Glucolipotoxicity age-dependently impairs beta cell function in rats despite a marked increase in beta cell mass.

AIMS/HYPOTHESIS: Prolonged exposure of pancreatic beta cells to excessive levels of glucose and fatty acids, referred to as glucolipotoxicity, is postulated to contribute to impaired glucose homeostasis in patients with type 2 diabetes. However, the relative contribution of defective beta cell function vs diminished beta cell mass under glucolipotoxic conditions in vivo remains a subject of debate. We therefore sought to determine whether glucolipotoxicity in rats is due to impaired beta cell function and/or reduced beta cell mass, and whether older animals are more susceptible to glucolipotoxic condition. METHODS: Wistar rats (2 and 6 months old) received a 72 h infusion of glucose + intravenous fat emulsion or saline control. In vivo insulin secretion and sensitivity were assessed by hyperglycaemic clamps. Ex vivo insulin secretion, insulin biosynthesis and gene expression were measured in isolated islets. Beta cell mass and proliferation were examined by immunohistochemistry. RESULTS: A 72 h infusion of glucose + intravenous fat emulsion in 2-month-old Wistar rats did not affect insulin sensitivity, insulin secretion or beta cell mass. In 6-month-old rats by contrast it led to insulin resistance and reduced insulin secretion in vivo, despite an increase in beta cell mass and proliferation. This was associated with: (1) diminished glucose-stimulated second-phase insulin secretion and proinsulin biosynthesis; (2) lower insulin content; and (3) reduced expression of beta cell genes in isolated islets. CONCLUSIONS/INTERPRETATION: In this in vivo model, glucolipotoxicity is characterised by an age-dependent impairment of glucose-regulated beta cell function despite a marked increase in beta cell mass.

Composted municipal waste effects on chemical properties of a Brazilian soil.

The spread of composted municipal waste (CMW) on land can be used for sustainable crop production. Nevertheless, heavy metals availability may be a problem. Therefore, the main objective of this study was to assess the impact of CMW disposal on heavy metal accumulation in soil and plants. The treatments consisted of an untreated plot (control) and four rates of CMW application. All plots were cultivated in succession of carrot, cauliflower, sweet corn, and radish. Cu and Pb significantly accumulated in the topsoil (0-5 cm) with a similar pattern in the depths of 5-10 cm and 10-20 cm. Cauliflower, for Fe and Cu, and radish, for Pb and Cu, had their tissue analysis significantly affected due to the increasing rates of application of CMW. Nevertheless, the levels of accumulation in both, soil and plant, are within permissible limits. The evidences provided by this experiment indicated that heavy metals are less likely to cause problems for the estimation of CMW loadings to Brazilian agricultural land.

Effects of substrate polarity and chain length on conformational and thermal properties of phosphonic acid self-assembled bilayers.

Conformational and thermal behavior of self-assembled structures of three phosphonic acids, OPA (octadecylphosphonic acid), TPA (tetradecylphosphonic acid), and OcPA (octylphosphonic acid), with different alkyl chain lengths are investigated and compared. The orientation of self-assembled bilayers depends on whether the substrate is nonpolar (graphite) or polar (mica). For nonpolar substrates, bilayers lay parallel to the surface, and for polar substrates, bilayers lay perpendicular to the surface. Thermal behaviors of these structures on mica and graphite are also investigated, showing that, depending on the temperature they are submitted to, molecules stack, unstack, or agglomerate on mica and form larger domains on graphite.

Early programmed cell death in human NT2 cell cultures during differentiation induced by all-trans-retinoic acid.

Previous studies have demonstrated that programmed cell death takes place at different stages during the development of the CNS in vivo. Our purpose in this study was to detect early programmed cell death associated with the induction of differentiation by retinoic acid (RA) in the NT2 cell line. By using the annexin V labeling as a marker of apoptosis, a significant apoptotic cell death was quantified during the third and the fourth days of the RA treatment. Double-labeling studies using the staining of the genomic DNA strand breaks with the terminal deoxyribosyl-transferase-mediated dUTP nick end-labeling (TUNEL) assay and either nestin or microtubule-associated protein 2 (MAP2) showed that 1) the early apoptotic cell death affected mostly nestin-positive cells and 2) after 8 days of differentiation, although cells with neuronal phenotypes are present, no colabeled TUNEL/MAP2 cells were detected. With regard to the neuronal protein MAP2, we observed discrete immunolabeling of a few NT2 cells as early as day 3 of the differentiation and a significant emergence of MAP2-immunopositive cells at days 6-8. Thus, our results show that, when as a whole the differentiating NT2 cell population is considered, 1) the apoptotic cell death observed during the third day of differentiation occurs mostly in undifferentiated cells, 2) this process coincides with the first detection of the neuronal phenotype in NT2 cell cultures, and 3) the end of the cell death period in NT2 cell cultures is marked by both the accumulation of MAP2-positive cells and the beginning of expression of the Bcl-2 protein in the cultures.

[Prevalence of canine filariasis by Dirofilaria immitis and Dipetalonema reconditum in Maceió, Alagoas State, Brazil]. / Prevalência da filariose canina causada por Dirofilaria immitis e Dipetalonema reconditum em Maceió, Alagoas, Brasil.

A survey on the prevalence of Dirofilaria immitis and Dipetalonema reconditum was conducted in 1,519 dogs from Maceió and two coastal areas in the State of Alagoas, Northeast Brazil, from 1995 to 1999, by testing for microfilariae in blood. All blood samples were from exclusively domiciled dogs with a known history, showing that the infections were autochthonous, confirming transmission of canine filariasis in these areas. In Greater Metropolitan Maceió, 15 (1.3%) microfilaremic dogs were detected with D. immitis and 15 (1,3%) with D. reconditum. In the southern coastal area there was an estimated prevalence of 12.7% for D. immitis. D. immitis and D. reconditum microfilaria were 298.1 micrometer and 249.2 micrometer long and 7.3 micrometer and 4.4 micrometer wide, respectively. A Witness immunotest that detects D. immitis antigen was used to confirm parasitological results and reveal occult dirofilariasis cases. Of the total 6,579 females examined, 8 (0.1%) Culex quinquefasciatus were observed to be naturally infected with D. immitis larvae. These results proved dirofilariasis transmission in Maceió and demonstrated D. reconditum in the same geographic area.

The microfilarial periodicity of Wuchereria bancrofti in north-eastern Brazil.

The periodicity of Wuchereria bancrofti microfilariae (mff) in peripheral blood was analysed in 42 microfilaraemics living in Maceió, in Alagoas state, north-eastern Brazil. Nine blood samples were collected from each subject, over a 24-h period, and two quantitative (60-microliter) thick smears were prepared from each sample. Although all the subjects had detectable microfilaraemias from 23.00 hours to 06.00 hours, no mff could be detected in most (71.4%) of the smears prepared from samples collected at 15.00 hours. Samples collected during the day, at 15.00 hours, contained 170 times fewer mff/microliter than those collected at 01.00 hours, when microfilaraemias were generally most intense. For diagnosis of bancroftian filariasis in Maceió, blood samples should be collected between 22.00 and 03.00 hours, when microfilarial counts will be at least 90% of the peak counts. The circadian variation observed was independent of the subject's gender and microfilarial density. Mathematical analysis, using a simple harmonic-wave model, indicated a periodicity index of 127.6 and that maximum microfilarial densities occurred at 00.51 hours, confirming the nocturnal pattern of microfilaraemia in the study area.

Differential expression of Bcl-2-related proteins in differentiating NT2 cells.

Although the role of Bcl-2-related proteins as regulators of the apoptotic process has been well documented, recent studies suggest that they might also be implicated in neuronal differentiation. We have studied by immunocytochemistry, Western blotting and RT-PCR the expression pattern of Bcl-xL, Bcl-2 and BAX in the in vitro model of neuronal differentiation constituted by retinoic acid (RA)-treated NTera-2/D1 (NT2/D1) cells. Whereas BAX level did not change significantly during the RA treatment, Bcl-xL level increased markedly during the first week, before returning to basal level during the second week. Bcl-2 expression, undetectable in undifferentiated cells, increased progressively from the first week. From our results, we suggest that, at least in our model, Bcl-2-related proteins might be involved in neuronal differentiation.

Infecçäo por Dirofilaria immitis em cäes de Maceió / Dirofilaria immitis infection in dogs from Maceió, Alagoas, Northeast region of Brazil

De 2.007 amostras de sangue examinadas de cäes da cidade de Maceió-AL, foram detectados 62 (3,1 por cento) animais positivos para a presença de microfilária (mf). Em 11 cäes, escolhidos aleatoriamente, foi colhido sangue venoso para a identificaçäo específica de Dirofilaria immitis. Para tal, foram utilizadas a motilidade, o tamanho, a morfologia das mf e a presença de antígenos solúveis do parasito, sendo encontrados cinco animais portadores de D. immitis. Mosquitos da espécies Culex quinquefasciatus foram alimentados com sangue de um cäo portador de D. immitis. O desenvolvimento de formas larvárias foi obsevado nos títulos de Malpighi, confirmando a ocorrência da dirofilariose canina por D. immitis na cidade de Maceió-AL

[Bancroftian filariasis in urban areas of Alagoas State, Northeast Brazil: study in the general population]. / Filariose bancroftiana em áreas urbanas do Estado de Alagoas, nordeste do Brasil: estudo em populaçao geral.

In order to assess the present status of lymphatic filariasis in Alagoas State, Brazil, hemoscopic surveys were carried out in the human population of the three different physiographic regions of the State. Blood samples were collected by thick smear technique taken after 10:00 p.m. From a total of 101 cities of the State, 10 were randomly selected, Bancroftian filariasis was only found in Maceió, the capital of Alagoas State. In a cross-sectional survey conducted among the general population of 4 neighborhoods in the city, 10,973 individuals were examined, 226 were microfilaraemic with prevalence in the city neighborhoods ranging from 0 to 5.4%. Prevalence rates and microfilariae density were significantly higher in males. Among the examined inhabitants born out of Maceió, microfilariae carriers had lived a significantly longer time in endemic areas than the amicrofilaraemic subjects. Based on the data obtained in the present study, measures to avoid expansion of bancroftian filariasis in the region were established.

[Bancroftian filariasis in Brazil]. / Filariose bancroftiana no Brasil.

The past and present distribution of Bancroftian filariasis in Brazil is reviewed. Parasitological and entomological surveys were conducted between 1951 and 1958, the autochthonous transmission of Wuchereria bancrofti having been found only in 11 places in the country as follows, with the corresponding prevalences; Ponta Grossa (SC), 14.5% Belém (PA), 9.8%; Barra de Laguna (SC), 9.4%; Recife (PE), 6.9%; Castro Alves (BA), 5.9%; Florianópolis (SC), 1.4%; São Luis (MA), 0.6%; Salvador (BA), 0.4%; Maceió (AL), 0.3%; Manaus (AM). 0.2% and Porto Alegre (RS), 0.1%. The distribution of infection was urban and focal, occurring mainly along the coast. Control measures carried out against filariasis achieved considerable success, reducing infection and transmission, only Belém and Recife being considered endemic areas. Recent studies show the active transmission of filariasis with higher prevalences than those observed in the past, in Maceió, considered to be free from infection, and in Recife. The knowledge of the present status of Bancroftian filariasis in Brazil is important as baseline information, because it will allow for the establishment of control measures by Public Health organizations.

Bancroftian filariasis in Maceio, state of Alagoas, Brazil: Observations on Culex quinquefasciatus after blood feeding on individuals with different densities of microfilariae in the peripheral blood stream.

Females of laboratory-reared Culex quinquefasciatus were allowed to take blood meals on individuals with low (1-100 microfilariae/ml of peripheral blood), moderate (101-500 microfilariae/ml), and high (> 500 microfilariae/ml) microfilaremia. The mosquitoes ingested 1.39-3.80 microl of blood and infective third-stage (L3) larvae were first recorded 13-14 days after the infecting blood meal. The number of microfilariae ingested by mosquitoes was proportional to the density of microfilariae in the peripheral blood of the human subjects, but with a concentration factor of up to 6.5 times the expected number. Survival of mosquitoes was not influenced by the density of microfilariae in the peripheral blood of infected individuals. Infectivity indices were proportional to microfilaremia in human subjects. The number of L3 larvae/female (intensity of infection) was not influenced by individual microfilaremia. The highest vector efficiency and the best experimental infection index were recorded in mosquitoes that blood fed on individuals with moderate microfilaremia. The results are discussed in relation to the transmission on Bancroftian filariasis in the study area.

Lymphatic filariasis in Brazilian urban area (Maceió, Alagoas).

A cross-sectional survey conducted among evening students was used to determine the prevalence of Wuchereria bancrofti infection in Maceió, capital of the State of Alagoas, northeast Brazil. A single thick-blood smear was used, being collected between 10 p.m. and 12 a.m. From a total of 29,551 students enrolled at evening elementary schools in the 33 city sectors, 16,569 (56.4%) were random selected for inclusion in the study. From those, 10,857 (65.5%) were interviewed and examined and 73 (0.7%) were found to have microfilaraemia. Autochthonous W. bancrofti carriers live in 10 of the 33 city sectors, suggesting a focal distribution. Moreover, 84% of infections were diagnosed among 29% of all students examined, inhabiting three contiguous sectors at the city central area, presenting infection rates up to 5.3%. Students living in city sectors with prevalence of microfilariae carriers greater than 1% were found to have a higher risk for infection when compared to students from the rest of the town [Relative Odds (RO) 12.8, 95% CI 6.7-25.1]. Eleven positive individuals from non endemic areas were living in Maceió for more than 10 years; time of residence in the area was a major risk factor for infection among students not born in the region (p < 0.01). Regarding sex, male students presented a higher proportion of positive (RO 1.7, 95% CI 1.1-2.9).

Experimental infection of Culex (Culex) quinquefasciatus and Aedes (Stegomyia) aegypti with Wuchereria bancrofti.

A study was conducted to determine the susceptibility of local strains of Culex quinquefasciatus and Aedes aegypti to infection with the strain of Wuchereria bancrofti that occurs in Maceió. State of Alagoas, Brazil. Cx. quinquefasciatus blood fed simultaneously on the same microfilariae carrier ingested more blood and 2-3x more microfilariae than Ae. aegypti. Survival rates of both species of insects living for 21 days after blood feeding on microfilaraemic patients were not significantly different from the survival rates of mosquitoes that blood fed on amicrofilaraemic individuals. W. bancrofti parasites underwent normal development in Cx. quinquefasciatus, with third stage larvae first being recorded on the 11th day post infection, and their numbers increasing thereafter. Development of filariae in Ae. aegypti did not proceed beyond the first larval stage, and there was a progressively increasing number of non-viable larvae with the passage of time. It is concluded that Ae. aegypti is not involved in the transmission of W. bancrofti in Maceió.

A comparison of two Brazilian populations of Culex quinquefasciatus (Say, 1823) from endemic and non-endemic areas to infection with Wuchereria bancrofti (Cobbold, 1877).

Culex quinquefasciatus is known to be an efficient insect host of Wuchereria bancrofti. In Brazil Cx. quinquefasciatus is widely distributed throughout the country and is often abundant in and around human habitations. In contrast, Bancroftian filariasis is limited to three foci in Brazil. Experiments were undertaken to compare the vector capacities of Cx. quinquefasciatus originating from Maceió (Alagoas), one of the endemic areas of W. bancrofti infection in Brazil, and Belo Horizonte (Minas Gerais), a non endemic area. Laboratory-reared Cx. quinquefasciatus were dissected 20 days after blood feeding on microfilaraemic patients. Survival rates and the number of infective larvae that developed did not differ in female mosquitoes of different origins. Thus both populations of Culex were susceptible to infection with W. bancrofti.

[Present status of bancroftian filariasis in Maceió, State of Alagoas, Brazil]. / Situação atual da filariose bancroftiana na cidade de Maceió, estado de Alagoas, Brasil.

Epidemiological and entomological surveys were carried out in the human and mosquito populations in Maceió, Alagoas, in order to assess the present status of bancroftian lymphatic filariasis. Examination of thick blood smears of 10,450 students from different areas of the city revealed 0.66% Wuchereria bancrofti microfilaria carriers. The distribution of filariasis is focal in the city, 80% of the individuals with patent infection living in two neighboring areas with 1.24% and 5.25% prevalence. Parallel studies performed with samples of all age groups in the human population showed similar microfilaria prevalence rates observed previously in the student survey. However, thick blood smears taken from members of families with at least one subject with patent infection gave a prevalence six times greater suggesting, increased transmission in households. The percentage of carriers was higher in the youngest age group (< 20 years). Culex quinquefasciatus mosquitos caught at the locations where the autochthonous cases were found presented natural infection rates ranging from 0.28% to 4.62%. The combination of all these findings indicates occurrence of active transmission of W. bancrofti in the urban area of Maceió, Alagoas State. Based on these data, measures for the potential control of filariasis were planned.