Imaging technique selection for the preoperative planning of oral implants: a review of the literature

Background: As the use of oral implants for the treatment of partially as well as fully edentulous patients has increased the past two decades, more specialized radiographie techniques have become available for the preoperative planning of oral implant placement. Purpose: The goal of this article was to enable clinicians to select the appropriate imaging techniques when planning for oral implants. Materials and Methods: This article reviews the available literature about various imaging techniques and their indication for the preoperative planning of oral implants. The advantages and drawbacks of each technique are described. A dosimet‐ric overview is given relative to different radiologie techniques used in various clinical situations. Results: For preoperative planning of implant placement, advantages and drawbacks of the available imaging techniques have been considered, which allows guidelines for image technique selection to be formulated based on the clinical situation provided, considering the diagnostic yield of each technique and the radiation doses involved. Conclusions: From the available literature, it can be stated that many clinical situations demand the use of cross‐sectional imaging techniques for optimal preoperative planning of implant placement. Nevertheless, such techniques are not required in cases in which the clinical examination reveals sufficient bone width and where standard radiographie examinations, such as intraoral and panoramic radiography, reveal adequate bone height and space for implant placement.     

Balloon-assisted coil placement in wide-neck bifurcation aneurysms by use of a new,compliant balloon microcatheter

Two types of balloon are usually employed to perform balloon-assisted coil placement in cerebral aneurysms: oval, guide-dependent balloons for sidewall aneurysms and round balloons for bifurcation aneurysms. We report on the use of a new, more compliant, guide-dependent oval balloon microcatheter to seal wide-neck bifurcation aneurysms with coils during endovascular occlusion.     

The L-type calcium channel blocker nimodipine mitigates "learned helplessness" in rats

We assessed the effect of nimodipine, an L-type calcium channel blocker, on the escape deficit induced by prior exposure to inescapable shock in rats in four experiments. In Experiment 1, we injected rats at each of three time points (i.e., before shock exposure, after shock exposure, and before shuttle escape testing) with one of four doses of nimodipine (0, 0.5, 2.5, 5.0 mg/kg). The 5.0-mg/kg dose was most effective, acting to reduce shuttle escape latencies of inescapably shocked rats to a level comparable with nonshocked controls. No benefit occurred in Experiment 2, however, when nimodipine was administered at only one of the three time points used in the first experiment. Moreover, escape performance did not improve when rats received injections of nimodipine on the 2 days prior the experiment, and then one additional injection at one of the three time points identified above in Experiment 3. Finally, administration of nimodipine at two of the three time points did improve escape responding, but only when injected immediately prior both to shock exposure and the shuttle escape test.     

Effect of lipopolysaccharide on uterine contractions and prostaglandin production in pregnant rats

OBJECTIVE: Our aim was to evaluate the effect of lipopolysaccharide on prostaglandin production and on contraction of isolated myometrial strips from preterm pregnant rats. STUDY DESIGN: Pregnant Wistar rats on day 17 of gestation were killed 3 hours after intraperitoneal injection of lipopolysaccharide (1.5 mg/kg) or vehicle, with or without pretreatment with indomethacin (5 mg/kg administered intraperitoneally) 1 hour beforehand. Concentrations of endotoxin in maternal serum and amniotic fluid, prostaglandin F2alpha and prostaglandin E2 in amniotic fluid, and progesterone in maternal serum were determined. Longitudinal uterine strips were prepared, placed in organ chambers with Krebs-Ringer solution, aerated with 95% oxygen and 5% carbon dioxide (37 degrees C, pH approximately 7.4), and equilibrated at 1g passive tension. Concentration-contraction relationships to oxytocin were determined. Samples of bathing solution were collected 10 minutes after the concentration of oxytocin was maximal. Prostaglandins and progesterone were measured by radioimmunoassay and endotoxin was measured by the Endospecy (Seikagaku Kogyo, Tokyo, Japan) kit. RESULTS: Lipopolysaccharide treatment significantly increased the levels of prostaglandin F2alpha and prostaglandin E2 in amniotic fluid. Treatment with lipopolysaccharide inhibited the production and release of prostaglandin F2alpha and prostaglandin E2 that were activated by oxytocin in uterine strips and increased the sensitivity of strips to the contractile effect of oxytocin. Indomethacin did not affect the basal or the lipopolysaccharide-activated levels of endotoxin in serum and amniotic fluid and exerted a counteraction on lipopolysaccharide-induced increases in concentrations of prostaglandin F2alpha and prostaglandin E2 in amniotic fluid. Indomethacin counteracted oxytocin-activated production and release of prostaglandin F2alpha and prostaglandin E2 in uterine tissues after lipopolysaccharide administration without changing the sensitivity of uterine strips to oxytocin. Concentrations of progesterone were not changed after lipopolysaccharide, indomethacin, or their combined application, which suggests that the changes described were not associated with alterations in the levels of the hormone. CONCLUSIONS: The activation of the uterine contractile system by prostaglandin and oxytocin during intra-amniotic infection may be one of the causes of preterm delivery. A combination of an oxytocin receptor antagonist and an inhibitor of cyclooxygenase may be beneficial in prevention or treatment of preterm labor.     

Computerized hemodynamic evaluation of the cerebral circulation for bypass

This article describes details of the application of computer modeling of cerebral blood circulation. A brief review of the different computer modeling techniques and the current models used today for predicting surgical options for bypass surgery are presented. The use of phase contrast MR for estimating intracranial flow rates makes these models even more accurate. Two case studies are presented with computer simulation results with verification of predicted outcome both clinically and from actual flow of measurements.     

Effect of stimulatory and inhibitory drugs on uterine electrical activity measured noninvasively from the abdominal surface of pregnant rats

OBJECTIVE: Our purposes were (1) to identify and analyze parameters of uterine electrical activity that change during active term and preterm labor in response to stimulatory (oxytocin) or inhibitory (terbutaline) agents and (2) to correlate the information obtained from abdominal surface measurement of electrical activity with intrauterine pressure and with the electrical activity measured directly from the uterine surface in vivo. STUDY DESIGN: Electromyographic activity was acquired simultaneously from the uterine wall and the abdominal surface by means of unipolar electrodes. Electromyographic activity was recorded in the 0.3 to 50-Hz range and digitized at 200 samples per second. Intrauterine pressure was measured via an intrauterine catheter. The effect of cumulative doses of oxytocin and terbutaline on power density spectrum, amplitude, number and duration of electromyographic bursts, and intrauterine pressure was recorded in anesthetized rats during spontaneous active term labor (n = 7) and induced preterm labor (n = 6). RESULTS: Bursts of electromyographic activity recorded from the abdominal surface mirrored those from the uterine wall, albeit at a lower amplitude. During active term labor, lower concentrations of oxytocin did not significantly affect power-density-spectrum energy, amplitude, or number of bursts per unit time. The duration of electromyographic bursts increased dose dependently. Myometrial contractions were phasic, with return to the baseline between phases. As the concentration of oxytocin increased, the energy, amplitude, and number of bursts per unit time declined while the intrauterine pressure continued to rise until the contraction became tetanic, without return to the baseline. In rats with induced preterm labor, terbutaline inhibited uterine contractility by decreasing the intrauterine pressure. This was accompanied by a progressive decrease in the power density spectrum, amplitude, number, and duration of the uterine wall and abdominal surface electrical bursts. CONCLUSIONS: First, uterine electromyographic activity measured noninvasively from the abdominal surface reflects changes in uterine electrical activity and intrauterine pressure measured directly and invasively in term and preterm labor, as well as during treatments to stimulate or inhibit labor. Second, this noninvasive method may be useful in monitoring uterine activity in vivo. Third, clinical studies to evaluate this technology in human subjects are warranted.     

The effect of fetal neck position on nuchal fold thickness

OBJECTIVE: Our purpose was to determine whether ultrasonographic measurements of nuchal fold thickness are affected by the position of the fetal neck. STUDY DESIGN: Fetal nuchal fold thickness was prospectively measured in 258 women undergoing routine ultrasonography at 15 to 21 completed weeks of gestation. Patients with fetal structural or chromosomal anomalies were excluded. At the time of examination the position of the fetal head was noted as being extended or flexed on the basis of the angle between the spine and the base of the skull. Gestational age was based on menstrual dates or ultrasonographic biometric parameters. Data were tested for normality. Mann-Whitney U test and analysis of covariance were used (significance was considered to be P <.05). Data are presented as median and range. RESULTS: A total of 258 fetuses were examined with 167 (65%) in the flexed and 91 (35%) in the extended neck position. Gestational age was not significantly different between the flexed and extended groups (median, 19.1 weeks; range, 15.5-21.6 weeks; vs median, 19.1 weeks; range, 15.6-22 weeks; P =.23). Nuchal fold thickness was significantly lower in the flexed group than in the extended group (median, 3.5 mm; range, 1.3-6.2 mm; vs median, 3.9 mm; range, 2.2-4.9 mm; P =.0097). Nuchal fold thickness increased significantly with gestational age in both groups. The difference in nuchal fold thickness between the 2 groups persisted even after the increase in nuchal fold thickness was adjusted for with gestational age (P =.002, analysis of covariance). The difference between the 2 groups was higher at earlier gestations. CONCLUSION: Nuchal fold thickness is affected by gestational age and fetal neck position. Correction for these variables may improve the accuracy of nuchal fold thickness measurements in screening for fetal chromosomal anomalies.     

A rare manifestation of hypothyroidism: intestinal obstruction. Report of 2 cases and review of the literature

Gastrointestinal manifestations of hypothyroidism are unfrequent. They consist particularly in hypomotility, intestinal atony, and pseudoobstruction. A high index of suspicion must exist, especially in elder subjects, in order to avoid unnecessary and even harmful investigation and intervention. We are reporting two cases of intestinal occlusion due to hypothyroidism with review of the literature.