The sylvatic transmission cycle of Trypanosoma cruzi in a rural area in the humid Chaco of Argentina

Little is known about the sylvatic transmission cycle of Trypanosoma cruzi in the Gran Chaco ecoregion. We conducted surveys to identify the main sylvatic hosts of T. cruzi, parasite discrete typing units and vector species involved in Pampa del Indio, a rural area in the humid Argentinean Chaco. A total of 44 mammals from 14 species were captured and examined for infection by xenodiagnosis and polymerase chain reaction amplification of the hyper-variable region of kinetoplast DNA minicircles of T. cruzi (kDNA-PCR). Ten (22.7%) mammals were positive by xenodiagnosis or kDNA-PCR. Four of 11 (36%) Didelphis albiventris (white-eared opossums) and six of nine (67%) Dasypus novemcinctus (nine-banded armadillos) were positive by xenodiagnosis and or kDNA-PCR. Rodents, other armadillo species, felids, crab-eating raccoons, hares and rabbits were not infected. Positive animals were highly infectious to the bugs that fed upon them as determined by xenodiagnosis. All positive opossums were infected with T. cruzi I and all positive nine-banded armadillos with T. cruzi III. Extensive searches in sylvatic habitats using 718 Noireau trap-nights only yielded Triatoma sordida whereas no bug was collected in 26 light-trap nights. Four armadillos or opossums fitted with a spool-and-line device were successfully tracked to their refuges; only one Panstrongylus geniculatus was found in an armadillo burrow. No sylvatic triatomine was infected with T. cruzi by microscopical examination or kDNA-PCR. Our results indicate that two independent sylvatic transmission cycles of T. cruzi occur in the humid Chaco. The putative vectors of both cycles need to be identified conclusively.

Effect of various surface treatment methods on the bond strength of the heat-pressed ceramic samples

This in vitro study was conducted to evaluate the interaction between the shear bond strength and the surface treatment method for a commercial dental ceramic. Ninety bonded ceramic units were manufactured for this study. Each unit was made by luting two cylinder-shaped ceramic samples to each other with a resin-composite luting agent. The units were then divided into nine groups, containing 10 units in each group. Samples from each group were treated with one of the following: etching with 4.9% hydrofluoric acid for 10, 20 and 40 s, 9.5% hydrofluoric acid for 10, 20 and 40 s, 40% orthophosphoric acid for 40 s, air abrasion with alumina in 50-microm particles, and grinding with a high-speed diamond bur. The treated samples were then silanated and luted with a resin-composite luting agent. The luted units were then loaded to failure. Two samples from each group were neither silanated nor luted after the surface treatment procedure, and morphological changes obtained by various surface treatment regimens were investigated by scanning electron microscopy. A statistically significant difference was observed among the mean shear bond strengths of the groups prepared with different surface treatment techniques (P = 0.00). Hydrofluoric acid appeared to be the most suitable chemical medium to produce a reliable ceramic bond. Etching time and concentration of the acidic medium were also observed as important prognostic variates. Orthophosphoric acid treatment was observed to be the least effective surface treatment method on the heat-pressed ceramic samples. Physical applications such as bur grinding and air blasting maintained stronger bonds than the orthophosphoric acid, while producing weaker bonds than surfaces treated with hydrofluoric acid in all concentrations and etching periods. The effect of the silane priming agent was not considered in this study.

Modified flasking technique for processing a maxillary resection obturator with continuous pressure injection

It is not possible for the wax pattern of most large-volume maxillary resection obturators to be placed into a flask for conventional compression molding processing and positioning of the wax pattern. However, these wax patterns and their channel access design often can be modified and aligned in position for processing with the continuous pressure injection technique. This article describes the use of the continuous pressure injection technique to process the perpendicularly aligned wax pattern of a maxillary resection obturator. It also describes a modified channel design and a simple method to pull back the injection funnel to increase the volume of the flask.

Can tumour marker assays be a guide in the prescription of bone scan for breast and lung cancers?

Considering the current need to improve cost-effectiveness in cancer patient management, a prospective study was undertaken in order to define the optimal combination of bone scan and tumour marker assays in breast and lung cancer strategies, as has been done in the case of prostate cancer. All patients with breast or lung cancer referred to the Nuclear Medicine Department of the Grenoble Teaching Hospital between December 1995 and April 1997 were included. A blood sample was drawn in each case for marker assay (CA15-3 or CEA and CYFRA 21-1) on the same day as the bone scan. Two hundred and seventy-five patients were included: 118 with lung cancer and 157 with breast cancer. With regard to lung cancer, no information useful for guiding bone scan prescription was obtained through CEA and CYFRA 21-1 assays. For breast cancer, the results suggest that in asymptomatic patients, a CA15-3 level of less than 25 U/ml (upper normal value chosen as the threshold) is strongly predictive of a negative bone scan; by contrast, high tumour marker levels are predictive of neoplastic bone involvement. When a doubtful bone scan is obtained in a patient with breast cancer, a normal marker level makes it highly probable that bone scan abnormalities are not related to malignancy.

Clinical application of a cantilevered adhesive prosthesis: a case report

A cantilevered adhesive prosthesis was designed for a patient whose maxillary right central incisor was extracted. The width of the edentulous space was much greater than the mesiodistal width of the lost tooth, impeding the construction of a conventional fixed partial denture. A much more conservative and esthetic result was achieved by the construction of a cantilevered adhesive prosthesis in which the extracted tooth was used as a pontic.