Flexural and fatigue strengths of root canal posts

Abstract – This study measured the flexural and fatigue strengths of root canal posts of different alloy, design, and diameter. Fixed posts were loaded up to a preset force and the number of loadings endured until fracture was recorded at each loading force. The flexural strength was defined as the maximum force a post could endure before fracture when loaded once. The fatigue strength was determined as the maximum force a post could endure when loaded 10000 times. Both modes of strength were found to increase with increasing diameter. Aluminum posts had lower flexural and fatigue strengths than posts of titanium, stainless steel, and a Ag-Pd alloy, all of which had strength values of about the same magnitude. Among the investigated brands, Triax and Radix were stronger than the others at comparable diameters. The high strength of Triax may be explained by the design of the post, whereas a superior alloy may account for the high strength of Radix.     

Level of purposeful hand function as a marker of clinical severity in Rett syndrome

Aim We investigated relationships between hand function and genotype and aspects of phenotype in Rett syndrome. Method Video assessment in naturalistic settings was supplemented by parent‐reported data in a cross‐sectional study of 144 females with a mean age of 14 years 10 months (SD 7y 10mo; range 2y–31y 10mo), 110 of whom had a mutation of the methyl CpG binding protein 2 (MECP2) gene. Ordinal logistic regression was used to assess relationships between hand function and MECP2 mutation, age, a modified Kerr score, Functional Independence Measure for Children (WeeFIM), ambulation level, and frequency of hand stereotypies. Results Approximately two‐thirds of participants demonstrated purposeful hand function, ranging from simple grasping skills to picking up and manipulating small objects. In participants with a confirmed MECP2 mutation, those with the p.R168X mutation had the poorest hand function on multivariate analysis with C‐terminal deletion as the baseline (odds ratio [OR] 0.19; 95% confidence interval [CI] 0.04–0.95), whereas those with the p.R133C or p.R294X mutation had better hand function. Participants aged 19 years or older had lower hand function than those aged less than 8 years (OR 0.36; 95% CI 0.14–0.92). Factors that were associated with better hand function were lower Kerr scores for a 1‐point increase in score (OR 0.77; 95% CI 0.69–0.86), higher WeeFIM scores for a 1‐point increase in score (OR 1.08; 95% CI 1.04–1.12), and greater ambulation than those completely dependent on carers for mobility (OR 22.64; 95% CI 7.02–73.08). The results for participants with a confirmed pathogenic mutation were similar to results obtained when participants without a mutation were also included. Interpretation Our novel assessment of hand function in Rett syndrome correlated well with known profiles of common MECP2 mutations and overall clinical severity. This promising assessment could measure clinical responses to therapy.     

Delayed pressure urticaria, objective evaluation of a variable disease using a dermographometer and assessment of treatment using colchicine

A randomized double-blind placebo controlled trial of colchicine in the treatment of 13 patients with delayed pressure urticaria enabled us to assess some of the variables in this disorder. We have modified a previously described method of pressure testing using a calibrated dermographometer and shown a pressure induced papular dose response curve. Assessment of disease activity was based on the number of pressure weals which occurred, the size of delayed pressure induced papules using a dermographometer calibrated at 9.75 x 10(5) pascals for five separate time periods on the back and estimations of erythrocyte sedimentation rate and the acute phase protein levels. We have been unable to show a therapeutic effect using colchicine 0.5 mg bd for I week.     

Clinical Characteristics and Aetiological Classification of Insulin-dependent Diabetes in the Elderly

In a prospective study of 195 newly-diagnosed diabetic patientsaged 65 years or over, 80 (41.0 per cent) were treated initiallyby diet, 89 (45.6 per cent) by diet and oral hypoglycaemic agents,and 26 (13.3 per cent) by diet and insulin. Fifteen patients(7.7 per cent) died within a year of diagnosis. Of 26 patients treated with insulin, six died in the first year,14 were successfully transferred to diet and oral agent treatmentand six continued on insulin - two of whom failed a trial oforal agents, two showed only a temporary response and two receivedno trial. A further nine patients were taking insulin 12 monthsafter diagnosis because of no response (eight patients) or atransient response (one patient) only to oral agents. Age, percentage ideal body weight, history of acute onset, bloodglucose, glycosylated haemoglobin, and random C-peptide concentrationat diagnosis did not discriminate between patients requiringinsulin at 12 months and those successfully treated withoutinsulin. Patients who were insulin-dependent 12 months afterdiagnosis had an increased frequency of ketonuria at diagnosisand a previous medical history of endocrine disease. In insulin-dependent patients there was an increased frequencyof HLA DR3 but not DR4 and an increased frequency of thyroidmicrosomal and gastric parietal cell antibodies but not isletcell antibodies. It is concluded that elderly newly-diagnosed diabetic patientswho are treated at diagnosis with insulin are not necessarilyinsulin dependent and can be given a trial of oral agents withsafety. Elderly patients who are insulin-dependent within 12months of diagnosis have an increased frequency of HLA DR3 similarto young type 1 (insulin-dependent) diabetic patients but thereis no increased frequency of islet cell antibodies in this agegroup.     

Short-term decrease of skin-test sensitivity after rush desensitization in Hymenoptera venom hypersensitivity

Thirty-seven patients with a history of systemic anaphylactic stings were desensitized by the rush method. Patients were evaluated by skin testing twice, before and 6 weeks after desensitization. An additional control group of 10 patients, not yet desensitized, were tested for skin test technique reproducibility at 6-week intervals. Results were compared with IgE and IgG antibody levels, and with platelet reactivity towards specific Hymenoptera venom. Before desensitization, the maximum skin-test sensitivity was observed at 10(-5) micrograms venom/ml in 56% of patients and decreased to 10(-1) micrograms venom/ml after desensitization (48.6% of patients). Decrease of cutaneous tests was observed in 28/37 patients (75%) (P less than 0.001) and was not associated with significant variations of specific IgE or IgG antibody levels, but was correlated with the decrease of platelet reactivity (P less than 0.05). Conversely, variations of skin-test sensitivity in the control group was not significant.     

EFFECT OF GLUCOSE CONCENTRATION ON THE INTRATHECAL SPREAD OF 0.5% BUPIVACAINE

We have studied the effects of intrathecal injection of 0.5%bupivacaine in solutions containing different concentrationsof glucose (0.33%, 0.83% and 8%) in three groups of 10 patients.The mean maximum extent of sensory block was significantly higherwith 8% glucose (T3.6) than with 0.83% glucose (T7.2) or 0.33%glucose (T9.5). Administration of solutions containing 0.33%glucose produced a greater variability in upper level of sensoryblock (11 dermatomes) than the two other concentrations (sixdermatomes each). The rate of onset of sensory block to T12was fastest with solutions containing 8% glucose. Complete motorblock of the legs was produced in every patient. ^*Department of Anaesthetics, Ninewells Hospital & MedicalSchool, Dundee DD1 9SY     

Glucosyltransferase activity in human in vivo formed enamel pellicle and in whole saliva

Abstract – Two hour in vivo formed enamel pellicle samples and paraffin wax-stimulated saliva samples were collected from 10 volunteers for analyses of glucosyltransferase activity (GTF). GTF activity was recorded by monitoring incorporation of radioactivity from ¹⁴C-glucose labeled sucrose into glucan. Pellicle and saliva samples from all 10 subjects demonstrated GTF activity. The GTF activity in the pellicle samples was highest in subjects, with high GTF activity-producing adhesive glucan in saliva.     

Cesarean Section Prophylaxis: Comparison of Two Doses With Three Doses of Mezlocillin

ABSTRACT: A prospective randomized double-blind comparison of two doses, with three doses of mezlocillin for nonelective cesarean section prophylaxis was performed. One hundred seven (107) patients were evaluated. Mezlocillin (4 g) was given post-cord clamping and then at 4-h intervals for a total of two doses or three doses. The incidence of febrile morbidity was lower in the three-dose group (2 of 46, 4%) than the two-dose group (14 of 61, 23%) (P<0.02). However, the incidence of infectious morbidity was not different between the three-dose group (3 of 46, 7%) and the two-dose group (10 of 61, 16%), and the incidence of endomyometritis was similar in the two groups (6.5% vs 9.8%). Among failures of prophylaxis there were no differences compared to successes in the number of potential commensals or potential pathogens cultured from amniotic fluid. However, the proportion of failures among patients with both commensals and potential pathogens isolated (10/58) was significantly greater than among patients with none or only commensals isolated (1/37) (P<0.03). We found mezlocillin to be an effective agent for perioperative cesarean section prophylaxis with two doses as effective as three doses. The presence of clinically important organisms in the amniotic fluid at the time of operation typified patients with postoperative infectious complications despite perioperative prophylaxis.     

The Impact of Pulse Generator Longevity on the Long-Term Costs of Cardiac Pacing

The long-term costs of cardiac pacing include the device costs, the procedural costs, the follow-up costs, and the replacement costs. At present, there is significant variability in the efficiencies of the integrated circuits and the total battery capacity among different pulse generators that will influence replacement rates over time. Accordingly, we compared the influence of pulse generator longevity on the long-term costs of pacing. The longevity of pulse generators was calculated based on the electrical characteristics of the device and the percentage of time the patient is paced. Replacement rates of pulse generators were estimated for our patient population over a 20-year period, based on patient survival and pulse generator longevity. The costs of pacing over this 20-year follow-up period were then calculated. The longevity of DDDR devices presently implanted in the United States ranges from 8–14 years, assuming that patients are paced 50% of the time. Replacement rates in this population over a 20-year follow-up period were calculated to range from 0.34–0.66, and the total costs of pacing would range from $11,898–14,900 per patient. The longevity of SSIR devices ranges from 7–20 years, assuming that patients are paced 50% of the time. Replacement rates were calculated over the 20-year follow-up period to range from 0.20–0.84, and the total costs of VVIR pacing would range from $8,331–13,286. Based on the proportion of pulse generator models implanted in patients in the United States, the maximum cost differential to the health care system is approximately $424 million/year comparing the devices with the shortest and greatest longevities. Thus, pulse generator longevity may significantly influence the long-term costs of pacing. Patient survival and pulse generator system longevity should be considered when selecting the appropriate pacing system for the individual patient.