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At least 703 records · Page 39Linked to original sources
PubMed2000

Successful palliation of Ebstein's malformation on the first day of life following fetal diagnosis.

Severe Ebstein's malformation has a poor prognosis when diagnosed during the neonatal period. Surgical options that have proved successful in older patients have been associated with high mortality and morbidity in neonates. We report here our success with a policy of induction at term and immediate surgical intervention when Ebstein's malformation was diagnosed prenatally.

Blood Vessel Prosthesis↗
PubMed2003

Magnetic beads (Dynabead) toxicity to endothelial cells at high bead concentration: implication for tissue engineering of vascular prosthesis.

Magnetic beads (Dynabeads) have been used for the purification of endothelial cells. One application for this procedure may be for single-stage seeding of bypass grafts. The number of endothelial cells (EC) isolated is crucial and therefore to increase the number of cells extracted, a higher number of Dynabeads per cell may need to be used. The effect of large numbers of CD31 Dynabeads on cell proliferation/metabolism is unknown. We undertook this study using CD31-coated Dynabeads and EC from human umbilical vein. EC were coated at concentrations of 4, 10, or 50 beads per cell. The cells were cultured for 6 days with control being normal EC. Cellular proliferation was assessed by trypsinization of cells and metabolism assessed with an Alamar blue viability assay. In a further experiment a compliant polyurethane graft was single-stage seeded with both coated Dynabeads and normal EC. The results showed that using a higher number of beads per cell resulted in a reduction in cell proliferation and a reduction in cell metabolism. The total number of Dynabeads-coated cells in culture compared to controls (%) by day 6 were 30.7 +/- 2.56, 41.3 +/- 9.8 and 59.2 +/- 7.3 for 50, 10, and 4 beads per cell, respectively. The corresponding results for Alamar blue were 43.7 +/- 1.2, 61.8 +/- 1.4, and 72.1 +/- 4.3. The seeded grafts showed reduced metabolism with the Dynabeads-coated EC. In conclusion, high numbers of beads per cell have a late detrimental effect on cell proliferation and metabolism. Therefore for single-stage seeding lower numbers of Dynabeads will need to be used with resultant reduction in the number of available EC.

Biocompatible Materials↗
PubMed2002

Bone response to alteration of surface topography and surface composition of sandblasted and acid etched (SLA) implants.

The titanium surface obtained by sandblasting and etching (SLA) is an easily alterable surface that smears and loose its typical texture. In addition, the etching process modifies the surface composition of commercially pure titanium; the latter contains titanium and an added 20-40% of titanium hydride. Therefore, the influence of a heavy surface alteration and the influence of the composition at the SLA surface, i.e. with and without titanium hydride, were investigated in vivo. Three implant groups were inserted in the mandible of Land Race pigs and left to heal during 10 weeks in a submerged way: (1). a standard SLA control group (SLAstd) with the SLA surface containing titanium hydride; (2). a test group with the SLA surface heavily altered at the thread level (SLAalt); (3). a test group with an SLA surface devoid of titanium hydride (SLAT). Sample size was n = 8. Histomorphometry analysis did not show a statistically significant difference between the control group (SLAstd: 82.12 + 6.1%), the altered surface test group (SLAalt: 86.25 + 7.4%) and the SLA without titanium hydride test group (SLAT: 75.12 + 7.6%). The data suggest that alteration of the SLA surface, if it occurs, should not be detrimental to bone response. The soft and easy smearable SLA surface might even be an advantage when surface maintenance is required. Surface composition did not play a significant role in the bone response to the SLA surface and it can therefore be concluded that the osteophilic properties of the SLA surface are due to its surface topography and not to its specific surface composition.

Acid Etching, Dental↗
PubMed2002

Morphofunctional and clinical study on mandibular alveolar distraction osteogenesis.

Alveolar Distraction Osteogenesis (ADO) is a process which forms new alveolar bone to correct alveolar deformities in ridge height and width. This work aims (a). to verify the predictability of the augmentation of height of atrophic alveolar ridges using an extra-alveolar distraction device and (b). to study the bone processes in order to optimize implanto-prosthetic rehabilitation. ADO was performed on 10 patients with ridge deformities to obtain the required ridge augmentation. Clinical and radiological (OPT and CT with densitometric assay) evaluations were carried out during the following 12 weeks, before implant insertion. Biopsies at 40, 60 and 88 days were studied after general, specific and histochemical staining of slides; microradiographs were analyzed to evaluate the Trabecular Bone Volume. Forty days after the end of distraction, soft callus indicated the start of ossification. Sixty days after the end of distraction, the soft callus was largely converted into a network of trabecular woven bone; osteogenic activity was high and TBV was about 50%. Eighty-eight days after the end of distraction, the amount of bone appeared reduced, with a more ordered structure; bone formation activity and TBV also diminished, whereas osteoclast erosion was active. The densitometric assay shows values increasing from the end of distraction, particularly after implant insertion. Histological results show a regression in bone deposition processes 88 days after the end of distraction culminating in a virtual steady-state after a certain time. The results suggest that early implant insertion may be desirable to avoid bone loss due to mechanical unloading.

Absorptiometry, Photon↗
PubMed2001

Left ventricular apex to descending aorta valved conduit: description of transthoracic and transesophageal echocardiographic findings in four cases.

Patients with critical aortic stenosis and a "porcelain" aorta are at an increased risk for complications with aortic cross-clamping during valve replacement. To our knowledge, this is the first report of both transthoracic and transesophageal echocardiographic findings of the left ventricle to the descending aorta (LVDA) valved conduit. We present results of four patients in whom this procedure was performed for critical aortic stenosis, who also had a porcelain aorta. "Normal" echo and Doppler findings, along with those of development of a regurgitant valve within the conduit, are presented.

Aorta, Thoracic↗
PubMed2001

Dental color standards: shade tab arrangement.

PURPOSE: The aim of this study was to analyze the shade tab arrangement of two popular dental shade guides, suggest possible improvements, and propose clinical guidelines. MATERIALS AND METHODS: Data were recorded using a colorimeter set to standard illuminant source C and CIE L*a*b* system. The manufacturers' shade tab arrangement as well as the possible improvements in the arrangement of shade tabs of Vitapan Classical and Vitapan 3-D Master (Vita Zahnfabrik, Bad Säckingen, Germany) shade guides were examined by regression analysis. RESULTS: Certain shortcomings in the manufacturers' arrangement of both color standards were observed. The Vitapan 3-D Master arrangement was more consistent, but with a decrease in lightness, tab saturation decreased as well in four of its five groups. When Vitapan Classical and Vitapan 3-D Master tabs were arranged according to deltaE* in relation to the lightest tab, r2 was 0.98 and 0.96, respectively. After dividing the total deltaE* range into four equal segments for the newly established Vitapan Classical guide, r2 was 0.91, 0.95, 0.68, and 0.94, respectively. Corresponding r2 values for Vitapan 3-D Master were 0.96, 0.94, 0.90, 0.94, and 1.0. CLINICAL SIGNIFICANCE: Total color difference in relation to the lightest tab, followed by the tab division into an adequate number of groups, is recommended as a possible and universally applicable mode of tab arrangement in dental color standards.

Calibration↗
PubMed1987

Calibration of color Doppler flow mapping during extreme hemodynamic conditions in vitro: a foundation for a reliable quantitative grading system for aortic incompetence.

If color Doppler imaging is to continue to evolve into a reliable clinical method to noninvasively evaluate regurgitant lesions, then its grading methods must be quantitated and calibrated under extreme hemodynamic conditions. A left heart pulse duplicator was used to provide a completely controllable system to study aortic incompetence jet morphologies as a function of hemodynamic extremes. The system was first used to calibrate the limits of resolution of color Doppler imaging. Next, to define which jet features reliably predict the defect size or the regurgitant fraction and which are primarily influenced by instantaneous hemodynamic variables, we measured the jets' maximal length, width, proximal width, and temporal pattern of color variance during independent variations in the heart rate, cardiac output, and pressure gradient across the incompetent valve. The proximal jet width (immediately below the valve plane) was the only reliable independent predictor of both the defect size and the regurgitant fraction. Jet depth accurately predicted peak velocity (quantitated by laser Doppler velocimetry); it reliably predicted the severity of incompetence only at a known pressure gradient across the valve. Large defects (5 mm) produced jets with maximal color variance in early diastole, whereas small defects produced pandiastolic variance.

Aortic Valve↗
PubMed1979

Color stability of a pigmented elastomer for maxillofacial appliances.

The color stability of a series of eleven maxillofacial pigments was determined after accelerated aging using reflection spectrophotometry. The results indicate that seven of the pigments demonstrated good to excellent color stability, while four of the pigments were less promising for clinical use.

Color↗
PubMed1980

Physical properties of a pigmented silicone maxillofacial material as a function of accelerated aging.

The effects of accelerated aging on a pigmented elastomer were evaluated by using a weathering chamber. Silastic 44210, a maxillofacial material with proven color and physical property stability, was chosen for pigmentation with 11 maxillofacial pigments. The values of ultimate tensile strength, maximum percent elongation, shear strength, Shore A hardness, and permanent deformation were determined for the pigmented elastomer before and after accelerated aging for 900 h. Results obtained indicate that the incorporation of 0.2% by weight of pigments can alter the physical and mechanical properties of the base elastomer. Accelerated aging had no effect on the physical properties of the pigment/elastomer combinations.

Chemical Phenomena↗
PubMed1998

An unusual case of left upper lobe pulmonary edema.

This is a report of an unusual case of left, predominantly upper lobe, pulmonary edema secondary to paravalvular mitral regurgitation (MR) complicating mitral valve replacement. Transesophageal echocardiography proved helpful in making the diagnosis of MR and suggesting the mechanism of the pulmonary edema.

Aged↗
PubMedDate not supplied

Color subtraction arthrography in the diagnosis of component loosening in hip arthroplasty.

While component loosening in arthroplasty of the hip joint may not always be associated with pain, the painful total hip arthroplasty frequently can be shown to be associated with loosening of one or both components. The application of color subtraction techniques to routine arthrography of the hip has greatly increased the authors' accuracy in identifying component loosening in the painful total hip. The technique and its method of application are described in this preliminary report. Several examples of its use are presented. The authors have found this technique to be a useful adjunct to routine arthrography of the hip in selected instances. It has improved overall diagnostic accuracy and is more rapid and less costly than standard photographic subtraction techniques.

Arthrography↗
PubMed2003

Tooth brush abrasion of paint-on resins for shade modification of crown and bridge resins.

The purpose of this study was to evaluate the surface roughness and resistance to toothbrush abrasion of three experimental paint-on composite resins developed for the shade modification of crown and bridge resins. The paint-on resins had less filler volume fraction than restorative composites or the crown and bridge resins and consequently were of low viscosity. The maximum surface roughness (Rmax) and the maximum depth loss by abrasion for the paint-on resins following 40,000 cycles of brushing ranged from 2.45 to 4.07 microm and 8.63 to 13.67 microm, respectively. Rmax values were 37.7-67.5% lower than that for the crown and bridge resin subjected to the same test. Wear depth was 19.9-49.4% lower than for the crown and bridge resin. These results suggest that the paint-on resins are expected to have adequate resistance to toothbrush abrasion and may therefore be suitable for clinical use.

Color↗