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1.  Proteomic analysis of endodontic infections by liquid chromatography–tandem mass spectrometry 
Oral microbiology and immunology  2009;24(4):347-352.
Endodontic infections are very prevalent and have a polymicrobial etiology characterized by complex interrelationships between endodontic microorganisms and the host defenses. Proteomic analysis of endodontic infections can provide global insights into the invasion, pathogenicity mechanisms, and multifactorial interactions existing between root canal bacteria and the host in the initiation and progression of apical periodontitis. The purpose of this study was to apply proteomic techniques such as liquid chromatography–tandem mass spectrometry (LC–MS/MS) for the identification of proteins of bacterial origin present in endodontic infections.
Endodontic specimens were aseptically obtained from seven patients with root canal infections. Protein mixtures were subjected to tryptic in-solution digestion and analysed by reverse-phase nano-LC–MS/MS followed by a database search.
Proteins, mainly of cell wall or membrane origin, from endodontic bacteria especially Enterococcus faecalis, Enterococcus faecium, Porphyromonas gingivalis, Fusobacterium nucleatum, and Treponema denticola were identified from all the samples tested. Identified proteins included adhesins, autolysins, proteases, virulence factors, and antibiotic-resistance proteins.
LC–MS/MS offers a sensitive analytical platform to study the disease processes in the root canal environment. The array of proteins expressed in endodontic infections reflects the complex microbial presence and highlights the bacterial species involved in the inflammatory process.
PMCID: PMC2744886  PMID: 19572900
bacteria; endodontics; liquid chromatography/mass spectroscopy; proteomics; virulence
2.  The Microbial Challenge to Pulp Regeneration 
Advances in Dental Research  2011;23(3):285-289.
Pulp regeneration is considered in cases where the dental pulp has been destroyed because of microbial irritation. Diverse oral and food-borne micro-organisms are able to invade the pulp space, form biofilm on canal walls, and infiltrate dentinal tubules. Prior to pulp regeneration procedures, the pulp space and dentinal walls need to be sufficiently disinfected to allow for and promote regeneration. The necessary level of disinfection is likely higher than that accepted for traditional endodontic therapy, because in traditional techniques the mere lowering of bacterial loads and prevention of bacterial access to periapical tissues is conducive to healing. Moreover, several of the non-specific antimicrobials used in traditional endodontic therapy may cause significant changes in remaining dentin that interfere with its inherent potential to mediate regeneration. Non-specific antimicrobials also suppress all microbial taxa, which may allow residual virulent micro-organisms to preferentially repopulate the pulp space. Therefore, it is important for endodontic pathogens to be studied by molecular methods that allow for a broad depth of coverage. It is then essential to determine the most effective protocols to disinfect the pulp space, with minimal disruption of remaining dentin. These protocols include the topical use of effective antibiotics, including newer agents that have demonstrated efficacy against endodontic pathogens.
PMCID: PMC3144036  PMID: 21677080
pulp necrosis; pulp regeneration; endodontic pathogens; endodontic irrigants; topical antibiotics; microbiota
3.  Analyzing Endodontic Infections by Deep Coverage Pyrosequencing 
Journal of Dental Research  2010;89(9):980-984.
Bacterial diversity in endodontic infections has not been sufficiently studied. The use of modern pyrosequencing technology should allow for more comprehensive analysis than traditional Sanger sequencing. This study investigated bacterial diversity in endodontic infections through taxonomic classification based on 16S rRNA gene sequences generated by 454 GS-FLX pyrosequencing and conventional Sanger capillary sequencing technologies. Sequencings were performed on 7 specimens from endodontic infections. On average, 47 vs. 28,590 sequences were obtained per sample for Sanger sequencing vs. pyrosequencing, representing a 600-fold difference in “depth-of-coverage”. Based on Ribosomal Database Project (RDP II) Classifier analysis, pyrosequencing identified 179 bacterial genera in 13 phyla, which was significantly more than Sanger sequencing. The phylum Bacteroidetes was the most prevalent bacterial phylum. These results indicate that bacterial communities in endodontic infections are more diverse than previously demonstrated. In addition, deep-coverage pyrosequencing of the 16S rRNA gene revealed low-abundance micro-organisms with potential clinical implications.
PMCID: PMC3318071  PMID: 20519493
endodontic infection; pyrosequencing; 16S rRNA gene; bacterial diversity; taxonomy
4.  Risk Factors for Tube Shunt Exposure: A Matched Case-Control Study 
Journal of Ophthalmology  2013;2013:196215.
Purpose. To evaluate potential risk factors for developing tube shunt exposure in glaucoma patients. Patients and Methods. Forty-one cases from 41 patients that had tube shunt exposure from 1996 to 2005 were identified from the Robert Cizik Eye Clinic and Bascom Palmer Eye Institute. Each case was matched with 2 controls of the same gender and with tube shunts implanted within 6 months of the index case. Conditional logistic regression was used to determine risk factors. Results. The study cohort includes a total of 121 eyes from 121 patients. The mean age was 63.6 ± 19.7 years, ranging from 1 to 96 years. The average time to exposure was 19.29 ± 23.75 months (range 0.36–85.74 months). Risk factors associated with tube exposure were Hispanic ethnicity (P = 0.0115; OR = 3.6; 95% CI, 1.3–9.7), neovascular glaucoma (P = 0.0064; OR = 28.5; 95% CI, 2.6–316.9), previous trabeculectomy (P = 0.0070; OR = 5.3; 95% CI, 1.6–17.7), and combined surgery (P = 0.0381; OR = 3.7; 95% CI, 1.1–12.7). Conclusions. Hispanic ethnicity, neovascular glaucoma, previous trabeculectomy, and combined surgery were identified as potential risk factors for tube shunt exposure. These potential risk factors should be considered when determining the indication for performing tube shunt implantation and the frequency of long-term followup.
PMCID: PMC3736453  PMID: 23970955
5.  Vertical fracture of root filled teeth restored with posts: the effects of patient age and dentine thickness 
International Endodontic Journal  2010;43(3):218-225.
To determine whether patient age contributed to the fracture resistance of teeth subjected to root canal treatment and post placement.
Forty-five single-rooted, single-canal human teeth were mounted, instrumented, obturated and prepared for a post. The teeth were divided into young (18 ≤ age ≤ 35) and old (60 ≤ age) groups and subjected to cyclic loading until fracture; those reaching 200 000 cycles without undergoing failure were then subjected to static loading to fracture. Statistical differences between groups were examined using one-way ANOVAS, and correlations were identified using Pearson’s r; significance was established at P ≤ 0.05.
There was no significant difference between the two age groups in terms of the number of cycles to fracture (P > 0.05) or the load to fracture (P > 0.05). However, there was a significant correlation (P ≤ 0.05) between the root fracture resistance and individual age, indicating that the susceptibility to root fracture increases significantly with increasing patient age. Also, the dentine thickness of roots that fractured was significantly less than those that did not (P = 0.04).
Vertical root fracture of teeth receiving root canal treatment with posts is more likely to occur in the teeth of older patients (60+) and particularly in those with low dentine thickness.
PMCID: PMC3353984  PMID: 20158533
age; cyclic loading; dentine thickness; vertical root fracture
6.  Identification of selected respiratory pathogens in endodontic infections 
To determine whether endodontic infections could harbor common etiologic agents of respiratory infections such as Streptococcus pneumoniae and Chlamydia pneumoniae.
Specimens were aseptically obtained from 40 patients with endodontic infections. For the detection of C. pneumoniae, a single step 16S rRNA based PCR and a nested PCR targeting aromatic amino acid hydroxylase were used. For the identification of S. pneumoniae, primers targeting 16S rRNA gene and autolysin (lytA) were used.
Of 21 patient samples tested with the 16S rRNA-based PCR for S. pneumoniae, positive amplification was observed in all except three specimens. However, sequencing and phylogenetic analysis revealed that the product belonged to other bacterial phylotypes. The lytA-based PCR for S. pneumoniae and both PCR assays for C. pneumoniae failed to detect these organisms in all the specimens tested.
S. pneumoniae and C. pneumoniae were not present in endodontic infections. PCR primers with less stringent specificity will inaccurately identify respiratory pathogens.
PMCID: PMC2515822  PMID: 18585629
Streptococcus pneumoniae; Chlamydia pneumoniae; endodontic infections; PCR
7.  Transient renal dysfunction during initial inhibition of converting enzyme in congestive heart failure. 
British Heart Journal  1984;52(1):63-71.
Treatment with captopril in resistant normotensive congestive heart failure is associated with a pronounced reduction in blood pressure, particularly after the first dose. The effects of this reduction on renal function were assessed in 10 patients at the beginning of and during chronic treatment (at one week and three months). Renal plasma flow and glomerular filtration rates were measured by isotope clearance during water diuresis. The first dose of captopril (25 mg) led to a pronounced fall in renal plasma flow and glomerular filtration rates together with a decrease in mean arterial pressure; this fall correlated with baseline plasma renin activity. These changes were paralleled by decreases in water and sodium excretion. In contrast, by the end of the first week of treatment a similar fall in mean arterial pressure occurred together with a pronounced increase in renal plasma flow; the glomerular filtration rate was maintained and there was no decrease in water and sodium excretion. This new response pattern recurred after three months of treatment. The difference in response at different stages of treatment may reflect the balance between the different mechanisms influencing kidney dynamics in heart failure and their alteration by converting enzyme inhibition. The sustained increase in renal plasma flow during chronic treatment with captopril may account for the continued control of heart failure in these patients.
PMCID: PMC481586  PMID: 6378228

Results 1-7 (7)