Search

Bacterial adherence to the acquired dental pellicle, important in dental caries (caries), is mediated by receptor-adhesins such as salivary agglutinin binding to Streptococcus mutans antigen I/II (I/II). Ten selected I/II epitopes were chosen to determine their reactivity to human salivary IgA. Previous studies suggested that a specific HLA biomarker group (HLA-DRB1*04) may have differential influence of immune responses to I/II. However, it was not known whether secretory IgA (SIgA) responses to the selected epitopes from HLA-DRB1*04 positive subjects were different compared to controls, or across other caries-related factors such as total IgA (TIgA). Thirty-two total subjects were matched according to HLA type, gender, ethnicity and age. HLA genotyping, oral bacterial, immunoglobulin and antibody analyses were performed. A large observed difference emerged with regard to the natural immune reservoir of TIgA in HLA-DRB1*04 positive subjects, specifically, a 27.6% reduction compared to controls. In contrast to all other epitopes studied, HLA-DRB1*04 positive subjects also exhibited reduced reactivity to I/II epitope 834–853. HLA-DRB1*04 positive subjects exhibited lower specific SIgA activity/TIgA to 834–853 and also a lower specific reactivity to 834–853/whole cell S. mutans UA159. Furthermore, HLA-DRB1*04 positive subjects exhibited lower responses to I/II in its entirety. The large observed difference in TIgA and the 834–853 reactivity pattern across multiple measures suggest potentially important connections pertaining to the link between HLA-DRB1*04 and caries.

The primary focus of this thesis was to investigate the critical strain energy release rates (G) for mixed-mode (I/II) fracture of wood adhesive joints. The aims of the study were: (1) quantifying the fracture properties of two material systems, (2) analyzing the aspects that influence the fracture properties of bonded wood, (3) refining test procedures that particularly address layered orthotropic systems in which the layers are not parallel to the laminate faces, of which wood is often a particular case, and (4) developing testing methods that enhance the usefulness of performing mixed-mode tests with a dual-actuator load frame. The material systems evaluated experimentally involved yellow-poplar (Liriodendron tulipifera), a hardwood of the Magnoliaceae family, as adherends and two different adhesives: a moisture-cure polyurethane (PU) and a phenol/resorcinol/-formaldehyde (PRF) resin. The geometry tested in the study was the double cantilever beam that, in a dual-actuator load frame, can be used for testing different levels of mode-mixity. The mixed-mode loading condition is obtained by applying different displacement rates with the two independently controlled actuators of the testing machine. Characteristic aspects such as the large variability of the adhesive layer thickness and the intrinsic nature of many wood species, where latewood layers are alternated with earlywood layers, often combine to confound the measures of the critical values of strain energy release rate, Gc. Adhesive layer thickness variations were observed to be substantial also in specimens prepared with power-planed wood boards and affect the value of Gc of the specimens. The grain orientation of latewood and earlywood, materials that often have different densities and elastic moduli, limits the accuracy of traditional standard methods for the evaluation of Gc. The traditional methods, described in the standards ASTM D3433-99 and BS 7991:2001, were originally developed for uniform and isotropic materials but are widely used by researchers also for bonded wood, where they tend to confound stiffness variations with Gc variations. Experimental analysis and analytical computations were developed for quantifying the spread of Gc data that is expected to be caused by variability of the adhesive layer thickness and by the variability of the bending stiffness along wooden beams. Ph. D.

Purpose: A prospective phase II trial was conducted by the Institute of Oncology, istanbul University in December 1994 on patients with locally-advanced non-small cell lung cancer to assess acute toxicity and the feasibility of a combination of radiosensitizer and accelerated radiotherapy with concomitant boost. Materials and methods: Patients were irradiated using 'large' fields (primary tumour and locoregional lymph nodes) with 1.8 Gy per fraction, five fractions a week. Reduced 'boost' fields (primary and involved nodes only) were also irradiated twice-weekly 1.8 Gy per fraction in ten fractions concomitantly 6 h after the administration of large field. Total radiation dose was 63 Gy in 5 weeks (45 Gy 'large' fields and 18 Gy 'boost'). The maximum allowed dose to the spinal cord was 3750 cGy. Cisplatinum, 6 mg/m(2) was given daily just before 'large' field irradiation, Results: As of January1997, 15 patients were evaluated (median follow-up of 12.5 months with a range of 5.5-23 months). The overall acute toxicity rate was 38% and Grade 3 acute toxicity was 8%. Grade 4 or greater acute toxicities were not observed. The overall rate of cisplatinum-induced nausea and vomiting was 80% (severe in 60%), but all were easily treated with antiemetics. Complete response rate (clinical and radiological) was 40% and an overall response rate was 73%. Median survival was 16 months and progression-free survival was 5.5 months (range of 2.5-21 months). Conclusions: Toxicity was well tolerated and no treatment-related death occurred with this combined treatment regimen. Although it appears that better local control rates can be achieved, additional phase II/III studies are needed. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.