Articulator selection for restorative dentistry

There are many types of articulators that can be used for making fixed restorations. While unquestionably the most accurate, the fully adjustable instrument is not feasible or necessary for many forms of simple occlusal treatment.The effects of tooth-hinge axis radius, intercondylar distance, and condylar inclination on occlusal morphology have been discussed. Guidelines have been proposed for matching the type of articulator with the extent of treatment anticipated. The use of small, nonadjustable hinge articulators is not recommended.     

Growth Inhibition by Acycloguanosine of Herpesviruses Isolated from Human Infections

Inhibition by acycloguanosine (ACG) of plaque formation by harpes simplex virus types 1 and 2 (HSV-1 and HSV-2), varicella-zoster virus, and cytomegalovirus was studied. Seventeen clinical isolates of HSV-1 were inhibited by ACG at a mean 50% inhibitory dose (ID(50)) of 0.15 +/- 0.09 muM. The mean ID(50) for 10 isolates of HSV-2 was 1.62 +/- 0.76 muM, and for four isolates of varicella-zoster virus it was 3.75 +/- 1.30 muM. The ID(50)'s for two cytomegalovirus isolates were 100 and 160 muM, and for four additional isolates of cytomegalovirus no end point (ID(50)) was reached at 200 muM. ACG at a concentration of 200 muM had no effect on deoxyribonucleic acid synthesis in human fibroblast cells and only inhibited thymidine incorporation by Vero cells by one-third. These studies demonstrated the antiviral activity of ACG against clinical isolates of HSV-1, HSV-2, and varicella-zoster virus and the lack of toxicity to monkey or human cells in culture at concentrations which markedly inhibited these viruses. ACG had little effect on cytomegalovirus at concentrations in excess of 100 muM.     

Use of a heat exchanger in liver transplantation

Of the first 16 patients who underwent orthoptic liver transplantation, 81% were observed to be hypothermic at termination of bypass (x = 34.5 degrees C, n = 16). In response, an in-line heat exchanger was added to the bypass circuit. Subsequently, 72% of the next 11 patients terminated bypass normothermic (x = 38.2 degrees C, n = 11). By removing from the sample those patients who incurred low blood flows, 100% of the patients terminated bypass normothermic (x = 38.2 degrees C, n = 8). At temperatures of 30-33 degrees C cardiac arrhythmias have been observed. Hypothermia has been documented to cause thrombocytopenia and neutropenia which can lead to blood loss. These low counts are only partially reversible with platelet infusion and white blood cells (WBC). The use of an in-line heat exchanger during liver transplantation is essential in preventing hypothermia in our experience.     

Postoperative fluid overload: not a benign problem

The incidence and consequences of fluid overload in the surgical ICU (SICU) have not been well defined, but may influence length of stay, days requiring mechanical ventilation, and mortality. Forty-eight consecutive patients admitted to our SICU were prospectively monitored for acute changes in weight and its impact on clinical management and outcome. When defined as a gain greater than 10% from their preoperative or premorbid weight (or an approximately 20% increase in total body water), 40% of patients had fluid overload. Patients were divided into three groups: those who had gained less than or equal to 10%, those with a weight gain between 11% and 20%, and those with greater than 20% increase in weight. Significant differences were found with respect to vasopressor dependence, colloid administration, and mortality. When indexed by initial Acute Physiology and Chronic Health Evaluation (APACHE II) mortality prediction scores, all groups had similar degrees of illness. On average, presumably due to volume limitations, patients were inadequately nourished during 85% of their SICU stay. Our results suggest that the morbidity of fluid overload can be significant, and warrants a fresh look at the methods of intraoperative fluid resuscitation.     

Diagnosis of Plantar Plate Injury by Magnetic Resonance Imaging with Reference to Intraoperative Findings

The objective of the present study was to assess the utility of magnetic resonance imaging in evaluating injury to the plantar plate and to determine whether conventional low-field magnetic resonance imaging is a valid tool for diagnostic evaluation. Magnetic resonance imaging scans of 45 feet in 41 patients (38 females and 3 males, with an average age of 52.1 years) were prospectively evaluated to assess the integrity of the plantar plate ligament and compared with a reference standard of intraoperative findings. The concordance of tear severity observed on magnetic resonance imaging with the intraoperative findings was also assessed using a newly proposed grading scheme for plantar plate injuries. Intraoperatively, 41 plantar plate tears and 4 intact ligaments were found. The accuracy, sensitivity, specificity, positive predictive value, and negative predictive value was 96%, 95%, 100%, 100%, and 67%, respectively. The clinical diagnosis of plantar plate injury was also highly accurate in our study population (41/45, 91%). Finally, we observed moderate concordance between the magnetic resonance imaging grade and surgical grade of plantar plate tear (28/45, 62%), with greater concordance occurring at higher grades. Our results have demonstrated that magnetic resonance imaging is an accurate and valid test for the diagnosing injuries of the plantar plate ligament. Given the high accuracy of the clinical findings, magnetic resonance imaging is most useful when the decision to operate will be sufficiently influenced by either a normal magnetic resonance imaging appearance of the plantar plate or the presence of a high-grade tear.     

The effect of speaking context on spectral- and cepstral-based acoustic features of normal voice

The effect of speaking context on four cepstral- and spectral-based acoustic measures was investigated in 20 participants with normal voice. Speakers produced three different continuous speaking tasks that varied in duration and phonemic content. Cepstral and spectral measures that can be validly derived from continuous speech were computed across the three speaking contexts. Cepstral peak prominence (CPP), low/high spectral ratio, and the standard deviation (SD) of the low/high spectral ratio did not significantly differ across speaking contexts, and correlations for the first two measures were strong among the three speaking tasks. The SD of the CPP showed significant task differences, and relationships between the speaking contexts were generally moderate. These findings suggest that in speakers with normal voice, the differing phonemic content across several frequently used speaking stimuli minimally impacted group means for three clinically relevant cepstral- and spectral-based acoustic measures.