Microbiota of severe early childhood caries before and after therapy.

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.

Cultivable anaerobic microbiota of severe early childhood caries.

Severe early childhood caries (ECC), while strongly associated with Streptococcus mutans using selective detection (culture, PCR), has also been associated with a widely diverse microbiota using molecular cloning approaches. The aim of this study was to evaluate the microbiota of severe ECC using anaerobic culture. The microbial composition of dental plaque from 42 severe ECC children was compared with that of 40 caries-free children. Bacterial samples were cultured anaerobically on blood and acid (pH 5) agars. Isolates were purified, and partial sequences for the 16S rRNA gene were obtained from 5,608 isolates. Sequence-based analysis of the 16S rRNA isolate libraries from blood and acid agars of severe ECC and caries-free children had >90% population coverage, with greater diversity occurring in the blood isolate library. Isolate sequences were compared with taxon sequences in the Human Oral Microbiome Database (HOMD), and 198 HOMD taxa were identified, including 45 previously uncultivated taxa, 29 extended HOMD taxa, and 45 potential novel groups. The major species associated with severe ECC included Streptococcus mutans, Scardovia wiggsiae, Veillonella parvula, Streptococcus cristatus, and Actinomyces gerensceriae. S. wiggsiae was significantly associated with severe ECC children in the presence and absence of S. mutans detection. We conclude that anaerobic culture detected as wide a diversity of species in ECC as that observed using cloning approaches. Culture coupled with 16S rRNA identification identified over 74 isolates for human oral taxa without previously cultivated representatives. The major caries-associated species were S. mutans and S. wiggsiae, the latter of which is a candidate as a newly recognized caries pathogen.

Diet and caries-associated bacteria in severe early childhood caries.

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.

Clonal analysis of the microbiota of severe early childhood caries.

BACKGROUND/AIMS: Severe early childhood caries is a microbial infection that severely compromises the dentition of young children. The aim of this study was to characterize the microbiota of severe early childhood caries. METHODS: Dental plaque samples from 2- to 6-year-old children were analyzed using 16S rRNA gene cloning and sequencing, and by specific PCR amplification for Streptococcus mutans and Bifidobacteriaceae species. RESULTS: Children with severe caries (n = 39) had more dental plaque and gingival inflammation than caries-free children (n = 41). Analysis of phylotypes from operational taxonomic unit analysis of 16S rRNA clonal metalibraries from severe caries and caries-free children indicated that while libraries differed significantly (p < 0.0001), there was increased diversity than detected in this clonal analysis. Using the Human Oral Microbiome Database, 139 different taxa were identified. Within the limits of this study, caries-associated taxa included Granulicatella elegans (p < 0.01) and Veillonella sp. HOT-780 (p < 0.01). The species associated with caries-free children included Capnocytophaga gingivalis (p < 0.01), Abiotrophia defectiva (p < 0.01), Lachnospiraceae sp. HOT-100 (p < 0.05), Streptococcus sanguinis (p < 0.05) and Streptococcus cristatus (p < 0.05). By specific PCR, S. mutans (p < 0.005) and Bifidobacteriaceae spp. (p < 0.0001) were significantly associated with severe caries. CONCLUSION: Clonal analysis of 80 children identified a diverse microbiota that differed between severe caries and caries-free children, but the association of S. mutans with caries was from specific PCR analysis, not from clonal analysis, of samples.

Mutational analysis of the adcCBA genes in Streptococcus gordonii biofilm formation.

Streptococcus gordonii, a primary colonizer, is part of the pioneer biofilm consortium that initiates dental plaque development on tooth surfaces. An insertion of Tn917-lac transposon into the adcR gene produced a biofilm-defective phenotype. S. gordonii adcR is a regulatory gene and is part of an operon (adc) that includes three other genes, adcCBA. AdcC contains a putative consensus-binding site for adenosine triphosphate, AdcB is a putative hydrophobic membrane protein, and AdcA is a putative lipoprotein permease. Mutants were constructed by insertional inactivation in each of the three adcCBA genes and their effects on biofilm formation examined. The adcC::spec(R) and adcB::spec(R) mutations displayed a biofilm-defective phenotype, whereas the adcA::spec(R) mutant was biofilm-positive in a static polystyrene microtiter plate biofilm assay. All three mutants formed poor biofilms in a flow-cell system and were competence-defective, suggesting the adc operon plays an important role in S. gordonii biofilm formation and competence.

Role of a nosX homolog in Streptococcus gordonii in aerobic growth and biofilm formation.

Oral streptococci such as Streptococcus gordonii are facultative anaerobes that initiate biofilm formation on tooth surfaces. An isolated S. gordonii::Tn917-lac biofilm-defective mutant contained a transposon insertion in an open reading frame (ORF) encoding a homolog of NosX of Ralstonia eutropha, a putative maturation factor of nitrous oxide reductase. Located downstream are two genes, qor1 and qor2, predicted to encode two putative NADPH quinone oxidoreductases. These three genes are cotranscribed, forming a putative oxidative stress response (osr) operon in S. gordonii. Inactivation of nosX, qor1, or qor2 resulted in biofilm-defective phenotypes. Expression of nosX, measured by the beta-galactosidase activity of the nosX::Tn917-lac mutant, was growth-phase dependent and enhanced when grown under aerobic conditions or in the presence of paraquat. Real-time reverse transcription-PCR revealed that nosX-specific mRNA levels were increased approximately 8.4 and 3.5 fold in biofilm-derived cells grown on plastic and glass, respectively, when compared to planktonic cells. Expression of nosX increased 19.9 fold in cells grown under aerated aerobic conditions and 4.7 fold in cells grown under static aerobic conditions. Two ORFs immediately adjacent to the osr operon encode a putative NADH oxidase (Nox) and a putative thiol-specific antioxidant enzyme (AhpC, for alkyl hydroperoxide peroxidase C). Expression of nox and ahpC was also significantly increased in cells grown under aerated and static aerobic conditions when compared to anaerobic conditions. In addition, nox expression was increased in biofilm cells compared to planktonic cells. These genes may be part of an island that deals with oxidoreductive response, some of which may be important in S. gordonii biofilm formation.

Role of a Streptococcus gordonii copper-transport operon, copYAZ, in biofilm detachment.

Streptococcus gordonii is a pioneer oral bacterium that is associated with the initiation of dental plaque development. Located downstream of the S. gordonii adc operon, which is involved in competence and biofilm formation, were three open reading frames, designated copY, copA and copZ. These open reading frames were homologous to the copYAZ genes in Streptococcus mutans that are involved in copper homeostasis and biofilm detachment. This study examined whether copYAZ genes play any role in the biofilm formation and detachment of S. gordonii. The copY gene encodes a 143-amino acid protein homologous to the negative transcriptional regulator of a copper-transport operon, copA encodes a 748-amino acid copper-transporting P-type ATPase, and copZ encodes a 69-amino acid putative metallochaperone protein in S. mutans. Each open reading frame in the copYAZ operon in S. gordonii was inactivated by insertional mutation and the growth, biofilm formation and detachment of each mutant were examined. S. gordonii copY::specR, copA::specR, and copZ::specR mutants were able to form biofilms on both polystyrene and glass surfaces. However, inactivation of copZ and to a lesser extent copY resulted in phenotypes that were defective in biofilm detachment, which is consistent with previous observations in S. mutans and suggests that the trace element copper might influence biofilm detachment of bacterial biofilms.

Involvement of an inducible fructose phosphotransferase operon in Streptococcus gordonii biofilm formation.

Oral streptococci, such as Streptococcus gordonii, are the predominant early colonizers that initiate biofilm formation on tooth surfaces. Investigation of an S. gordonii::Tn917-lac biofilm-defective mutant isolated by using an in vitro biofilm formation assay showed that the transposon insertion is near the 3' end of an open reading frame (ORF) encoding a protein homologous to Streptococcus mutans FruK. Three genes, fruR, fruK, and fruI, were predicted to encode polypeptides that are part of the fructose phosphotransferase system (PTS) in S. gordonii. These proteins, FruR, FruK, and FruI, are homologous to proteins encoded by the inducible fruRKI operon of S. mutans. In S. mutans, FruR is a transcriptional repressor, FruK is a fructose-1-phosphate kinase, and FruI is the fructose-specific enzyme II (fructose permease) of the phosphoenolpyruvate-dependent sugar PTS. Reverse transcription-PCR confirmed that fruR, fruK, and fruI are cotranscribed as an operon in S. gordonii, and the transposon insertion in S. gordonii fruK::Tn917-lac resulted in a nonpolar mutation. Nonpolar inactivation of either fruK or fruI generated by allelic replacement resulted in a biofilm-defective phenotype, whereas a nonpolar mutant with an inactivated fruR gene retained the ability to form a biofilm. Expression of fruK, as measured by the beta-galactosidase activity of the fruK::Tn917-lac mutant, was observed to be growth phase dependent and was enhanced when the mutant was grown in media with high levels of fructose, sucrose, xylitol, and human serum, indicating that the fructose PTS operon was fructose and xylitol inducible, similar to the S. mutans fructose PTS. The induction by fructose was inhibited by the presence of glucose, indicating that glucose is able to catabolite repress fruK expression. Nonpolar inactivation of the fruR gene in the fruK::Tn917-lac mutant resulted in a greater increase in beta-galactosidase activity when the organism was grown in media supplemented with fructose, confirming that fruR is a transcriptional repressor of the fructose PTS operon. These results suggest that the regulation of fructose transport and metabolism in S. gordonii is intricately tied to carbon catabolite control and the ability to form biofilms. Carbon catabolite control, which modulates carbon flux in response to environmental nutritional levels, appears to be important in the regulation of bacterial biofilms.

Cloning and expression of alpha-D-glucosidase and N-acetyl-beta-glucosaminidase from the periodontal pathogen, Tannerella forsythensis (Bacteroides forsythus).

Screening a genomic library of Tannerella forsythensis (Bacteroides forsythus), using synthetic substrates conjugated to a fluorogen, 4-methylumbelliferone identified two glycosidase genes, which encode alpha-D-glucosidase and N-acetyl-beta-D-glucosaminidase, respectively. The alpha-D-glucosidase has a Mr of 81,141 and is homologous to an alpha-D-glucosidase from Bacteroides thetaiotaomicron. The N-acetyl-beta-D-glucosaminidase has a Mr of 87,787 and is homologous to an N-acetyl-beta-D-glucosaminidase in Porphyromonas gingivalis W83.

Involvement of the adc operon and manganese homeostasis in Streptococcus gordonii biofilm formation.

Pioneer oral bacteria, including Streptococcus gordonii, initiate the formation of oral biofilms on tooth surfaces, which requires differential expression of genes that recognize unique environmental cues. An S. gordonii::Tn917-lac biofilm-defective mutant was isolated by using an in vitro biofilm formation assay. Subsequent inverse PCR and sequence analyses identified the transposon insertion to be near the 3' end of an open reading frame (ORF) encoding a protein homologous to a Streptococcus pneumoniae repressor, AdcR. The S. gordonii adc operon, consisting of the four ORFs adcR, adcC, adcB, and adcA, is homologous to the adc operon of S. pneumoniae, which plays a role in zinc and/or manganese transport and genetic competence in S. pneumoniae. AdcR is a metal-dependent repressor protein containing a putative metal-binding site, AdcC contains a consensus-binding site for ATP, AdcB is a hydrophobic protein with seven hydrophobic membrane-spanning regions, and AdcA is a lipoprotein permease with a putative metal-binding site. The three proteins (AdcC through -A) are similar to those of the binding-lipoprotein-dependent transport system of gram-positive bacteria. Reverse transcriptase PCR confirmed that adcRCBA are cotranscribed as an operon in S. gordonii and that the transposon insertion in S. gordonii adcR::Tn917-lac had resulted in a polar mutation. Expression of adcR, measured by the beta-galactosidase activity of the adcR::Tn917-lac mutant, was growth phase dependent and increased when the mutant was grown in media with high levels of manganese (>1 mM) and to a lesser extent in media with zinc, indicating that AdcR may be a regulator at high levels of extracellular manganese. A nonpolar inactivation of adcR generated by allelic replacement resulted in a biofilm- and competence-defective phenotype. The biofilm-defective phenotype observed suggests that AdcR is an active repressor when synthesized and acts at a distant site(s) on the chromosome. Thus, the adc operon is involved in manganese acquisition in S. gordonii and manganese homeostasis and appears to modulate sessile growth in this bacterium.

Reasons for dental extractions in children.

PURPOSE: The purpose of this study was to investigate the principal reason for primary tooth extraction and the tooth type most frequently extracted in children aged 3-13 years. METHODS: The patients selected for this retrospective study were identified by analyzing dental records of children receiving treatment at Franciscan Children's Hospital & Rehabilitation Center, Boston, MA (FCH & RC). In total, 2,000 records were reviewed, and 567 extracted primary teeth were analyzed from 277 patients who had at least one primary tooth extracted under local anesthesia. The criteria for inclusion in this study included children between the ages of 3 and 13 years. RESULTS: First primary molars were the most common tooth type extracted and comprised 30% of teeth removed. Central incisors were the next common tooth type extracted and accounted for 25% of the extractions. There was no difference, by gender, in the extraction of tooth type but there were striking differences according to age. Almost half of the primary teeth extracted in subjects 3 to 5 years were incisors, and in patients 6 to 9 years the first primary molar was the most common tooth type extracted. Molars were the tooth type most frequently extracted from those patients aged 10 to 13 years. There were significant differences in the reasons for extraction of various tooth types, and, while extractions due to caries predominated overall, this was not the case for all tooth types. CONCLUSIONS: This study has concluded that despite the dramatic improvements in pediatric oral health over the last decades, caries and the resulting pulpal pathology remains the most common reason for extraction of primary teeth.

Reactive arthritis: preliminary microbiologic analysis of the human temporomandibular joint.

PURPOSE: The presence of Chlamydia trachomatis has been previously shown in the temporomandibular joint (TMJ). This study investigated whether the presence of other bacteria associated with reactive arthritis (ReA) can be identified in the TMJ. MATERIALS AND METHODS: Posterior bilaminar tissue removed during TMJ surgery from 26 patients (24 F, 2 M) was evaluated for the presence of C. trachomatis, Mycoplasma fermentans, Mycoplasma genitalium, Campylobacter jejuni, Yersinia enterocolitica, Salmonella spp, and Shigella spp by highly specific polymerase chain reaction (PCR) assays. RESULTS: Bacterial DNA was identified in the TMJ as follows: C. trachomatis, 11 of 26 (42%); M. fermentans/orale, 6 of 26 (23%); M. genitalium, 9 of 26 (35%). Nine of 26 TMJs (35%) had the presence of a single bacterial species. Eight of 26 TMJs (31%) had more than 1 species, as follows: C. trachomatis with either M. genitalium or M. fermentans/orale in 5 of 26 (19%), M. fermentans/orale with M. genitalium 2 of 26 (8%), and C. trachomatis/M. fermentans/orale/M. genitalium, 1 of 26 (4%). A total of 17 of 26 (65%) of TMJs had the presence of bacteria identified in the TMJ. Campylobacter jejuni, Y. enterocolitica, Salmonella spp, and Shigella spp were not identified in any samples. CONCLUSIONS: The presence of M. genitalium in the human TMJ has not been previously reported. The presence of bacteria in the TMJ, either singly or concurrently with other bacteria, may serve as the pathogenetic mechanism of TMJ inflammation. The presence of 2 bacteria from the urogenital tract in the TMJ suggests that internal derangement of the TMJ may occur as a result of a sexually acquired infection.

Future caries susceptibility in children with early childhood caries following treatment under general anesthesia.

PURPOSE: The purpose of this study was to assess the susceptibility of children to the future development of caries following comprehensive treatment for early childhood caries (ECC) under general anesthesia. METHODS: The patients selected for this retrospective study were identified by analyzing dental records of children receiving treatment at the Franciscan Children's Hospital & Rehabilitation Center, Boston, MA (FCH & RC). In total, 4,143 records were reviewed. Of these, ECC was diagnosed in 42 patients before their admission to the operating room. Thirty-one control children were selected randomly from the dental records reviewed at FCH & RC. The control group was initially caries-free. The caries status of the children diagnosed with ECC was evaluated and compared with the control group. Children in both groups were seen for recall at intervals of six to nine months over a two-year period. The carious lesions were recorded in two categories; new smooth surface caries (NSSC) and new pit and fissure caries (NPFC). RESULTS: Thirty-three of 42 (79%) ECC children compared to nine of 31 (29%) control children had detectable carious lesions at subsequent recall visits. Children with ECC demonstrated a mean number of 3.2 +/- 3.3 new carious lesions compared to a mean of only 0.8 +/- 1.6 carious lesions in the control group. These differences were statistically significant (t71 = 3.8; P < 0.001). In addition, of the 42 patients treated for ECC under general anesthesia, seven (17%) required retreatment under general anesthesia within two years following their initial full-mouth rehabilitation. The prevalence of NSSC in the ECC group was significantly higher than the control group (t71 = 3.5; P < 0.001). CONCLUSIONS: Despite increased preventive measures implemented for children who experienced ECC, this study concluded that this group of children is still highly predisposed to greater caries incidence in later years. These findings strongly suggest that more aggressive preventive therapies may be required to prevent the future development of carious lesions in children who experienced ECC.

Identification and characterization of a protease from Streptococcus oralis C104.

Streptococcus oralis is among the earliest colonizers of the tooth surface during plaque formation. As such, its enzymatic activities may influence ecologic succession on the tooth surface. In the current study, we use zymograms and preparative polyacrylamide gel electrophoresis to identify and purify a protease from S. oralis (sanguis) C104. Proteases from S. oralis C104 were detected in cell pellets at 133, 146 and 176 kDa as clear proteolytic bands on gelatin-substrate zymograms. Preparation of the major (146 kDa) protease were obtained by continuous-elution electrophoresis. The protease was active over the pH range of 7 to 9 with optimum activity between pH 8 and 9. Protease activity was inhibited by several serine protease inhibitors including phenylmethylsulfonyl fluoride, di-isopropyl-phosphofluoridate and aprotinin. The protease showed highest hydrolytic activity against azoalbumin and Bz-Pro-Phe-Arg-NA. Immunofluorescence studies with a polyclonal antiserum to the 146-kDa protease suggest it is present on the cell surface of S. oralis C104. Zymograms of cell pellets from other S. oralis strains as well as S. sanguis and Streptococcus mitis suggest that functionally similar proteases are elaborated by many early colonizers of the tooth surface.

Detection of Mycoplasma fermentans in human saliva with a polymerase chain reaction-based assay.

Mycoplasma fermentans and other mycoplasma species may be associated with human immunodeficiency virus infection. Little is known about the ecology of this micro-organism and its natural habitat. A polymerase chain reaction (PCR)-based assay was used to detect M. fermentans in whole saliva. The hypothesis was tested that M. fermentans is present on the mucosal surfaces of the mouth and oropharynx. Whole saliva was collected from 110 adults. The 206-bp amplification product of DNA purified from these samples was detected in ethidium bromide-stained 6% polyacrylamide gels in 49 (44%) samples tested. All samples were confirmed by Southern blotting with a probe based on an internal sequence of the expected amplification product. The data suggest that this organism is often found in saliva and on oropharyngeal mucosal surfaces. Saliva may play a part in its transmission between individuals. Saliva sampling may be helpful in further studies of the ecology and distribution of the micro-organism in human populations.

Adhesin receptors of human oral bacteria and modeling of putative adhesin-binding domains.

Adherence by bacteria to a surface is critical to their survival in the human oral cavity. Many types of molecules are present in the saliva and serous exudates that form the acquired pellicle, a coating on the tooth surface, and serve as receptor molecules for adherent bacteria. The primary colonizing bacteria utilize adhesins to adhere to specific pellicle receptor molecules, then may adhere to other primary colonizers via adhesins, or may present receptor molecules to be utilized by secondary colonizing species. The most common primary colonizing bacteria are streptococci, and six streptococcal cell wall polysaccharide receptor molecules have been structurally characterized. A comparison of the putative adhesin disaccharide-binding regions of the six polysaccharides suggests three groups. A representative of each group was modeled in molecular dynamics simulations. In each case it was found that a loop formed between the galactofuranose beta (Galf beta) and an oxygen of the nearest phosphate group on the reducing side of the Galf beta, that this loop was stabilized by hydrogen bonds, and that within each loop resides the putative disaccharide-binding domain.

IgA antibodies to Streptococcus mutans in caries-resistant and -susceptible children.

Previous studies have shown a positive correlation between salivary IgA antibody levels to Streptococcus mutans and caries resistance in adults. In this study, enzyme-linked immunosorbent assay (ELISA) was used to compare IgA antibody levels with S. mutans in whole and parotid saliva from 20 caries-susceptible (CS; DMFS > 5) and 20 caries-resistant (CR; DMFS < or = 1) children (aged 7-11 years). Whole salivary S. mutans numbers were significantly greater (P < or = 0.05) in the CS group (mean of 31.2% of total oral streptococci) than in the CR group (mean of 1.6% of total oral streptococci). Whole saliva, but not parotid saliva, from CR children had significantly higher (P < or = 0.05) levels of IgA antibodies to S. mutans than saliva from CS children. These results suggest that salivary IgA antibodies to S. mutans may play a role in natural protection from dental caries in children and that the source of increased salivary IgA antibody in CR children may be either the minor, submandibular, or sublingual salivary glands.

Parallel up-regulation of CD11B and CD45 on neutrophilic leukocytes exposed to soluble factors of oral pathogens.

We tested culture supernatants from a battery of oral bacterial strains for their ability to influence the expression of CD11b and CD45 on the neutrophil plasma membrane. Several bacterial extracts stimulated the up-regulation of both CD11b and CD45 simultaneously. Two supernatants in particular (a clinical isolate of A. actinomycetemcomitans and F. nucleatum ATCC25586) potently stimulated the deployment of CD11b and CD45 from their intracellular storage site to the plasma membrane. Both supernatants inhibited superoxide release stimulated by exposure of neutrophils to formyl methionyl leucyl phenylalanine (FMLP) but had variable effects on superoxide release stimulated by phorbol myristate acetate (PMA). The ability of products of oral bacteria to modulate neutrophil plasma membrane antigen composition may regulate functional reactivity and thus be an important factor in the pathogenesis of periodontal infection and inflammation.

Influence of age on mechanisms and prognosis of heart failure. The V-HeFT VA Cooperative Studies Group.

BACKGROUND: Advanced age is commonly thought to carry a poor prognosis in congestive heart failure, but the case has not been established. The Department of Veterans Affairs Cooperative Vasodilator-Heart Failure Trials (V-HeFT I and II) provided a large data base to assess the effect of age on hemodynamic profiles and survival in the failing heart. METHODS AND RESULTS: Patients were stratified into four categories according to age: < or = 55, 56-60, 61-65, and > 65 years. The distributions of treatments and baseline characteristics from history, physical findings, and laboratory data were analyzed for differences across age categories. Survival curves were calculated for age strata according to treatment, presence or absence of coronary artery disease, ejection fraction, and peak oxygen consumption. Risk ratios for age and treatment categories showed no consistent trend of treatment effect on mortality. Age was significantly associated with coronary artery disease, hypertension, rhythm disturbances, systolic blood pressure, ejection fraction, and peak oxygen uptake, but successive age strata did not show incremental changes. Survival curves did not show progressively steeper slopes with advancing age. In V-HeFT I, the oldest patients did have the poorest survival, but age interacted with the presence of coronary artery disease and randomization into the placebo group. CONCLUSIONS: Contrary to intuitive thinking, age alone did not shorten the survival in congestive heart failure patients who were < 75 years old and receiving optimal therapy.

Coaggregation: specific adherence among human oral plaque bacteria.

Nearly all human oral bacteria exhibit coaggregation, cell-to-cell recognition of genetically distinct cell types. Clumps or coaggregates composed of the two kinds of cells are formed immediately upon mixing two partner cell types. Members of all 18 genera tested exhibit lactose-reversible coaggregation. Many of these interactions appear to be mediated by a lectin on one cell type that interacts with a complementary carbohydrate receptor on the other cell type. A lactose-sensitive adhesin has been isolated from Prevotella loescheii PK1295, and it exhibits the adherence properties observed with whole cells. Other adhesins have been identified and the genes for some of them have been cloned and sequenced. One Streptococcus sanguis adhesin is a lipoprotein that appears to have a dual function of recognizing both a bacterial carbohydrate receptor and a receptor in human saliva. Carbohydrate receptors for some adhesins have been purified from five oral streptococci, and they specifically block the coaggregations with the streptococcal partners that express the complementary adhesins. Coaggregation offers an explanation for the temporally related accretion of dental plaque and bacterial recognition of mucosal surfaces. Early colonizers of the tooth surface coaggregate with each other and late colonizers of the tooth surface coaggregate with each other, but with few exceptions, early colonizers do not recognize late colonizers. Furthermore, bacteria that colonize mucosal surfaces coaggregate with each other, indicating the high degree of specificity of coaggregation in the oral bacterial population.