTS</b>The primers were specific for Sm and the minimum detectable level by real-time PCR was 0.1 microg/L. The total number of bacteria in the dental caries and people without caries was 51.4 x 10(8) cell copies/L and 221.6 x 10(8) cell copies/L respectively, in which the ratio of Sm to bacteria was 0.0193 and 0.0059 respectively. The differences were significantly different between the people with dental caries and those without caries in the total number of bacteria and the ratio of Sm to bacteria.</p><p><b>CONCLUSIONS</b>The primers can be used to detect the Sm by real-time PCR. The ratio of Sm to bacteria was closely associated with the prevalence of dental caries.</p>