Blood transfusion and iatrogenic risks in Mexico city: anti-Trypanosoma cruzi seroprevalence in 43,048 blood donors, evaluation of parasitemia, and electrocardiogram findings in seropositive

Iatrogenous transmission of Trypanosoma cruziby blood transfusion was suggested as a potential risk by Pellegrino (1949). Seropositive blood donors in Mexico were first reported in 1978, however, limited information is available due to small sampling, the use of heterogeneous serologic assays, and geographically limited studies. A wide survey carried out in 18 out of the 32 states of Mexico, showed a national mean of 1.6% seropositive among 64,969 donors, ranging from 0.2 to 2.8%. In the present study, we have screened 43,048 voluntary blood donors in a period of five years at the Instituto Nacional de Cardiología I. Chávez, a concentration hospital located in Mexico city which serves mainly the metropolitan area and accepts from all over the country. Standardized ELISA and IIF were used to identify seropositive individuals in addition to hemoculture, PCR and standard 12 lead ECG tests that were applied to a group of seropositive patients (29/161). The result showed a seropositivity of 0.37% (161/43,048). From the group of seropositive individuals 40% (12/29) were potential carriers of T. cruzi at the donation time and 5/29 had subclinical ECG abnormalities. Parasitological tests performed in 70 erythrocyte and platelet fractions from seropositive units (70/161) showed negative results. Our findings strongly support T. cruzi screening in the transfusion medicine practice and identify subclinical heart disease among seropositive blood donors.

Clinical versus ultrasound examination in the evaluation of hepatosplenic schistosomiasis mansoni in endemic areas

The best way to appraise the size of abdominal organs remains undefined. Herein we compare the size of liver and spleen in hepatosplenic schistosomiasis using clinical and ultrasound (US) examination, and the size of the organs measured by US with their visualization below the costal margin ("palpable by US"). For this study, 411 individuals from an endemic area for schistosomiasis mansoni in Brazil have been selected. We found that palpable spleens and left liver lobes are larger than non palpable ones. Also, 23% of normal spleens measured by US were palpable on clinical examination, and 22% of spleens increased in size on US were non palpable. A total of 21% of normal spleens were "palpable by US". We also found 54% of normal sized right liver lobes palpable on clinical examination, whilst 54% of the increased livers, measured by US, were non palpable. About 76% of normal right liver lobes were "palpable by US". We conclude that the association of clinical, ultrasound and magnetic resonance imaging (MRI) examinations, in the near future, should give the investigators the necessary tools to perform a more accurate clinical diagnosis of hepatosplenic schistosomiasis mansoni.

Evaluation of phenotypic and genotypic alterations induced by long periods of subculturing of Cryptococcus neoformans strains

Cryptococcus neoformans is an encapsulated fungal organism that can cause disease in apparently immunocompetent, as well as immunocompromised, hosts. Since 1930, successive subculture has been used to preserve C. neoformans isolates in our Fungus Collection. In the 1970s, some of these Fungus Collection samples were selected to be subjected to a different methods of maintenance - that of lyophilized. Our objective was to analyze C. neoformans isolates in order to make a comparative evaluation between these two methods of preservation. The overall aim of this study was to qualify the preservation technique used in our mycology laboratory since the technique used might affect the survival, stability and purity of the primary isolates in culture. The samples were analyzed using classical mycology methods and using the randomly amplified polymorphic DNA technique In the analysis of phenotypes and genotypes, the typical characteristics of C. neoformans were found to differ in relation to the different methods of preservation employed. The aim of this study was to demonstrate the importance of selecting the appropriate method of preservation for fungus collections. This selection can affect the survival and purity of the cultures, and preserve the stability of their physiological, biochemical, and genetic characteristics.

Evaluation of oxacillin and cefoxitin disks for detection of resistance in coagulase negative staphylococci

Coagulase-negative Staphylococcus spp. was considered nonpathogenic until the emergence of multiresistance and the demonstration of their participation as infectious agents. In Brazil, oxacillin resistance may be present in over 80% of isolates, and the Clinical and Laboratory Standards Institute standardized a disk-diffusion method to predict this resistance in Staphylococcus. The aim of this study was to evaluate the variability among commercial disks of oxacillin (1 µg) and cefoxitin (30 µg) widely used in clinical laboratories of microbiology, compared with mecA gene and minimum inhibitory concentration (MIC) of oxacillin. The use of oxacillin and cefoxitin disks simultaneously allowed the detection of important differences, particularly, in less frequent species such as S. cohnii, S. haemolyticus, S. saprophyticus, and S. sciuri. Disks of cefoxitin of the brand 2 displayed good correlation with the mecA gene (98.7%) and oxacillin MIC (97.8%), while major discrepancies were observed using disks of brand 1. One of the critical points in the diffusion disk test is the quality of the disks: the use of better quality disks associated with molecular methods lead to better results to define the best antibiotic therapy.

Cessation of alcohol drinking, tobacco smoking and the reversal of head and neck cancer risk.

BACKGROUND: Quitting tobacco or alcohol use has been reported to reduce the head and neck cancer risk in previous studies. However, it is unclear how many years must pass following cessation of these habits before the risk is reduced, and whether the risk ultimately declines to the level of never smokers or never drinkers. METHODS: We pooled individual-level data from case-control studies in the International Head and Neck Cancer Epidemiology Consortium. Data were available from 13 studies on drinking cessation (9167 cases and 12 593 controls), and from 17 studies on smoking cessation (12 040 cases and 16 884 controls). We estimated the effect of quitting smoking and drinking on the risk of head and neck cancer and its subsites, by calculating odds ratios (ORs) using logistic regression models. RESULTS: Quitting tobacco smoking for 1-4 years resulted in a head and neck cancer risk reduction [OR 0.70, confidence interval (CI) 0.61-0.81 compared with current smoking], with the risk reduction due to smoking cessation after >/=20 years (OR 0.23, CI 0.18-0.31), reaching the level of never smokers. For alcohol use, a beneficial effect on the risk of head and neck cancer was only observed after >/=20 years of quitting (OR 0.60, CI 0.40-0.89 compared with current drinking), reaching the level of never drinkers. CONCLUSIONS: Our results support that cessation of tobacco smoking and cessation of alcohol drinking protect against the development of head and neck cancer.

Evaluation of immunomodulatory and anti-inflammatory effects and phytochemical screening of Alternanthera tenella Colla (Amaranthaceae) aqueous extracts

Alternanthera tenella Colla extracts are used in Brazilian traditional folk medicine to treat a variety of infectious diseases as well as inflammation and fever. In this work, the immunomodulatory, anti-inflammatory and potential toxic effects of cold (CAE) and hot (HAE) aqueous extracts of A. tenella were investigated in vivo. In addition, we analyzed the phytochemical properties of both extracts. BALB/c mice were immunized in vivo with sheep red blood cells and concomitantly inoculated intraperitoneally (i.p.) with each extract (50, 100 or 200 mg/kg). Specific antibody-producing cells were enumerated using plaque-forming cell assays (PFC) and anti-SRBC IgG and IgM serum levels were measured via enzyme-linked immunosorbent assay. Body and lymphoid organ weights were determined after treatments in order to evaluate toxic effects. Carrageenan-induced paw edema was employed to investigate anti-inflammatory activity in mice inoculated i.p. with CAE or HAE (200 or 400 mg/kg). Phytochemical screening was performed using spectrometric and chromatographic approaches and revealed that CAE possessed higher tannin and flavonoid levels than HAE. PFC numbers were increased after treatment with CAE (100 mg/kg) four days after immunization, as were the serum antibody titers after four and seven days, suggesting immunostimulatory activity through modulation of B lymphocyte functions. Body and organ weights did not show major changes, suggesting that extracts administered to mice did not induce significant toxicity. Both extracts had significant anti-inflammatory activity in the paw edema assay. These results suggested that aqueous extracts from A. tenella contained several chemical compounds that possess positive and/or negative modulator effects on the immune system, which appeared to correlate with tannin and flavonoid levels in those extracts. In summary, these studies provide important insight into the biological activities of A. tenella.

Robust regression in biological assay: application to the evaluation of alternative experimental techniques.

Robust Huber type regression and testing of linear hypotheses are adapted to statistical analysis of parallel line and slope ratio assays. They are applied in the evaluation of results of several experiments carried out in order to compare and validate alternatives to animal experimentation based on embryo and cell cultures. Computational procedures necessary for the application of robust methods of analysis used the conversational statistical package ROBSYS. Special commands for the analysis of parallel line and slope ratio assays have been added to ROBSYS.

Comparative evaluation of phenol and thimerosal as preservatives for a candidate vaccine against American cutaneous leishmaniasis

For decades thimerosal has been used as a preservative in the candidate vaccine for cutaneous leishmaniasis, which was developed by Mayrink et al. The use of thimerosal in humans has been banned due to its mercury content. This study addresses the standardization of phenol as a new candidate vaccine preservative. We have found that the proteolytic activity was abolished when the test was conducted using the candidate vaccine added to merthiolate (MtVac) as well as to phenol (PhVac). The Montenegro's skin test conversion rates induced by MtVac and by PhVac was 68.06% and 85.9%, respectively, and these values were statistically significant (p < 0.05). The proliferative response of peripheral mononuclear blood cells shows that the stimulation index of mice immunized with both candidate vaccines was higher than the one in control animals (p < 0.05). The ability of the candidate vaccines to induce protection in C57BL/10 mice against a challenge with infective Leishmania amazonensis promastigotes was tested and the mice immunized with PhVac developed smaller lesions than the mice immunized with MtVac. Electrophoresis of phenol-preserved antigen revealed a number of proteins, which were better preserved in PhVac. These results do in fact encourage the use of phenol for preserving the immunogenic and biochemical properties of the candidate vaccine for cutaneous leishmaniasis.

Meaning of the λ parameter of skew–normal and log–skew normal distributions in fluid geochemistry

The literature related to skew–normal distributions has grown rapidly in recent yearsbut at the moment few applications concern the description of natural phenomena withthis type of probability models, as well as the interpretation of their parameters. Theskew–normal distributions family represents an extension of the normal family to whicha parameter (λ) has been added to regulate the skewness. The development of this theoreticalfield has followed the general tendency in Statistics towards more flexible methodsto represent features of the data, as adequately as possible, and to reduce unrealisticassumptions as the normality that underlies most methods of univariate and multivariateanalysis. In this paper an investigation on the shape of the frequency distribution of thelogratio ln(Cl−/Na+) whose components are related to waters composition for 26 wells,has been performed. Samples have been collected around the active center of Vulcanoisland (Aeolian archipelago, southern Italy) from 1977 up to now at time intervals ofabout six months. Data of the logratio have been tentatively modeled by evaluating theperformance of the skew–normal model for each well. Values of the λ parameter havebeen compared by considering temperature and spatial position of the sampling points.Preliminary results indicate that changes in λ values can be related to the nature ofenvironmental processes affecting the data

Leprosy reactions: the effect of gender and household contacts

Various host-related factors have been reported as relevant risk factors for leprosy reactions. To support a new hypothesis that an antigenic load in local tissues that is sufficient to trigger the immune response may come from an external supply of Mycobacterium leprae organisms, the prevalence of reactional leprosy was assessed against the number of household contacts. The number of contacts was ascertained at diagnosis in leprosy patients coming from an endemic area of Brazil. The prevalence of reactions (patients with reactions/total patients) was fitted by binomial regression and the risk difference (RD) was estimated with a semi-robust estimation of variance as a measure of effect. Five regression models were fitted. Model 1 included only the main exposure variable "number of household contacts"; model 2 included all four explanatory variables ("contacts", "fertile age", "number of skin lesions" and "bacillary index") that were found to be associated with the outcome upon univariate analysis; models 3-5 contained various combinations of three predictors. Male and female patients were analyzed separately. In females, household contacts were a significant predictor for leprosy reactions in model 1 [crude RD = 0.06; 95% confidence interval (CI) = 0.01; 0.12] and model 5 (RD = 0.05; CI = 0.02; 0.09), which included contacts, bacillary index and skin lesions as predictors. Other models were unsatisfactory because the joint presence of fertile age and bacillary index was a likely source of multicollinearity. No significant results were obtained for males. The likely interpretation of our findings might suggest that in female patients, leprosy reactions may be triggered by an external spreading of M. leprae by healthy carrier family members. The small number of observations is an obvious limitation of our study which requires larger confirmatory studies.

Evaluation of RbCl and CrCl3 as markers of Triatoma brasiliensis (Hemiptera: Reduviidae) nymphs: persistence and influence of Rb and Cr on triatomine biology

In order to mark Triatoma brasiliensis, the vector of Chagas disease in Brazil, two chemical compounds, rubidium chloride (RbCl) and chromium chloride (CrCl3), were tested. First, 199 N2-N5 nymphs were fed on blood with 0.025M RbCl. Rb marker positivity ranged from 2.5% (N3)-70% (N2), with a maximum persistence of 98 days. Second, 265 N2-N5 nymphs were fed on blood containing 0.0015M CrCl3. Cr marker positivity ranged up to 93% (N5), with a maximum persistence of 119 days. Finally, we blood fed 213 T. brasiliensis to investigate whether CrCl3 altered the biology of this insect. The developmental time of T. brasiliensis was unaltered, but the survival of the Cr-marked group was lower than that of the control group. Differences in the mean fecundity of the control (mean of 156.1) and experimental (mean of 135.6) groups were not statistically significant and 100% of the egg batches of females Cr-marked as nymphs were positive. In conclusion, CrCl3 is a useful tool for marking T. brasiliensis nymphs due to its high positivity and persistence.

A comparative evaluation of endemic and non-endemic region of visceral leishmaniasis (Kala-azar) in India with ground survey and space technology

In visceral leishmaniasis, phlebotomine vectors are targets for control measures. Understanding the ecosystem of the vectors is a prerequisite for creating these control measures. This study endeavours to delineate the suitable locations of Phlebotomus argentipes with relation to environmental characteristics between endemic and non-endemic districts in India. A cross-sectional survey was conducted on 25 villages in each district. Environmental data were obtained through remote sensing images and vector density was measured using a CDC light trap. Simple linear regression analysis was used to measure the association between climatic parameters and vector density. Using factor analysis, the relationship between land cover classes and P. argentipes density among the villages in both districts was investigated. The results of the regression analysis indicated that indoor temperature and relative humidity are the best predictors for P. argentipes distribution. Factor analysis confirmed breeding preferences for P. argentipes by landscape element. Minimum Normalised Difference Vegetation Index, marshy land and orchard/settlement produced high loading in an endemic region, whereas water bodies and dense forest were preferred in non-endemic sites. Soil properties between the two districts were studied and indicated that soil pH and moisture content is higher in endemic sites compared to non-endemic sites. The present study should be utilised to make critical decisions for vector surveillance and controlling Kala-azar disease vectors.

Ultrasound versus biological markers in the evaluation of periportal fibrosis in human Schistosoma mansoni

In this paper, the authors review the literature and share their experience of the principal biological markers of fibrosis for the evaluation of periportal fibrosis (PPF) caused by mansoni schistosomiasis. These biological markers are compared to diagnostic ultrasound (US) scans as means of grading PPF. We also review procollagen type I and III, collagen type IV, laminin, hyaluronic acid (HA), immunoglobulin G, platelets, aspartate aminotransferase to platelet ratio index (APRI) and gamma-glutamyl transpeptidase as markers of the disease. Although there are several good markers for evaluating PPF and portal hypertension, such as HA, platelets or APRI, none can yet replace US. These markers may, however, be used to identify patients at greater risk of developing advanced disease in endemic areas and determine who will need further care and US studies.

Polymerase chain reaction for the evaluation of Schistosoma mansoni infection in two low endemicity areas of Minas Gerais, Brazil

This study aimed to evaluate the occurrence of schistosomiasis in areas with low endemicity using polymerase chain reaction (PCR) as a diagnostic method. We analysed faecal samples from 219 individuals residing in Piau and Coronel Pacheco, state of Minas Gerais, Brazil, using a single faecal sample from each individual and two slides of the Kato-Katz technique as a gold standard. Fifteen out of the 219 samples were positive with both methods of diagnosis. One sample was diagnosed as positive by the Kato-Katz technique only and 61 were diagnosed only by PCR. The positivity rates were 7.3% with the Kato-Katz method and 34.7% with PCR. When both techniques were assumed to have 100% specificity and positive individuals were identified by both methods, the sensitivity of the Kato-Katz method was 20.8% and the PCR sensitivity was 98.7%. The Kappa index between the two techniques was 0.234, suggesting weak agreement. The assessment of a single faecal sample by PCR detected more cases of infection than the analysis of one sample with two slides using the Kato-Katz technique, suggesting that PCR can be a useful diagnostic tool, particularly in areas with low endemicity.

Insights from animal models on the immunogenetics of leprosy: a review

A variety of host immunogenetic factors appear to influence both an individual's susceptibility to infection with Mycobacterium leprae and the pathologic course of the disease. Animal models can contribute to a better understanding of the role of immunogenetics in leprosy through comparative studies helping to confirm the significance of various identified traits and in deciphering the underlying mechanisms that may be involved in expression of different disease related phenotypes. Genetically engineered mice, with specific immune or biochemical pathway defects, are particularly useful for investigating granuloma formation and resistance to infection and are shedding new light on borderline areas of the leprosy spectrum which are clinically unstable and have a tendency toward immunological complications. Though armadillos are less developed in this regard, these animals are the only other natural hosts of M. leprae and they present a unique opportunity for comparative study of genetic markers and mechanisms associable with disease susceptibility or resistance, especially the neurological aspects of leprosy. In this paper, we review the recent contributions of genetically engineered mice and armadillos toward our understanding of the immunogenetics of leprosy.