Tooth surface loss: an overview.
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Adolescent↗
Biomedical subjects
K Bishop
Publications and source records attributed to K Bishop.
Modulation of nuclear localization of the influenza virus nucleoprotein through interaction with actin filaments.
The influenza virus genome is transcribed in the nuclei of infected cells but assembled into progeny virions in the cytoplasm. This is reflected in the cellular distribution of the virus nucleoprotein (NP), a protein which encapsidates genomic RNA to form ribonucleoprotein structures. At early times postinfection NP is found in the nucleus, but at later times it is found predominantly in the cytoplasm. NP contains several sequences proposed to act as nuclear localization signals (NLSs), and it is not clear how these are overridden to allow cytoplasmic accumulation of the protein. We find that NP binds tightly to filamentous actin in vitro and have identified a cluster of residues in NP essential for the interaction. Complexes containing RNA, NP, and actin could be formed, suggesting that viral ribonucleoproteins also bind actin. In cells, exogenously expressed NP when expressed at a high level partitioned to the cytoplasm, where it associated with F-actin stress fibers. In contrast, mutants unable to bind F-actin efficiently were imported into the nucleus even under conditions of high-level expression. Similarly, nuclear import of NLS-deficient NP molecules was restored by concomitant disruption of F-actin binding. We propose that the interaction of NP with F-actin causes the cytoplasmic retention of influenza virus ribonucleoproteins.
Actins↗
Pilot study of nimorazole as a hypoxic-cell sensitizer with the "chart" regimen in head and neck cancer.
PURPOSE: A potential disadvantage of accelerated fractionation in radiotherapy is the lack of time for reoxygenation, so that hypoxia becomes a more potent cause of failure. Accordingly, we have combined nimorazole, the only hypoxic radiosensitizer shown to significantly improve local control in head and neck cancer, with continuous hyperfractionated accelerated radiation therapy (CHART). METHODS AND MATERIALS: Twenty-two patients with locally advanced (stage IV) squamous cell carcinoma of the head and neck were treated with escalating doses of nimorazole given concomitantly with CHART (three fractions of 1.5 Gy per day, spaced 5 1/2 hours apart, on 12 consecutive days). All patients received 1.2 g/m2 nimorazole 90 minutes before each first daily fraction. Seventeen patients received a further 0.6 g/m2 before each second daily fraction and six of these patients received an additional dose of 0.6 g/m2 before each third fraction. RESULTS: The three times daily schedule yielded mean plasma drug concentrations at the time of irradiation of 37.7 microg/ml with the morning fractions, 31.2 microg/ml with the afternoon fractions, and 30.4 microg/ml with the evening fractions. In view of these results the midday dose was increased to 0.9 microg/m2 in an ongoing Phase II study. Drug toxicity was limited to nausea and vomiting apart from two cases of mild paraesthesia at the highest dose level. CONCLUSIONS: Comparison with a historical group of patients, treated with the CHART regimen alone and matched for irradiation volume and technique, showed that nimorazole did not increase the severity of acute normal tissue radiation effects. Encouraging tumor responses have been seen in the patients receiving nimorazole with every radiotherapy fraction.
Carcinoma, Squamous Cell↗
Maxillofacial prosthodontics and reconstruction: a Canadian view.
A craniofacial osseointegration and maxillofacial prosthetic rehabilitation unit in Edmonton, Canada was visited by the author as part of a higher specialist training programme. The unit has an international reputation as a centre of excellence for the treatment of patients with head and neck abnormalities. The report examines the activities of the unit and how it achieves its 'patient centred' approach to care.
Canada↗
Nicotine exposure during a critical period of development leads to persistent changes in nicotinic acetylcholine receptors of adult rat brain.
Effects of neonatal nicotine exposure on the development of nicotinic acetylcholine receptor (nAChR) alpha2, alpha3, alpha4, alpha7, and beta2 subunit mRNAs and the number of nAChR isoforms in rat brain were studied. The mRNA levels for nAChR subunits were measured by ribonuclease protection assay, and the number of nAChR isoforms was measured with (-)-[3H]nicotine, [3H]epibatidine, and alpha-[3H]bungarotoxin ([3H]alpha-Bgt). Pups were divided into two groups: One group received (-)-nicotine treatment (0.1 mg/kg s.c. free base twice per day) during postnatal day (P)1 to P21 and the other during P8 to P16. The period from P8 to P16 was chosen due to persistent changes that occur in brain nAChRs and in the behavior of adult mice that received (-)-nicotine treatment during P10 to P16. (-)-Nicotine exposure from P1 to P21 significantly up-regulated the number of [3H]epibatidine and high-affinity (-)-[3H]nicotine binding sites in most of the brain regions studied but did not influence the number of [3H]alpha-Bgt binding sites. This effect was a transient one: The up-regulated binding sites returned to control level 1 week after withdrawal from nicotine. (-)-Nicotine exposure during P8 to P16 resulted in a significant and long-lasting increase in the number of nAChR isoforms labeled by (-)-[3H]nicotine, but not by [3H]epibatidine, in the cortex, hippocampus, and striatum of adult rat. This treatment converted the low-affinity binding sites of (-)-nicotine into a high-affinity state revealed by the competition studies of (-)-[3H]nicotine/(-)-nicotine. No changes in the mRNA levels of the subunits studied were observed following nicotine treatment during these two periods. These results suggest that the second postnatal week is a critical period during which nicotine treatment can induce permanent effects on the nAChRs in rat brain. The underlying mechanisms involved in the up-regulation of the number of nAChRs observed in this study are posttranscriptional.
Aging↗
Comparison of PCR-heteroduplex characterization by automated DNA sequencing and line probe assay for the detection of rifampicin resistance in Mycobacterium tuberculosis isolates from KwaZulu-Natal, South Africa.
Progress in understanding the basis of resistance to rifampicin (RifR) has allowed molecular tests for the detection of drug-resistant tuberculosis to be developed. One hundred thirteen strains of Mycobacterium tuberculosis isolated from patients with multidrug resistant tuberculosis (MDR-TB) were investigated for genotypic analysis of RifR by polymerase chain reaction-heteroduplex formation (PCR-HDF) and characterization of mutations by automated DNA sequencing of the rpoB gene. A subset of isolates (22) representative of different mutations as confirmed by sequence analysis were also evaluated by the Line Probe Assay (LiPA). In 106 of the RifR strains, 24 mutations within an 81-bp region of the rpoB gene affecting 13 amino acids were observed. Most isolates (7/8) harboring Leu533 --> Pro codon mutation required minimum inhibitory concentrations (MICs) of < or = 8 microg/ml. There was geographic variation in the frequency of occurrence of particular rpoB mutations, with the Ser531 --> Leu/Trp codon mutation found in 59/113 of isolates. Although there are certain limitations in the use of both the rapid PCR-HDF diagnostic assay and the LiPA for the detection of rifampicin susceptibility of M. tuberculosis, these provide important and convenient tools for identifying and managing patients with MDR-TB.
Antibiotics, Antitubercular↗
Differential binding of apo and holo human transferrin to meningococci and co-localisation of the transferrin-binding proteins (TbpA and TbpB).
Apo-transferrin (apo-hTf) and holo-transferrin (holo-hTf) were separately conjugated to 15-nm colloidal gold. Iron-restricted Neisseria meningitidis strain SD (B:15:P1.16) bound up to three-fold more holo-hTf than apo-hTf (p <0.001). The ability of meningococcal mutants lacking either transferrin-binding protein A (TbpA) or TbpB to discriminate between apo-hTf and holo-hTf was also investigated. There was no significant difference between the amount of gold-labelled apo-transferrin bound by the isogenic TbpA mutant (expressing TbpB) and the parent strain, whereas an isogenic TbpB mutant (expressing TbpA) bound significantly less gold-labelled apo-hTf. The isogenic TbpA and TbpB mutants and the parent strain all bound significantly more holo-hTf than apo-hTf, whereas the double 'knock-out' mutant failed to bind hTf irrespective of the iron-loading. In the isogenic mutants, TbpB was more effective in binding either apo- or holo-hTf than TbpA. Monoclonal antibodies against TbpA and TbpB were used to co-localise the transferrin-binding proteins on strain SD. The ratio of TbpA:TbpB was approximately 1:1. TbpA and TbpB were occasionally observed in close proximity to each other, but the two proteins were generally quite separate, which may indicate that they do not usually form a complex to act as a transferrin receptor.
Antibodies, Monoclonal↗
Molecular cloning of a 32-kilodalton lipoprotein component of a novel iron-regulated Staphylococcus epidermidis ABC transporter.
Our previous studies identified two iron-regulated cytoplasmic membrane proteins of 32 and 36 kDa expressed by both Staphylococcus epidermidis and Staphylococcus aureus. In this study we show by Triton X-114 phase partitioning and tritiated palmitic acid labelling that these proteins are lipoproteins which are anchored into the cytoplasmic membrane by their lipid-modified N termini. In common with those of some other gram-positive bacteria, these highly immunogenic lipoproteins were released from the bacterial cell into the culture supernatants, with release being promoted by growth of the bacteria under iron-restricted conditions. Immunoelectron microscopy with a monospecific rabbit antiserum to the 32-kDa S. epidermidis lipoprotein showed that the majority of the antigen was distributed throughout the staphylococcal cell wall. Only minor quantities were detected in the cytoplasmic membrane, and exposure of the lipoprotein on the bacterial surface was minimal. A monoclonal antibody raised to the 32-kDa lipoprotein of S. aureus was used in immunoblotting studies to investigate the conservation of this antigen among a variety of staphylococci. The monoclonal antibody reacted with polypeptides of 32 kDa in S. epidermidis and S. aureus and of 40 kDa in Staphylococcus hominis. No reactivity was detected with Staphylococcus lugdunensis, Staphylococcus cohni, or Staphylococcus haemolyticus. The gene encoding the 32-kDa lipoprotein from S. epidermidis has been isolated from a Lambda Zap II genomic DNA library and found to be a component of an iron-regulated operon encoding a novel ABC-type transporter. The operon contains three genes, designated sitA, -B, and -C, encoding an ATPase, a cytoplasmic membrane protein, and the 32-kDa lipoprotein, respectively. SitC shows significant homology both with a number of bacterial adhesins, including FimA of Streptococcus parasanguis and ScaA of Streptococcus gordonii, and with lipoproteins of a recently described family of ABC transporters with proven or putative metal ion transport functions. Although the solute specificity of this novel transporter has not yet been determined, we speculate that it may be involved in either siderophore- or transferrin-mediated iron uptake in S. epidermidis.
ATP-Binding Cassette Transporters↗
Creutzfeldt-Jakob disease in a husband and wife.
A 53-year-old man died of sporadic Creutzfeldt-Jakob disease (CJD) after a 1.5-year clinical course. Four and a half years later, his then 55-year-old widow died from CJD after a 1-month illness. Both patients had typical clinical and neuropathologic features of the disease, and pathognomonic proteinase-resistant amyloid protein ("prion" protein, or PrP) was present in both brains. Neither patient had a family history of neurologic disease, and molecular genetic analysis of their PrP genes was normal. No medical, surgical, or dietary antecedent of CJD was identified; therefore, we are left with the unanswerable alternatives of human-to-human transmission or the chance occurrence of sporadic CJD in a husband and wife.
Animals↗
Area agency on aging outreach and assistance for households with older carers of an adult with a developmental disability.
A demonstration project was undertaken in the state of New York to assess how area agencies on aging (AAAs) would approach outreach and direct aid to families caring for someone with a developmental disability. It was found that AAAs organized their outreach and direct-aid efforts using three main approaches: direct operation, contract operations, and multi-organizational. They generally organized staff time so that about two days per week of effort was devoted to undertaking outreach activities, conducting community education, and providing casework and referrals for target families. Four major distinctions were identified that differentiated work with older carers of persons with a developmental disability from that with other kinds of carers: complexity of problems presented by households identified, vagaries of fiscal resources, diverse household composition, and planning for eventualities. It was concluded that targeting AAAs for outreach and providing help to these carers was effective and productive and should be replicated throughout the United States.
Adult↗
The clinical evolution of the 'Dahl Principle'.
The restorative management of patients with localised tooth wear is a major challenge to the dental profession. There is rarely adequate interocclusal space available to place restorations without the need for extensive tooth preparation or the involvement of many unaffected teeth. In 1975, a method was described which created interocclusal space by the use of a partial coverage appliance made of cobalt chromium alloy. The technique reduced the need for more invasive palatal reduction. This paper, with the aid of clinical case examples, highlights the development and evolution of the original removable appliance. However, there remains a need for further clinical studies to evaluate fully these techniques.
Adolescent↗
The use of adhesive metal-ceramic restorations as an alternative to conventional crown and bridge materials.
A compromise is often necessary when choosing the most appropriate material in the construction of crowns and bridges. The most commonly used material is porcelain fused to metal since it is aesthetic and has acceptable physical characteristics to be used in the restoration of both anterior and posterior teeth. Unfortunately, to achieve a predictable and durable result extensive tooth preparation is invariably necessary. More conservative alternatives such as dentine-bonded crowns may have inferior physical characteristics and allow less predictable control over the occlusal contour. This paper describes the construction of fixed restorations which use both lost wax and refractory die techniques in their construction. This results in a restoration which has the combined advantages of both traditional porcelain fused to metal and dentine-bonded crowns and bridges.
Adhesiveness↗
Prolonged prior infection with Chlamydia prevents adverse pregnancy outcome in a murine model.
OBJECTIVE: Our purpose was to compare the rate of adverse pregnancy outcome in pregnant mice with lower genital tract chlamydial infection who had a prior short chlamydial infection versus a prior long-term infection. STUDY DESIGN: A total of 127 female mice were divided into short-term and long-term infection groups. We infected the lower genital tracts with Chlamydia trachomatis. After 7 days in the short-term infection group and 30 days in the long-term infection group, we treated the mice with tetracycline-impregnated chow. After documentation of cure, the mice were mated and transvaginally reinfected with Chlamydia trachomatis. Forty-one of the 127 (32%) mice became pregnant. We noted the number of mice with fetal death and the number of pups present. We cultured the lower uterine segment and the pups for Chlamydia. RESULTS: Seven of 21 (33%) mice in the short-term infection group had fetal deaths compared with 1 of 20 (5%) in the long-term infection group (p < 0.05). In the short-term infection group 21 of 21 (100%) mice had positive transvaginal chlamydial cultures after reinoculation compared with only 7 of 20 (35%) in the long-term infection group (p < 0.000004). Seventeen of 21 (81 %) mice in the short-term infection group had positive chlamydial cultures from the lower uterine segment versus 1 of 20 (5%) in the long-term infection group (p < 0.000001). Sixty-five percent of pups in the short-term infection group and none (0%) of the pups in the long-term infection group were positive for Chlamydia (p < 0.00001). CONCLUSIONS: We conclude that in this murine model a prior 30-day genital tract infection with Chlamydia protects pregnant mice from subsequent reinfection and adverse pregnancy outcomes.
Animals↗
The effect of cocaine on mitogen-induced lymphyocyte proliferation in pregnant women.
Cocaine use during pregnancy is associated with increased risk of sexually transmitted diseases, including syphilis and HIV. Many sociological and economic factors related to cocaine use have been shown to contribute to this increased risk. Cocaine may also affect immunological function thereby increasing risk for sexually transmitted diseases. The objective of this study was to determine if cocaine suppresses mitogen-induced lymphocyte proliferation in pregnant women. Peripheral blood mononuclear cells were obtained from 39 pregnant women. Lymphocyte proliferation was stimulated with concanavalin A (conA, 1 microg/mL). Cocaine was added at time zero to one set of cultures and at 0, 24, and 48 hr to a second set of cultures (to correct for cocaine degradation in culture). Three doses of cocaine were used: 0.1, 1 and 10 microg/mL. The cells were pulsed with 1 microCi 3H thymidine at 72 hr and harvested 19 hr after addition of the isotope. Lymphocyte proliferation, as determined by radioactivity (cpm) was assessed. Cocaine had no statistically significant effect on conA-stimulated lymphocyte proliferation when added at time = 0 or when added daily. Cocaine, in concentrations similar to those found in clinical experiments with drug users, does not suppress in vitro concanavalin A-induced lymphocyte proliferation in cells obtained from pregnant women.
Cell Division↗
A comparison of stainless steel Flexofiles and nickel-titanium NiTiFlex files during the shaping of simulated canals.
The aim of this study was to compare the shaping ability of stainless steel Flexofiles and nickel-titanium NiTiFlex files during the preparation of simulated canals in resin blocks. A total of 80 canals with various angles and position of curvature were prepared by one operator using either Flexofiles or NiTiFlex files in a modified double-flared technique with balanced force method of instrument manipulation. Canal shape was assessed at two stages during the procedure, after apical enlargement to size 30 and subsequently at size 45. Pre- and post-operative images of the canals were taken with a video camera and stored and manipulated in a computer with image analysis software. The presence of canal aberrations and the amount of material removed as a result of preparation were determined from composite images of superimposed pre- and post-operative views. Canal preparation using NiTiFlex files was significantly quicker (P < 0.0001) up to size 30. More instrument failures occurred with Flexofiles (12) compared to NiTiFlex files (7) but there were no statistically significant differences between file type, instrument size or canal shape. Flexofiles created significantly more zips, perforations and ledges; there were no differences in terms of danger zones. Overall, canals prepared with Flexofiles were significantly wider because more material was removed from the outer aspect of the curve at the end-point of preparation and from the inner aspect of the curve at the apex. Under the conditions of this study, preparation with NiTiFlex files was more effective and produced more appropriate canal shapes than Flexofiles.
Analysis of Variance↗
Assessing case records using monitor criteria developed from consensus guidelines.
OBJECTIVE: To develop criteria to enable the monitoring of general practitioner (GP) case records using consensus guidelines for conditions commonly managed in general practice and to measure how well the case records of a non random sample of GPs conformed to these criteria. METHOD: An iterative process was used to develop criteria from consensus guidelines for 19 conditions. Criteria were also developed to enable monitoring of the structure and content of the patient case record. A non random sample of GPs in Adelaide was approached to allow measurement of the content of their case records against these criteria. This measurement was undertaken by allied health professionals. An overall percentage score of conformity with the criteria was created for 10 acute, and six chronic conditions and for the patient case record review. These were rank ordered and Kendall's rank order correlation coefficients were used to compare the results in these three areas of practice. RESULTS: Criteria were successfully developed for each condition. Thirty-one GPs had their patient case records assessed. There was substantial variability between these practitioners in their conformity to the criteria. Kendall's rank order coefficients found statistically significant correlation between the results for acute and chronic conditions, and between acute conditions and the patient case record review section. CONCLUSION: It is feasible to develop criteria that enable measurement of the conformity of GP case records to these criteria. The overall level of conformity, together with the substantial variability found between practitioners suggest that there is a need for GPs to address this area of their practice.
Clinical Competence↗
Wear now? An update on the etiology of tooth wear.
Tooth wear is an ever-increasing problem, and younger patients are particularly at risk. The problem is likely to continue as patients' demands and expectations rise and as more natural teeth are retained into old age. The etiology of tooth wear is reviewed, with emphasis on those factors that appear to be major contributors to the problem at the moment. The clinical appearance of tooth wear is also discussed. It would appear that erosive factors are a significant cause of tooth wear. The prominence of acidic damage of tooth tissue is probably a reflection of society's concern with healthy eating and appearance.
Humans↗
Case report: the advantage of close liaison between primary and secondary health workers in the restorative care of hemi-maxillectomy patients.
The expansion of the maxillofacial speciality outside major teaching hospitals has not been mirrored by a similar expansion in Consultant-led restorative services. This has resulted in general dental practitioners being asked to provide both immediate and long-term restorative support for patients following surgery. Alternatively, the patient may have to travel long-distances to access specialist restorative advice. This paper describes the restorative management of a patient who, ten years after a hemi-maxillectomy, was referred to a Consultant in Restorative Dentistry for care. The treatment provided is detailed and the importance and benefit for the patient of close co-operation between the hospital and the general dental practitioner is highlighted.
Aged↗