Evaluation of four blood pump geometries: the optical tracer technique.

Artificial blood pump assistance of the failing human heart can allow it to recover. Analysis of blood pump fluid flow is a useful tool for design development and thrombosis minimization. The aim of this study was to investigate fluid flow, particularly ventricular clearance rate and stagnation areas, in four different blood pump geometries and to determine the best design. The blood pumps consisted of a polyurethane ventricle, and combinations of inlet/outlet pipe angles and compression plate shapes. A video camera recorded the motion of fluid labelled with an optical tracer (Methyl Blue histological dye). A novel processing method was developed to produce colour maps of tracer concentration, experimentally calibrated. An overall picture of fluid flow in each pump geometry was generated by considering clearance curves, tracer concentration maps and inflow jet animations. Overall and local mixing coefficients are calculated for each pump. The best geometry featured straight inlet/outlet pipes and a domed compression plate. This optical tracer technique has proven convenient, economical, sensitive to low concentrations of tracer and provides instantaneous pictures of tracer distribution in a ventricle.

Effect of different luting procedures on the seating of ceramic inlays.

This in vitro study evaluated the effect of different luting procedures on the proper seating of ceramic inlays and on the marginal seal through microleakage testing. Sixty mesial-, occlusal-, distal- (MOD) cavities were prepared in third molars, and distributed among four groups. In the control group 1, the cavity surface was treated with dentin and enamel bonding agents; ceramic inlays were placed into the cavity and light cured. In group 2, the dentin and enamel bonding agents were cured prior to the placing of the inlays, and following the insertion. In group 3, the inlays were luted without enamel bonding. In group 4, the inlays were cemented using a one-bottle bonding and two times light curing. The groups with only one time light curing at the end of the luting process exhibited the smallest luting space following cementation. The smallest dye penetration values were obtained for the two groups with separate light curing of the dentin bonding agent. Reducing the film thickness of polymerized dentin bonding agents, i.e. by changing the composition of the bonding agents, could facilitate proper seating of ceramic inlays together with a better marginal seal.

Acute anterior myocardial infarction: increased dye intensity in the myocardial risk area after coronary angioplasty is associated with reduction of diastolic volumes.

BACKGROUND: Myocardial perfusion in the risk area during the acute phase of myocardial infarction has been extensively investigated over the last few years. The so-called "no-reflow" or "low-reflow phenomenon" (absence of myocardial perfusion despite patency of the infarct-related coronary artery) was shown to correlate with worse postinfarction remodeling, in particular when myocardial contrast echocardiography was used. The aim of this study was to determine, during routine coronary angiography performed before and after coronary angioplasty (PTCA) during the acute phase of myocardial infarction, the existence of the no-reflow phenomenon and its relation with ventricular remodeling, by evaluating the dye video density in the myocardial risk area. This confirmation by a different diagnostic technique may serve to highlight the role of myocardial perfusion as an index of prognosis in the clinical setting of acute myocardial infarction. METHODS: Twenty-six patients (23 males, 3 females, mean age 57 +/- 8.7 years) who underwent either rescue (n = 11, 42.3%) or primary PTCA, according to clinical indications, of the left anterior descending coronary artery during an acute anterior myocardial infarction and who did not have stenosis of the left circumflex or right coronary artery, were retrospectively selected from a 6 year intake. The extent of coronary stenosis was assessed using biplane quantitative coronary angiography, while end-diastolic and end-systolic volume indexes, together with regional wall motion, were computed from echocardiography performed in the first 24 hours and at 6 months. Patients were subdivided into two groups on the basis of dye video intensity in the risk area, as assessed from images obtained during left main coronary artery injections before and immediately after PTCA. It was used a subtraction technique (Group A: increased video intensity, n = 12; Group B: no change, n = 14), assuming that higher peak intensity reflects greater myocardial blood volume. Three patients in Group B with ineffective PTCA were excluded, so that the final number of considered patients was 11. RESULTS: The distribution of rescue PTCA was similar in the two groups (7 in Group A vs 3 in Group B, p = 0.13) as were clinical characteristics and therapeutic regimen. There was a significant time * group interaction for end-diastolic volumes (-4.6 +/- 23% in Group A vs +22 +/- 22% in Group B, p = 0.029), whereas end-systolic volumes showed a tendency to greater dilation in Group B (+19 +/- 28% vs +0.9 +/- 31% in Group A), although this difference was not significant (p = 0.27). No interaction was evident for increase in the vessel area (+46 +/- 12.5% in Group A vs +43.2 +/- 13.6% in Group B, p = 0.99), or for extent of regional dysfunction (+3.08 +/- 10.9 chords in Group A vs -2.5 +/- 9.5 chords in Group B, p = 0.50). CONCLUSIONS: The detection of myocardial blood volume in the risk area using dye video intensity during left main dye contrast injection, is useful to distinguish whether there is improved perfusion at the muscular level, following successful angioplasty of the infarct-related coronary artery. Lack of improved myocardial perfusion has an adverse effect on left ventricular volumes independently of coronary stenosis resolution and regional wall motion changes in the time.

Effect of nail varnishes and petroleum jelly combinations on glass ionomer dye uptake.

PURPOSE: To evaluate the effectiveness of different brands of nail varnish alone or associated with petroleum jelly as surface protectors for glass ionomer cements by determining dye uptake spectrophotometrically. MATERIALS AND METHODS: Three hundred thirty six specimens, 3.0 mm in diameter and 1.0 mm thick, were made with Chelon-Fil (CF) and ChemFil II (CII) and divided into 14 groups for each material. Positive control (A) and negative control (B) specimens were not protected, while experimental specimens were protected with six brands of nail varnish used with and without petroleum jelly. The specimens were immersed in 0.05% methylene blue solution 10 minutes after mixing except for negative control specimens that were immersed in deionized water. RESULTS: Dye uptake (microgram dye/restoration) for CF was: A = 11.3 +/- 3.1; B = 0.0 +/- 0.0 with varnish groups ranging from 0.6 to 2.5 and for CII: A = 12.4 +/- 2.5; B = 0.0 +/- 0.0 with varnish groups ranging from 0.4 to 2.4. The data were analyzed by ANOVA. The dye uptake among the groups was not significantly different (P < 0.01), except for the control group (unprotected cements).

Comparison of methods for measuring albumin in peritoneal dialysis and hemodialysis patients.

Serum albumin levels have been used extensively as an indicator of morbidity in patients with end-stage renal disease. Recent evidence suggests that albumin levels vary considerably in hemodialysis patients depending on the laboratory method used, but formulas for comparing albumin values by different methods have not been developed. We prospectively evaluated the effects of measuring albumin by three different methods on paired plasma and serum from 23 patients on continuous ambulatory peritoneal dialysis (CAPD) and 53 patients on chronic maintenance hemodialysis. Plasma and serum gave virtually identical results independent of method used. In CAPD patients, bromcresol green and nephelometry gave nearly identical albumin measurements through the entire range of plasma levels. In contrast, bromcresol purple gave values that were 9.9 percent +/- 1.3 percent lower (P < 0.05). Hemodialysis patients showed a similar pattern with close agreement between bromcresol green and nephelometry, but bromcresol purple gave lower albumin levels by 19.1 percent +/- 1.2 percent (P < 0.05). The discrepancy in albumin in CAPD patients was significantly less than in the hemodialysis patients (P < 0.05), suggesting that there were fewer interfering substances in the blood of CAPD patients than in hemodialysis patients. Linear regression analysis was used to develop simple formulas for comparing albumin values obtained by the different methods in CAPD and hemodialysis patients. These studies show that values for albumin in blood vary significantly by method of analysis in CAPD and hemodialysis patients. By the use of these formulas, it becomes possible to compare albumin values between centers using different methods for the purpose of quality management.

Evaluation of new scoring systems for dye penetration for in vitro comparative microleakage studies.

This study was designed to evaluate one of the commonly used scoring systems--Score I--(categories from 0-5) to other two suggested scoring systems--Score II & III--(categories from 0-1 and 0-2 respectively), to test the degree of dye penetration for leakage studies. Class V cavities were prepared on 100 extracted human upper central incisors and filled with light cured composite. Herculite, and high copper amalgam. Tytin. All teeth were immersed in sodium fluorescein dye to test the degree of dye penetration. The results revealed that the suggested score II is very easy, simplified and representative but not indicative regarding the severity of dye penetration as score I. Score III are indicative and obvious discussion can be obtained rather than score I. For any leakage study the use of non parametric measurement is preferable than parametric ones.

Marginal adaptation of resin in relation to application technique and use of a dental adhesive system.

Class V abrasion, erosion and caries lesions restored with composite resin seem to be more susceptible to microleakage, because the gingival margin is usually placed in cementum and/or dentine. The purpose of this study was to evaluate the microleakage, in vitro, of a dentinal bonding system using a technique of restoration with a positive and a negative control. This study was accomplished using extracted human teeth and dye penetration technique. The teeth were examined for microleakage after one month. It was concluded that in the gingival wall of the cavity microleakage was significantly reduced when the dentinal bonding agent and composite resin was placed and polymerized incrementally from enamel, to cementum.

Comparative sealability study on root canal obturation using multiphase gutta percha and lateral condensation technique.

An in-vitro dye leakage study was performed to compare the apical microleakage of recently introduced multiphase obturation system to lateral condensation technique using methylene blue dye. Thirty single rooted human teeth were divided randomly into two equal groups. Group A were filled with multiphase technique using Tubliseal sealer and group B were filled with lateral condensation technique using the same sealer (control). Root canal preparation of both groups were carried out with nickel titanium files. Statistical analysis revealed that multiphase technique exhibited lower mean leakage (0.6) than lateral condensation technique (1.72). In addition some specimen filled with multiphase technique showed zero degree leakage.