RESUMO
The exploration of unconventional hydrocarbons may be very effective in promoting economic development and confronting energy crisis around the world. However, the environmental risks associated with this practice might be an impediment if not adequately dimensioned. In this context, naturally occurring radioactive materials and ionizing radiation are sensitive aspects in the unconventional gas industry that may compromise the environmental sustainability of gas production and they should be properly monitored. This paper provides a radioecological assessment of the São Francisco Basin (Brazil) as part of an environmental baseline evaluation regarding the Brazilian potential for exploring its unconventional gas reserves. Eleven and thirteen samples of surface waters and groundwater were analyzed for gross alpha and beta using a gas flow proportional counter. A radiological background range was proposed using the ± 2 Median Absolute Deviation method. Using geoprocessing tools, the annual equivalent doses and lifetime cancer risk indexes were spatialized. Gross alpha and beta background thresholds in surface water ranged from 0.04-0.40 Bq L-1 to 0.17-0.46 Bq L-, respectively. Groundwater radiological background varies from 0.006-0.81 Bq L-1 to 0.06-0.72 Bq L-1 for gross alpha and beta, respectively. All environmental indexes are relatively higher in the south of the basin, probably a direct response to the local volcanic formations. Traçadal fault and local gas seepages might also influence the gross alpha and beta distribution. All samples have radiological indexes below the environmental thresholds, and should remain at acceptable levels with the development of the unconventional gas industry in Brazil.
Assuntos
Água Subterrânea , Gás Natural , Campos de Petróleo e Gás , Monitoramento Ambiental , Medição de Risco , Radiação IonizanteRESUMO
Deterministic walks over a random set of N points in one and two dimensions ( d = 1,2) are considered. Points ("cities") are randomly scattered in R(d) following a uniform distribution. A walker ("tourist"), at each time step, goes to the nearest neighbor city that has not been visited in the past tau steps. Each initial city leads to a different trajectory composed of a transient part and a final p-cycle attractor. Transient times (for d = 1,2) follow an exponential law with a tau-dependent decay time but the density of p cycles can be approximately described by D(p)proportional to p(-alpha(tau)). For tau>>1 and tau/N<<1, the exponent is independent of tau. Some analytical results are given for the d = 1 case.
RESUMO
The accuracy of an indirect immunofluorescence (IIF) test for the serodiagnosis of Helicobacter pylori infections was evaluated in adult patients and compared with culture, preformed urease test and smears stained with carbolfuchsin. We studied 80 consecutive patients submitted to gastroduodenioscopy (17 of whom were found to have duodenal ulcer) plus 57 patients with duodenal ulcer. H. pylori was identified by microbiological mehtods in 65 of the 80 consecutive patients and in all 57 patients with duodenal ulcer. Among the 74 patients with duodenal ulcer, 71 presented antibody titers *1:20 and 46 of the 48 H. pylori-positive patients without duodenal ulcer presented antibody titers *1:20. Thirteen of the 15 H. pylori-negative patients presented antibody titers *1:10. The sensitivity,m specificity and positive predictive value of the IIF test were 95.9%, 88.8% and 98.4%, respectively. The seroprevalence of H. pylori in 380 asymptomatic Brazilian was also studied by the IIF teset. The presence of IgG antibodies against H. pylori was observed in 62.1% of the individuals. The prevalence of H. pylori infection increased with age and no difference was observed between males (60.3%) and females (66.6%)
Assuntos
Anticorpos Antibacterianos , Doadores de Sangue , Imunofluorescência , Helicobacter pylori , Testes Sorológicos , Úlcera Duodenal , DuodenoscopiaRESUMO
An enzyme isotopic assay was used to determine the histamine concentration in the gastric mucosa of patients positive for Helicobacter pylori with (n = 11) and without duodenal ulceration (n = 9) and in negative controls (n = 7). A significant difference was observed when the histamine content of H pylori negative subjects was compared with that of positive patients. On the other hand, there was no significant difference in histamine concentration between H pylori positive patients with duodenal ulceration and those without duodenal ulceration. H pylori positive patients with and without duodenal ulceration had significantly lower gastric histamine concentrations than H pylori negative subjects. The lower gastric histamine concentration observed in H pylori positive patients might be due to increased histamine release which could in turn induce increased gastric acid secretion.
Assuntos
Mucosa Gástrica/metabolismo , Infecções por Helicobacter/metabolismo , Helicobacter pylori , Histamina/análise , Adulto , Biópsia , Úlcera Duodenal/complicações , Úlcera Duodenal/metabolismo , Feminino , Mucosa Gástrica/patologia , Infecções por Helicobacter/complicações , Humanos , MasculinoRESUMO
The presence of Helicobacter pylori and the gastric mucosa histology were investigated in 15 children and 15 adults with duodenal ulcer. The microorganism was isolated from antral and oxyntic mucosa in 100% of patients, both adults and children. The results of Gram stain and preformed urease test were compared with those of culture and there was no difference in sensitivity among the tests. Antral chronic gastritis was observed in all patients. However, children presented oxyntic gastritis more frequently than adults. It was also observed that the endoscopic aspects were different in the two groups of patients. The results here observed strongly support the idea that, as well as in adults, H. pylori is the causative agent of the gastritis seen in children with duodenal ulceration. On the other hand, the histological findings of oxyntic mucosa of children with duodenal ulcer were different from those of adults.
Assuntos
Úlcera Duodenal/complicações , Úlcera Duodenal/microbiologia , Gastrite/microbiologia , Infecções por Helicobacter/epidemiologia , Helicobacter pylori/isolamento & purificação , Adolescente , Adulto , Criança , Feminino , Gastrite/complicações , Gastrite/epidemiologia , Infecções por Helicobacter/patologia , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
The presence of Campylobacter pylori and histological changes of gastric mucosa were studied in 50 consecutive patients with gastric complaints. C. pylori was isolated from the antrum, body, and fundus of 40 patients with (n = 20) and without (n = 20) duodenal ulcer. The incidence of gastritis was not significantly different in the antrum of C. pylori-positive patients with and without ulcer. Otherwise, oxyntic mucosa of both body and fundus regions exhibited gastritis in 64.1% of the C. pylori-positive non-ulcer patients, whereas those with duodenal ulcer presented oxyntic mucosa that was histologically normal or near normal.
Assuntos
Campylobacter/isolamento & purificação , Úlcera Duodenal/microbiologia , Gastrite/microbiologia , Estômago/microbiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Fundo Gástrico/microbiologia , Mucosa Gástrica/microbiologia , Humanos , Masculino , Pessoa de Meia-Idade , Antro Pilórico/microbiologiaRESUMO
Endoscopic biopsy specimens of antral mucosa from 25 patients presenting with gastric complaints were obtained for culture and histologic and immunocytochemical studies. The histopathologic study revealed chronic gastritis in 22 patients and borderline chronic gastritis in three patients. The unlabeled-antibody peroxidase-antiperoxidase (PAP) method was applied for the detection of Campylobacter pylori, and its results were compared with those obtained with the culture technique. Strongly positive immunoperoxidase staining was localized in spiral, curved bacteria that were present in the mucus layer adjacent to the gastric epithelial cell surface. The microorganisms were frequently congregated in clumps and were sectioned in several directions. The PAP stains were positive in 19 specimens (76%), and the cultures were positive in 20 (80%). All results negative by culture were also negative by PAP method. Compared with the cultures, the sensitivity and positive predictive value of the PAP method for identification of C pylori in antral mucosa obtained from endoscopic biopsy specimens were 95% and 100%, respectively.
Assuntos
Infecções por Campylobacter/microbiologia , Campylobacter/isolamento & purificação , Gastrite/microbiologia , Biópsia , Doença Crônica , Gastrite/patologia , Humanos , Técnicas Imunoenzimáticas , Manejo de EspécimesRESUMO
Among the benign tumors of the esophagus, the discovery of a granular cell tumor is exceptional. Although endoscopy permits recognition of this tumor and supports its benign nature, only histologic examination of the endoscopic biopsy specimen permits one to determine its precise nature. The endoscopic appearance of esophageal granular cell tumor ranges from a plaque-like thickening of the mucosa to a polypoid mass. We describe here seven cases of granular cell tumor of the esophagus diagnosed by histologic examination of endoscopic biopsy specimens. We believe the actual incidence of this tumor in this location might be greater if every esophagus were given as much attention at endoscopic examination and at autopsy.