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Biomedical subjects

R Holt

Publications and source records attributed to R Holt.

At least 19 recordsLinked to original sources
PubMed2001

Dopamine receptor subtype density as a function of age in Aplysia californica.

The age-associated changes in dopamine subtype receptors were examined in Aplysia californica. The density of the subtype receptors D1, D2, D3 and D4 was examined in the ganglia from 4.5-, 6-, 8-, 9- and 12-month animals. Receptor analysis was performed by examining the binding of radiolabeled ligands to the individual subtypes. [3H]SCH23390 and [3H]Clozapine were used to analyze D1 and D4 specific binding. [3H]Quinpirole was used for determining D2 and D3 specific binding. Specific binding was found to be present for all four receptor subtypes. All receptor subtypes showed an increase in density from 4.5 to 6 months. From 6 to 8 months D2 and D3 decreased, while D1 and D4 increased. D4 showed the strongest increase. All four subtypes examined showed decreases from 8 to 12 months. ANOVA results indicated age was a significant factor in the subtype receptor density for all receptor types.

Age Factors↗
PubMed2001

Oral health status of heroin users in a rehabilitation centre in Hubei province, China.

OBJECTIVE: To report on the oral health of heroin users and to determine risk factors for oral health status. DESIGN: All heroin users at one rehabilitation camp received an interview using a pre-tested questionnaire from one of three trained interviewers and a dental examination using World Health Organization recommended procedures from one of three calibrated dentists. SETTING: Interviews and examinations were carried out at Hubei Province camp. PARTICIPANTS: All 520 resident heroin users at the camp participated in the study. OUTCOME MEASURES: Oral hygiene expressed using the Debris Index; caries status by DMFT; periodontal status by percentage with bleeding, pocketing and calculus; mucosal status using standard World Health Organization criteria. RESULTS: One hundred (19%) of the heroin users were caries free; their mean DMFT was 4.2. The majority (92%) of the DMFT was decay and only a small proportion (8%) was treatment related. The proportion of heroin users with bleeding, calculus, shallow pocketing and deep pocketing was 42%, 95%, 42% and 8% respectively. The mean Debris Index score was 3.2. Mucosal lesions were present in 31 subjects (6%). Using multivariate analysis, duration of heroin use and education were risk factors for DMFT, route of drug administration was a risk factor for calculus and gender was a risk factor for deep pocketing. CONCLUSIONS: There are indications of poorer periodontal health as well as higher caries experience in this group when compared to provincial dental epidemiological data. Mucosal lesions were not widely prevalent. Both social factors and characteristics of drug use were related to oral health in this group.

Administration, Oral↗
PubMed2001

Effect of early exposure on the integration of dental implants: Part 2--Clinical findings at 6 months postloading.

Implant exposure during initial healing after placement has been considered important in both implant integration and postloading effects. This study evaluated the effect of early implant exposure on the clinical findings prerestoration and 6 months postrestoration. Forty-eight implants (24 CPTi and 24 Ti-13-13) were placed in maxillary and mandibular posterior sites in six baboons. Implant exposure was evaluated for 24 of the submerged implants at placement and at each weekly visit for 3 weeks after implant placement. The crestal bone level at maxillary posterior sites was measured at 6-month uncovering, and mandibular sites were measured at 3-month uncovering. All sites were again measured 6 months after restoration placement. Periotest readings were recorded at implant uncovering and again 6 months postloading. Arbitrary groupings of the Periotest values were assigned as good = -7 to -1; guarded = 0 to +2; and poor = +3 to +27. At 6 months postloading, there were no statistical differences between CPTi and Ti-13-13 for change in crestal bone height in either arch. The mean change in maxillary crestal bone height varied from a 0.59- to 1.35-mm loss. The differences between the mean exposed and nonexposed changes were not statistically significant The mean change in mandibular crestal bone height varied from a 0.25- to 0.88-mm loss. Changes in crestal bone height for nonexposed sites from 3-month implant uncovering to 6 months postloading were statistically significant at the mesial, buccal, and lingual aspects. The mean change for the nonexposed distal aspect approached significance. The differences between the mean exposed and nonexposed changes were not statistically significant. The overall percentage of maxillary implants in the good category for nonexposed sites decreased by 41% from uncovering to 6 months after loading, while no change occurred for exposed sites; the percentage of implants in the good category was comparable for early exposed and nonexposed sites (57% and 59%, respectively). At 6 months after loading, the percentage of implants in the good category was more favorable for early exposed (88%) than nonexposed sites (50%). A one-stage implant approach should provide similar postloading clinical results as the two-stage surgical approach.

Alveolar Bone Loss↗
PubMed2000

Dental care for children and young people who have a hearing impairment.

AIM: The aim was to determine whether there are indications that hearing-impaired children experience difficulties in accessing dental care and/or in receiving dental treatment. METHOD: The study was carried out by means of a questionnaire. Parents of 84 children contacted through the National Deaf Children's Society returned completed questionnaires. RESULTS: Eighty-two children (98%) had visited a dentist. Nearly two-thirds (63%) were reported to have at least one problem in communication while receiving dental care, this increased significantly as the severity of the hearing impairment increased. Fifty-nine children (70%) reported having at least one problem in communication at the doctors'. Fifty-two (62%) reported that the dentist had worn a mask while communicating with the child and 48 (57%) that there had been background noise in the surgery during appointments. CONCLUSIONS: Removing masks while talking, reducing background noise and learning to use simple signs may improve communication with hearing-impaired children.

Adolescent↗
PubMed2000

Reliability of radiographic observations recorded on a proforma measured using inter- and intra-observer variation: a preliminary study.

AIM: The aim of this preliminary study was to test the reliability of radiographic evaluation of features of endodontic interest using a newly devised data collection system. METHODOLOGY: Twelve endodontic MSc postgraduate students and one specialist endodontist examined sample radiographs derived from a random selection of 42 patients seen previously on an Endodontic New Patient Clinic (EDI). Each student examined a random selection of 8-9 roots on periapical radiographs of single- and multirooted teeth, with and without previous root canal therapy and 3-4 dental panoramic tomograms (DPTs). A total of 100 roots were examined. A proforma was used to record observations on 67 radiographic features using predefined criteria. Intra-observer agreement was tested by asking the students to re-examine the radiographs. The principle investigator and the specialist endodontist examined the same radiographs and devised a Gold Standard using the same criteria. This was compared with the student assessments to determine inter-observer variation. The postgraduates then attended a revision session on the use of the form. Each student subsequently examined 8-9 different roots from the pool of radiographs. A further assessment of inter-observer variation was made by comparing these observations with the Gold Standard. RESULTS: Of the 67 radiographic features, only 25 had sufficient response to allow statistical analysis. Kappa values for intra- and inter-observer variation were estimated. These varied depending on the particular radiographic feature being assessed. Fifteen out of 25 intra-observer recordings showed 'good' or 'very good' Kappa agreement, but only three out of 25 inter-observer observations achieved 'good' or 'very good' values. Inter-observer variation was improved following the revision session with 16 out of 25 observations achieving 'good' or 'very good' Kappa agreement. CONCLUSIONS: Modification to the proforma, the criteria used, and training for radiographic assessment were considered necessary to improve the accuracy and reproducibility of the observations entered.

Data Collection↗
PubMed2000

Tropisetron plus dexamethasone is more effective than tropisetron alone for the prevention of postoperative nausea and vomiting in children undergoing tonsillectomy.

The 5-HT3 antagonists are effective in reducing postoperative nausea and vomiting (PONV) associated with paediatric tonsillectomy. Although prophylactic tropisetron can reduce the incidence of PONV by half, the resulting level of over 40% is still unacceptably high. The aim of this study was to evaluate the effect of adding dexamethasone to tropisetron. In a blinded study, 59 children (mean age 6.1 years) were administered 0.1 mg.kg-1 up to 2 mg of tropisetron and 66 children (mean age 5.7 years) received the same dose of tropisetron plus 0.5 mg.kg-1 up to 8 mg of dexamethasone. Both drugs were given intravenously during induction of anaesthesia for tonsillectomy. During the inpatient stay of 24 h, the incidence of postoperative vomiting in the tropisetron alone group was 53% compared with 26% in the combination group (P=0.002, chi-squared). A significant reduction in nausea from 53% to 30% was also observed (P=0.02). Parents completed a daily diary for 5 days following discharge. Delayed vomiting occurred in 27% and 11% of the tropisetron and combination therapy groups, respectively (P=0.025) Sixteen percent and 9%, respectively, required medical attention (P=0.27). Tropisetron plus dexamethasone is more effective than tropisetron alone in reducing the incidence of PONV following paediatric tonsillectomy.

Adolescent↗
PubMed2000

Caries patterns and their relationship to infant feeding and socio-economic status in 2-4-year-old Chinese children.

AIMS: To describe the prevalence, severity and patterns of caries in 2-4-year-old children and to evaluate the association between caries experience of the children and their feeding patterns and socio-economic background in terms of mothers' education and family income. DESIGN: Cross-sectional survey. SETTING: Suburban area of Hanchuan in Hubei province, China. PARTICIPANTS: A sample of 426 children (250 boys and 176 girls). METHODS: Dental-examinations were undertaken in kindergartens using World Health Organization diagnostic criteria for dental caries. Mothers completed a short questionnaire. OUTCOME MEASURES: Prevalence of caries; rampant caries; caries in incisors; caries in incisors and/or canines and molars; mean number of decayed, missing and filled teeth/surfaces (dmft/s). RESULTS: 36% of the children had caries, 7% had rampant caries. The more extensive pattern of caries involving primary molars as well as incisors and/or canines was seen in 12% of children. Children who had been wholly bottle-fed had five times the risk of having rampant caries compared to children who were breast-fed. CONCLUSIONS: The results indicated that infant feeding practice might be a key risk factor for the development of caries at an early age in this country as elsewhere.

Bottle Feeding↗
PubMed2000

Effect of early exposure on the integration of dental implants in the baboon: Part 1--Clinical findings at uncovering.

There has been increased discussion on the advantages of a one- versus a two-stage surgical approach in the placement of dental endosseous implants. This study evaluated the influence of early implant exposure on crestal bone height adjacent to the implant surface and Periotest values at uncovering in the baboon. Forty-eight implants (24 commercially pure titanium, 24 titanium alloy) were placed in maxillary and mandibular posterior sites in 6 baboons. Implant exposure was evaluated weekly for 3 weeks after implant placement. The level of bone adjacent to the dental implants was measured at placement from the top of the implant collar to the crest of the bone at the mesial, distal, buccal, and lingual surfaces. The maxillary sites were measured again at a 6-month uncovering, while the mandibular sites were measured at a 3-month uncovering. Periotest readings were also recorded at uncovering. Early implant exposure was more common in the mandible, with the majority occurring by the second week postplacement. There were no significant differences in the crestal bone height changes at uncovering between the pure titanium and alloy implants in either arch. In the maxilla, the changes in crestal bone height were not statistically different between exposed and nonexposed implants at any aspect. In the mandible, the difference in 3-month changes between exposed and nonexposed implants was significant for the distal, buccal, and lingual aspects. The overall percentage of implants with a Periotest reading in the "good" category was greater for the nonexposed sites as compared to exposed sites. The results of this study suggest that the two-stage surgical approach results in a better clinical outcome as compared to the one-stage approach in the baboon model.

Alveolar Process↗
PubMed2000

Effect of unintentional exposure of 2-stage implants upon subsequent osseointegration: histologic findings 6 months postloading.

The purpose of this study was to evaluate the effect of early spontaneous exposure of 2-stage implants upon subsequent histologic bone contact following occlusal loading. As part of a study comparing 2 types of metallic threaded implants, 48 implants (24 CPTi and 24 Ti-13Nb-13Zr) were placed in maxillary and mandibular posterior sites in 6 baboons. Implant exposure was evaluated at time of placement and at each weekly visit for the first 3 weeks, then at 1, 2, and 3 months, and also at 6 months for the maxilla. Block sections were removed 6 months after the implant restoration was placed into function. One third (33%) of the maxillary implants became exposed, while 66.5% of the mandibular implants became exposed, mostly at 1 to 3 weeks. For all maxillary implants, fibrous tissue contact in the unintentionally exposed group (20.0%) was significantly greater than in the group that remained submerged (7.7%). Maxillary implants remaining submerged exhibited more sinus contact. For all mandibular implants, bone contact in the exposed group (38.9%) was significantly greater than in the submerged group (24.3%). Similarly, exposed implants exhibited less fibrous tissue contact. All other parameters in both maxillary and mandibular arches were statistically similar when comparing unintentionally exposed implants to those that remained submerged. This study suggests that accidental exposure of 2-stage implants should result in overall similarities in postloading bone contact to 2-stage implants that remain submerged during the early postoperative healing period.

Animals↗
PubMed1998

Development of an immunoassay for monitoring the levels of ciprofloxacin in patient samples.

It has been traditional to measure drug concentrations using high pressure liquid chromatography (HPLC). While this method is highly accurate, it is time consuming and requires the use of appropriate standards for identification of the compound. In addition, identification and quantification of drugs from patient samples requires significant manipulation to remove protein. In contrast, enzyme-linked immunoassays (EIA) are able to assay samples with a high degree of specificity, and are able to process multiple samples at a time. In addition, serum proteins do not interfere with sample quantification and samples may be tested without significant preparation. We describe the development of an EIA for the detection of ciprofloxacin in serum and dialysate samples. The immunoassay is specific for ciprofloxacin and is sensitive for picogram amounts of the antibiotic.

Animals↗
PubMed1998

The role of disclosure in coping with HIV infection.

A qualitative investigation was conducted to explore the role of disclosure in HIV infection. Forty homosexual and bisexual men completed a short demographic questionnaire and participated in a one-to-one, semi-structured interview. The interview was designed to address a variety of personal, interpersonal and organizational issues related to their HIV status and participants were invited to talk about their personal experiences from immediately prior to their diagnosis to the time of the interview. The results from the interviews are presented in three sections: immediately post-diagnosis, asymptomatic phase and symptomatic/AIDS phases. The data revealed that disclosing one's HIV status was an acute and recurrent stressor. Immediately post-diagnosis, individuals were more likely to adopt a policy of non-disclosure and this provided them with an opportunity to come to terms with their diagnosis before having to contend with the reactions of others. After this phase, there was evidence that individuals increasingly used disclosure as a mechanism for coping with the disease. Disclosure of one's status was used to increase both practical and emotional support, share responsibility for sex and to facilitate self-acceptance of one's condition. The results from this investigation revealed that disclosure has a dual role in HIV infection acting as both a stressor and a mechanism by which individuals contend with their infection.

Acquired Immunodeficiency Syndrome↗
PubMed1998

An in vitro comparison of thermoplasticised gutta-percha obturation techniques with cold lateral condensation.

This study compared the apical sealing ability, obturation time and extrusion of gutta-percha and sealer when root canals were obturated using either cold lateral condensation or one of the three methods using thermoplasticised gutta-percha (Alpha Seal, Thermafil or JS Quick Fill) in vitro. One hundred and thirty-one root canals from 78 extracted human teeth were used; 116 canals were divided into five groups so that they were balanced with respect to prepared canal anatomy, and the remaining 15 canals were used as positive and negative controls. The canals in the first four groups were prepared with hand files using the step-down technique to a standard apical size and flare. The last group was prepared using engine-driven rotary nickel-titanium files (McSpadden) to a similar apical size and flare. One of the four obturating techniques was used to fill the canals in each of the first four groups. The fifth group was obturated using the Alpha Seal technique. The roots were immersed in india ink, demineralised and rendered transparent to assess the extent of maximum lincar dye penetration. The Alpha Seal groups had the highest number of specimens without any leakage. There was a significant difference in the proportions of specimens that did not leak when the Alpha Seal (P < 0.01) and cold lateral condensation groups (P < 0.05) were compared with JS Quick Fill. Cold lateral condensation had a higher proportion of specimens with leakage in canals with curvature greater than 20 degrees than in canals with curvatures less than 20 degrees (P < 0.05). The curvature of canals had no effect on the sealing ability of the other techniques. The method of canal preparation had no effect on the sealing ability of Alpha Seal. Alpha Seal, Thermafil and JS Quick Fill were significantly quicker to perform than cold lateral condensation.

Analysis of Variance↗