Biomedical subjects

Karen Williams

Publications and source records attributed to Karen Williams.

At least 19 recordsLinked to original sources

PubMed2007

Characterization of photopolymerization of dentin adhesives as a function of light source and irradiance.

Manufacturers have attempted to address the limitations associated with dentin bonding by eliminating as many steps as possible in the bonding protocol. Theoretically, this approach increases the efficiency of the procedure and reduces technique sensitivity. These trends are reflected in the introduction of all-in one, single-step adhesive systems; the increased concentration of acidic resin monomers in these systems allows for simultaneous etching and priming of the prepared dentin surface. Ideally, the degree of monomer conversion would be high enough that the acidic reaction would be self-limiting. The purpose of this study was to investigate the effect of light irradiance and source on the photopolymerization of three commercial dental adhesives by monitoring the double bond conversion as a function of time during and after irradiation. The photopolymerization curing efficiency of the commercial adhesives investigated in this study varied as a function of light source and distance. The use of LED performed better than the halogen light in terms of polymerization rate and degree of conversion for the commercial single-step, sixth generation adhesive, Adper Prompt. In contrast, polymerization of commercial single-bottle, fifth generation adhesive, Single Bond and One-Up Bond F, was mainly a function of exposure time, irrespective of the two light units or intensities.

Bisphenol A-Glycidyl Methacrylate↗

PubMed2006

Fatal pneumonia among metalworkers due to inhalation exposure to Bacillus cereus Containing Bacillus anthracis toxin genes.

Bacillus cereus pneumonia is unusual in nonimmunocompromised hosts. We describe fatal cases in 2 metalworkers and the associated investigation. Anthrax toxin genes were identified in B. cereus isolates from both patients using polymerase chain reaction. Finding anthrax toxin genes in non-Bacillus anthracis isolates has, to our knowledge, only been reported once previously.

Adult↗

PubMed2006

Persistence of caliciviruses on environmental surfaces and their transfer to food.

The noroviruses (NoV) are a common cause of human gastroenteritis whose transmission by foodborne routes is well documented. Fecally contaminated surfaces are likely to contribute to this foodborne transmission and to the propagation of viral disease outbreaks. The purpose of this study was to (i) investigate the stability of NoV on various food preparation surfaces; and (ii) evaluate the degree of virus transfer from these surfaces to a model-ready-to-eat (RTE) food. For the virus persistence experiments, stainless steel, formica and ceramic coupons were artificially contaminated with Norwalk virus (NV), the prototype genogroup I NoV; NV RNA; or feline calicivirus (FCV) F9 (a NoV surrogate), stored at ambient temperature for up to 7 d, and periodically assayed for detection. In the transfer experiments, stainless steel coupons were inoculated with NV or FCV F9 and allowed to dry for 10, 30 and 60 min, after which lettuce leaves were exposed to the surface of the coupons at various contact pressures (10, 100, and 1000 g/9 cm2). Virus recovery was evaluated by RT-PCR (for NV and NV RNA) or by plaque assay (for FCV F9) using Crandell Reese Feline Kidney (CRFK) cells. NV and FCV were detected on all three surfaces for up to 7 d post-inoculation; for FCV, there was an approximate 6 to 7-log10 drop in virus titer over the 7 d evaluation period. By contrast, when stainless steel was inoculated with purified NV RNA, RT-PCR detection was not possible beyond 24 h. Transfer of both NV and FCV from stainless steel surfaces to lettuce occurred with relative ease. This study confirms lengthy NoV persistence on common food preparation surfaces and their ease of transfer, confirming a potential role for environmental contamination in the propagation of viral gastroenteritis.

Calicivirus, Feline↗

PubMed2006

m-Calpain is required for preimplantation embryonic development in mice.

BACKGROUND: Mu-calpain and m-calpain are ubiquitously expressed proteases implicated in cellular migration, cell cycle progression, degenerative processes and cell death. These heterodimeric enzymes are composed of distinct catalytic subunits, encoded by Capn1 (mu-calpain) or Capn2 (m-calpain), and a common regulatory subunit encoded by Capn4. Disruption of the mouse Capn4 gene abolished both mu-calpain and m-calpain activity, and resulted in embryonic lethality, thereby suggesting essential roles for one or both of these enzymes during mammalian embryogenesis. Disruption of the Capn1 gene produced viable, fertile mice implying that either m-calpain could compensate for the loss of mu-calpain, or that the loss of m-calpain was responsible for death of Capn4-/- mice. RESULTS: To distinguish between the alternatives described above, we deleted an essential coding region in the mouse Capn2 gene in embryonic stems cells and transmitted this mutant allele through the mouse germline. Breeding of heterozygous animals failed to produce homozygous mutant live offspring or implanted embryos. A nested PCR genotyping protocol was established, and homozygous preimplantation mutant embryos were detected at the morula but not at the blastocyts stage. CONCLUSION: We conclude that homozygous disruption of the Capn2 gene results in pre-implantation embryonic lethality between the morula and blastocyst stage. This establishes that mu-calpain and m-calpain have distinct functions, and that m-calpain is vital for development of the preimplantation murine embryo.

Animals↗

PubMed2006

Sealing ability of three materials in the orifice of root canal systems obturated with gutta-percha.

There were 130 single roots randomly assigned to one of 12 experimental or two control groups. Forty specimens each were sealed with 1, 2, 3, or 4 mm of Cavit, ProRoot MTA, or Tetric. After creation of a uniform orifice diameter, the smear layer was removed and the canal systems obturated using warm lateral compaction of gutta-percha (GP). GP was removed to the experimental depth, experimental materials placed in the orifice, and roots submerged in India ink in a vacuum flask. Specimens were demineralized and leakage measured using a 10x stereomicroscope and graded for depth of leakage by one calibrated, blinded rater. There was no significant interaction (p > 0.05) between test materials and orifice depths, nor main effect of orifice depth (p > 0.05). However, there was a statistically significant main effect of test materials with Tetric demonstrating a significantly better seal than Pro Root or Cavit (p < 0.0001) irrespective of orifice depth.

Aluminum Compounds↗

PubMed2006

A randomised control trial of patient self-management of oral anticoagulation compared with patient self-testing.

Several studies suggest that patient self-management (PSM) may improve the quality of oral anticoagulation therapy as measured by time spent within the international normalised ratio (INR) target range. We performed a prospective randomised control trial to determine whether the improvement in quality of treatment afforded by PSM is greater than that achieved by patient self-testing (PST) alone. A total of 104 of 800 eligible patients aged 22-88 years (median = 59.8), attending our hospital anticoagulant clinic and receiving long-term warfarin for >8 months agreed to participate. Patients were randomised to PSM (n = 55) or PST (n = 49). Both groups measured their INR using the CoaguChek S every 2 weeks or more frequently if required, for a period of 6 months. Seventy-seven of 104 (74%) patients completed the study (PSM = 41 and PST = 36). The 'drop out' rates for both groups were similar. There was no significant difference between the percentage time in target therapeutic range for PSM (69.9%) and PST (71.8%). Both groups combined showed a significant improvement over the previous 6 months (71.0% vs. 62.5%; P = 0.04). Changes in time within the therapeutic range in individual patients (+5.86) also showed a significant difference. The quality of warfarin control in both PST and PSM may be superior to that achieved by conventional management in a specialised hospital anticoagulation clinic.

Administration, Oral↗

PubMed2005

Safety and immunogenicity of concomitant versus nonconcomitant administration of hepatitis B, tetanus-diphtheria, and measles-mumps-rubella vaccines in healthy eleven- to twelve-year-olds.

PURPOSE: To study safety and immunogenicity of concomitant administration of hepatitis B (HB), Tetanus-diphtheria (Td), and Measles-mumps-rubella (MMR) vaccines in healthy 11-12-year-olds. METHOD: One hundred ninety-seven healthy 11-12-year-olds from the general community were randomized in an unblinded study to concomitant vaccination with Recombivax HB brand of HB vaccine and Td and MMR vaccines or to HB given at a separate time from Td and MMR vaccination. Primary analyses were for induction of protective immunity and safety. Secondary endpoints were mean geometric antibody titers for HB and a boosting effect for Td and MMR. Differences in immunogenicity were analyzed using the one-sided Pearson's Chi-square test. RESULTS: Concomitant vaccination for HB, Td, and MMR had a significantly increased incidence of headache, red eyes, and rash compared with nonconcomitant vaccination. There was no significant difference in incidence of serious adverse events, rates of protective immunity, or in secondary endpoints. CONCLUSIONS: Concomitant HB, Td, and MMR vaccination in 11-12-year-olds is as safe and immunogenic as nonconcomitant vaccination.

Antibody Formation↗

PubMed2005

Patient self-testing is a reliable and acceptable alternative to laboratory INR monitoring.

SAn ageing population and the continuing expansion of clinical indications for coumadin therapy have increased pressure on hospital anticoagulant clinics. One solution is patient self-testing (PST) of the international normalized ratio (INR) using capillary blood samples on point-of-care coagulation monitors at home. We conducted a prospective study to determine whether patients can achieve accurate INR values through PST, using the CoaguChek S (Roche Diagnostics, Lewes, UK). The main outcome measurements were: comparability of INR values obtained by PST and the hospital laboratory, patient acceptability as assessed by a questionnaire and anticoagulant control. Eighty-four patients [53 men, 31 women; median age 59 years (range 26-83)], receiving long-term oral anticoagulation (warfarin), were recruited from our Anticoagulation Clinic. Patients were randomized to weekly self-testing or continuing 4-weekly hospital laboratory monitoring of INR. Comparison of INRs (n = 234) showed no significant differences between the CoaguChek (median INR 3.02) and laboratory testing (median INR 3.07). There was excellent correlation between the two methods (r = 0.95), with 85% of CoaguChek results within 0.5 INR units of the laboratory method. On four occasions, differences of >1 unit INR were obtained, but in each case the patient's anticoagulation was unstable (INR >4.5 by both methods) and the differences in INR would not have altered patient management. 87% of patients found self-testing straightforward, 87% were confident in the result they obtained and 77% preferred self-testing. We conclude that PST is a reliable alternative to hospital clinic attendance and is acceptable to the majority of suitably trained patients.

Adult↗

PubMed2005

A survey of U.S. prosthodontists and dental schools on the current materials and methods for final impressions for complete denture prosthodontics.

PURPOSE: The purpose of this study was to survey members of The American College of Prosthodontists (ACP) to evaluate current materials and methods for final impressions for complete denture prosthodontics in the United States. In addition, those methods were compared with methods and materials taught in U.S. dental schools via a second survey sent to the chairpersons of prosthodontic/restorative departments. MATERIALS AND METHODS: An anonymous questionnaire was mailed to all 1762 active ACP members in the United States in 2003. A slightly modified questionnaire was also distributed to chairpersons of prosthodontic/restorative departments in the 54 U.S. dental schools. Data analysis was performed via frequency distribution and chi-square statistics. RESULTS: Nine hundred and forty-five questionnaires were returned by members of the ACP (54% return rate) and 42 questionnaires were returned by the U.S. dental schools (78% return rate). The majority of the reporting prosthodontists (88%) and dental schools (98%) use a border-molded custom tray for final impressions for complete denture prosthodontics. The most popular material for border molding was plastic modeling compound (67% of reporting ACP members, and 95% of the responding dental schools). Variability of the materials used for final impressions was observed, with the most popular materials being polyvinylsiloxane for the ACP members (36%) and polysulfide for the dental schools (64%). Statistically significant differences were found in the materials used for border molding by prosthodontists based on the time elapsed since completion of prosthodontic training. No differences were found in the materials used for impression of edentulous arches based on years of experience. Geographic location did not influence the materials and methods used by prosthodontists for complete denture final impressions. CONCLUSIONS: There was variability of the materials and techniques used for final impressions by ACP members and dental schools; however, overall there was an agreement on the materials and techniques used by prosthodontists and dental schools. Distinct trends for increasing use of polyvinylsiloxane and polyether for border molding procedures and impressions of edentulous arches were observed both in members of the ACP and in the U.S. dental schools.

Dental Impression Materials↗

PubMed2005

Moisture effect on polyether and polyvinylsiloxane dimensional accuracy and detail reproduction.

PURPOSE: This investigation evaluated and compared the dimensional accuracy and surface detail reproduction of two hydrophilic polyvinylsiloxane (PVS) and two polyether (PE) impression materials when used under dry and moist conditions. METHODS: Impressions were made of stainless steel dies as described in ANSI/ADA specification no. 19, with two vertical and three horizontal lines inscribed on the die superior surface. Impressions were made under dry and moist conditions (17 impressions per condition for each material). Dimensional accuracy was measured by comparing the average length of the middle horizontal line in each impression with the same line on the metal die using a measuring microscope with an accuracy of 0.001 mm. Surface detail reproduction was evaluated by using criteria similar to ADA specification no. 19: continuous replication of at least two of the three horizontal lines. RESULTS: The mean percent dimensional change and SD values ranged from -0.135% (0.035) to 0.053% (0.031). A two-way analysis of variance (ANOVA) indicated that moisture did not cause significant adverse effects on the dimensional accuracy of any material (p > 0.05); however, significant differences were found between the materials (p < .05). The surface detail evaluation indicated that moisture had a significant effect on detail reproduction of PVS materials (Pearson's Chi square, p < 0.05). Under dry conditions, all materials produced satisfactory detail reproduction 100% of the time; however, under moist conditions, only 29% of Aquasil and Genie Ultra PVS impressions produced satisfactory detail reproduction, while 100% of Permadyne Garant and Impregum Penta Soft PE impressions still met the surface detail criteria. CONCLUSIONS: Although moisture may not adversely affect the dimensional accuracy of either PE or hydrophilic PVS material, the evidence suggests that PE material is more likely to produce impressions with superior detail reproduction in the presence of moisture.

Analysis of Variance↗

PubMed2005

Tooth contact in patients with temporomandibular disorders.

Both experimental and retrospective studies suggest a link between parafunctions and pain in temporomandibular disorder (TMD) patients. To investigate the role of parafunctions in TMD, experience sampling methodology was used as a prospective test of the hypothesis that patients with TMD have higher levels of tooth contact and tension than non-TMD controls. Three groups of TMD patients and a group of normal controls carried pagers for one week, were contacted approximately every two hours by an automated calling system, and completed questionnaires assessing tooth contact, tension, and pain at each contact. Results showed that tooth contact was much more frequent among normal controls than is commonly presumed. Patients with myofascial pain with/without arthralgia reported more frequent contact, higher intensity contact, and more tension than patients with disk displacement or normal controls. Increased masticatory muscle activity responsible for tooth contact and tension may be an important mechanism in the etiology and maintenance of the myofascial pain and arthralgia of TMD.

Adult↗

PubMed2005

The role of parafunctions, emotions and stress in predicting facial pain.

BACKGROUND: The authors conducted a study to examine the degree to which parafunctions and emotional states predicted jaw pain in subjects with temporomandibular disorder (TMD) and control subjects. METHODS: Ninety-six subjects diagnosed with myofascial pain, myofascial pain and arthralgia, disk displacement or no TMD symptoms participated. The authors used experience sampling methodology to collect data on pain, behaviors and emotions. They paged subjects approximately every two hours, but not during sleep. When paged, subjects completed a brief questionnaire containing rating scales of jaw pain, masticatory muscle tension, time and intensity of tooth contact, mood and stress level. RESULTS: Analyses of variance showed that groups differed significantly (P < .05) in terms of pain; masticatory muscle tension; and a composite variable measuring time and intensity of contact; mood; and stress. The two myofascial pain groups scored higher on these measures than did the group with disk displacement and the control group. The authors used masticatory muscle tension, the composite variable, mood and stress to predict jaw pain using linear regression. The model was significant and accounted for 69 percent of the variance in jaw pain. Because tension was so highly correlated with jaw pain, the authors removed this variable and re-ran the analysis. The second model also was significant and accounted for 46 percent of the variance in jaw pain. CONCLUSIONS: Parafunctional behaviors, especially those that increase muscle tension, and emotional states are good predictors of jaw pain levels in patients with TMD and healthy control subjects. CLINICAL IMPLICATIONS: Treatment that helps patients reduce parafunctions, excess masticatory muscle tension, stress and emotional distress should be effective in reducing TMD pain.

Adult↗

PubMed2005

Utilization of evidence-based informational resources for clinical decisions related to posterior composite restorations.

The purpose of this study was to characterize evidence-based informational resources utilization patterns of a sample of general dentists with respect to clinical decisions regarding posterior composite restorations. A stratified random sample of general practitioners belonging to the Academy of General Dentistry (n = 2880) was mailed a questionnaire that elicited information about practice characteristics and informational resources used for clinical decision making related to posterior composite restorations. Six hundred ninety-nine dentists responded (24 percent response rate). Use of evidence-based (EB) resources (journals and online data bases) was low for all respondents (14 percent) for all levels of experience; however, more experienced clinicians were more likely to use EB resources than recent graduates. AGD Master-level members were significantly more likely to use EB resources than their counterparts (p < .05). Within the limitation of this study, current patterns suggest a low reliance on evidence-based informational resources in the practice of clinical dentistry.

Bicuspid↗

PubMed2004

One- and 3-minute plaque removal by a battery-powered versus a manual toothbrush.

BACKGROUND: A new battery-powered toothbrush with a fundamentally different design than other powered toothbrushes has recently been introduced. The new toothbrush has a powered oscillating round head and a second powered head that translates back and forth. This study compared the plaque removal efficacy of a manual toothbrush to this new powered toothbrush. METHODS: This randomized, controlled, examiner-masked, four-period cross-over study examined plaque removal with the two toothbrushes following a single use in 40 subjects. Plaque was scored before brushing and after 1 and 3 minutes of brushing using the Turesky modification of the Quigley-Hein index. RESULTS: Baseline plaque scores were 2.98 prior to using the powered toothbrush and 2.99 prior to using the manual toothbrush. The powered toothbrush delivered a covariance-adjusted mean plaque score change from baseline of 0.61 after 1 minute of brushing and 0.93 after 3 minutes of brushing. The adjusted mean changes for the manual toothbrush were 0.43 and 0.62, respectively. The differences between treatment groups were statistically significant (P < 0.001) after both 1 and 3 minutes of brushing. The powered toothbrush had, on average, 42.1% and 49.6% greater plaque removal scores after 1 minute and 3 minutes of brushing, respectively. Both toothbrushes had statistically significantly greater plaque removal scores after 3 minutes than after 1 minute of brushing (P < 0.001). Plaque removal scores for each toothbrush after 3 minutes of brushing were about 50% higher than the scores after 1 minute of brushing. CONCLUSIONS: The powered toothbrush delivered statistically significantly superior plaque removal after both 1 and 3 minutes of brushing compared to the manual toothbrush. Both toothbrushes showed statistically significantly greater plaque removal following 3 minutes of brushing than following 1 minute of brushing, and the difference between the toothbrushes was greater following 3 minutes of brushing than following 1 minute of brushing.

Adult↗

PubMed2003

Evaluation of saturation labelling two-dimensional difference gel electrophoresis fluorescent dyes.

Two-dimensional difference gel electrophoresis (2-D DIGE) enables an increased confidence in detection of protein differences. However, due to the nature of the minimal labelling where only approximately 5% of a given protein is labelled, spots cannot be directly excised for mass spectrometry (MS) analysis and detection sensitivity could be further enhanced. Amersham Biosciences have developed a second set of CyDye DIGE Cy 3 and Cy5 dyes, which aim to overcome these limitations through saturation-labelling of cysteine residues. The dyes were evaluated in relation to their sensitivity and dynamic range, their useability as multiplexing reagents and the possibility of direct spot picking from saturation-labelled gels for MS analysis. The saturation-labelling dyes were superior in sensitivity to their minimal-labelling counterparts, silver stain and Sypro Ruby, however, the resulting 2-D spot pattern was significantly altered from that of unlabelled or minimal-labelled protein. The dyes were found to be useful as multiplexing reagents although preferential labelling of proteins with one dye over another was observed but was controlled for through experimental design. Protein identities were successfully obtained from material directly excised from saturation-labelled gels eliminating the need for post-stained preparative gels.

Animals↗

PubMed2003

Comparison of recordings obtained with computerized axiography and mechanical pantography at 2 time intervals.

PURPOSE: The purpose of this study was to compare recordings of mandibular movements obtained with a Denar mechanical pantograph to those obtained with a Denar computerized axiograph (Cadiax compact). MATERIALS AND METHODS: Pantographic recordings and computerized axiograms were collected on 10 subjects. All of the subjects had intact dentition and no clinical signs or symptoms of temporomandibular dysfunction. Tracings produced with the 2 instruments were compared using pantographic reproducibility indices (PRIs). Recordings with each instrument were repeated twice and assessed for consistency. Pearson's correlation coefficient was used to compare PRI scores obtained with the pantograph and the axiograph. Recordings with both instruments were repeated 2 weeks to 1 month later, and new PRI scores were calculated. Consistency between initial and second PRI scores for each instrument was assessed using a coefficient of stability. RESULTS: The coefficients of stability between the initial and second recordings were r = 0.91 for mechanical pantography and r = -0.06 for computerized axiography. Comparison of recordings made by mechanical pantography and computerized axiography at the initial and second recordings showed poor concordance, with coefficients of 0.23 and -0.11, respectively. CONCLUSIONS: PRI scores recorded with the mechanical pantograph were consistent between the initial and second recordings. In contrast, recordings with the computerized axiograph appeared highly inconsistent across time. PRI scores calculated from the axiographs were significantly higher than PRI scores calculated from pantographic tracings for the same subject.

Adult↗

PubMed2003

Sentenced to treatment: early experience of drug treatment and testing orders in England.

Drug Treatment and Testing Orders (DTTOs) were introduced in the 1998 Crime and Disorder Bill and were piloted in three areas in England over the subsequent 18 months. The orders, funded by the Home Office, allow drug using offenders to be coerced into attending for treatment, to have regular urine tests and to be reviewed by the courts. In Croydon an equal partnership was set up between probation, a local statutory provider of drug services and a voluntary sector agency. Treatment plans were individualised and included a variety of treatment options. Forty-eight orders were imposed mainly for persistent shoplifting. Sixty-three percent of individuals had used heroin and 54% crack cocaine in the 30 days before the order was imposed. Ethical issues raised in coerced treatment were important for the individuals providing treatment although the clients all had to consent to treatment. The pilot programme raised issues about the nature of treatment, clinical responsibility, the selection of clients for orders and the objectives of treatment. Frequent urine testing was problematic but in the vast majority of cases clients were not breached just because of positive tests. The provision of DTTOs in an area created unacceptable inequalities in access to treatment. The paper concludes that partnership working and clear objectives are vital for treatment programmes to operate effectively. More research is needed to explore the most optimum way to deliver treatment in the context of a DTTO.

Adolescent↗

PubMed2003

Plaque removal efficacy of a prototype power toothbrush compared to a positive control manual toothbrush.

PURPOSE: Recently, a new experimental battery-powered toothbrush was developed as a second generation to Crest SpinBrush. The brush head of this new prototype toothbrush (Crest SpinBrush Pro) incorporates a dual moving head design with one oscillating and the other translating back and forth. The objective of this study was to compare the plaque removal efficacy of a positive control manual toothbrush (Oral-B Cross Action) to this prototype power toothbrush following a repeated single use study design. In addition, this paper reports the results of a study examining the relative plaque removal efficacy of the positive control manual toothbrush to seven representative manual toothbrushes. METHODS: This study was a randomized, controlled, examiner-blind, four-period crossover design, which examined plaque removal with the two toothbrushes following a single use in 40 subjects. Plaque was scored before and after brushing using the Turesky Modification of the Quigley-Hein Index. RESULTS: Baseline plaque scores were 2.61 and 2.66 for the prototype power toothbrush and control toothbrush treatment groups, respectively. With respect to all surfaces examined, the prototype power toothbrush delivered an adjusted (via analysis of covariance) mean difference between baseline and post-brushing plaque scores of 0.98 while the control toothbrush delivered an adjusted mean difference of 0.74. The experimental toothbrush group, on average, had a 32.8% larger plaque removal score than the control toothbrush. These results were statistically significant (P < 0.001). Similar results were observed on buccal and lingual surfaces. In addition, results from the study comparing manual toothbrushes showed that the positive control manual toothbrush had higher plaque removal scores compared to seven representative manual toothbrushes. The plaque removal score differences reached statistical significance for five of the seven toothbrushes.

Adult↗