Anterior tooth autotransplantation: a case series.

Tooth autotransplantation is the technique of transplanting embedded, impacted or erupted teeth from one site into another in the same individual. It is relatively common for the anterior segment of the mouth to be affected by traumatic tooth injuries, impacted and/or congenitally missing permanent teeth. Autotransplantation of teeth into the anterior dental arch can provide unrivalled biological solutions when such issues arise in this critical aesthetic zone, particularly for adolescent patients. The combination of meticulous pre-surgical assessment, synergistic interdisciplinary collaboration and carefully performed anterior tooth autotransplantation has been demonstrated to achieve impressive outcomes, with respect to both transplant survival and clinical success. © 2023 Australian Dental Association.

Posterior tooth autotransplantation: a case series.

Tooth autotransplantation is the technique of transplanting embedded, impacted or erupted teeth from one site into another in the same individual. Autotransplantation can provide a long-term, cost-effective and biological solution for adolescent patients with congenitally missing teeth or significantly compromised teeth when a suitable donor tooth is available. Successful autotransplantation of immature teeth can offer many advantages for a growing patient, including a normally functioning periodontium, proprioception and preservation of alveolar bone volume. Even in the event that an autotransplanted tooth does eventually fail, the bone and soft tissue conditions are likely to be conducive for subsequent implant treatment. Despite the significant physiological and cost-benefit advantages, tooth autotransplantation remains relatively underutilized, as the procedure is considered to be technique-sensitive. Although carefully considered individual case selection and surgical skill are the critical determinants for success, advances in three-dimensional computed tomography and rapid prototyping have the potential to simultaneously reduce the technique sensitivity and increase the predictability of the autotransplantation procedure. It is hoped that this case series will provide greater awareness and an appreciation of the tremendous value of autotransplantation for the management of patients with congenitally missing or significantly compromised posterior teeth.

APOBEC-1 dependent cytidine to uridine editing of apolipoprotein B RNA in yeast.

Cytidine to uridine editing of apolipoprotein B (apoB) mRNA requires the cytidine deaminase APOBEC-1 as well as a tripartite sequence motif flanking a target cytidine in apoB mRNA and an undefined number of auxiliary proteins that mediate RNA recognition and determine site-specific editing. Yeast engineered to express APOBEC-1 and apoB mRNA supported editing under conditions of late log phase growth and stationary phase. The cis -acting sequence requirements and the intracellular distribution of APOBEC-1 in yeast were similar to those described in mammalian cells. These findings suggest that auxiliary protein functions necessary for the assembly of editing complexes, or 'editosomes', are expressed in yeast and that the distribution of editing activity is to the cell nucleus.

Identification of the yeast cytidine deaminase CDD1 as an orphan C-->U RNA editase.

Yeast co-expressing rat APOBEC-1 and a fragment of human apolipoprotein B (apoB) mRNA assembled functional editosomes and deaminated C6666 to U in a mooring sequence-dependent fashion. The occurrence of APOBEC-1-complementing proteins suggested a naturally occurring mRNA editing mechanism in yeast. Previously, a hidden Markov model identified seven yeast genes encoding proteins possessing putative zinc-dependent deaminase motifs. Here, only CDD1, a cytidine deaminase, is shown to have the capacity to carry out C-->U editing on a reporter mRNA. This is only the second report of a cytidine deaminase that can use mRNA as a substrate. CDD1-dependent editing was growth phase regulated and demonstrated mooring sequence-dependent editing activity. Candidate yeast mRNA substrates were identified based on their homology with the mooring sequence-containing tripartite motif at the editing site of apoB mRNA and their ability to be edited by ectopically expressed APOBEC-1. Naturally occurring yeast mRNAs edited to a significant extent by CDD1 were, however, not detected. We propose that CDD1 be designated an orphan C-->U editase until its native RNA substrate, if any, can be identified and that it be added to the CDAR (cytidine deaminase acting on RNA) family of editing enzymes.

Autotransplantation: a viable treatment option for adolescent patients with significantly compromised teeth.

Autotransplantation is the technique of transplanting embedded, impacted or erupted teeth from one site into another in the same individual. Despite current scientific evidence indicating that autotransplantation has favourable long-term survival rates, autotransplantation is still not generally regarded as mainstream practice outside of Scandinavian countries. Successful autotransplantation can offer many advantages in a growing patient, including a normally functioning periodontium, proprioception and preservation of alveolar bone volume. In the event that the autotransplantation eventually fails, the bone and soft tissue conditions would still be likely to be favourable for subsequent implant treatment. This review article will identify and discuss the factors that influence case selection, the ideal timing for autotransplantation and the critical determinants for achieving a successful outcome. The limitations of the technique and alternative treatment options will also be discussed. It is hoped that through greater awareness and recognition by the dental profession, autotransplantation will become another viable treatment option in the management of compromised teeth in patients with significant remaining growth potential.

mRNA degradation by processive 3'-5' exoribonucleases in vitro and the implications for prokaryotic mRNA decay in vivo.

Two 3'-5' exoribonucleases, polynucleotide phosphorylase and ribonuclease II play a central role in the degradation of bacterial mRNA to ribonucleotides. Sequences with the potential to form stem-loop structures can stabilize upstream mRNA against 3'-5' exoribonucleolytic attack in vivo by blocking the processive activities of these enzymes. For many mRNA species stem-loop structures appear to provide a very efficient block to decay from the 3' end, such that the rate-determining step for mRNA decay occurs elsewhere in the transcript. We have examined the stalling of 3'-5' exoribonucleases at stem-loop structures in vitro. Although stem-loop structures alone can impede the progress of both enzymes, the duration of stalling at these structures in vitro is insufficient to account for the increased half-lives that they confer on mRNA in vivo. These data suggest that an additional factor, such as a stem-loop binding protein, is required for stabilization of mRNA by stem-loop structures in vivo. The implications for the regulation of mRNA stability are discussed.

Effect of fluocarbon exchange transfusion on myocardial infarction size in dogs.

Fluosol DA (20%), a perfluocarbon with high oxygen solubility, was administered by concurrent exchange transfusion (30 ml/kg) to anesthetized open-chested adult greyhounds (n = 9) 1 hour after left anterior descending coronary ligation. Mechanical ventilation using 100% oxygen was used throughout the experiment. A second similar group (n = 9) received 0.9% normal saline solution (30 ml/kg), and a third group (n = 9) received no further intervention. Systemic, right atrial, and left atrial pressures were not altered by the exchange transfusion. Monastryl blue dye was injected through the left atrial line at 6 hours after ligation to define the area of myocardium at risk (AR); the animals were then killed and the heart was excised. The left ventricle was sliced at 5 mm intervals and stained using triphenyltetrazolium chloride, defining areas of necrosis (AN). The ratio of AN/AR and total left ventricular mass were then compared with the use of planimetry. The results were as follows: the AN/AR ratio in the 9 control animals was 90 +/- 2 (mean +/- standard error of the mean); in the 9 animals who received saline solution it was 88 +/- 2; and in the animals who received Fluosol it was 67 +/- 4 (p less than 0.01 compared with control; p less than 0.001 compared with the saline group). Fluocarbon exchange transfusion may reduce infarct size when administered after coronary occlusion.

Hemodynamic, metabolic, and morphological effects of cardiopulmonary bypass with a fluorocarbon priming solution.

Systemic perfusion, myocardial contractility, and morphological changes during and after cardiopulmonary bypass (CPB) were investigated in 22 greyhounds; Fluosol-DA 20% (FDA) and normal saline (NaCl) were compared as priming solutions for hypothermic (25 degrees C) CPB. Hemodynamic and oxygenation indices were similar in all groups. Animals with fluorocarbon primes had higher serum lactate concentrations (mean +/- standard error of the mean [SEM]) during CPB (NaCl 1.64 +/- 0.2, FDA 2.39 +/- 0.3, p less than 0.01), representing an increase over the control of 12% and 319% in the NaCl and FDA groups, respectively. After CPB, serum lactate concentration remained elevated in the FDA group, but it returned to the level of the control in the NaCl group (NaCl 1.49 +/- 0.5, FDA 2.29 +/- 1.1, p less than 0.01); increases over the control level were 7% and 302% in the NaCl and FDA groups, respectively. Myocardial contractility after CPB, expressed as dP/dt[40], was similar in the two experimental groups. Three weeks after CPB, a histological examination by light microscopy of multiple organs obtained from a separate group of 12 animals treated similarly was performed, demonstrating no significant morphological differences between animals primed with fluorocarbon or with saline. The results suggest that FDA is a satisfactory priming agent for hypothermic CPB. It adequately preserves myocardial function and causes no adverse morphological changes, but a persistent, as yet unexplained, elevation in serum lactate concentration occurs.

Inotropic response of the salvaged myocardium after acute coronary occlusion.

We determined the response of the reperfused myocardium to inotropic stimulation with dobutamine hydrochloride. The middle part of the left anterior descending coronary artery (LAD) was occluded in 15 greyhounds for 3 hours. Group 1 (N = 8) was reperfused for 3 hours in the beating, working heart. Group 2 (N = 7) was put on cardiopulmonary bypass (CPB) for 1 hour, received 500 ml of potassium cardioplegia in the aortic root and in the area of ischemia through an internal mammary-LAD graft, and the LAD was reperfused off CPB for 3 hours. After 3 hours of reperfusion, dobutamine was given at 10 micrograms/kg/min for 20 minutes. Regional myocardial function was determined with subendocardial ultrasonic crystals in the area of ischemia and in the base of the heart; segmental contractility was determined from the ratio of peak left ventricular pressure to end-systolic segment length; and global contractility was determined by the slope of the ventricular pressure wave at a developed pressure of 40 mm Hg. Measurements were made prior to LAD occlusion (control), at the end of 3 hours of reperfusion (6 hours from the beginning of occlusion), and after 20 minutes of dobutamine infusion. Dobutamine infusion improved segmental function in all animals compared with 3 hours of reperfusion. The study shows that the reperfused myocardium responds favorably to inotropic stimulation after 3 hours of occlusion and 3 hours of reperfusion, and that the contractile response both to reperfusion and to inotropic stimulation is greatly affected by the method of reperfusion.

Main effects of sleep disorders related to shift work-opportunities for preventive programs.

The sleep-related problems of shift workers usually occur as transient phenomena related to the timing of work. Sleep disorders, related to sleep deprivation, have a major impact on the quality of life and health status of healthcare workers. Reduced quantity and quality of sleep negatively affects the activities of shift workers, particularly in terms of their social functioning, quality of life and health. However, it seems that health authorities and the medical staff are negligent when it comes to the negative effects on health caused by work in night shifts. Recently published studies in this field suggest that appropriate public health preventive programs dealing with sleep disorders successfully contribute towards the quality of life of workers.

Augmentation of venous return by adrenergic agonists during spinal anesthesia.

To test the effectiveness of adrenergic agonists in correcting the vascular sequelae of spinal anesthesia, we used venous reservoir volume (RV) and mean arterial pressure (MAP) as indices of the changes in venous capacitance and arterial resistance produced by adrenergic agonists in dogs anesthetized with pentobarbital and undergoing cardiopulmonary bypass (CPB). A CPB-based technique was chosen both to prevent drug and reflex effects on the heart from influencing the results and to provide a convenient means by which to monitor venous capacitance. Total spinal anesthesia significantly decreased both RV and MAP relative to steady-state CPB values. Return of these hemodynamic alterations to baseline was attempted using pure alpha- and beta-adrenergic agonists, and a mixed adrenergic agonist (phenylephrine, isoproterenol, and ephedrine, respectively). Isoproterenol increased RV, but further decreased MAP. Phenylephrine increased MAP but not RV. Ephedrine increased both MAP and RV. We conclude that a mixed adrenergic agonist such as ephedrine more ideally corrects the noncardiac circulatory sequelae of spinal anesthesia than does either a pure alpha- or beta-adrenergic agonist.

Effect of total spinal anesthesia on arterial and venous responses to dopamine and dobutamine.

To test whether acute denervation alters the vascular effects of dopamine and dobutamine, we anesthetized 16 greyhounds and placed them on total cardiopulmonary bypass (CPB). Eight dogs received total spinal anesthesia before drug testing; eight dogs were tested in the absence of total spinal anesthesia. During dopamine and dobutamine infusions, venous capacitance [determined by the volume of the CPB venous reservoir (VR)] and mean arterial pressure (MAP) were monitored. The CPB pump flows remained constant throughout our studies. Every dog received six increasing doses of both drugs. In the absence of total spinal anesthesia, both dopamine and dobutamine increased VR (decreased venous capacitance) in a dose-dependent manner. Dobutamine decreased MAP in a dose-related fashion but dopamine had no significant effect on MAP. After total spinal anesthesia, both dopamine and dobutamine produced greater dose-related increases in VR (i.e., decreases in venous capacitance) than in the absence of spinal anesthesia. Dopamine increased MAP but dobutamine had no significant effect. These data demonstrate how dopamine and dobutamine differ in their effects on the arterial circulation in the presence or absence of spinal anesthesia. The acute denervation of spinal anesthesia altered venous and arterial dose-response relationships of both drugs. Finally, our study demonstrates the effectiveness of dobutamine and, perhaps even more so, dopamine as possible alternatives to ephedrine for the pharmacologic correction of the noncardiac circulatory sequelae of spinal anesthesia.