Alveolar bone development after decoronation of ankylosed teeth

Decoronation of ankylosed teeth in infraposition was introduced in 1984 by Malmgren and co‐workers ( 1 ). This method is used all over the world today. It has been clinically shown that the procedure preserves the alveolar width and rebuilds lost vertical bone of the alveolar ridge in growing individuals. The biological explanation is that the decoronated root serves as a matrix for new bone development during resorption of the root and that the lost vertical alveolar bone is rebuilt during eruption of adjacent teeth. First a new periosteum is formed over the decoronated root, allowing vertical alveolar growth. Then the interdental fibers that have been severed by the decoronation procedure are reorganized between adjacent teeth. The continued eruption of these teeth mediates marginal bone apposition via the dental‐periosteal fiber complex. The erupting teeth are linked with the periosteum covering the top of the alveolar socket and indirectly via the alveolar gingival fibers, which are inserted in the alveolar crest and in the lamina propria of the interdental papilla. Both structures can generate a traction force resulting in bone apposition on top of the alveolar crest. This theoretical biological explanation is based on known anatomical features, known eruption processes and clinical observations.     

Real‐World Data on the Lifespan of Implantable Cardioverter‐Defibrillators Depending on Manufacturers and the Amount of Ventricular Pacing

Real‐World Data on the Lifespan of ICDs Introduction: Implantable cardioverter‐defibrillator (ICD) longevity is crucial for both patients and public health systems because it determines the number of surgical ICD replacements, which can generally be considered an additional risk factor for complications, and the cost‐effectiveness of ICD therapy. Our objective was to obtain insight into the “real‐world” longevities of implantable cardioverter‐defibrillators, which quite often differ from those stated in the manufacturers’ declarations. Methods and Results: On the basis of a prospective database, we analyzed all ICD implantations performed in our hospital from June 1988 to June 2009. We studied 980 patients (follow‐up 58 ± 51 months) with 1,502 ICDs and all respective data until August 2010. We compared the percentage of still operating ICDs at different points in time in relation to manufacturers, types of device (single chamber 623, dual chamber 588, cardiac resynchronization therapy ICDs [CRT‐D] 291), and amount of right ventricular pacing (VP). We found distinct differences between the mean lifespans of ICDs of different manufacturers (Biotronik 4.3 years, Sorin 4.5 years, Guidant/Boston Scientific 4.7 years, St. Jude Medical 5 years, Medtronic 5.8 years). CRT‐D devices (hazard ratio [HR] 1.778, P = 0.0005) were associated with an elevated annual relative risk for device replacement while a decrease in the proportion of VP (HR 0.934 for each 10% decrease in VP, P < 0.0001) and Medtronic ICDs were associated with a reduced risk of device replacement (HR 0.544, P < 0.0001). Conclusion: CRT‐Ds and an elevated percentage of VP are associated with a significantly elevated risk for device replacement, while Medtronic ICDs showed the longest lifespans. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1336‐1342, December 2012)     

Assessment of Intersignal Variability for Discrimination of Atrial Fibrillation from Atrial Flutter

The analysis of endocardial signals obtained from an electrode located in the right atrium enabled by new dual chamber implantable cardioverter defibrillators may be helpful to provide additional therapies such as overdrive pacing or low energy atrial cardioversion for the treatment of concomitant atrial flutter (AFL) or atrial fibrillation (AF). Algorithms for discrimination of atrial tachyarrhythmias based on rate counting are of limited efficacy. The aim of this study was to assess the intersignal variability by using fast discrete wavelet transforms (FDWT) as a new method of discrimination of AF from AFL. Patients with spontaneous episodes of AF/AFL or patients who developed AF/AFL during an electrophysiological study were studied. The endocardial signals were recorded from the high right atrium using a transvenous 5 Fr bipolar electrode catheter (interelectrode spacing: 1 cm). The signals were digitized (2 kHz, 12-bit resolution) after amplification and filtering (40–500 Hz). Within data segments of 10-second duration, 25 consecutive signals were selected and normalized and FDWT was applied. Standard deviations of the wavelet coefficients (SD) from coarse scales (scale 4–8) were calculated. A total of 94 data segments (AF: 52, AFL: 42) from 28 patients were analyzed. SD at each considered scale was higher for AF than for AFL (P < 0.001). SD at scale 8 discriminated between AF from AFL with 100% sensitivity and specificity. We conclude that assessment of intersignal variability of bipolar endocardial recordings using FDWT is an effective method for the discrimination of AF from AFL. The implementation of this tool in a discrimination algorithm of an implantable device may help provide the appropriate differential therapy for atrial tachyarrhythmias.     

Sarcoidosis causes abnormal seasonal variation in 1,25-dihydroxy-cholecalciferol

Bonnema SJ, Møller J, Marving J, Kvetny J (Departments of Internal Medicine and Clinical Physiology and Nuclear Medicine, Esbjerg Centralsygehus, Esbjerg, Denmark). Sarcoidosis causes abnormal seasonal variation in 1,25-dihydroxy-cholecalciferol. J Intern Med 1996; 239 : 393–98. Objectives. The spontaneous seasonal variations in the calcium regulating hormones 1,25-dihydroxy-cholecalciferol (1,25-DHCC) and parathyroid hormone (PTH) were investigated in patients with sarcoidosis. Design. Controlled, prospective observational study with measurements in the winter and summer seasons, respectively. Subjects. Twelve patients (age: median 33, range 21–54 years) with biopsy-verified (n=8) sarcoidosis were included as well as 11 age-matched healthy control subjects. Main outcome measures. Serum values of calcium, ionized calcium, phosphate, chloride, bicarbonate, creatinine, albumin, angiotensin-converting enzyme, alkaline phosphatase, 1,25-DHCC, and PTH. Also, 24-h whole-body retention of 99mTc methylene-diphosphonate was assessed. Results. The patient group showed an increased level of 1,25-DHCC in the summer season (w:146±67, s:198±73 pmol L^-1; P<0.01) in contrast to the opposite finding among controls (w:161±34, s:144±43 pmol L^-1; P<0.05). Comparing the individual seasonal changes between the two groups, the difference was marked (P<0.001). Compared with controls, total serum calcium was elevated in the summer season in the patient group (P<0.05), in which the same parameter correlated positively with 1,25-DHCC (r=0.658; P<0.01). PTH was increased two to three times above the control values throughout the year (patients: w:0.37±0.13, s:0.24±0.08 μg L^-1; controls: w:0.14±0.09, s:0.10±0.04 μg L^-1; P<0.001); although, the level of this hormone was still found within the reference interval. 24-h whole body bone scintigraphy failed to show any seasonal variation in bone metabolism. In contrast, serum alkaline phosphatase was found to be increased during the summer season compared with the control group (P<0.001). Angiotensin-converting enzyme showed no seasonal variation. Conclusions. In sarcoidosis, 1,25-DHCC is abnormally regulated throughout the year, with a significantly higher serum level in the summer season. Uncontrolled production of 1,25-DHCC in sarcoid pulmonary alveolary macrophages is possibly responsible for hypercalcaemic episodes, and this parameter should be used as a marker of disease activity.     

Ventilatory strategy in catastrophic lung disease. Inversed ratio ventilation (IRV) and combined high frequency ventilation (CHFV)

In 105 patients with well-defined catastrophic lung disease, in whom conventional settings were unable to maintain life-sustaining gas exchange, the ventilatory strategy was changed from volume-controlled ventilation with an inspiratory-expiratory ratio (I:E) of 1:2 and PEEP of 15–20 cm H₂O to pressure-controlled inverse ratio ventilation with an I:E of 2:1, 3:1 or 4:1 and a set PEEP of 4–8 cm H₂O. All patients were ventilated on a Servo 900 B or C ventilator, the primary goal being to decrease the F1O₂ below 0.6 and the peak pressure to below 50 cm H₂O, while maintaining a Pao₂ of 8.00 kPa and a Paco₂ within 10% of the upper limit of normal. In 67 patients the intervention was successful and peak pressure could be reduced to a median of 44 cm H₂O (range 37–50). Fio₂ could be reduced to a median of 0.50 (range 0.40-0.60). The auto-PEEP effect of IRV increased to a median of 12 cm H₂O (range 7–22). No consistent pattern of change in cardiac output was observed. Sixty patients survived more than 3 weeks and 48 were discharged from hospital. The 38 IRV "failures" were changed to pressure-controlled ventilation with superimposed high frequency ventilation (CHFV). In 30 cases the Fio₂ could be reduced to a median of 0.60 (range 0.50-0.60) and peak pressures to a median of 50 cm H₂O (range 45–60). In 21 patients the Paco₂ increased. Auto-PEEP with CHFV had a median value of 15 cm H₂O (range 10–25). Only 12 patients survived more than 3 weeks and only four were discharged. It is concluded that changing the ventilatory strategy to IRV or CHFV can improve gas-exchange and might alter the outcome in catastrophic lung disease.     

Extracellular polysaccharides of smooth and rough variants of Streptococcus salivarius

Abstract – Some, but not all strains of Streptococcus salivarius were demonstrated to occur in smooth (S) and rough (R) variants, growing in distinctly different colonies on sucrose-containing agar plates. Sucrosederived extracellular polysaccharides (EP) of NCTC 8666, ATCC9759S and R, ATCC13419S and R, IAS And R, and Tove S and R were isolated, puridied, and chemically studied. Extracellular enzymes of R variants yielded more water-insoluble than soluble material, while the opposite was true for 8 variants. The insoluble material consisted mainly of glucan, the soluble mainly of levan. Enzymatic hydrolysis suggested a predominance of α-1, 3linkages in the water-insoluble glucan. Cell-associated enzymes gave rise to cell-associated and -free EP. The cell-associated EP of sS variants was insoluble, while that of R variants contained water-insoluble glucan and water-soluble fructan. Cells coated with cell-associated EP flocculated due to interaction of the Ep, mainly by hydrogen bonding, in part by divalent cation bridging. The sucrose-derived EP gave rise to plaque deposit formation in sucrose broth cultures, S variant deposits being thin and firmly adherent to glass, R variant deposits being thick, rough, coherent, but only weakly adherent. The variant types were not altered by the curing agents ethidium bromide and acridine orange.     

Differences in renal and submaxillary renin release after stimulation with isoprenaline and noradrenaline

It is confirmed that while noradrenaline stimulates release of submaxillary as well as renal renin, isoprenaline only stimulates renal renin release. The effects of these two adrenergic agonists differ in several other ways. The kidneys respond to isoprenaline with a dose dependant renin release. As a contrast the submaxillary glands respond to noradrenaline by no or by non-dose-dependant release. After single doses of the agonists the isoprenaline induced renin release is of short duration, contrasting with a prolonged renin release after injection of noradrenaline. The kidneys are able to respond to repeated doses of both agonists, while the submaxillary glands most often only respond to the first dose. While the effect of noradrenaline is blocked by pretreatment with phenoxybenzamine, this blocker is without effect when given after noradrenaline. The two agonists do not provoke any increase in plasma renin in mice which have been both sialoadenectomized and nephrectomized.