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Biomedical subjects

J F Roberts

Publications and source records attributed to J F Roberts.

At least 19 recordsLinked to original sources
PubMed2005

The survival of resin modified glass ionomer and stainless steel crown restorations in primary molars, placed in a specialist paediatric dental practice.

AIMS: To prospectively report on the survival of resin-modified glass ionomer cement (RMGIC), photac-fil and pre-formed stainless steel crown (SSC) restorations in primary molar teeth placed over a seven-year period in a specialist paediatric dental practice under private contract of remuneration. METHOD: All primary molar restorations placed by a specialist paediatric dentist over a seven-year period were reviewed and the outcome results recorded. Data were recorded at review visits until June 30, 2003. Data recorded included Class I restorations, Class II restorations and SSC. The Class II cavities were either mesial or distal, with or without buccal/palatal extensions. If both proximal surfaces were decayed or if after cavity preparation the resultant outline form was significantly larger than the minimal classical form, RMGIC was not used; an SSC was placed instead. Stainless steel crown preparation followed conventional guidelines. The crowns were cemented with reinforced zinc oxide and eugenol (Kalzinol). The status was recorded as satisfactory restoration, tooth exfoliated, tooth extracted for orthodontic reasons with the date of extraction, or needing replacement. If replaced then the reason for replacement was also recorded. RESULTS: A total of 544 Class I RMGICs, 962 Class II RMGICs, and 1,010 SSCs were placed. At the last review of each restoration, 98.3% of Class I, 97.3% of Class II RMGICs and 97.0% of SSCs were either satisfactory or withdrawn intact. CONCLUSION: Under the conditions of private specialist practice-based study SSCs continued to prove very successful for the restoration of larger cavities and for pulp-treated primary molar teeth. For the smaller cavities RMGIC were also very successful.

Adolescent↗
PubMed2004

Conscious sedation.

Explore the source record for details and available documents.

Anesthesia, Dental↗
PubMed2004

Restoration of primary teeth affected by Early Childhood Caries.

AIM: This was to review the literature on Early Childhood Caries (ECC) for the approaches to prevention and restoration of affected primary teeth. METHODS: The methods are reviewed and suggestions made as the approaches necessary for treating very young children. The special problems associated with the need to restore primary incisors in children with very low levels of cooperation are described. The options are outlined and indications for each approach discussed.

Child, Preschool↗
PubMed1998

Isolation and characterization of a monoclonal anti-quadruplex DNA antibody from autoimmune "viable motheaten" mice.

A cell line that produces an autoantibody specific for DNA quadruplex structures has been isolated and cloned from a hybridoma library derived from 3-month-old nonimmunized autoimmune, immunodeficient "viable motheaten" mice. This antibody has been tested extensively in vitro and found to bind specifically to DNA quadruplex structures formed by two biologically relevant sequence motifs. Scatchard and nonlinear regression analyses using both one- and two-site models were used to derive association constants for the antibody-DNA binding reactions. In both cases, quadruplexes had higher association constants than triplex and duplex molecules. The anti-quadruplex antibody binds to the quadruplex formed by the promoter-region-derived oligonucleotide d(CGCG4GCG) (Ka = 3.3 x 10(6) M-1), and has enhanced affinity for telomere-derived quadruplexes formed by the oligonucleotides d(TG4) and d(T2G4T2G4T2G4T2G4) (Ka = 5.38 x 10(6) and 1.66 x 10(7) M-1, respectively). The antibody binds both types of quadruplexes but has preferential affinity for the parallel four-stranded structure. In vitro radioimmunofilter binding experiments demonstrated that purified anti-DNA quadruplex antibodies from anti-quadruplex antibody-producing tissue culture supernatants have at least 10-fold higher affinity for quadruplexes than for triplex and duplex DNA structures of similar base composition and length. The antibody binds intramolecular DNA triplexes formed by d(G4T3G4T3C4) and d(C4T3G4T3G4), and the duplex d(CGCGCGCGCG)2 with an affinities of 6. 76 x 10(5), 5.59 x 10(5), and 8.26 x 10(5) M-1, respectively. Competition experiments showed that melted quadruplexes are not effective competitors for antibody binding when compared to native structures, confirming that the quadruplex is bound structure-specifically. To our knowledge, this is the first immunological reagent known to specifically recognize quadruplex structures. Subsequent sequence analysis demonstrates homologies between the antibody complementarity determining regions and sequences from Myb family telomere binding proteins, which are hypothesized to control cell aging via telomeric DNA interactions. The presence of this antibody in the autoimmune repertoire suggests a possible linkage between autoimmunity, telomeric DNA binding proteins, and aging.

Animals↗
PubMed1996

Technetium-99m-MAG3 renal studies in spinal cord injury patients: normal range, reproducibility, and change as a function of duration and level of injury.

UNLABELLED: The normal range, reproducibility, and change as a function of duration and level of injury for Tc-99m-MAG3 renal studies were quantitated in spinal cord injury (SCI) patients. METHODS: Five SCI patients without evidence of renal disease in each of four groups: less than 2 months, 2-12 months, 1-2 years, and greater than 2 years from time of injury, were each studied twice. There were at least two patients with paraplegia and two with tetraplegia in each group. Renal clearance (camera based method), percent function in each kidney, time of peak renal parenchymal activity, and half time of parenchymal activity following the peak were evaluated. The peak and half times were determined with regions of interest (ROIs) over the entire kidney and over just the cortex. All results were compared to normal ranges previously established in normal subjects of the same age range using the same methodology. RESULTS: Renal clearance in the less than 2 month SCI patients was not significantly different from normal subjects in either paraplegic or in tetraplegic individuals. However, clearance in tetraplegics was increased by 28.5% at 2-12 month, increased by 50.6% at 1-2 years, and decreased by 25.9% at greater than 2 years compared to normal subjects (all P < 0.02). Clearance in those with paraplegia showed a similar, but less marked, trend (P = NS). The time of peak parenchymal activity when measured with cortical ROIs did not vary among patient groups or level of injury, but was increased compared to normal subjects (P < 0.05). The percent function in each kidney and half time following the peak were symmetrical, did not differ among patient groups or with level of injury, and did not differ from normal subjects. The parenchymal peak time was significantly shorter with cortical rather than renal ROIs in all patient groups (P < 0.05). In serial studies in the same patient the percent standard deviation in total renal clearance was less than between single studies in different patients, but the decrease was significant for only the right kidney (P < 0.03), and the decrease was not as great as in normal subjects. In addition, the percent standard deviation for percent function in each kidney was significantly less than the percent standard deviations in single studies (P < 0.02). There were no significant differences between intra- and interpatient studies for any other parameter. CONCLUSION: We conclude that: (1) renal clearance measured with Tc-99m-MAG3 in tetraplegic patients increases significantly during the first 2 years following injury and decreases significantly thereafter; there is a similar, but much less marked, trend in paraplegics, (2) parenchymal peak times with cortical ROIs occur later for SCI patients than for normal subjects, and (3) there is more intrapatient variation in total renal clearance and percent renal clearance on a side in SCI patients than in normal subjects suggesting that it may be harder to study SCI patients reproducibly. These findings should be taken into account when performing and interpreting Tc-99m-MAG3 renal studies in SCI patients.

Adult↗
PubMed1996

Treatment of vital and non-vital primary molar teeth by one-stage formocresol pulpotomy: clinical success and effect upon age at exfoliation.

The clinical success and effect upon the age at which teeth exfoliated was prospectively observed in 175 primary molars that had received formoceresol pulpotomies performed by one operator. The success rate among 142 vital teeth was 99.3% and among 33 non-vital teeth 84.8%. There was no significant effect upon age at exfoliation after either type of pulpal treatment.

Child↗
PubMed1995

Antibodies specific for the DNA quadruplex [d(CGC G4 GCG)4] isolated from autoimmune mice.

An autoantibody specific for a DNA quadruplex structure has been isolated and cloned from three-month-old autoimmune "viable motheaten" mice. This antibody (mev-alpha Q1) has been tested extensively in vitro and found to bind specifically and preferentially to the parallel-stranded quadruplex structure formed by the oligonucleotide d(CGC G4 GCG). The anti-quadruplex antibody does not show specific affinity for single-, double-, or triple-stranded oligonuclotides of similar CG-rich sequence motifs.

Animals↗
PubMed1993

In vivo evaluation of reuterin and its combinations with suramin, melarsoprol, DL-alpha-difluoromethylornithine and bleomycin in mice infected with Trypanosoma brucei brucei.

1. Trypanosoma brucei brucei-infected mouse models treated with a new antibiotic, reuterin, showed reduction of the levels of parasitemia and prolonged survival of the mice. 2. Cures of the parasitemia were observed in groups of mice treated with combinations of reuterin and suramin or melarsoprol. 3. Reuterin administered in combination with bleomycin or DL-alpha-difluoromethylornithine showed temporary remission of the parasitemia in groups of mice.

Aldehydes↗
PubMed1992

A new oral surgery teaching model.

An anatomical model for teaching the practical aspects of routine oral surgery in a clinical or laboratory environment, is described. Replaceable sections allow the model to be rapidly re-used so that successive students may practise procedures such as incisions, flap reflection, bone removal, tooth removal, apicectomy and suturing. Keeping the cost per procedure to a minimum was considered to be of fundamental importance and this has been achieved through the use of 'factory produced' replacement parts.

Equipment Design↗
PubMed1992

The in vitro efficacy of reuterin on the culture and bloodstream forms of Trypanosoma brucei brucei.

1. The in vitro effects of a new antibiotic, reuterin, were determined for culture and bloodstream forms of Trypanosoma brucei brucei. It inhibited growth of the culture forms and motility, viability and DNA and protein syntheses of culture and bloodstream forms. 2. Reuterin administered with inhibitors of ribonucleotide reductase (hydroxyurea and deoxyadenosine) was synergistic only for growth of the culture form of the parasite. 3. Reuterin was trypanocidal at lower doses than DFMO, Mel B, and Suramin and was antagonistic when used with these drugs.

Aldehydes↗
PubMed1992

Children's expectations and recollections of discomfort associated with dental treatment.

It has been reported that adults, especially those most anxious about dentistry, expect more discomfort than they actually experience during treatment, and that, months after conservative treatment, they describe that experience as more uncomfortable than they had done immediately after treatment. This study sought to determine whether children's expectations and recollections of their discomfort are distorted in this way. Thirty-four children were asked to estimate, using a standard rating-scale, the degree of discomfort, if any, which they expected to experience in the dental treatment that was to follow. Immediately after treatment, which involved injection of local anaesthetic and preparation of a cavity, the children were asked to rate the degree of discomfort which they had just experienced. Six weeks and three months later, the children were sent an identical rating-scale and asked to record, under the supervision of their parents, the degree of discomfort which they recalled having experienced during that treatment. Like adults, the children experienced less discomfort during treatment than they had expected. Unlike adults, even the most anxious children recalled, 6 weeks and 3 months later, no more discomfort than they had reported immediately after treatment. Nevertheless, the unrealistic expectations of discomfort by children should be a prominent target for behavioural management by dentists.

Adolescent↗
PubMed1990

The fate and survival of amalgam and preformed crown molar restorations placed in a specialist paediatric dental practice.

The fate of 1688 amalgam restorations and 716 preformed crowns placed in permanent and primary molars in a specialist paediatric dental practice over a 10-year period by one operator is reported. For primary molar amalgams, the replacement rate, true failure rate and 5-year survival estimates were, for Class 1 restorations, 16.1%, 3.9%, 73.3%, respectively, with an estimated median survival time greater than 8.5 years, and for Class 2 cavities 14.7%, 11.6%, 66.6%, with an estimated median survival time greater than 7.5 years. For permanent molar amalgams, the replacement rate, true failure rate and 5-year survival estimates were for Class 1 restorations 11.5%, 6.5%, 76.8%, respectively, with an estimated median survival time greater than 9.3 years, and for Class 2 restorations 9.8%, 8.0%, 82.2%, with a median survival time greater than 8.5 years. For all preformed crowns, the replacement rate, true failure rate and 5-year survival estimates were 2.8%, 1.9%, 92.0%, and the estimated median survival time greater than 7.64 years. No relationship was observed between the age of the patient and the age of replaced restorations. No significant difference was found between the survival rates of Class 1 and 2 amalgam restorations in primary or permanent molars, nor between first and second primary molars.

Adolescent↗
PubMed1986

Macrophage uptake of a lipoprotein-sequestered toxicant: a potential route of immunotoxicity.

An experimental system was chosen to investigate the bioactivity of a lipoprotein-sequestered toxicant at the cellular level based on recent studies demonstrating receptor-mediated uptake of lipoproteins by macrophages. Rat peritoneal exudate cell suspensions (PEC) were exposed to DDT and lipoprotein-sequestered DDT, followed by measurement of DDT uptake, metabolism, and cellular toxicity. In vitro uptake assays demonstrated that PEC suspensions treated for 10, 20, and 30 min with 2.5 microM lipoprotein-sequestered DDT had approximately a twofold increase over the amount of DDT associated with PEC treated with 2.5 microM free DDT. PEC were assayed for DDT metabolites to serve as a measure of the cellular internalization of the toxicant after treatment in vitro for 18 hr with either 1.5 microM DDT or lipoprotein-sequestered DDT. Evidence of DDT metabolism was only observed with PEC which had been treated with lipoprotein-sequestered DDT. These cells contained significantly higher amounts of DDT metabolites as compared to cells treated with unsequestered DDT (over an eightfold difference). Assays measuring macrophage phagocytic activity indicated that macrophages treated for 4.5 hr in vitro with 2.5 microM lipoprotein-sequestered DDT showed significant inhibition in their ability to phagocytize yeast particles. These results suggest that serum lipoproteins may facilitate the cellular uptake of lipoprotein-sequestered toxicants leading to altered cellular function (phagocytosis).

Animals↗