Frequent consumption of cariogenic foods and bacterial infection are risk factors for early childhood caries (ECC). This study hypothesized that a short diet survey focused on frequency of foods, ...categorized by putative cariogenicity, would differentiate severe ECC (S-ECC) from caries-free children. Children’s diets were obtained by survey and plaque bacteria detected by PCR from 72 S-ECC and 38 caries-free children. S-ECC children had higher scores for between-meal juice (p < 0.01), solid-retentive foods (p < 0.001), eating frequency (p < 0.005), and estimated food cariogenicity (p < 0.0001) than caries-free children. S-ECC children with lesion recurrence ate fewer putative caries-protective foods than children without new lesions. Streptococcus mutans (p < 0.005), Streptococcus sobrinus (p < 0.005), and Bifidobacteria (p < 0.0001) were associated with S-ECC, and S. mutans with S. sobrinus was associated with lesion recurrence (p < 0.05). S. mutans-positive children had higher food cariogenicity scores. Food frequency, putative cariogenicity, and S. mutans were associated with S-ECC individually and in combination.
Establishment of the microbiota of the gut has been shown to differ between infants delivered by Caesarian section (C-section) and those delivered vaginally. The aim of the present study was to ...compare the oral microbiota in infants delivered by these different routes. The oral biofilm was assayed by the Human Oral Microbe Identification Microarray (HOMIM) in healthy three-month-old infants, 38 infants born by C-section, and 25 infants delivered vaginally. Among over 300 bacterial taxa targeted by the HOMIM microarray, Slackia exigua was detected only in infants delivered by C-section. Further, significantly more bacterial taxa were detected in the infants delivered vaginally (79 species/species clusters) compared with infants delivered by C-section (54 species/species clusters). Multivariate modeling revealed a strong model that separated the microbiota of C-section and vaginally delivered infants into two distinct colonization patterns. In conclusion, our study indicated differences in the oral microbiota in infants due to mode of delivery, with vaginally delivered infants having a higher number of taxa detected by the HOMIM microarray.
Severe early childhood caries (ECC) is difficult to treat successfully. This study aimed to characterize the microbiota of severe ECC and evaluate whether baseline or follow-up microbiotas are ...associated with new lesions post-treatment. Plaque samples from 2- to 6-year-old children were analyzed by a 16S rRNA-based microarray and by PCR for selected taxa. Severe-ECC children were monitored for 12 months post-therapy. By microarray, species associated with severe-ECC (n = 53) compared with caries-free (n = 32) children included Slackia exigua (p = 0.002), Streptococcus parasanguinis (p = 0.013), and Prevotella species (p < 0.02). By PCR, severe-ECC-associated taxa included Bifidobacteriaceae (p < 0.001), Scardovia wiggsiae (p = 0.003), Streptococcus mutans with bifidobacteria (p < 0.001), and S. mutans with S. wiggsiae (p = 0.001). In follow-up, children without new lesions (n = 36) showed lower detection of taxa including S. mutans, changes not observed in children with follow-up lesions (n = 17). Partial least-squares modeling separated the children into caries-free and two severe-ECC groups with either a stronger bacterial or a stronger dietary component. We conclude that several species, including S. wiggsiae and S. exigua, are associated with the ecology of advanced caries, that successful treatment is accompanied by a change in the microbiota, and that severe ECC is diverse, with influences from selected bacteria or from diet.
Dental caries in pre-school children has significant public health and health disparity implications. To determine microbial risk markers for this infection, this study aimed to compare the ...microbiota of children with early childhood caries with that of caries-free children. Plaque samples from incisors, molars, and the tongue from 195 children attending pediatricians’ offices were assayed by 74 DNA probes and by PCR to Streptococcus mutans. Caries-associated factors included visible plaque, child age, race, and snacking habits. Species were detected more frequently from tooth than tongue samples. Lactobacillus gasseri (p < 0.01), Lactobacillus fermentum, Lactobacillus vaginalis, and S. mutans with Streptococcus sobrinus (all p < 0.05) were positively associated with caries. By multifactorial analysis, the probiotic Lactobacillus acidophilus was negatively associated with caries. Prevotella nigrescens was the only species (p < 0.05) significantly associated with caries by the ‘false discovery’ rate. Analysis of the data suggests that selected Lactobacillus species, in addition to mutans streptococci, are risk markers for early childhood caries.
Over the last hundred years, groundbreaking research in oral microbiology has provided a broad and deep understanding about the oral microbiome, its interactions with our body, and how the community ...can affect our health, be protective, or lead to the development of dental diseases. During this exciting journey, hypotheses were proposed, and concepts were established, discarded, and later revisited from updated perspectives. Dental plaque, previously considered a polymicrobial community of unspecific pathogenicity, is recognized as microbial biofilms with healthy, cariogenic, or periodontopathogenic profiles, resulting from specific ecologic determinants and host factors. The “one pathogen, one disease” paradigm of oral infections has been replaced by a holistic concept of a microbial community as the entity of pathogenicity. Cutting-edge technology can now explore large microbial communities related to different clinical conditions, which has led to finding several novel disease-associated species and potential pathobionts and pathobiomes. This vast amount of data generated over time has widened our view of the etiology of caries and periodontal and peri-implant diseases and has promoted updated strategies to treat and prevent the oral diseases.
Background and Objective: Photodynamic therapy has been advocated as an alternative to antimicrobial agents to suppress subgingival species and to treat periodontitis. Bacteria located within dense ...biofilms, such as those encountered in dental plaque, have been found to be relatively resistant to antimicrobial therapy. In the present study, we investigated the ability of photodynamic therapy to reduce the number of bacteria in biofilms by comparing the photodynamic effects of methylene blue on human dental plaque microorganisms in the planktonic phase and in biofilms.
Material and Methods: Dental plaque samples were obtained from 10 subjects with chronic periodontitis. Suspensions of plaque microorganisms from five subjects were sensitized with methylene blue (25 μg/mL) for 5 min then exposed to red light. Multispecies microbial biofilms developed from the same plaque samples were also exposed to methylene blue (25 μg/mL) and the same light conditions as their planktonic counterparts. In a second set of experiments, biofilms were developed with plaque bacteria from five subjects, sensitized with 25 or 50 μg/mL of methylene blue and then exposed to red light. After photodynamic therapy, survival fractions were calculated by counting the number of colony‐forming units.
Results: Photodynamic therapy killed approximately 63% of bacteria present in suspension. By contrast, in biofilms, photodynamic therapy had much less of an effect on the viability of bacteria (32% maximal killing).
Conclusion: Oral bacteria in biofilms are affected less by photodynamic therapy than bacteria in the planktonic phase. The antibacterial effect of photodynamic therapy is reduced in biofilm bacteria but not to the same degree as has been reported for treatment with antibiotics under similar conditions.
The oral microbiota was compared between Romanian adolescents with a high prevalence of caries and no dental care and Swedish caries-active and caries-free adolescents in caries prevention programs ...and with a low prevalence of caries. Biofilm samples were analyzed by FLX+ pyrosequencing of the V1 to V4 hypervariable regions of the 16S rRNA gene and polymerase chain reaction (PCR)/quantitative PCR (qPCR) for Streptococcus mutans and Streptococcus sobrinus. Sequences obtained blasted to 9 phyla, 66 genera, and 401 human oral taxa (HOT) in the 16S rRNA Human Oral Microbiome Database, of which 295 were represented by ≥20 sequences. The Romanian adolescents had more sequences in Firmicutes and fewer in Actinobacteria phyla and more sequences in the genera Bacteroidetes G-3, Porphyromonas, Abiotrophia, Filifactor, Peptostreptococcaceae 11G-4, Pseudoramibacter, Streptococcus, and Neisseria and fewer in Actinomyces, Selenomonas, Veillonella, Campylobacter, and TM7 G-1 than the Swedish groups. Multivariate modeling employing HOT, S. sobrinus and S. mutans (PCR/qPCR), and sugar snacks separated Romanian from Swedish adolescents. The Romanian adolescents’ microbiota was characterized by a panel of streptococci, including S. mutans, S. sobrinus, and Streptococcus australis, and Alloprevotella, Leptotrichia, Neisseria, Porphyromonas, and Prevotella. The Swedish adolescents were characterized by sweet snacks, and those with caries activity were also characterized by Prevotella, Actinomyces, and Capnocytophaga species and those free of caries by Actinomyces, Prevotella, Selenomonas, Streptococcus, and Mycoplasma. Eight species including Streptococcus mitis and Streptococcus species HOT070 were prevalent in Romanian and Swedish caries-active subjects but not caries-free subjects. In conclusion, S. mutans and S. sobrinus correlated with Romanian adolescents with caries and with limited access to dental care, whereas S. mutans and S. sobrinus were detected infrequently in Swedish adolescents in dental care programs. Swedish caries-active adolescents were typically colonized by Actinomyces, Selenomonas, Prevotella, and Capnocytophaga. Hence, the role of mutans streptococci as a primary caries pathogen appears less pronounced in populations with prevention programs compared to populations lacking caries treatment and prevention strategies.
Summary
The anthocyanin and proanthocyanidin (PA) biosynthetic pathways share common intermediates until leucocyanidin, which may be used by leucoanthocyanidin dioxygenase (LDOX) to produce ...anthocyanin, or the enzyme leucoanthocyanidin reductase (LAR) to produce catechin, a precursor of PA. The Arabidopsis mutant tannin deficient seed 4 (tds4‐1) has a reduced PA level and altered pattern PA accumulation. We identified the TDS4 gene as LDOX by complementation of the tds4‐1 mutation either with a cosmid encoding LDOX or a 35S:LDOX construct. Independent Arabidopsis lines with a T‐DNA insertion in the LDOX gene had a similar phenotype, and one was allelic to tds4‐1. The seed phenotype of ban tds4 double mutants showed that LDOX precedes BANYULS (BAN) in the PA pathway, confirming recent biochemical characterisation of BAN as an anthocyanidin reductase. Double mutant analysis was also used to order the other TDS genes. Analysis of the PA intermediates in tds4‐1 revealed three dimethylaminocinnamaldehyde (DMACA) reacting compounds that accumulated in extracts from developing seeds. Analysis of Arabidopsis PA and its precursors indicates that Arabidopsis, unlike many other plants, exclusively uses the epicatechin and not the catechin pathway to PA. Transmission electron microscopy (TEM) showed that the pattern observed when seeds of tds4 were stained with DMACA was a result of the accumulation of PA intermediates in the cytoplasm of endothelial cells. Fluorescent marker dyes were used to show that tds4 endothelial cells had multiple small vacuoles, instead of a large central vacuole as observed in the wild types (WT). These results show that in addition to its established role in the formation of anthocyanin, LDOX is also part of the PA biosynthesis pathway.
LJ001 is a lipophilic thiazolidine derivative that inhibits the entry of numerous enveloped viruses at non-cytotoxic concentrations (IC50 ≤ 0.5 µM), and was posited to exploit the physiological ...difference between static viral membranes and biogenic cellular membranes. We now report on the molecular mechanism that results in LJ001's specific inhibition of virus-cell fusion. The antiviral activity of LJ001 was light-dependent, required the presence of molecular oxygen, and was reversed by singlet oxygen ((1)O2) quenchers, qualifying LJ001 as a type II photosensitizer. Unsaturated phospholipids were the main target modified by LJ001-generated (1)O2. Hydroxylated fatty acid species were detected in model and viral membranes treated with LJ001, but not its inactive molecular analog, LJ025. (1)O2-mediated allylic hydroxylation of unsaturated phospholipids leads to a trans-isomerization of the double bond and concurrent formation of a hydroxyl group in the middle of the hydrophobic lipid bilayer. LJ001-induced (1)O2-mediated lipid oxidation negatively impacts on the biophysical properties of viral membranes (membrane curvature and fluidity) critical for productive virus-cell membrane fusion. LJ001 did not mediate any apparent damage on biogenic cellular membranes, likely due to multiple endogenous cytoprotection mechanisms against phospholipid hydroperoxides. Based on our understanding of LJ001's mechanism of action, we designed a new class of membrane-intercalating photosensitizers to overcome LJ001's limitations for use as an in vivo antiviral agent. Structure activity relationship (SAR) studies led to a novel class of compounds (oxazolidine-2,4-dithiones) with (1) 100-fold improved in vitro potency (IC50<10 nM), (2) red-shifted absorption spectra (for better tissue penetration), (3) increased quantum yield (efficiency of (1)O2 generation), and (4) 10-100-fold improved bioavailability. Candidate compounds in our new series moderately but significantly (p≤0.01) delayed the time to death in a murine lethal challenge model of Rift Valley Fever Virus (RVFV). The viral membrane may be a viable target for broad-spectrum antivirals that target virus-cell fusion.
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