Determination of reactivity rates of silicate particle-size fractions

The efficiency of sources used for soil acidity correction depends on reactivity rate (RR) and neutralization power (NP), indicated by effective calcium carbonate (ECC). Few studies establish relative efficiency of reactivity (RER) for silicate particle-size fractions, therefore, the RER applied for lime are used. This study aimed to evaluate the reactivity of silicate materials affected by particle size throughout incubation periods in comparison to lime, and to calculate the RER for silicate particle-size fractions. Six correction sources were evaluated: three slags from distinct origins, dolomitic and calcitic lime separated into four particle-size fractions (2, 0.84, 0.30 and <0.30-mm sieves), and wollastonite, as an additional treatment. The treatments were applied to three soils with different texture classes. The dose of neutralizing material (calcium and magnesium oxides) was applied at equal quantities, and the only variation was the particle-size material. After a 90-day incubation period, the RER was calculated for each particle-size fraction, as well as the RR and ECC of each source. The neutralization of soil acidity of the same particle-size fraction for different sources showed distinct solubility and a distinct reaction between silicates and lime. The RER for slag were higher than the limits established by Brazilian legislation, indicating that the method used for limes should not be used for the slags studied here.

Comparison of different methods for the determination of total organic carbon and humic substances in Brazilian soils

ABSTRACTAiming to compare three different methods for the determination of organic carbon (OC) in the soil and fractions of humic substances, seventeen Brazilian soil samples of different classes and textures were evaluated. Amounts of OC in the soil samples and the humic fractions were measured by the dichromate-oxidation method, with and without external heating in a digestion block at 130 °C for 30 min; by the loss-on-ignition method at 450 °C during 5 h and at 600 °C during 6 h; and by the dry combustion method. Dry combustion was used as reference in order to measure the efficiency of the other methods. Soil OC measured by the dichromate-oxidation method with external heating had the highest efficiency and the best results comparing to the reference method. When external heating was not used, the mean recovery efficiency dropped to 71%. The amount of OC was overestimated by the loss-on-ignition methods. Regression equations obtained between total OC contents of the reference method and those of the other methods showed relatively good adjustment, but all intercepts were different from zero (p < 0.01), which suggests that more accuracy can be obtained using not one single correction factor, but considering also the intercept. The Walkley-Black method underestimated the OC contents of the humic fractions, which was associated with the partial oxidation of the humin fraction. Better results were obtained when external heating was used. For the organic matter fractions, the OC in the humic and fulvic acid fractions can be determined without external heating if the reference method is not available, but the humin fraction requires the external heating.

Enzyme linked immunosorbent assay: determination of anti-adenovirus antibodies in an infant population

In order to define an accurate assay for anti-adenovirus antibody detection, a recently developed ELISA was compared with IFA and CF. On 58 sera, the ELISA was more sensitive than both CF and IFA, which showed relative sensitivities of 63% and 94%, respectively. It was not possible to determine the exact specificity of the tests because of the lack of a gold standard. Furthermore, the ELISA was used to define the prevalence of adenovirus antibodies in 116 infants between 1 and 24 months old (mean 7.28). The data showed that maternal antibodies waned by the age of 5 to 6 months and that more than 80% of the children had been infected by adenoviruses by the age of 10 months.

Seroprevalence of hepatitis B virus infection in individuals with clinical evidence of hepatitis in Goiânia, Goiás: detection of viral DNA and determination of subtypes

The presence of serological markers for hepatitis B virus (HBsAg, anti-HBc IgM and Anti-HBc total) was investigated in the serum of 1,396 individuals who had clinical suspect of hepatitis. It was observed that 50.7% of the individuals were positive and, from the total of the studied individuals, 14.5% were positive for HBsAg. From these, 8.5% were also positive for anti-HBc IgM. The analysis in relation to gender showed a higher seroprevalence index among male individuals (p < 0.0001). It was observed the occurrence of subtypes adw2 (62.7%), ayw3 (23.5%), ayw2 (9.8%) and adw4 (3.9%). The viral DNA was detected in 61 (33.9%) HBsAg positive samples and in one sample positive only for anti-HBc total. These results indicate an important incidence of the HBV infection in this population, and reinforce previous studies regarding this virus in the central west region of Brazil.

Determination of human cytomegalovirus genetic diversity in different patient populations in Costa Rica

Seroprevalence of HCMV in Costa Rica is greater than 95% in adults; primary infections occur early in life and is the most frequent congenital infection in newborns. The objectives of this study were to determine the genetic variability and genotypes of HCMV gB gene in Costa Rica. Samples were collected from alcoholics, pregnant women, blood donors, AIDS patients, hematology-oncology (HO) children and HCMV isolates from neonates with cytomegalic inclusion disease. A semi-nested PCR system was used to obtain a product of 293-296 bp of the gB gene to be analyzed by Single Stranded Conformational Polymorphism (SSCP) and sequencing to determine the genetic polymorphic pattern and genotypes, respectively. AIDS patients showed the highest polymorphic diversity with 14 different patterns while fifty-six percent of HO children samples showed the same polymorphic pattern, suggesting in this group a possible nosocomial infection. In neonates three genotypes (gB1, gB2 and gB3), were determined while AIDS patients and blood donors only showed one (gB2). Of all samples analyzed only genotypes gB1, 2 and 3 were determined, genotype gB2 was the most frequent (73%) and mixed infections were not detected. The results of the study indicate that SSCP could be an important tool to detect HCMV intra-hospital infections and suggests a need to include additional study populations to better determine the genotype diversity and prevalence.

Genotyping, serotyping and determination of mating-type of Cryptococcus neoformans clinical isolates from São Paulo State, Brazil

The basidiomycetous yeast Cryptococcus neoformans is an important fungal pathogen mainly in immunocompromised patients. In this study, 47 clinical isolates of C. neoformans from regions of São Paulo State were studied serologically by using the Crypto Check Iatron RM 304-K kit, their genetic diversity was estimated by PCR-fingerprinting with a microsatellite-specific sequence (GACA)4, RAPD with primer 6 (Amersham Pharmacia Biotech), PCR-restriction fragment length polymorphism (RFLP) analysis of the phospholipase B gene (PLB1) digested with AvaI and mating type analysis by PCR. All 47 strains isolated from HIV positive patients included in this study were serotype A and MATalpha. The majority of the isolates (45/47) were VNI and only two were VNII by PCR-fingerprinting and PCR-RFLP analysis. High degree of homogeneity was observed when (GACA)4 was used, being highly correlated (> 0.9). In contrast, the RAPD analysis was more heterogeneous with higher number of molecular profiles. By PCR-RFLP, no new molecular type was found, enhancing the suggestion that the differences based on conserved gene as PLB1, can be resultant of ongoing divergent evolution within the C. neoformans complex, into the current eight subtypes. Our results furnish new information on the molecular epidemiology of C. neoformans in the southeast region of Brazil.

DETERMINATION OF VIRAL TROPISM BY GENOTYPING AND PHENOTYPING ASSAYS IN BRAZILIAN HIV-1-INFECTED PATIENTS

The clinical application of CCR5 antagonists involves first determining the coreceptor usage by the infecting viral strain. Bioinformatics programs that predict coreceptor usage could provide an alternative method to screen candidates for treatment with CCR5 antagonists, particularly in countries with limited financial resources. Thus, the present study aims to identify the best approach using bioinformatics tools for determining HIV-1 coreceptor usage in clinical practice. Proviral DNA sequences and Trofile results from 99 HIV-1-infected subjects under clinical monitoring were analyzed in this study. Based on the Trofile results, the viral variants present were 81.1% R5, 21.4% R5X4 and 1.8% X4. Determination of tropism using a Geno2pheno[coreceptor] analysis with a false positive rate of 10% gave the most suitable performance in this sampling: the R5 and X4 strains were found at frequencies of 78.5% and 28.4%, respectively, and there was 78.6% concordance between the phenotypic and genotypic results. Further studies are needed to clarify how genetic diversity amongst virus strains affects bioinformatics-driven approaches for determining tropism. Although this strategy could be useful for screening patients in developing countries, some limitations remain that restrict the wider application of coreceptor usage tests in clinical practice.

Determination of germ tube, phospholipase, and proteinase production by bloodstream isolates of Candida albicans

Introduction Candida albicans is a commensal and opportunistic agent that causes infection in immunocompromised individuals. Several attributes contribute to the virulence and pathogenicity of this yeast, including the production of germ tubes (GTs) and extracellular hydrolytic enzymes, particularly phospholipase and proteinase. This study aimed to investigate GT production and phospholipase and proteinase activities in bloodstream isolates of C. albicans. Methods One hundred fifty-three C. albicans isolates were obtained from blood samples and analyzed for GT, phospholipase, and proteinase production. The assays were performed in duplicate in egg yolk medium containing bovine serum albumin and human serum. Results Detectable amounts of proteinase were produced by 97% of the isolates, and 78% of the isolates produced phospholipase. GTs were produced by 95% of the isolates. A majority of the isolates exhibited low levels of phospholipase production and high levels of proteinase production. Conclusions Bloodstream isolates of C. albicans produce virulence factors such as GT and hydrolytic enzymes that enable them to cause infection under favorable conditions.

Experimental determination of bone cortex holding power of orthopedic screw

Cylindrical specimens of bone measuring 15 mm in diameter were obtained from the lateral cortical layer of 10 pairs of femurs and tibias. A central hole 3.2 mm in diameter was drilled in each specimen. The hole was tapped, and a 4.5 mm cortical bone screw was inserted from the outer surface. The montage was submitted to push-out testing up to a complete strip of the bone threads. The cortical thickness and rupture load were measured, and the shear stress was calculated. The results were grouped according to the bone segment from which the specimen was obtained. The results showed that bone cortex screw holding power is dependent on the bone site. Additionally, the diaphyseal cortical bone tissue is both quantitatively and qualitatively more resistant to screw extraction than the metaphyseal tissue.

Determination of fat soluble vitamins from amazonian fresh-water fishes. I. HPLC analysis of tambaqui, pirarucu and cuiu-cuiu livers .

It was found that fish livers from the Amazon have considerable amounts of vitamins A, D and E compared with the values of the standartized cod-liver oil. Tambaqui liver oil has high concentration of vitamin A1(retinol) and vitamin A2 (degidroretinol) whereas the liver oils of pirarucu and cuiu-cuiu have preferently the vitamin A2. The contents of the vitamins D and E observed in the liver oils of tambaqui and cuiu-cuiu was extremely high.

On line pre-concentration for simultaneous determination of low molecular weight organic acids and inorganic anions in Amazonian river water samples employing ion chromatography with conductivity detection

An ion chromatography procedure, employing an IonPac AC15 concentrator column was used to investigate on line preconcentration for the simultaneous determination of inorganic anions and organic acids in river water. Twelve organic acids and nine inorganic anions were separated without any interference from other compounds and carry-over problems between samples. The injection loop was replaced by a Dionex AC15 concentrator column. The proposed procedure employed an auto-sampler that injected 1.5 ml of sample into a KOH mobile phase, generated by an Eluent Generator, at 1.5 mL min-1, which carried the sample to the chromatographic columns (one guard column, model AG-15, and one analytical column, model AS15, with 250 x 4mm i.d.). The gradient elution concentrations consisted of a 10.0 mmol l-1 KOH solution from 0 to 6.5 min, gradually increased to 45.0 mmol l-1 KOH at 21 min., and immediatelly returned and maintained at the initial concentrations until 24 min. of total run. The compounds were eluted and transported to an electro-conductivity detection cell that was attached to an electrochemical detector. The advantage of using concentrator column was the capability of performing routine simultaneous determinations for ions from 0.01 to 1.0 mg l-1 organic acids (acetate, propionic acid, formic acid, butyric acid, glycolic acid, pyruvate, tartaric acid, phthalic acid, methanesulfonic acid, valeric acid, maleic acid, oxalic acid, chlorate and citric acid) and 0.01 to 5.0 mg l-1 inorganic anions (fluoride, chloride, nitrite, nitrate, bromide, sulfate and phosphate), without extensive sample pretreatment and with an analysis time of only 24 minutes.

Brazil nuts: determination of natural elements and aflatoxin

A study was carried out to evaluate the association of levels of radioactivity, selenium and aflatoxin in shelled Brazil nuts, which were classified in different sizes, for export. The selenium determinations were performed by inductively coupled plasma optical emission spectrometry (LOQ = 3.0 µg g-1), and aflatoxins were detected by Liquid chromatography-mass spectrometry (LOQ = 0.85 µg kg-1), recovery rates were between 92 and 100%. Radioactivity was measured by high-resolution gamma spectrometry. The selenium mean concentration was (22.7 ± 7.4) µg g-1. (n = 30). Mean activities determined for the following radium isotopes were: 15.77 Bq kg-1 for 224Ra, 104.8 Bq kg-1 for 226Ra and 99.48 Bq kg-1 for 228Ra. For 226Ra, the levels did not vary significantly with nut sizes, although such differences were observed for 224Ra and 228Ra. There was no statistically significant association between the level of selenium and the activity of radionuclides, however, there was correlation between the radionuclides. Aflatoxins above the quantification limit were not found.

National alert campaign about increased cholesterol: determination of cholesterol levels in 81,262 Brazilians

OBJECTIVE: To determine the levels of total cholesterol in a significant sample of the Brazilian population. METHODS: Blood cholesterol was determined in 81.262 individuals > 18 years old (51% male, 44.7 ± 15.7 years), using Accutrend equipment, in the cities São Paulo, Campinas, Campos do Jordão, São José dos Campos, Santos, Santo André, Ribeirão Preto, Porto Alegre, Rio de Janeiro, Belo Horizonte, Curitiba, Brasília, Salvador and documented in the presence of other risk factors (RF) for coronary artery disease (CAD) (systemic hypertension, CAD in the family, smoking, and diabetes). Participants were classified according to sex, age, and the presence or absence of RF, respectively, as 0 RF, 1 RF and > 2 RF. The percentage of individuals with cholesterol > 200 mg/dL and > 240 mg/dL was evaluated. RESULTS: The prevalence of individuals with 0, 1, and > 2 risk factors was 30% (n = 24,589), 36% (n =29,324), and 34% (n = 27,349) respectively, (P=0.657), and the mean total cholesterol of the population was 199.0 ± 35.0 mg/dL. Cholesterol levels above 200 and 240 mg/dL were found, respectively, in 40% (n = 32,515) and 13% (10.942) of individuals. The greater the number of risk factors the higher the levels of cholesterol (P<0.0001) and the greater the proportion of individuals with cholesterol > 200 mg/dL (P=0.032). No difference existed in the proportion of individuals with cholesterol > 240 mg/dL (P=0.11). CONCLUSION: A great percentage of individuals with cholesterol levels above those recommended to prevent coronary artery disease was found.

On the determination of reducing corticosteroids

1. The authors preconize the use of Folin-Ciocalteu's reagent in the colorimetric determination of reducing cortcosteroids. 2. The reaction follows Beer's law in the range 0-50 μg of 11-desoxycorticosterone. 3. Determinations made in human urine and adrenal glands of rats and guinea pigs are comparable with results obtained by other methods.

Use of PCR for the determination of the frequency of the deltaF508 mutation in Brasilian cistic fibrosis patients

The [Delta]F508 mutation in the cystic fibrosis (CF) gene was studied in a population of 18 Brazilian CF patients and their 17 families by use of PCR and differential hybridization with oligonucleotides. In a total of 34 chromosomes considered, 12 (35%) carried the F508 deletion, a frequency much lower than that reported in most other populations. As a consequence, CF in Brazil would be predominantly caused by mutations different from the F508 deletion