Effect of Chairside CAD/CAM Restoration Type on Marginal Fit Accuracy: A Comparison of Crown, Inlay and Onlay Restorations.

Chairside CAD/CAM is a convenient approach for fabricating dental restorations. However, the effect of CAD/CAM restoration type on marginal fit accuracy has not been fully investigated. This study evaluated of the marginal fit accuracy of 3 chairside CAD/ CAM restoration types (crown, inlay and onlay) using CEREC Bluecam (BC) and CEREC Omnicam (OC) scanners. Three artificial maxillary first molars received crown, inlay and onlay preparations. A total of 10 CAD/CAM ceramic restorations were produced for each tooth by each intraoral scanner. The marginal gap was measured along the preparation margin. For the BC, all the restorations had similar marginal gaps (crowns = 113.9 µm; inlays = 120.9 µm; onlays = 132.5 µm) (p = 0.20), while for the OC, the crowns (72.2 µm) and the inlays (74.9 µm) exhibited better marginal fit than the onlays (96.4 µm) (p = 0.003). For every restoration type, the OC provided a superior outcome compared with the BC. Therefore, the restoration type influenced the marginal gap, where the crowns tended to have the least marginal gap while the onlays had the greatest marginal gap. The newer scanner (OC) of the same manufacturer was more accurate than the older scanner (BC).

A hemolysis study of an intravascular blood cooling system for localized organ tissue cooling.

Therapeutic hypothermia can reduce both ischemic and reperfusion injury arising after strokes and heart attacks. New localized organ cooling systems offer a way to reduce tissue damage more effectively with fewer side effects. To assess initial blood safety of our new organ cooling system, the CoolGuide Cooling System (CCS), we investigated safe operating conditions and configurations from a hemolysis perspective. The CCS consists of a peristaltic pump, a custom-built external heat exchanger, a chiller, biocompatible polyvinyl cellulose (PVC) tubing, and a control console. The CCS cools and circulates autologous blood externally and re-delivers cooled blood to the patient through a conventional catheter inserted directly into the organ at risk. Catheter configurations used included: a 7F guide catheter only, a 7F guide with a 0.038" wire inserted through the center and advanced 2 cm distal to the catheter distal tip, a 6F guide catheter only and a 6F guide with a 0.014" guidewire similarly inserted through the center. Using porcine blood, an in vitro test rig was used to measure the degree of hemolysis generation, defined as the percentage change in free hemoglobin, adjusted for total hemoglobin and hematocrit, between exiting and entering blood. The highest degree of hemolysis generation was 0.11±0.04%, based on the average behavior with a 6F catheter and a 0.014" guidewire configuration at a blood flow rate of approximately 130 mL/min. In terms of average percentage free hemoglobin exiting the system, based on total hemoglobin, the highest value measured was 0.17%±0.03%, using this 6F and 0.014" guidewire configuration. This result is significantly below the most stringent European guideline of 0.8% used for blood storage and transfusion. This study provides initial evidence showing hemolysis generation arising from the CoolGuide Cooling System is likely to be clinically insignificant.

Avian Health across the Landscape: Nestling Immunity Covaries with Changing Landcover.

The landscape composition of an organism's home range or territory should influence aspects of its condition, including measures of immune function. Changes in immunocompetence arising from variation in landcover may provide important links between habitat changes and patterns of disease spread. To establish a baseline understanding for whether immune measures covary with changes in landcover, we examined associations between immunological parameters and landcover composition for adults and nestlings of five shrubland bird species. Specifically, we examined the bacteria-killing ability (BKA) of the blood plasma and profiles of the five avian leukocytes as our measures of immune function, and assessed the proportion of area around each bird's nest that was composed of the four major landcover types in the Midwestern USA: row crop agriculture, developed, forest, and grass/shrub. We performed landcover assessments at 100 and 1000 m radius buffers to identify whether associations between habitat and immune function differed at the two spatial scales. As part of this work, we examined age and species-related immunological variation, as well as associations among the immune parameters. There was little evidence linking variation in immune function to landcover composition for the adults at either spatial scale, but there were numerous associations for nestlings, and these were stronger at the 1000 than 100 m spatial scale. The proportion of grass/shrub around the nest had the largest impact on immune function, although the effect varied by immune parameter and species. BKA and basophils were inversely associated with grass/shrub for all species, whereas lymphocytes were positively associated with grass/shrub for all species. We also documented species-level differences among adults and nestlings for BKA and all leukocytes except monocytes. As expected, we found that nestlings had reduced levels of BKA, lymphocytes, monocytes, and elevated heterophils compared with adults (except for field sparrow-Spizella pusilla-nestlings, which had higher lymphocytes). Basophils generally did not differ by age class, and eosinophils exhibited species-specific patterns, in which they were higher for nestling American robins (Turdus migratorius) and gray catbirds (Dumetella carolinensis) compared with adults, but lower in the other nestlings. Heterophils and lymphocytes were inversely associated for all species and age classes, and basophil levels were positively associated with BKA across species and age classes. Together, these findings bolster our understanding of age and species-specific variation in immune function, and provide evidence that immune measures can covary with changes in landcover.

The HIV wasting syndrome: a review.

The HIV wasting syndrome and other HIV-associated weight loss is a major problem in HIV-infected patients. The available data strongly suggest that wasting is associated with decreased survival. It may also further impair immune function. A variety of etiologies probably contribute to this wasting, including hypermetabolism, alterations in metabolism, lessened oral intake, malabsorption, cytokine effects, and endocrine dysfunction. The relative contributions of each of these etiologies to wasting probably varies considerably from patient to patient. Successful treatment calls for identification of possible etiologies of wasting in the individual patient with AIDS. Further treatment may include treating underlying conditions and controlling such symptoms as diarrhea, nausea, or fever. Nutritional support, including both parenteral and enteral nutrition, has shown some promise of efficacy, and a variety of drugs appears to be helpful. Future treatment to reverse wasting may include the use of several of these agents in combination. Currently, there is much that clinicians can do to evaluate and treat the HIV wasting syndrome, with significant potential benefits to their patients.

Use of quantitative analysis of urine to assess exposure to asbestos fibers in drinking water in the Puget Sound region.

An earlier epidemiologic and electron microscopy study of drinking water in the Everett area of Washington State indicated large numbers of naturally occurring chrysotile asbestos fibers in the water. The purpose of the present study was to determine whether significant numbers of asbestos fiber could be demonstrated in the urine of donors residing in that area for less than 3 yr and over 20 yr where the tapwater contained about 200 X 10(6) fibers/L. A control group was obtained from Seattle where the tapwater asbestos fiber content was 100 times less. Urine samples, filtered control water, tapwater samples, and additional controls were processed for transmission electron microscopy by the use of the Nuclepore membrane filter-Jaffe wick procedure. Interference by mucus in the urine was reduced by treatment with hydrogen peroxide. Samples were taken over a period of 21 months. At no time during this period did the asbestos content of the urine samples consistently exceed that of the control waters. There was a significant difference (p less than 0.05) in the asbestos content of urine samples from subjects with less than 3 yr residence times versus greater than 20 yr. Asbestos concentration in urine samples from Everett residents as a whole did not differ significantly from that in samples from Seattle residents. Variable degrees of chrysotile contamination of control water samples and of Nuclepore membrane filters presented a problem. At present, the data are inconclusive but would suggest no relationship between high concentrations of fibers in drinking water and the numbers estimated for voided urine.

Functional MR spectroscopy of the auditory cortex in healthy subjects and patients with sudden hearing loss.

PURPOSE: To use MR spectroscopy to study the biochemical changes produced by auditory stimuli in patients with sudden sensorineural hearing loss and to compare these findings with the biochemical changes seen in healthy volunteers. METHODS: Single-voxel MR spectroscopy was used to study biochemical changes in the auditory cortex in 11 control subjects and 19 patients with sudden sensorineural hearing loss. MR spectroscopic signals were measured during three different sound conditions (scanner noise, music, and sirens). RESULTS: A lower MR spectroscopic lactate signal was observed in control subjects during the music stimulus than during the other sound conditions. This music-induced lactate change was not observed in patients with hearing loss. The other proton metabolites (choline, creatine, N-acetylaspartate [NAA]) remained stable during the different auditory stimuli. However, the NAA/creatine ratio was higher in the auditory cortex of patients than in the control subjects, and was not dependent on the sound condition. CONCLUSION: The detection of stimulus-induced and stable biochemical MR spectroscopic changes in patients with hearing loss may be useful in assessing disease activity.

Three-dimensional response of a lumped parameter head-neck model due to impact and impulsive loading.

A numerical procedure developed previously for predicting sagittal-plane motion of the human head-neck system due to impact and impulsive loading has been extended to three dimensions. In both situations, a lumped parameter approach is employed, but the current model lumps the mechanical response of each intervertebral joint into a single force-deformation relation evaluated from mechanical properties assembled by various investigators. Computations were performed to obtain the response of the model to a two-dimensional case of flexion whiplash, to one three-dimensional case of side impact to the skull and to another involving base acceleration normal to the sagittal plane. Agreement of the kinematic variables with the results of both the previous two-dimensional analysis and experimental data from a volunteer run is satisfactory, but somewhat poorer correspondence was found for the three-dimensional predictions upon comparison with data obtained from a physical model and from a volunteer when subjected to the prescribed loading. The differences in response are attributed to higher stiffness of facet separation of the model relative both to the structure and the volunteer, to insufficient damping, as well as to substantial differences in the mechanical deformation characteristic of the components of the prototypes and the numerical model.

Ex vivo testing of the intravenous membrane oxygenator.

Intravenous oxygenation represents a potential respiratory support modality for patients with acute respiratory failure or with acute exacerbations of chronic respiratory conditions. Our group has been developing an intravenous oxygenator, the IMO, which uses a constrained fiber bundle and a rapidly pulsating balloon within the fiber bundle. Balloon pulsation drives blood flow past the fibers at greater relative velocities than would otherwise exist within the host vessel, and gas exchange rates are enhanced. The purpose of this study was twofold: (1) to characterize the gas exchange performance of the current IMO in an extracorporeal mock vena cava vessel under conditions of known fixed vessel geometry and controlled blood flow rates; and (2) to compare the IMO gas exchange performance to that reported for the clinically tested IVOX device within a comparable ex vivo set-up. The ex vivo flow loop consisted of a 1 inch ID tube as a mock vena cava that was perfused directly from an anesthetized calf at blood flow rates ranging from 1 to 4 1/2 L/min. O2 and CO2 exchange rates were measured for balloon pulsation rates, which ranged from 0 to 180 bpm. Balloon pulsation significantly increased gas exchange, by 200-300% at the lowest blood flow rate and 50-100% at the highest blood flow rate. Balloon pulsation eliminated much if not all of the dependence of the gas exchange rate on blood flow rate as seen in passive oxygenators. This suggests that in clinical application the IMO may exhibit less gas transfer variability due to differences in cardiac output Over the entire flow rate range studied, the CO2 and O2 gas exchange rates of the IMO at maximal balloon pulsation varied from approximately 250 to 350 ml/min/m2. At maximum balloon pulsation the IMO exchanged CO2 and O2 at rates from 50-500% greater, depending upon the blood flow rate, than the exchange rates reported for the IVOX device in ex vivo tests.

Acute in vivo testing of an intravascular respiratory support catheter.

Current treatment for acute respiratory failure (ARF) includes the use of mechanical ventilation and/or extracorporeal membrane oxygenation, both of which can exacerbate lung injury. Intravenous respiratory support, using hollow fiber membranes placed in the vena cava, represents an attractive potential treatment for ARF, which could help reduce or eliminate ventilator induced trauma and/or other problems. Our group has been developing a respiratory support catheter (the Hattler catheter [HC]) that consists of a constrained hollow fiber bundle with a centrally located balloon. The balloon can be pulsated rapidly to increase blood flow across the fibers and decrease diffusional transfer resistance there, thus increasing gas exchange. The purpose of this study was to evaluate the HC in acute animal implants and to compare performance with that achieved in previous ex vivo studies. The HC was implanted into four calves by means of the external jugular vein and placed in the superior and inferior vena cava spanning the right atrium. Gas exchange, hemodynamics, and hematologic parameters were assessed over a range of balloon pulsation rates from 30 to 300 beats/minute. A <10% reduction in cardiac output was associated with catheter insertion and operation. The maximum CO2 exchange rate occurred at the highest pulsation rate and averaged 56 +/- 3 ml/min, or 327 +/- 15 ml/min per m2 when averaged to catheter membrane area, a level comparable to that achieved in the previous ex vivo studies. Balloon pulsation did not produce significant levels of hemolysis, as plasma-free hemoglobin remained below 10-15 mg/dl.

Double-blind study of pulsing magnetic field effects on multiple sclerosis.

We performed a double-blind study to measure the clinical and subclinical effects of an alternative medicine magnetic device on disease activity in multiple sclerosis (MS). The MS patients were exposed to a magnetic pulsing device (Enermed) where the frequency of the magnetic pulse was in the 4-13 Hz range (50-100 milliGauss). A total of 30 MS patients wore the device on preselected sites between 10 and 24 hours a day for 2 months. Half of the patients (15) randomly received an Enermed device that was magnetically inactive and the other half received an active device. Each MS patient received a set of tests to evaluate MS disease status before and after wearing the Enermed device. The tests included (1) a clinical rating (Kurtzke, EDSS), (2) patient-reported performance scales, and (3) quantitative electroencephalography (QEEG) during a language task. Although there was no significant change between pretreatment and posttreatment in the EDSS scale, there was a significant improvement in the performance scale (PS) combined rating for bladder control, cognitive function, fatigue level, mobility, spasticity, and vision (active group -3.83 +/- 1.08, p < 0.005; placebo group -0.17 +/- 1.07, change in PS scale). There was also a significant change between pretreatment and posttreatment in alpha EEG magnitude during the language task recorded at various electrode sites on the left side. In this double-blind, placebo-controlled study, we have demonstrated a statistically significant effect of the Enermed magnetic pulsing device on patient performance scales and on alpha EEG magnitude during a language task.

A novel method for patch-clamp automation.

An increasing demand of the pharmaceutical industry for automated electrophysiological stations for ion channel drug discovery has recently resulted in the development of several commercial platforms for secondary and safety screening of ion channel modulators. These commercial systems have demonstrated an enhanced throughput, however, often at the expense of some quality-sensitive aspects of traditional patch-clamp recordings. To improve data quality and content, we have developed a patch-clamp robot that fully automates manual patch-clamp recordings, including patch pipette handling, gigaseal formation, obtaining whole-cell or perforated-cell configuration, drug application, and data acquisition. Utilization of glass micropipettes results in high-quality electrophysiological recordings with an overall success rate of about 30% in perforated-cell mode. A fast drug application system with low volume requirements (1-1.5 ml) allows the study of ligand-gated ion channels on a millisecond scale. As proof-of-concept, we present two assays developed for voltage-gated human ether-a-go-go-related and ligand-gated alpha(7) nicotinic receptor ion channels. The system throughput was a single concentration-response curve every 30-40 min or 12-17 6-point concentration-response curves daily, representing a significant improvement of typical manual patch-clamp throughput. This system represents an efficient method for patch-clamp automation without the need for a complex and expensive electrophysiological set-up for cell visualization.

Difficult mammographic needle localizations: use of alternate orthogonal projections.

Lesions deep within the breast are occasionally visible on only one standard mammographic projection and are therefore difficult to localize preoperatively. Such abnormalities can often be visualized on two orthogonal 45 degrees oblique views. In these cases, needle localizations may be performed in a routine manner without computed tomography or stereotactic methods.

Contralateral loop snare removal of a ruptured and entrapped angioplasty balloon.

We describe a technique that extracted a ruptured angioplasty balloon which had become entrapped by a calcified left common iliac artery stenosis. The balloon catheter had been advanced crossover from the right and could not be retracted directly into a sheath across the aortic bifurcation. Therefore, a guidewire was inserted through the balloon catheter and captured by a loop snare advanced from the left femoral artery. The loop snare was also used to free the balloon wings from the stenosis. The balloon was then pulled into a 10 Fr sheath and removed as a unit with the sheath.

Subacute subcapsular hematoma of the spleen complicating pancreatitis: successful percutaneous drainage.

Subcapsular hematoma of the spleen is a rare complication of pancreatitis. In one patient successful percutaneous drainage of a large hematoma was performed during the subacute phase, preventing rupture of the splenic capsule and obviating splenectomy.

Grand rounds: first metatarsophalangeal joint replacement.

For approximately 30 years foot and ankle surgeons have been using a variety of techniques and devices to replace the first metatarsophalangeal joint. During this time there have been a multitude of implant designs and modifications, most attempting to anatomically and functionally replace the natural joint surfaces. The advantages and disadvantages of these many designs and various biomaterials has long been debated in scientific meetings and publications. Surgical technique, implant design, materials, and patient selection remain areas of heated debate and ongoing research. With this in mind, we asked leading foot and ankle surgeons to give their opinions on indications and utilization for joint replacement of the first metatarsophalangeal joint.

The LLNL high-speed sorter: design features, operational characteristics, and biological utility.

This report describes a dual-beam, high-speed sorter (HiSS) with a droplet production rate of 220,000 s-1 now in routine use at the Lawrence Livermore National Laboratory. The system can process and sort objects at rates in excess of 20,000 s-1. We report here on the development of HiSS, describe its operational characteristics, and evaluate its utility for analysis and purification of human chromosomes, human erythrocytes, and living Chinese hamster ovary cells.