Scanning electron-microscopic study of pellicle and plaque formation on tetracyclineimpregnated dentin

Abstract — Previous experiments have shown that tetracyclinecs may react with hydrosyapatite, e.g. in enamel and dentin, without losing their antimicrobial capacity. The present paper examines the pattern of pellicle and plaque formation on doxycycline-treated dentin by the use of scanning electron microscopy (SEM). From newly extracted human teeth were prepared standardized dentin slabs, half of which were soaked in aqueous solutions of doxycycline HC1, 10 mg/ml (pH 2.5) for 10 min. Seven volunteers carried doxycycline-impregnated specimens ligated to the buccal surface of a maxillary molar for 2 h, 8 h, 24 h and 120 h, respectively. Untreated control specimens were ligated to the contralateral teeth. After removal from the oral cavity, the dentin slabs were briefly rinsed in water, allowed to air dry and processed for SEM. SEM assessment of the specimens showed that doxycycline-impregnation resulted in a superficial etching of the dentin, a reduced rate of pellicle formation as well as an impairment of pellicle adhesion, and a retarded bacterial plaque formation on the dentin surfaces.     

A Group-Based Training Programme for General Practitioners: A Norwegian Experience

Westin S, stensen A I, Lvslett K, Prytz J, Telje J, TelstadW and Lie A. A group-based training programme for general practitioners:a Norwegian experience. Family Practice 1988; 5: 244–252. There are approximately 3000 general practitioners in Norway,serving a population of slightly above four million people.A three year postgraduate education scheme for general practitionershas been in effect since 1973, to be replaced by a five yearvocational training programme from January 1985, making generalpractice a fully recognized specialty from that date. The educationalrequirements consist of one year of hospital training, fouryears of training in general practice, and a total of 400 hoursof course education, mainly in clinical subjects. The core elementof the training is attendance at a group-based structured educationalprogramme of two years' duration. This article describes theconcepts and content of this decentralized group-based education,as well as some of the conflicting considerations which eventuallyled to this new Norwegian model of general practice training.The first evaluation studies indicate that the educational programmehas met a long standing need among general practitioners.     

Enhanced Predictive Power of Quantitative TWA during Routine Exercise Testing in the Finnish Cardiovascular Study

Introduction: We examined whether quantification of T-wave alternans (TWA) enhances this parameter's capacity to evaluate the risk for total and cardiovascular mortality and sudden cardiac death (SCD).
Methods and Results: The Finnish Cardiovascular Study (FINCAVAS) enrolled consecutive patients (n = 2,119; 1,342 men and 777 women) with a clinically indicated exercise test with bicycle ergometer. TWA (time domain-modified moving average method) was analyzed from precordial leads, and the results were grouped in increments of 10 μV. Hazard ratios (HR) for total and cardiovascular mortality and SCD were estimated for preexercise, routine exercise, and postexercise stages. Cox regression analysis was performed. During follow-up of 47.1 ± 12.9 months (mean ± standard deviation [SD]), 126 patients died: 62 were cardiovascular deaths, and 33 of these deaths were sudden. During preexercise, TWA ≥ 20 μV predicted the risk for total and cardiovascular mortality (maximum HR >4.4 at 60 μV, P < 0.02 for both). During exercise, HRs of total and cardiovascular mortality were significant when TWA measured ≥50 μV, with 90 μV TWA yielding maximum HRs for total and cardiovascular death of 3.1 (P = 0.03) and 6.4 (P = 0.002), respectively. During postexercise, TWA ≥60 μV indicated risk for total and cardiovascular mortality, with maximum HR of 3.4 at 70 μV (P = 0.01) for cardiovascular mortality. SCD was strongly predicted by TWA levels ≥60 μV during exercise, with maximum HR of 4.6 at 60 μV (P = 0.002), but was not predicted during pre- or postexercise.
Conclusion: Quantification of TWA enhances its capacity for determination of the risk for total and cardiovascular mortality and SCD in low-risk populations. Its prognostic power is superior during exercise compared to preexercise or postexercise.     

Myopotential Inhibition of Unipolar QRS-inhibited (VVI) Pacemakers, Assessed by Ambulatory Holter Monitoring of the Electrocardiogram

Seventy-four patients with unipolar QRS-inhibited pacemakers (VVI) were Holter monitored to assess the occurrence of pacemaker inhibition caused by skeletal muscle potentials during daily activities. Fifty patients had high-grade atrioventricular block and 24 had sinoatrial disease. Chest wall stimulation prior to monitoring revealed asystole of > 4 seconds duration in 22 patients, and ventricular rates between 25 and 56 beats per minute in 52 patients. Fifty-one patients (69%) had one or more episodes of pacemaker inhibition from myopotentials. Inhibition occurred in all types of pacemakers studies, but was most frequent and of longest duration in patients with Siemens-Elema 207/70 (13/14 patients), Cordis Omni-Stanicor (6/7 patients), CPI Microlith (5/6 patients), and Medtronic 5945 (8/10 patients). This was not unexpected considering the filter characteristics of the pacemakers. Nine patients (12%) presented symptoms which might be ascribed to pacemaker inhibition. The longest asystole observed was 3.2 s. Seven patients had pacemakers spikes falling on or near T-waves of spontaneous heart beats because their pacemakers had been rendered refractory by myopotentials. No serious arrhythmias were seen during episodes of pacemaker inhibition or interference. More emphasis should be put on the improvement of filter characteristics of unipolar VVI-pacemakers. Pacemaker patients with symptoms of myopotential inhibition should be equipped with either a bipolar or ventricular triggered (VVT) pacemaker or with a sensitivity and/or pacing mode programmable pacemaker.     

Pulse Width Dependent Increase in the Pacemaker Automatic Interval

From a total of 51 patients equipped with rate and pulse width adjustable pulse gen erators (Microlith-P 0505, Microthin-PI 0522) implanted over the last 3 years, 10 (19.6%) showed an un expected drop in pacemaker pulse rate during pulse width programming. For one of the pulse gen erators used (Microthin-PI 0522), unexpected rate decrease occurred in 7/13 cases (53.8%). For all ex cept one patient, decrease in pacemaker pulse rate corresponded with the total refractory period of the pulse generator (320 ms), at a certain pulse width when rate drop first occurred. In seven of the patients the pulse generator automatic interval was extended from 13 ms to 171 ms beyond the re fractory period. In two patients it was necessary to replace the pulse generators. Our study strongly proves that this abnormal pacemaker functioning is a result of sensing of the polarization voltage at the pacemaker electrode/tissue interface and/or the T-wave. The polarization voltage is highly dependent on the total pacemaker electrode/tissue interface impedance. Using typical values for pulse genera tor output and input resistance and output capacitance, Faraday resistance, Helmholtz capacitance and tissue resistance at the electrode/tissue interface it was shown mathematically that in some cases the polarization voltage alone would be of sufficient amplitude and slew rate for pacemaker inhibi tion. The study demonstrates an urgent need for change in the filter characteristics by making the pulse generators less sensitive in the low frequency region and reducing the polarization voltage by reducing the output circuit capacitance. (PACE, Vol. 5, May-June, 1982)     

Insomnia and long sleep duration are risk factors for later work disability. The Hordaland Health Study

Both insomnia and sleep duration have previously been linked with a range of adverse outcomes, but no studies have explored their relative effect on subsequent work disability. The aim of the present study was to investigate the contribution of insomnia versus sleep duration to later long-term work disability. Using a historical cohort design with 4-year follow-up, data on insomnia, sleep duration and potential confounders were gathered from 6599 working persons (40–45 years). The outcome was award of disability pension, as registered in the National Insurance Administration. After controlling for baseline exposure to disability and sick leave, insomnia was a strong predictor of permanent work disability [odds ratio (OR) = 4.56], and this effect remained significant after controlling for sleep duration, as well as for other possible confounders (OR = 1.88). Short sleep duration was not significantly associated with subsequent work disability, while long sleep duration (>8.5 h) did predict work disability (OR = 2.96), also in the fully adjusted model (OR = 2.14).The present study demonstrates that both insomnia and long sleep duration are strong and independent risk factors for subsequent work disability.     

Functional Response to Cardiac Resynchronization Therapy is Associated with Improved Clinical Outcome and Absence of Appropriate Shocks

Clinical Outcome in Cardiac Resynchronization Therapy (CRT) Functional Responders . Introduction : We evaluated clinical outcome and incidence of (in)appropriate shocks in consecutive chronic heart failure (CHF) patients treated with CRT with a defibrillator (CRT‐D) according to functional response status. Furthermore, we investigated which factors predict such functional response. Methods and Results : In a large teaching hospital, 179 consecutive CHF patients received CRT‐D in 2005–2010. Patients were considered functional responders if left ventricular ejection fraction (LVEF) increased to ≥35% postimplantation. Analysis was performed on 142 patients, who had CRT‐D as primary prevention, complete data and a baseline LVEF <35%. Endpoints consisted of all‐cause mortality, heart failure (HF) hospitalizations, appropriate shocks and inappropriate shocks. Median follow‐up was 3.0 years (interquartile range [IQR] 1.6–4.4) and median baseline LVEF was 20% (IQR 18–25%). The functional response‐group consisted of 42 patients. In this group no patients died, none were hospitalized for HF, none received appropriate shocks and 3 patients (7.1%) received ≥1 inappropriate shocks. In comparison, the functional nonresponse group consisted of 100 patients, of whom 22 (22%) died (P = 0.003), 17 (17%) were hospitalized for HF (P = 0.007), 17 (17%) had ≥1 appropriate shocks (P = 0.003) and 8 (8.1%) received ≥1 inappropriate shocks (P = 0.78). Multivariable analysis showed that left bundle branch block (LBBB), QRS duration ≥150 milliseconds and no need for diuretics at baseline are independent predictors of functional response. Conclusion : Functional responders to CRT have a good prognosis and rarely need ICD therapy. LBBB, QRS duration ≥150 milliseconds and lack of chronic diuretic use predict functional response. (J Cardiovasc Electrophysiol, Vol. 24, pp. 316‐322, March 2013)