Biomedical subjects

Michael L Myers

Publications and source records attributed to Michael L Myers.

8 recordsLinked to original sources

PubMed2006

Detection of pandemic Vibrio parahaemolyticus O3:K6 serovar in Gulf of Mexico water and shellfish using real-time PCR with Taqman fluorescent probes.

We describe a real-time multiplexed PCR method using Taqman probes for the detection of total and pandemic Vibrio parahaemolyticus O3:K6 serovar in oysters and Gulf of Mexico water (gulf water). The specificity of these primers and probes was tested for amplification of a 450 bp thermolabile hemolysin (tlh) and a 369 bp ORF8 amplicon representing all V. parahaemolyticus and post-1996 clinical isolates of pandemic serovar O3:K6, respectively. The sensitivity of detection was 10 pg purified DNA or 10(3) CFU in 1 mL pure culture. Enrichment of this pathogen in oyster tissue homogenate or gulf water for 5 or 8 h resulted in the detection of an initial inoculum of 1 CFU in 1 mL or 1 g of samples. Application of the Taqman PCR assay on natural oysters exhibited a positive detection of V. parahaemolyticus, ranging from 16% to 100% of the samples collected primarily during the summer months. None of the samples exhibited a positive detection of O3:K6 serovar. Rapid and sensitive detection of this pathogen will help shellfish industry and Interstate Shellfish Sanitation Conference (ISSC) undertake appropriate measures to monitor this pathogen in oysters and oyster-growing waters, thereby preventing disease outbreaks and consequently protecting consumer health.

Animals↗

PubMed2006

Performance of 2 packable composites at 12 months.

OBJECTIVE: The purpose of this randomized, double-blind, clinical trial was to compare the marginal seal of 2 packable resin composite materials in moderate to large lesions on molars. METHOD AND MATERIALS: Fifty participants in need of a moderate to large Class 2 or complex Class 1 molar restoration were randomly distributed into 4 groups, to receive either Alert (Jeneric/Pentron) or SureFil (Dentsply/Caulk) resin composite with or without a surface sealer. Each participant received one restoration. With the exception that study protocol limited increments to no more than 4 mm, teeth were restored according to the manufacturers' instructions, and surface sealer was applied after finishing in the designated groups. Use of Alert includes routine placement of a flowable composite liner. Clinical performance of the restorations was evaluated in 8 categories at baseline, 6 months, and 12 months. The 2 materials were compared to determine if a difference in marginal seal existed between groups. The number of restorations exhibiting marginal staining was compared using Fischer's exact test at a significance level of 5%. RESULTS: Six participants did not present for the 12-month recall. At 12 months, 19 (90.5%) Alert restorations and 15 (68.2%) SureFil restorations did not exhibit marginal staining. There was no statistically significant difference between the 2 restorative materials for marginal staining. Overall, 3 restorations were rated as failures. CONCLUSION: At 12 months, materials placed with a flowable liner were not associated with a significant reduction in marginal staining.

Adult↗

PubMed2004

Rapid detection of Vibrio vulnificus in shellfish and Gulf of Mexico water by real-time PCR.

In this paper we describe optimization of SYBR Green I-based real-time PCR parameters and testing of a large number of microbial species with vvh-specific oligonucleotide primers to establish a rapid, specific, and sensitive method for detection of Vibrio vulnificus in oyster tissue homogenate and Gulf of Mexico water (gulf water). Selected oligonucleotide primers for the vvh gene were tested for PCR amplification of a 205-bp DNA fragment with a melting temperature of approximately 87 degrees C for 84 clinical and environmental strains of V. vulnificus. No amplification was observed with other vibrios or nonvibrio strains with these primers. The minimum level of detection by the real-time PCR method was 1 pg of purified genomic DNA or 10(2) V. vulnificus cells in 1 g of unenriched oyster tissue homogenate or 10 ml of gulf water. It was possible to improve the level of detection to one V. vulnificus cell in samples that were enriched for 5 h. The standard curves prepared from the real-time PCR cycle threshold values revealed that there was a strong correlation between the number of cells in unenriched samples and the number of cells in enriched samples. Detection of a single cell of V. vulnificus in 1 g of enriched oyster tissue homogenate is in compliance with the recent Interstate Shellfish Sanitation Conference guidelines. The entire detection method, including sample processing, enrichment, and real-time PCR amplification, was completed within 8 h, making it a rapid single-day assay. Rapid and sensitive detection of V. vulnificus would ensure a steady supply of postharvest treated oysters to consumers, which should help decrease the number of illnesses or outbreaks caused by this pathogen.

Animals↗

PubMed2003

Clinical evaluation of a 3% hydrogen peroxide tooth-whitening gel.

PURPOSE: The purpose of this randomized double-blind investigation was to clinically evaluate the effectiveness of a commercially available 3% hydrogen peroxide tooth-whitening material (ADS Tooth Whitening Gel, Applied Dental Sciences, Inc., Lee, MA). The material was used over 2 weeks in a dentist-supervised, patient-applied application. MATERIALS AND METHODS: The evaluation was carried out in accordance with American Dental Association (ADA) Council on Scientific Affairs Acceptance Program Guidelines for Home-Use Tooth Whitening Products (May 1998). Sixty-five participants were randomized into two groups (active and placebo) for a double-blind, placebo-controlled study. A custom application tray, scalloped without reservoirs, was fabricated for each participant. Tooth shades were documented by matching with the Vita shade guide ordered according to value and assigned a numeric ranking from 1 to 16, darkest to lightest. Participants were supplied with the treatment solutions to use in the application tray. Duration of active treatment was 30 minutes 3 times a day for 2 weeks. Participants were evaluated at baseline, 1 week and 2 weeks treatment, and 12 and 26 weeks post-treatment. The statistical analysis used at each time point to determine the difference between the active and placebo groups based on the change in value was the two-sample t-test. Plaque and soft tissue indices were also recorded. RESULTS: The teeth treated with 3% hydrogen peroxide were significantly lighter at 2, 12, and 26 weeks (p < or = .0140, .0004, and .0001, respectively) compared with the placebo group. The mean shade change was 4.2 Vita shade tabs at 2 weeks. At 26 weeks (6 months), the degree of whitening was 4.1 tabs.

Adult↗

PubMed2003

PCR detection of a newly emerged pandemic Vibrio parahaemolyticus O3:K6 pathogen in pure cultures and seeded waters from the Gulf of Mexico.

This study describes the optimization of PCR parameters and testing of a wide number of microbial species to establish a highly specific and sensitive PCR-based method of detection of a newly emerged pandemic Vibrio parahaemolyticus O3:K6 strain in pure cultures and seeded waters from the Gulf of Mexico (gulf water). The selected open reading frame 8 (ORF8) DNA-specific oligonucleotide primers tested were found to specifically amplify all 35 pathogenic V. parahaemolyticus O3:K6 pandemic isolates, whereas these primers were not found to detectably amplify two strains of V. parahaemolyticus O3:K6 that were isolated prior to the 1996 outbreaks, 122 non-O3:K6 strains of V. parahaemolyticus, 198 non-V. parahaemolyticus spp., or 16 non-Vibrio bacterial spp. The minimum level of detection by the PCR method was 1 pg of purified genomic DNA or 10(2) ORF8-positive V. parahaemolyticus O3:K6 cells in 100 ml of water. The effectiveness of this method for the detection of ORF8-positive isolates in environmental samples was tested in gulf water seeded with 10-fold serial dilutions of this pathogen. A detection level of 10(3) cells per 100 ml of gulf water was achieved. Also, the applicability of this methodology was tested by the detection of this pathogen in gulf water incubated at various temperatures for 28 days. This PCR approach can potentially be used to monitor with high specificity and well within the required range of sensitivity the occurrence and distribution of this newly emerged pathogenic V. parahaemolyticus O3:K6 strain in coastal, marine, and ship ballast waters. Early detection of V. parahaemolyticus O3:K6 will help increase seafood safety and decrease the risk of infectious outbreaks caused by this pathogen.

Bacterial Typing Techniques↗

PubMed2002

Sensitivity and tooth whitening agents.

PURPOSE: Three commercially available dentist-prescribed home-applied bleaching systems were evaluated to identify the incidence of sensitivity and to compare the efficacy of whitening the maxillary anterior teeth of 18 patients. METHODS: NiteWhite Excel 2Z (Discus Dental), fx (Challenge Products), and Rembrandt Xtra-Comfort (DenMat Corp.) were randomly assigned to six patients each. The fx product was used as a control since it was not advertised as a zero sensitivity product. The manufacturers' instructions for tray fabrication and use were followed while the patients bleached for 2 weeks. The patients kept a diary and were recalled at 1 week, 2 weeks, and 4 weeks. The shade change and the presence or absence of any sensitivity were evaluated at each recall. RESULTS: NiteWhite Excel 2Z was used for 83 days of treatment with the following percentage of positive sensitivity reported: 0% hot and cold, 2.4% throat sensitivity, 2.4% tongue sensitivity, and 25.3% gingival sensitivity. Rembrandt Xtra-Comfort was used for 84 days with 0% hot and cold, 0% throat, 11.9% tongue, and 27.4% gingival sensitivity reported. The fx product was used for 83 days and resulted in 14.5% hot and cold, 3.6% throat, 1.2% tongue, and 16.9% gingival sensitivity. All products lightened the teeth an average of eight shade tabs on the Vita guide. There was a statistically significant difference between the groups when comparing the presence of sensitivity (chi-squared test, p < .001) but not when comparing the shade tab change. CLINICAL SIGNIFICANCE: Of the products tested, all produced similar change in shade tab value, none were sensitivity free, but NiteWhite Excel 2Z and Rembrandt Xtra-Comfort did not produce thermal sensitivity.

Carbamide Peroxide↗

PubMed2002

Comparison of luting cements for minimally retentive crown preparations.

OBJECTIVE: The purpose of this study was to compare the retentive strengths of resin, glass-ionomer, and zinc phosphate cements under adverse conditions. METHOD AND MATERIALS: Thirty extracted teeth were mounted and prepared in their long axis. The axial wall height was 3 mm and the convergence angle was 28 degrees. These conditions increased the role of the cement and decreased the role of the preparation in providing retention of the casting. The axial surface area was determined. Copings were fabricated with a ring aligned in the long axis to facilitate removal of the crown. They were cemented with a resin cement, a glass-ionomer cement, or a zinc phosphate cement. A block randomization scheme was used to assign cements so that the mean surface areas of the teeth were equivalent in all groups. The copings were loaded in tension, and the amount of force required to remove the coping was recorded. The stress required to remove the coping was calculated. RESULTS: The mean stress required to remove the copings was 9.4, 5.0, and 3.1 MPa for the resin, glass-ionomer, and zinc phosphate cements, respectively. CONCLUSION: The resin cement group was significantly stronger than both the glass-ionomer cement and the zinc phosphate cement groups. The glass-ionomer cement was significantly stronger than the zinc phosphate cement.

Analysis of Variance↗

PubMedDate not supplied

Predictors of non-carious loss of cervical tooth tissues.

This Predictor Variables study is designed to determine which one of 11 factors evaluated may be correlated to Non-carious Loss of Cervical Tooth Tissues (NLCTT) using subjects with and without NLCTT. The ultimate objective is to successfully predict the path toward risky behaviors and reduce the incidence of NLCTT.

Acids↗