Development and assessment of an objective method of colour change measurement for acrylic denture base resins

SUMMARY Current standard specifications for the laboratory evaluation of denture base materials require subjective assessment of colour stability. This study evaluates a new objective measurement technique for translucent denture base materials, by comparing quantitative data with the results obtained from a standard subjective method. Preliminary work on three representative commercial acrylic materials resulted in the selection of a white background for the quantification of colour change of these translucent materials. One half of each sample was exposed to artificial sunlight for 24 h.
The colour of both exposed and unexposed resin was measured on the CIE L*a*b* scale using a photoelectric colorimeter. Significant changes in the b* and E* values (P < 0.001) were observed following light exposure. Objective data for a wide range of commercial materials were compared with the results of a subjective evaluation and it was shown that a change in b* of 1.5 units was discernable subjectively by eye for 100% of the cases. It is suggested that this method and limit value could form the basis of a new objective colour change specification for polymeric dental materials.     

Lack of Influence of Atrioventricular Delay on Stroke Volume at Rest in Patients with Complete Atrioventricular Block and Dual Chamber Pacing

Dual chamber pacing (DDD) maintains atrioventricular (AV) sequence; AV delay programmability modifies the relationship between atrial and ventricular contraction. To evaluate the hemodynamic effects of such a modification, ten patients with a DDD unit for complete AV block were studied by time-motion (M-mode) and Doppler echocardiography during inhibited ventricular pacing (VVI), atrial-triggered ventricular pacing (VDD) and atrioventricular sequential pacing (DVI) at different AV delay (90, 140, 190, 240 msec). A significant improvement in stroke volume (SV) (15%-20%, P less than 0.05) was seen during DDD versus VVI pacing; no changes, however, were observed in the same patient with different AV delay or during DVI versus VDD pacing. These data suggest that programming of AV delay does not affect systolic performance at rest; longer diastolic filling times recorded during DDD pacing with "short" AV delay (90-140 msec) do not seem to be a hemodynamically relevant epi-phenomenon of PM programming.     

T‐cell responses in two unrelated hemophilia A inhibitor subjects include an epitope at the factor VIII R593C missense site

Summary. Background: Development of neutralizing anti‐factor (F)VIII antibodies (‘inhibitors’) is a serious clinical problem in hemophilia A. Increased inhibitor risk has been associated with certain FVIII missense substitutions, including R593C in the A2 domain. Objectives: The aim of the present study was to identify T‐cell epitopes in FVIII and characterize T‐cell responses in two unrelated hemophilia A subjects sharing F8‐R593C and HLA‐DRB1*1101 genotypes. We hypothesized that the hemophilic substitution site coincides with an important T‐cell epitope. Patients/methods: The binding affinities of peptides for recombinant HLA‐DR proteins were measured and compared with epitope prediction results. CD4+ T cells were stimulated using peptides and stained with fluorescent, peptide‐loaded tetramers. Results: The inhibitor subjects, but not HLA‐matched controls, had high‐avidity HLA‐DRB1*1101‐restricted T‐cell responses against FVIII_589–608, which contains the hemophilic missense site. Antigen‐specific T cells secreted Th1 and Th2 cytokines and proliferated in response to FVIII and FVIII_592–603. FVIII_589–608 bound with physiologically relevant (micromolar) IC₅₀ values to recombinant DR0101, DR1101 and DR1501 proteins. Conclusions: Hemophilia A patients with R593C missense substitutions and these HLA haplotypes had an increased incidence of inhibitors in our cohorts, supporting a paradigm in which presentation of FVIII epitopes containing the wild‐type R593 influences inhibitor risk in this hemophilia A sub‐population.     

Joint strength between two layers of different amalgam types condensed successively

The flexure strength of the joint between layers of different types of amalgam condensed consecutively one on to the other was evaluated in vitro. The data indicated no statistical differences in flexure strength between the combined samples (single composition spherical and lathe-cut eutectic amalgams) and the control (homogeneous lathe-cut eutectic amalgam).     

GLUCOCORTICOIDS AND GLUCOSE METABOLISM: HEPATIC GLUCOSE PRODUCTION IN UNTREATED ADDISONIAN PATIENTS AND ON TWO DIFFERENT LEVELS OF GLUCOCORTICOID ADMINISTRATION

Plasma glucose, insulin levels and hepatic glucose production rates were studied after an overnight fast in six Addisonian patients in three different conditions: off replacement treatment, on substitution therapy and on high-dose glucocorticoid treatment. For comparison eight normal subjects were evaluated in basal conditions. Fasting plasma glucose and hepatic glucose production did not change significantly with either level of glucocorticoid treatment when compared to the untreated state and the normal controls, but there was a significant increase in plasma glucose levels in the high-dose cortisone-treated Addisonian patients when compared to the untreated state. Insulin levels were significantly lower in the untreated state and significantly higher in the high dose-treated patients when compared to the normal controls. It is suggested that in these experimental conditions the peripheral actions of glucocorticoids are predominant over the hepatic effects by virtue of their ability to produce secondary changes in insulin levels, keeping the hepatic glucose production constant.     

S-IgA CHOLERA TOXIN AND ROTAVIRUS ANTIBODY IN HUMAN COLOSTRUM

Abstract. S-IgA antibodies against cholera toxin and rotavirus were assayed in 43 colostral samples by means of an enzyme-linked immunosorbent assay (ELISA). All specimens contained specific S-IgA antibodies against both antigens. Significant antibody titres to the antigens were demonstrated in almost all colostral samples.