Dental fluorosis in Brazil: a critical review

This paper discusses dental fluorosis as a relevant public health problem, using a review of epidemiological studies published in the last 10 years on the disease's prevalence, severity, and risk factors. The results suggest that there are already more cases than expected, although few studies refer to major severity. Thus, measures are needed for the prevention and surveillance of dental fluorosis.     

Paracoccidioidomycosis mortality in Brazil (1980-1995)

This study analyzes 3,181 deaths from paracoccidioidomycosis in Brazil, based on 16 years of sequential data (from 1980 to 1995). During this period paracoccidioidomycosis showed considerable magnitude and low visibility, representing the eighth most common cause of death from predominantly chronic or recurrent types of infectious and parasitic diseases. It also had the highest mortality rate among the systemic mycoses. The mean annual mortality rate was 1.45 per million inhabitants, indicating a downward long-term trend (reduction of 31.28%), while spatial distribution among the different regions and States of Brazil was non-homogenous. The South (with the highest regional rate) and the Southeast showed a downward trend, while the Central West had the second highest rate in the country. At least one-fifth of Brazilian municipalities (or 22.71% of the country's total area) reported deaths from paracoccidioidomycosis. Overall nationwide mortality per area was 3.73/10,000km2. The disease was endemic in non-metropolitan areas. The majority of deaths occurred in males (84.75%), and there was a sex ratio of 562 men/100 women. The 30-59-year and over-60-year age groups were the most affected. The study showed that the mortality rate justifies classifying this disease as a major health problem in Brazil.     

Chagas' disease seroprevalence among school-age children in Espírito Santo State,Brazil, 1999-2000

Although the Brazilian State of Espírito Santo is not considered endemic for Chagas' disease, the sylvatic triatomines occurring there frequently invade houses, increasing the chances of Trypanosoma cruzi transmission to man. The epidemiological pattern of the disease in Espírito Santo was evaluated by a serological survey of 5,243 schoolchildren ages 7 to 14 years, residents of 17 municipalities. Indirect immunofluorescence, indirect hemagglutination, and immunoenzymatic (ELISA) tests were positive in only one person, representing only 0.019% of the total. This result was similar to those found by other authors in previous studies. Based on the results of serological tests it is concluded that the epidemiological pattern of Chagas' disease in Espírito Santo remains stable, despite the intensive destruction of the Atlantic Forest that has occurred in recent decades.     

Effects of long-term low-dose cyanide administration to rats

Chronic exposure to cyanide has been associated with development of pancreatic diabetes, hypothyroidism, and several neurological diseases in both humans and animals. However, there is a limited number of experimental models for these pathologies. Thus, in the present study 0, 0.15, 0.3, or 0.6 mg KCN/kg body weight/day was administered for 3 months to 26 rats. On the last day, plasma samples were obtained for glucose, cholesterol, and thyroidal hormone measurement, and the pancreas, thyroids, and whole central nervous system were collected for histopathologic study. There were no significant difference in plasma concentrations of the substances measured between groups, and no lesions were found in the pancrease or thyroid. The CNS of experimental animals revealed the presence of spheroids on the ventral horn of the spinal cord, neuron loss in the hippocampus, damaged Purkinje cells, and loss of cerebellar white matter. In conclusion, cyanide administration could promote neuropathological lesions in rats without affecting pancreas or thyroid gland metabolism.     

Contribution of the raw material to the aluminum contamination in parenterals

BACKGROUND: The extent of aluminum contamination in parenteral nutrition solutions was measured in 35 different commercial products, including amino acids, electrolytes, glucose, lipids, vitamins trace elements, and albumin. The extent of aluminum contamination in substances used as raw material for preparation of parenterals was also measured. Chemicals from different manufacturers and of different quality grades were analyzed individually. METHODS: The measurements were done by atomic absorption spectrometry. RESULTS: The results showed that the same product might have different aluminum content depending on the manufacturer, either for commercial formulations or substances. The highest contaminated chemicals included cystine, NaOH, vitamin C, biotin, gluconate, and Fe and Cr salts. The lowest contaminated chemicals included lipids, apolar amino acids, glucose, HCI, acetic acid, KCl, NaCl, and heparin. Among commercial products, the major contamination rates appeared in calcium gluconate, followed by trace elements, some vitamins, bicarbonate, phosphates salts, and heparin. CONCLUSIONS: Comparing the aluminum in commercial products and substances, it can be concluded that the contamination may occur in parenterals because aluminum is present naturally in the chemicals. However, when the composition and concentration of the parenteral solution are considered, the contamination of calcium gluconate, trace elements, some vitamins, phosphates, bicarbonate, and heparin cannot be related only to the raw substances. The aluminum level present in these commercial formulations is too high to come only from the substances; therefore, it is possible that one of the steps of the manufacturing procedure is responsible for elevating the contamination of these products.     

Low-protein diet induces oral tolerance to ovalbumin in mice

The suitable development of oral tolerance against ingested dietary foods is of critical importance to escaping food allergy. Using mice as an animal model for oral tolerance against ovalbumin (OVA) as a dietary antigen, we investigated the effects of dietary protein on their immunological tolerance. Female BALB/c mice fed either a 20% or 5% protein diet were orally administered 5 mg of OVA for four consecutive days, then immunized intraperitoneally with 100 microg of OVA. The immunized group of mice were fed and treated in the same manner, except that they received orally distilled water for four consecutive days before receiving intraperitoneal immunization with the antigen. Immunization alone with OVA elevated the total IgE and induced the production of OVA-specific antibodies IgE, IgG, IgG1, and IgG2a in the sera of both the 20% and 5% protein diet groups. The oral administration of OVA to mice before intraperitoneal immunization significantly reduced the total IgE and OVA-specific antibodies in mice fed 5% protein diet, but it had hardly any effect on those in mice fed a 20% protein diet. When spleen cells from these groups of mice were cultured with OVA as a mitogen, they responded substantially to OVA in the immunized groups fed 20% and 5% protein diets and in the presensitized group fed 20% protein, but those from the presensitized group fed a 5% protein diet did not respond. Furthermore, when IL-4 was assayed in the spleen cell cultures of the 20% and 5% groups, mice in the presensitized group fed a 5% protein diet produced a significantly less amount of IL-4 than those fed a 20% protein diet. Moreover, irrelevant to the protein amount in the diet, the production of IFN-gamma from spleen cell cultures dramatically decreased in the group without presensitization and profoundly increased in the presensitized group of mice fed a 5% protein diet. These findings suggest that a low-protein diet leads to an induction of oral tolerance against dietary antigens; this appears to involve a clear down-regulation of Th2 cytokine, IL-4.     

Activation of anaplastic lymphoma kinase is responsible for hyperphosphorylation of ShcC in neuroblastoma cell lines

Shc family of docking proteins, ShcA, ShcB and ShcC, play roles in cellular signal transduction by binding to phosphotyrosine residues of various activated receptor tyrosine kinases. Both ShcB and ShcC proteins are selectively expressed in the neural system of adult mouse tissues. In most of neuroblastoma cells, obvious tyrosine phosphorylation of ShcC was observed, whereas expression of ShcB was considerably low. Phosphoproteins associated with hyperphosphorylated ShcC were purified from neuroblastoma cell lines, and identified by mass-spectrometry. Anaplastic lymphoma kinase (ALK), which turned out to be one of these phosphoproteins, was constitutively activated and associated with the PTB domain of ShcC in three neuroblastoma cells. In vitro kinase assay revealed that ShcC is a potent substrate of the activated ALK kinase. The ALK gene locus was significantly amplified in both of these cell lines, suggesting that gene amplification leads to constitutive activation of the ALK kinase, which results in hyperphosphorylation of ShcC. Constitutive activation of ALK appeared to interfere with signals from other receptor tyrosine kinases. ALK-ShcC signal activation, possibly caused by co-amplification with the N-myc gene, might give additional effects on malignant tumor progression of neuroblastoma.