Thermoluminescence, OSL and defect centers in Tb doped magnesium orthosilicate phosphor.

Mg2SiO4:Tb phosphor exhibits four thermoluminescence (TL) peaks at 124, 244, 300 and 370°C for a heating rate of 2°C/s, 244°C peak being the main dosimetry peak. The irradiated phosphor exhibits CW-OSL response on stimulation with blue (470nm) light. Thermal decay of OSL shows that all the TL traps contribute to CW-OSL signal. Its TL and OSL sensitivities are 0.21 and 0.038, respectively, than that of Al2O3:C (Landauer Inc.). Its CW-OSL response increases linearly up to 30Gy, thereafter increase was supralinear up to the studied dose of 1000Gy. Electron Spin Resonance (ESR) studies were carried out to study the defect centers induced in the phosphor by gamma irradiation and also to identify the centers responsible for the TL process. Room temperature ESR spectrum of irradiated phosphor appears to be a superposition of at least three distinct centers. One of the centers (center I) with an isotropic g-factor 2.0122 is attributable to an intrinsic O(-) radical and this correlates with the main TL peak at 244°C. Center II with an isotropic g-factor 2.0012 is assigned to an F(+)-center (singly ionized oxygen vacancy) and is the likely recombination center for all the TL peaks. Both the centers grow with radiation dose at least up to 1 kGy. Center III with an axial symmetric g-tensor with principal g-values g||=2.0049 and g⊥=2.0029 is identified as an F(+)-center and is not related to the observed TL peaks in the phosphor.

Identification of vascular territory resistances in one-dimensional hemodynamics simulations.

The present work deals with the parameter identification problem in outflow models used in one-dimensional simulations of arterial blood flow. Specifically, the resistive elements that define the models used to account for the blood supply to the vascular territories in arterial networks are computed by solving a system of non-linear equations using a Broyden method. This strategy is employed to compute the terminal parameters in the vascular territories of an anatomically detailed model of the arm comprising 67 arterial segments and 16 vascular territories. A comparison with a simple analytical approach, in terms of vascular territory resistances, average blood flows and time-dependent hemodynamic quantities, is performed. Also, a sensitivity analysis is presented to assess the performance of this new approach in normal and abnormal cardiovascular scenarios. This identification procedure allows to correctly set up hemodynamics simulations in highly detailed arterial networks making possible to gain insight in the aspects related to the blood circulation in arterial vessels.

PP138. Human fetal malformations associated with the use of angiotensin II receptor antagonist.

INTRODUCTION: antagonists of angiotensin II receptor (AAR) are commonly used for the treatment of chronic hypertension in the general population. Some of these pharmacological agents are losartan, candesartan, valsartan and tasosartan. Despite the good response achieved with these drugs in the control of hypertension, all medications that act directly on the renin-angiotensin system should be contraindicated during pregnancy. These drugs have been associated with fetal and neonatal injury, including hypotension, neonatal skull hypoplasia, anuria, reversible or irreversible renal failure and death.Here we report a case of fetal malformations and death associated with the use of losartan. OBJECTIVES: describing the association of fetal malformations and the use of losartan during first and second trimester of pregnancy. METHODS: this is a case report involving a 37-year-old pregnant woman at 26 gestational weeks. This patient had history of chronic hypertension for more than five years that was being regularly treated with Losartan 50mg/day. After her first consultation losartan was promptly discontinued and substituted for methyldopa. However, scan evaluation demonstrated severe oligohydramnios associated with altered fetal biophysical profile and altered Doppler fluxometry (absent diastolic flow at umbilical arteries). Therefore, a cesarean-section was performed after corticoid administration for fetal lung maturation. At first moment some characteristic alterations as fetal limb contractures and craniofacial deformation were detected at the 1007g new-born. This baby went to death 36h after delivery due to severe lung hypoplasia. RESULTS: the autopsy examination revealed renal tubular dysgenesis associated with changes secondary to nephropathy, probably induced by drug (Fig. 1). Associated findings were underdevelopment of bones of the skull with large fontanelles, thymus atrophy and signs of perinatal hypoxia. CONCLUSION: the difficulty of attending basic health assistance was attributed to be associated with this case, as this patient did not have opportunity and sufficient information about the necessity of changing her medication during pregnancy. Apart from this situation, this case report brings good information about the association between antagonists of angiotensin II receptor and human fetal malformations.

Thermoluminescence properties of natural zoisite mineral under γ-irradiations and high temperature annealing.

Natural silicate mineral of zoisite, Ca(2)Al(3)(SiO(4))(Si(2)O(7))O(OH), has been investigated concerning γ-radiation, UV-radiation and high temperature annealing effects on thermoluminescence (TL). X-ray diffraction (XRD) measurement confirmed zoisite structure and X-ray fluorescence (XRF) analysis revealed besides Si, Al and Ca that are the main crystal components, other oxides of Fe, Mg, Cr, Na, K, Sr, Ti, Ba and Mn which are present in more than 0.05 wt%. The TL glow curve of natural sample contains (130-150), (340-370) and (435-475)°C peaks. Their shapes indicated a possibility that they are result of composition of two or more peaks strongly superposed, a fact confirmed by deconvolution method. Once pre-annealed at 600°C for 1h, the shape of the glow curves change and the zoisite acquires high sensitivity. Several peaks between 100 and 400°C appear superposed, and the high temperature peak around 435°C cannot be seen. The ultraviolet radiation, on the other hand, produces one TL peak around 130°C and the second one around 200°C and no more.

Thermoluminescence dating of Brazilian indigenous ceramics.

Two indigenous ceramics fragments, one from Lagoa Queimada (LQ) and another from Barra dos Negros (BN), both sites located on Bahia state (Brazil), were dated by thermoluminescence (TL) method. Each fragment was physically prepared and divided into two fractions, one was used for TL measurement and the other for annual dose determination. The TL fraction was chemically treated, divided in sub samples and irradiated with several doses. The plot extrapolation from TL intensities as function of radiation dose enabled the determination of the accumulated dose (D(ac)), 3.99 Gy and 1.88 Gy for LQ and BN, respectively. The annual dose was obtained through the uranium, thorium and potassium determination by ICP-MS. The annual doses (D(an)) obtained were 2.86 and 2.26 mGy/year. The estimated ages were approximately 1375 and 709 y for BN and LQ ceramics, respectively. The ages agreed with the archaeologists' estimation for the Aratu and Tupi tradition periods, respectively.

Chemical process to separate iron oxides particles in pottery sample for EPR dating.

Ancient potteries usually are made of the local clay material, which contains relatively high concentration of iron. The powdered samples are usually quite black, due to magnetite, and, although they can be used for thermoluminescene (TL) dating, it is easiest to obtain better TL reading when clearest natural or pre-treated sample is used. For electron paramagnetic resonance (EPR) measurements, the huge signal due to iron spin-spin interaction, promotes an intense interference overlapping any other signal in this range. Sample dating is obtained by dividing the radiation dose, determined by the concentration of paramagnetic species generated by irradiation, by the natural dose so as a consequence, EPR dating cannot be used, since iron signal do not depend on radiation dose. In some cases, the density separation method using hydrated solution of sodium polytungstate [Na6(H2W12O40).H2O] becomes useful. However, the sodium polytungstate is very expensive in Brazil; hence an alternative method for eliminating this interference is proposed. A chemical process to eliminate about 90% of magnetite was developed. A sample of powdered ancient pottery was treated in a mixture (3:1:1) of HCl, HNO(3) and H(2)O(2) for 4h. After that, it was washed several times in distilled water to remove all acid matrixes. The original black sample becomes somewhat clearer. The resulting material was analyzed by plasma mass spectrometry (ICP-MS), with the result that the iron content is reduced by a factor of about 9. In EPR measurements a non-treated natural ceramic sample shows a broad spin-spin interaction signal, the chemically treated sample presents a narrow signal in g=2.00 region, possibly due to a radical of (SiO(3))(3-), mixed with signal of remaining iron [M. Ikeya, New Applications of Electron Spin Resonance, World Scientific, Singapore, 1993, p. 285]. This signal increases in intensity under gamma-irradiation. However, still due to iron influence, the additive method yielded too old age-value. Since annealing at 300 degrees C, Toyoda and Ikeya [S. Toyoda, M. Ikeya, Geochem. J. 25 (1991) 427-445] states that E1'-signal with maximum intensity is obtained, while annealing at 400 degrees C E1'-signal is completely eliminated, the subtraction of the second one from 300 degrees C heat-treated sample isolate E1'-like signal. Since this is radiation dose-dependent, we show that now EPR dating becomes possible.

Use of [Pb-Pb]3+ center of the amazonite for dating.

In the present work, dating of one type of amazonite sample using the [Pb-Pb]3+ dimeric center is carried out by electron spin resonance (ESR). The thermal stability of the center is investigated using isochronal annealing at several temperatures from 200 to 500 degrees C for 15 min. Using isothermal annealing, the lifetime of the center was also estimated. The extrapolation of the straight line in the Arrhenius plot gives a lifetime of approximately 0.25 Ma at room temperature. The age obtained from sample was 90 ka.

On the quasi-equilibrium problem in thermally stimulated luminescence and conductivity.

Strong doubts havc been expressed about the validity of the quasi-equilibrium (QE) assumption used in the derivation of the analytical expressions of thermoluminescence (TL). So far there is no established method available to check if QE actually prevails during the emission of an experimental TL signal. The present study shows that the level of QE changes with a change in the heating rate beta. The change in the level of QE in its turn gets reflected in a change in peak shape when the system turns to a non-QE condition. This property is used as the first ever experimental method to test whether or not the emission of a given glow peak occurs under the QE condition. An essential condition for holding the QE condition is found to be T(R)/taum> or = 10(-3) where T(R) and taum are the glow peak recording duration and the maximum value of the free carrier lifetime, respectively. This relation between T(R) and taum is useful in finding the approximate value of taum. The value of taum being a function of the concentration and cross section of the TL related centres, one may be able to assess these basic parameters from the study of TL glow curves. The theoretical results are discussed in the perspective of LiF (TLD-100).

TL, EPR and optical absorption studies on natural alexandrite compared to natural chrysoberyl.

The TL, optical absorption (OA) and EPR properties of natural Brazilian alexandrite and chrysoberyl have been investigated. The TL measurements for natural alexandrite show five peaks between 100 and 450 degrees C, with their emission spectrum having 370 and/or 570 nm components. The intensity of the 320 degrees C TL peak was found to be enhanced with pre-annealing treatment, more prominently above 600 degrees C. The OA and EPR measurements showed that this kind of heat treatment induces the Fe2+ --> Fe3+ conversion in the natural sample. Chrysoberyl samples exhibited the TL peaks at the same temperatures as alexandrite samples, but the glow curves were more than 200 times less intense than alexandrite ones.

Epstein-Barr virus-associated gastric carcinoma in Japanese Brazilians and non-Japanese Brazilians in São Paulo.

The proportion of Epstein-Barr virus-associated gastric carcinoma (EBV-GC) was examined in 149 Japanese-Brazilian and 151 non-Japanese-Brazilian gastric-carcinoma cases using in situ hybridization (ISH) assay to detect EBV-encoded small RNA (EBER), and the results were compared with our referent Japanese data. We found that 4.7% of cases in Japanese Brazilians were EBER-positive. This frequency was slightly lower than that of the referent Japanese, among whom 6.2% of 2038 gastric-carcinoma cases were EBER-positive. On the other hand, the non-Japanese-Brazilian series showed a significantly higher proportion of EBV-GC (11.2%) than the referent group did (P = 0.01). Although EBV-GC was predominant in males among non-Japanese Brazilians (M / F = 3.6, P = 0.047), as was the case in Japanese (M / F = 2.7), Japanese Brazilians did not show such a male predominance. The sex-ratio difference between the Japanese Brazilians and Japanese was statistically significant (P = 0.005). In conclusion, the present study in Japanese Brazilians and Japanese yielded no evidence suggesting any change in the frequency of EBV-GC caused by migration, except the absence of male predominance, which was observed both in Japanese and non-Japanese Brazilians.

Haloarcula argentinensis sp. nov. and Haloarcula mukohataei sp. nov., two new extremely halophilic archaea collected in Argentina.

Strains arg-1T (T = type strain) and arg-2T, two new strains of extremely halophilic archaea, were isolated from the soils of the Argentine salt flats. The taxonomic features of arg-1T were similar to, but distinct from, those of the type strain of Haloarcula vallismortis and other Haloarcula species. On the 16S rRNA phylogenetic tree, strain arg-1T formed a cluster together with Haloarcula species. Strain arg-2T differed in its glycolipid composition but still was more closely related to the genus Haloarcula than to other established genera. We propose that strain arg-1T be classified as a member of a new species, Haloarcula argentinensis, and that strain arg-2T be classified as a member of Haloarcula mukohataei sp. nov., although arg-2T may belong to a new genus or a subgenus of the genus Haloarcula. The type strain of H. argentinensis is strain arg-1 (= JCM 9737), and the type strain of H. mukohataei is strain arg-2 (= JCM 9738).

The heme-binding region polymorphism of cytochrome P450IA1 (CypIA1), rather than the RsaI polymorphism of IIE1 (CypIIE1), is associated with lung cancer in Rio de Janeiro.

Ile-Val polymorphism in exon 7 of cytochrome P450IA1 (CypIA1) and RsaI polymorphism of cytochrome P450IIE1 (CypIIE1) were examined in a case-control study of lung cancer in Rio de Janeiro, Brazil. The Val-containing genotype in exon 7 of CypIA1 was found to be associated with lung cancer in this population (odds ratio, 2.26; 95% confidence interval, 1.14-4.47 for 99 cases versus 108 controls of 123 matched pairs), whereas RsaI polymorphism in CypIIE1 was not associated with lung cancer susceptibility. In squamous cell carcinoma, the degree of association of Val-containing genotype was greater in those with fewer pack-years of smoking. The RsaI polymorphism of CypIIE1 has a different distribution from the Japanese pattern and is not associated with lung cancer. When we analyzed the association of Ile-Val polymorphism to MspI polymorphism of CypIA1, the Val/Val homozygote was found only in the subpopulation with the MspI site-present homozygote. The apparent lack of association of CypIA1 MspI polymorphism with lung cancer in this area reported in our previous study and the results of the present study indicate that the "true" responsible site for lung cancer susceptibility should be the Ile-Val polymorphism in the catalytic site of CypIA1.

Risk factors for lung cancer in Rio de Janeiro, Brazil: a case-control study.

The association between the risk of lung cancer and tobacco smoking, dietary factors and occupational exposures was examined in a hospital-based case-control study. The study involved 123 consecutive cases and 123 controls, matched by age (+/- 3), sex, and race. In this first study of lung cancer risk in Brazil, we found that tobacco smoking is the strongest risk factor with an odds ratio (OR) for current and former smokers of 22 (CI, 6.5-76) and 7.7 (CI, 2.2-27), respectively. An OR of 2.8 (CI, 1.0-7.7) was found for users of black tobacco in the form of hand-rolled cigarettes) in combination with conventional cigarettes, after adjustment for life-time consumption of any kind of tobacco; users of conventional cigarettes only were considered as a reference group. Cessation of smoking had an important influence in reducing the lung cancer risk, whereas early initiation of smoking increased the risk. Among dietary factors, frequent consumption of meat (P < 0.01) and pasta (P = 0.02) were positively associated with lung cancer risk after adjusting for smoking and income. No association was found with green/yellow vegetables or fruits. We were unable to detect any significant association related to occupational exposures. This study confirmed the association of lung cancer with smoking as the most important predictor of risk. It also indicates the increase in risk associated with the use of black tobacco in combination with conventional cigarettes.

Cytochrome P-450 lA1 genotype in lung cancer patients and controls in Rio de Janeiro, Brazil.

Mspl restriction fragment length polymorphism in cytochrome P-450 IA1 (CypIA1) gene, which has been associated with lung cancer susceptibility in Japanese, was studied in persons from Rio de Janeiro, in the framework of a hospital-based, age, race (black or nonblack), and gender-matched case-control study (n = 222; 110 cases and 112 controls). Contrary to the hypothesis, there was no difference in the frequency of the C genotype (Mspl site-present homozygous), even after racial breakdown. There were no significant differences between cases and controls when categorized according to tobacco consumption. The lifetime quantity of tobacco smoked was not different among lung cancer patients with three different genotypes (A, Mspl site-absent, homozygous; B, heterozygote; and C). The background frequency of the Mspl polymorphism C genotype is a little less than 10%, similar to that of the Japanese healthy population. The CyplA1 Mspl polymorphism itself does not seem to be related to susceptibility to bronchial carcinogenesis in this area.

Experimental visual agnosia in the pigeon.

Recent research on animal cognitive ability has clarified that cognitive ability spreads to several species besides humans. Such studies make it possible to compare brain mechanisms of animal cognition and human cognition. Experimental lesions of the ectostriatum in pigeons caused deficits in the artificial pattern recognition, arbitrary classification of natural objects, conspecific individual recognition and discrimination of two different avian species. The lesions did not result in deficits in natural concept, such as food or conspecific. These results suggest that the ectostriatal lesions selectively disrupt visual cognition acquired through discriminative training.

Phenylalanine ammonia lyase fromSporidiobolus pararoseus andRhodosporidium toruloides: Application for phenylalanine and tyrosine deamination.

Simultaneous depletion of phenylalanine and tyrosine by phenylalanine ammonia lyase is described in a mutual competitive inhibition model. The enzymes obtained fromSporidiobolus pararoseus andRhodosporidium toruloides were charaterized in terms of stability, optimal reaction parameters and kinetic behaviour. Both enzymes followed Michaelis-Menten kinetics with respect to the two amino acids. However, the enzyme fromRhodosporidium toruloides was inhibited by high tyrosine concentrations.

Proportional cancer incidence according to selected sites--comparison between residents in the city of S. Paulo, Brazil: Japanese and Brazilian/Portuguese descent.

The percentual distributions of selected sites of cancer cases according to origin, sex and age are compared. Data were obtained from the Registry of Cancer of S. Paulo (School of Public Health of the University of S. Paulo, Brazil). The reference period for inhabitants of Japanese descent was 1969/78 and for those of Brazilian descent, the period was 1969/75. Standardized Proportionate Incidence Ratios (SPIR) with approximate 95% Confidence Intervals (CI) were evaluated using age specific Incidence Ratios of S. Paulo, 1973, as standards. The results agree with findings of previous works on mortality, but show different patterns according to origin. The well known fact that some sub-groups of a population may be different from the overall group is once again brought to the fore. Attention should be drawn to the differences detected for stomach, skin and prostate, in males, and for stomach, skin, cervix and uterus in females.

Cancer incidence rates among Japanese immigrants in the city of São Paulo, Brazil, 1969-78.

Cancer incidence rates among first-generation Japanese immigrants in the city of São Paulo, Brazil, were estimated from the data of the São Paulo Cancer Registry during the years 1969 to 1978. From all registered cases, 2,179 cancer cases of Japan-born residents (1,288 males, 891 females) were selected and age-specific and summary age-adjusted incidence rates (AAIR) were calculated for the selected sites of cancer. The AAIR for all sites except non-melanoma skin cancer was 195.2 per 100,000 population (95 percent confidence interval: 176.4-214.1) in males and 147.3 (134.6-160.0) in females. Stomach cancer had the highest incidence rate of all cancers in both sexes (males, 69.3; females, 32.0). This was followed by cancer of the lung (22.5), esophagus (10.2), colon (8.3), and prostate (7.1) in males; and by breast (24.0), cervix (18.0), colon (8.4), and lung (7.2) in females. When these rates were compared with those among Japanese in Japan, cancer of the stomach and rectum revealed significantly lower rates, while non-melanoma skin cancer, and prostate and breast cancer showed higher rates. No significant increase of colorectal cancer was recognized among Japanese immigrants in São Paulo, contrary to the remarkably high rates of colorectal cancer being observed among Japanese immigrants in the US.

Hepatitis B virus markers in Japanese immigrants and their descendants in Bolivia and native Bolivians.

A survey of hepatitis B virus (HBV) markers of Japanese immigrants, their descendants and native Bolivians was performed in two agricultural settlements in Bolivia. The prevalence of HBV markers in sera, either hepatitis B surface antigen (HBsAg) or its antibody (HBsAb), was higher in the Japanese (46.4%) than in the native Bolivian (12.9%) adult generations of both colonies. There was no significant difference between Japanese (4.3%) and Bolivian (0.9%) school children in one colony, but a high percentage (32.6%) was recognized among Japanese children in the other colony. The numbers of adw subtypes were unexpectedly high among these HBsAg positive Japanese children, compared to those in Japan. Antibody to hepatitis delta virus (HDV) was detected in one case. These data suggested that although horizontal transmission of adw HBV had occurred within the Japanese population, HBV and HDV were not endemic to this geographic area.