Could the bug Triatoma sherlocki be vectoring Chagas disease in small mining communities in Bahia, Brazil?

Searches for Chagas disease vectors were performed at the type locality from which Triatoma sherlocki Papa et al. (Hemiptera: Reduviidae: Triatominae) was described in the municipality of Gentio do Ouro, in the state of Bahia, Brazil, and in a small artisan quarry-mining community approximately 13 km distant in a remote area of the same municipality. The latter site represents a new locality record for this species. Adults, nymphs and exuviae of T. sherlocki were found in 21% of human dwellings, indicating that the species is in the process of domiciliation. Prevalence of Trypanosoma cruzi infection in collected bugs was 10.8%. Simple predictive approaches based on environmental similarity were used to identify additional sites likely suitable for this species. The approach successfully predicted an additional five sites for the species in surrounding landscapes. Ecological and entomological indicators were combined to discuss whether this scenario likely represents an isolated case or an emerging public health problem.

Morphobiological, morphometric and ultrastructural characterization of sylvatic Trypanosoma cruzi isolates from Rio de Janeiro state, Brazil.

Triatoma vitticeps is a triatomine with geographic distribution restrict to Brazil, which exhibits high prevalence of Trypanosoma cruzi natural infection. Of special epidemiologic concern, this species often invades households in the states of Rio de Janeiro, Minas Gerais and Espírito Santo. The objective of this study was to evaluate morphological and ultrastructural parameters on three T. cruzi isolates obtained from wild T. vitticeps specimens. The growth and cell differentiation of the parasite was evaluated through epimastigote and trypomastigote forms obtained in the growth curves for three distinct isolates. The maximum growth showed differences at the 20th day of the curve. Our in vitro results show a heterogeneity, regarding these features for samples cultivated under the same conditions. Morphometric analyzes based on the shape of epimastigotes and trypomastigotes corroborated such differentiation. These results highlight the need of better understanding the meaning of this diversity under an eco-epidemiological perspective.

Quality assurance of HDR 192Ir sources using a Fricke dosimeter.

A prototype of a Fricke dosimetry system consisting of a 15 x 15 x 15 cm3 water phantom made of Plexiglas and a 11.3-ml Pyrex balloon fitted with a 0.2 cm thick Pyrex sleeve in its center was created to assess source strength and treatment planning algorithms for use in high dose rate (HDR) 192Ir afterloading units. In routine operation, the radioactive source is positioned at the end of a sleeve, which coincides with the center of the spherical balloon that is filled with Fricke solution, so that the solution is nearly isotropically irradiated. The Fricke system was calibrated in terms of source strength against a reference well-type ionization chamber, and in terms of radial dose by means of an existing algorithm from the HDR's treatment planning system. Because the system is based on the Fricke dosimeter itself, for a given type and model of 192Ir source, the system needs initial calibration but no recalibration. The results from measurements made over a 10 month period, including source decay and source substitutions, have shown the feasibility of using such a system for quality control (QC) of HDR afterloading equipment, including both the source activity and treatment planning parameters. The benefit of a large scale production and the use of this device for clinical HDR QC audits via mail are also discussed.

Genetic variability of Triatoma rubrovaria (Reduviidae: Triatominae) from Brazil, Argentina and Uruguay as revealed by two different molecular markers.

Randomly amplified polymorphic DNA (RAPD) and nuclear ribosomal DNA sequence analyses were used to assess the genetic population structure of the South American triatomine species Triatomo rubrovario throughout its geographical distribution. To investigate the genetic variability at both intraspecific and intrapopulational levels the RAPD profiles and the nucleotide sequences of the rDNA intergenic spacers, ITS-1 and ITS-2, were analysed and compared. The phenetic analysis based on RAPD profiles show three distinct clusters diverging by similarity coefficients ranging from 0.62 to 0.96. The ITS-1 and ITS-2 sequence variability detected may be considered very high, suggesting reproductive isolation between populations. A total of seven composite haplotypes (CH) were found, among which three are specific for Brazil, other three for Uruguay, and the last one common for the three countries studied. The population studied in Argentina does not represent an independent CH. Sequence analyses proved that the five populations studied are easily differentiable and that there is heterogeneity within each one. True mutations and indels are the responsible of sequence differences between haplotypes and populations, suggesting that divergence processes may presently go on within this species. The large intraspecific variability detected may underlie the known plasticity of T. rubrovaria, making it a potential intradomiciliary invader and consequently an appropriate vector for Chagas disease transmission. Therefore, this triatomine species must be continuously monitored throughout.

Colon cancer metastasis to the thyroid gland: A case report.

INTRODUCTION: Thyroid metastases from colorectal cancer are uncommon and few cases are described in literature. CASE PRESENTATION: A 64-year-old female patient presented with an asymptomatic right cervical nodule with a rapid growth six years after sigmoidectomy for cancer and two years after resection of colorectal lung metastases. Increased CA 19.9 was identified and a thoracoabdominal CT scan revealed the onset of new metastatic bilateral pulmonary lesions. Neck ultrasonography showed a suspicious nodule in the right thyroid lobe, and Fine-needle Aspiration Cytology (FNAC) of the nodule lead to the diagnosis of colorectal cancer metastasis. A right thyroid lobectomy with right central lymph node dissection was performed. The patient underwent chemotherapy with response, but this was posteriorly suspended due to haematological side effects, and the disease spread. DISCUSSION: Thyroid metastases from colorectal cancer are rare, but, with the improvement of radiologic exams and the higher survival rate of these patients, more cases are being described. The majority of the cases present pulmonary and hepatic metastases and the prognosis is poor. The decision to operate and the type of operation depend on the extent of the metastatic disease and the patient's overall condition. CONCLUSION: A low threshold of suspicion is crucial to make a timely diagnosis of thyroid metastases from colorectal cancer. Treatment is controversial, but, without surgery, the need may arise for tracheostomy.

Collagen implant with gentamicin sulphate as an option to treat a neuroischaemic diabetic foot ulcer: Case report.

INTRODUCTION: The ischaemic diabetic foot is associated with a faster evolving atherosclerosis affecting preferentially the bellow knee arteries. This distal ischemia associated with a wide distribution of multiple stenosis and occlusions throughout lower limb arteries, makes revascularization very hard or even impossible. This represents a major factor responsible for non-healing diabetic foot ulcer. In these cases all efforts should be made to find treatment alternatives that can promote ulcer healing. CASE PRESENTATION: Male patient with neuroischaemic diabetic foot ulcer with exposure tendon, without possibility for endovascular or surgical revascularization, was treated unsuccessfully with prostaglandin and several types of dressings for 7 months. Skin graft failed. Weekly dressings with collagen implant impregnated with gentamicin sulphate were then started and continued in an outpatient setting. Evolution was very positive, with 99% of epithelisation in 9 months. No pain or infection since the beginning of this treatment. DISCUSSION: Successful treatment of a neuroischaemic diabetic foot ulcer rests with the possibility of increasing the perfusion to the foot. Whether or not a revascularization procedure is possible will set the tone for the ensuing treatment. Using collagen implant with gentamicin sulphate, collagen is delivered to the wound bed helping in the granulation tissue formation, will increase microcirculation, and topic gentamicin will decrease bacterial load, exudate and proteases production, increasing cicatrisation. CONCLUSION: In neuroischaemic diabetic foot ulcer weekly dressings with collagen implant impregnated with gentamicin sulphate can be a good option for ulcer healing.

[Irradiation of internal mammary nodes: State of the art]. / État de l'art de l'irradiation des ganglions de la chaîne mammaire interne.

In the adjuvant breast cancer treatment, postoperative radiotherapy plays a principal part with an action against the microscopic residual disease in the lymph nodes after mastectomy as well as after breast conserving surgery. This positive effect is observed also in the case of small inner lesions in patients without lymph node involvement. At the same time, there is a recognized risk of cardiac toxicity directly related to the irradiation of internal mammary nodes. This paper is a report on the current available techniques to irradiate the internal mammary nodes, including promising new technology that may help limiting the risk of cardiac toxicity.

Fpg and UvrA proteins participate in the repair of DNA lesions induced by hydrogen peroxide in low iron level in Escherichia coli.

The survival of different DNA repair mutant strains of Escherichia coli treated with H2O2 was evaluated in the presence or absence of an iron chelator (dipyridyl). Our results suggest that Fpg and UvrA proteins participate in vivo in the repair of DNA lesions produced by higher H2O2 concentrations in the presence of an iron chelator while UvrB and UvrC proteins seem to be ineffective in the repair of these lesions.

Role of SOS and OxyR systems in the repair of Escherichia coli submitted to hydrogen peroxide under low iron conditions.

There are at least two mechanisms by which H2O2 induces DNA lesions in Escherichia coli: one in the presence of physiological iron levels and the other in low iron conditions. The survival as well as the induction of SOS response in different DNA repair mutant strains of E coli was evaluated after H2O2 treatment under low iron conditions (pretreatment with an iron chelator). Our results indicate that, in normal iron conditions RecA protein has a relevant role in recombination repair events, while in low iron conditions RecA protein is important as a positive regulator of the SOS response. On the other hand, the oxy delta R mutant is sensitive to the lethal effects of H2O2 only in low iron conditions and this sensitivity cannot be correlated with DNA strand breaks.

Quality assurance in radiation therapy: clinical and physical aspects. Teletherapy equipment and simulators.

A comprehensive Quality Assurance program in a radiation therapy center is desirable regardless of its size, and should cover among others the following areas: physical parameters of the therapy machines, dosimetric standards, preventive maintenance of radiation emitting sources and measuring instruments. In a radiation therapy center, regardless of its size and patient load, it is advisable to have a quality assurance program covering all the treatment planning steps. The following areas should be taken into consideration: physical parameters of the machines; dosimetric standards; radiation safety procedures and preventive maintenance of irradiators and radiation measuring instruments. The minimum instrumentation required and the critical parameters to be observed to establish a quality assurance program are discussed; the suggestions are applicable to the various sizes of radiation therapy centers. It is essential that all the procedures and results obtained are well documented and a critical evaluation of the program be performed periodically. The procedures and frequency suggested are applicable to low, medium and high energy treatment machines and simulators. The fluctuation on physical parameters currently observed in clinical physics practice strongly supports the efforts and costs of a quality assurance program.

Build-up curves of scanned high energy electron beams from the Sagittaire linear accelerator.

A study of the build-up curves using an extrapolation chamber for 7, 10, 13, 16, and 19 MeV electron beams, from a Sagittaire linear accelerator, is presented. The effect of the ionization chamber bias polarity, field size, collimation and surface obliquity on the shape of the relative ionization curve was investigated. No clinically significant change is observed except the displacement of the maximum ionization point was observed for the oblique incidence of the beam.

A simple device for testing the equilibrium of ion chambers in ambient conditions.

A simple device for testing the response of ion chambers when ambient pressure is varied was built from an inexpensive device normally used to maintain tennis balls under pressure. The results show that one may use this system in routine as well as for teaching purposes.

A graphite transmission ionization chamber.

A pancake-type transmission chamber made of high-purity graphite and open to the atmosphere has been designed and constructed at the Secondary Standard Dosimetry Laboratory (SSDL-Rio de Janeiro). Tests performed on the chamber following the International Electrotechnical Commission recommendations indicate that its performance characteristics are comparable to those expected from a secondary standard ionization chamber.

Experimental derivation of wall correction factors for ionization chambers used in high dose rate 192Ir source calibration.

At present there are no specific primary standards for 192Ir high dose rate sources used in brachytherapy. Traceability to primary standards is guaranteed through the method recommended by the AAPM that derives the air kerma calibration factor for the 192Ir gamma rays as the average of the air kerma calibration factors for x-rays and 137Cs gamma-rays or the Maréchal et al. method that uses the energy-weighted air kerma calibration factors for 250 kV x rays and 60Co gamma rays as the air kerma calibration factor for the 192Ir gamma rays. In order to use these methods, it is necessary to use the same buildup cap for all energies and the appropriate wall correction factor for each chamber. This work describes experimental work used to derive the A(W) for four different ionization chambers and different buildup cap materials for the three energies involved in the Maréchal et al. method. The A(W) for the two most common ionization chambers used in hospitals, the Farmer NE 2571 and PTW N30001 is 0.995 and 0.997, respectively, for 250 kV x rays, 0.982 and 0.985 for 192Ir gamma rays, and 0.979 and 0.991 for 60Co gamma rays, all for a PMMA build-up cap of 0.550 gm cm(-2). A comparison between the experimental values and Monte Carlo calculations shows an agreement better than 0.9%. Availability of the A(W) correction factors for all commercial chambers allows users of the in-air calibration jig, provided by the manufacturer, to alternatively use the Maréchal et al. method. Calibration laboratories may also used this method for calibration of a well-type ionization chamber with a comparable accuracy to the AAPM method.

Monte Carlo calculations of the ionization chamber wall correction factors for 192Ir and 60Co gamma rays and 250 kV x-rays for use in calibration of 192Ir HDR brachytherapy sources.

As in the method for the calibration of 192Ir high-dose-rate (HDR) brachytherapy sources, the ionization chamber wall correction factor A(w), is needed for 192Ir and 60Co gamma rays and 250 kV x-rays. This factor takes into account the variation in chamber response due to the attenuation of the photon beam in the chamber wall and build-up cap and the contribution of scattered photons. Monte Carlo calculations were performed using the EGS4 code system with the PRESTA algorithm, to calculate the A(w) factor for 51 commercial ionization chambers and build-up caps exposed to the typical energy spectrum of 192Ir and 60Co gamma rays and 250 kV x-rays. The calculated A(w) correction factors for 192Ir and 60Co sources and 250 kV x-rays agree very well to within 0.1% with published experimental data (the statistical uncertainty is less than 0.1% of the calculated correction factor value). For the 192Ir sources, A(w) varies from 0.973 to 0.993 and for the 250 kV x-rays the minimum value of A(w) for all chambers studied is 0.983. The calculated A(w) correction factors can be used to calculate the air kerma calibration factor of HDR brachytherapy sources, when interpolative methods are considered, contributing to the reduction in the overall uncertainties in the calibration procedure.

Perturbation corrections for flat and thimble-type cylindrical standard ionization chambers for 60Co gamma rays: Monte Carlo calculations.

The use of an ionization chamber for absorbed dose determinations in a medium requires one to take into account perturbation corrections due to the presence of the chamber cavity in the medium. Evaluation of these corrections for perturbation and their variation with depth in the medium has been performed for a flat cylindrical and a cylindrical (thimble-type) ionization chamber placed in a graphite phantom irradiated by a 60Co gamma beam using Monte Carlo calculations (EGS4 system with correlated sampling variance reduction technique). The results of these calculations agree with published experimental and theoretical data to better than 0.18%, with a statistical uncertainty of less than 0.17%.

Intercomparison of calibration procedures for 192Ir HDR sources in Brazil.

The lack of well established dosimetry protocols for HDR sources is a point of great concern regarding the uniformity of procedures within a particular country and worldwide. The main objective of this paper is to report the results from ten institutions of an intercomparison of calibration procedures for 192Ir HDR sources currently in use in Brazil. The treatment irradiator of one institution was calibrated by a reference system and used by all participants with their own measuring electrometers and ionization chambers under the same experimental conditions. Two methods were used: the calibration jig and the well-type ionization chamber. Each participant was allowed to use their own method and formalism. The results of this exercise were very positive since this was the first time in Brazil that a group of users gathered to share their experience and openly discuss the physical concepts behind the calibration procedures. The results were all within +/-3.0%, except one case where -4.6% was observed and later identified as a problem with the Nk value for x-rays. Though the magnitude of the deviations found was generally acceptable considering the diversity of formalisms currently in use, a proposal is now being prepared to be adopted as a national protocol. The identification of the institutions was left out for the sake of confidentiality.

Copper ions mediate the lethality induced by hydrogen peroxide in low iron conditions in Escherichia coli.

Iron ions mediate the formation of lethal DNA damage by hydrogen peroxide. However, when cells are depleted of iron ions by the treatment with iron chelators, DNA damage can still be detected. Here we show that the formation of such damage in low iron conditions is due to the participation of copper ions. Copper chelators can inhibit cell inactivation, DNA strand breakage and mutagenesis induced by hydrogen peroxide in cells pre-treated with iron chelators. The Fpg and UvrA proteins play an important role in the repair of DNA lesions formed in these conditions, as suggested by the great sensitivity of the uvrA and fpg mutant strains to the treatment when compared to the wild type strain.

Synergistic lethal effect between hydrogen peroxide and neocuproine (2,9-dimethyl 1,10-phenanthroline) in Escherichia coli.

Despite 2,9-dimethyl 1,10-phenanthroline (NC) has been extensively used as a potential inhibitor of damage due to oxidative stress in biological systems, the incubation of E. coli cultures with the copper ion chelator NC prior to the challenge with hydrogen peroxide caused a lethal synergistic effect. The SOS response seems to be involved in the repair of the synergistic lesions through the recombination pathway. Furthermore, there is evidence for the UvrABC excinuclease participation in the repair of the synergistic lesions, and the base excision repair may also be required for bacterial survival to the synergistic effect mainly at high concentrations of H2O2, being the action of Fpg protein an important event. Incubation of lexA (Ind-) cultures with iron (II) ion chelator 2,2'-dipyridyl simultaneously with NC prevented the lethal synergistic effect. This result suggests an important role of the Fenton reaction on the phenomenon. NC treatment was able to increase the number of DNA strand breaks (DNAsb) induced by 10 mM of H2O2 in lexA (Ind-) strain and the simultaneous treatment with 2,2'-dipyridyl was able to block this effect.

3-Methyl-5-hydroxy-5-trichloromethyl-1H-1-pyrazolcarboxyamide induces antinociception.

The antinociceptive action of a novel pyrazole-derived compound, 3-methyl-5-hydroxy-5-trichloromethyl-1H-1-pyrazolcarboxyamide (MPCA) was evaluated using the formalin and tail-immersion tests in mice. Anti-inflammatory activity was assessed by paw plethysmometry in adult rats using the carrageenin-induced paw edema test. Subcutaneous administration of MPCA (22, 66, and 200 mg/kg) induced a dose-dependent decrease in the time spent licking during the neurogenic and inflammatory phases of the formalin test, and preadministration of naloxone (1 mg/kg, sc) did not prevent MPCA-induced (200 mg/kg, sc) antinociception. Naloxone decreased the spontaneous locomotor activity of mice, while MPCA had no effect on locomotion. In contrast, administration of the opioid antagonist caused a significant increase in the locomotor behavior of mice previously injected with MPCA. MPCA was devoid of antinociceptive action by the tail-immersion test and of anti-inflammatory activity. Moreover, MPCA had no effect on the motor performance of mice in the rotarod test. These results suggest that MPCA induces antinociception in the neurogenic and inflammatory phases of the formalin test, an effect that does not involve opioid receptors.