Protein kinase C-mediated ATP stimulation of Na(+)-ATPase activity in LLC-PK1 cells involves a P2Y2 and/or P2Y4 receptor

ATP-activated P2Y receptors play an important role in renal sodium excretion. The aim of this study was to evaluate the modulation of ATPase-driven sodium reabsorption in the proximal tubule by ATP or adenosine (Ado). LLC-PK1 cells, a model of porcine proximal tubule cells, were used. ATP (10(-6)M) or Ado (10(-6)M) specifically stimulated Na(+)-ATPase activity without any changes in (Na(+)+K(+))-ATPase activity. Our results show that the Ado effect is mediated by its conversion to ATP. Furthermore, it was observed that the effect of ATP was mimicked by UTP, ATPγS and 2-thio-UTP, an agonist of P2Y2 and P2Y4 receptors. In addition, ATP-stimulated Na(+)-ATPase activity involves protein kinase C (PKC). Our results indicate that ATP-induced stimulation of proximal tubule Na(+)-ATPase activity is mediated by a PKC-dependent P2Y2 and/or P2Y4 pathway. These findings provide new perspectives on the role of the effect of P2Y-mediated extracellular ATP on renal sodium handling.

Functional redundancy and complementarities of seed dispersal by the last neotropical megafrugivores

BACKGROUND

Functional redundancy has been debated largely in ecology and conservation, yet we lack detailed empirical studies on the roles of functionally similar species in ecosystem function. Large bodied frugivores may disperse similar plant species and have strong impact on plant recruitment in tropical forests. The two largest frugivores in the neotropics, tapirs (Tapirus terrestris) and muriquis (Brachyteles arachnoides) are potential candidates for functional redundancy on seed dispersal effectiveness. Here we provide a comparison of the quantitative, qualitative and spatial effects on seed dispersal by these megafrugivores in a continuous Brazilian Atlantic forest.

METHODOLOGY/PRINCIPAL FINDINGS

We found a low overlap of plant species dispersed by both muriquis and tapirs. A group of 35 muriquis occupied an area of 850 ha and dispersed 5 times more plant species, and 13 times more seeds than 22 tapirs living in the same area. Muriquis dispersed 2.4 times more seeds in any random position than tapirs. This can be explained mainly because seed deposition by muriquis leaves less empty space than tapirs. However, tapirs are able to disperse larger seeds than muriquis and move them into sites not reached by primates, such as large forest gaps, open areas and fragments nearby. Based on published information we found 302 plant species that are dispersed by at least one of these megafrugivores in the Brazilian Atlantic forest.

CONCLUSIONS/SIGNIFICANCE

Our study showed that both megafrugivores play complementary rather than redundant roles as seed dispersers. Although tapirs disperse fewer seeds and species than muriquis, they disperse larger-seeded species and in places not used by primates. The selective extinction of these megafrugivores will change the spatial seed rain they generate and may have negative effects on the recruitment of several plant species, particularly those with large seeds that have muriquis and tapirs as the last living seed dispersers.

Characterization of ecto-ATPase activity in the surface of LLC-PK1 cells and its modulation by ischemic conditions

BACKGROUND

The concentration of extracellular nucleotides is regulated by enzymes that have their catalytic site facing the extracellular space, the so-called ecto-enzymes.

METHODS

We used LLC-PK1 cells, a well-characterized porcine renal proximal tubule cell line, to biochemically characterize ecto-ATPase activity in the luminal surface. The [γ-(32)P]Pi released after reaction was measured in aliquots of the supernatant by liquid scintillation.

RESULTS

This activity was linear with time up to 20min of reaction and stimulated by divalent metals. The ecto-ATPase activity measured in the presence of 5mM MgCl(2) was (1) optimum at pH 8, (2) insensitive to different inhibitors of intracellular ATPases, (3) inhibited by 1mM suramin, an inhibitor of ecto-ATPases, (4) sensitive to high concentrations of sodium azide (NaN(3)) and (5) also able to hydrolyze ADP in the extracellular medium. The ATP:ADP hydrolysis ratio calculated was 4:1. The ecto-ADPase activity was also inhibited by suramin and NaN(3). The dose-response of ATP revealed a hyperbolic profile with maximal velocity of 25.2±1.2nmol Pixmg(-1)xmin(-1) and K(0.5) of 0.07±0.01mM. When cells were submitted to ischemia, the E-NTPDase activity was reduced with time, achieving 71% inhibition at 60min of ischemia.

CONCLUSION

Our results suggest that the ecto-ATPase activity of LLC-PK1 cells has the characteristics of a type 3 E-NTPDase which is inhibited by ischemia.

GENERAL SIGNIFICANCE

This could represent an important pathophysiologic mechanism that explains the increase in ATP concentration in the extracellular milieu in the proximal tubule during ischemia.

Effect of intermittent convection movements on voltammogram and current transients

The influence of intermittent convection movements on electrochemical voltammograms is investigated. When the bath temperature rises to 315 K, the voltammograms exhibit irregular plateaus that differ for independent voltammetry scans, even when the setup is maintained under exactly the same conditions. In this paper, we show that such behavior can be caused by convection movements that develop in the electrolytic cell as a consequence of velocity fluctuations, since no bubbles or regular convective patterns are observed at this temperature. Theoretical current-potential curves for the heterogeneous deposition of metals on silicon electrodes is derived from a model consisting of a one-dimensional balance equation that includes diffusion, convection, and reaction through a time-dependent boundary condition. We obtain the current density associated with the adsorption of particles on the surface and, through this expression, we consider the effect of constant convective velocities on voltammograms. Finally, we examine the effect of random convective movements, described by a Monte Carlo algorithm that takes into account the random temporal fluctuations around a null convective current. The model predicts accentuated fluctuations on the current profiles, especially on the current plateaus that correspond to a stationary current regime. The validity of the theoretical model is checked against experimental data.

Atopic disease and body mass index

BACKGROUND

Obesity and atopy are two increasingly important population health issues. Excess weight and obesity are potential risk factors for atopy (specifically asthma).

OBJECTIVE AND METHODS

To determine the body mass index (BMI) in children with atopic disease compared with nonatopic children, and to determine whether obesity is associated to more severe disease. Children aged 5 to 16 years with diagnosed atopic disease that attended the Ambulatory Hospital Center where eligible as cases. Children aged 5 to 16 years without atopic disease from a school in the same geographic area were used as controls.

RESULTS

A total of 228 children where included in the analysis: 112 children with atopy (75.9% asthma, 21.4% rhinitis and 2.7% eczema) and 116 children without atopy. The median age was 10.5 and 10.3 years for the atopic and non-atopic children, respectively. The prevalence of overweight or obese subjects was significantly greater in the atopic group (44.6% vs 31.9%, p 0.05). The obese asthmatic children had a significantly higher prevalence of sleep disturbances due to wheezing in the last 12 months (45.5% vs 15.9%, p 0.05). They also reported dry cough at night more often (50% vs 28.6%, p = 0.07), and a higher number of wheezing attacks in the past 12 months (72.7% vs 50.8%, p = 0.074), than the non-obese asthmatic children. Most of the obese atopic children were already overweight or obese at the time of the diagnosis (66.6%). None of the associations were significantly different for boys or girls.

DISCUSSION

There is some evidence of an association between excess body weight or obesity and atopy--particularly asthma.

Nocturnal plasma levels of melatonin in quails (Coturnix japonica) injected with l-5-hydroxy-tryptophan

This study aimed to demonstrate the influence of the systemic administration of l-5-hydroxy-tryptophan (L-HTP) on the plasma levels of melatonin during the dark period in quails. Throughout daylight, the plasma levels of melatonin did not differ significantly, oscillating between 110.2 ± 15.8 pg.mL-1 and 157.4 ± 34.8 pg.mL-1, from 8 to 16 hours. L-HTP (25 mg.kg-1, through the intracelomic route) administered at 18 hours lessened significantly the nocturnal increase of the plasma levels of melatonin (controls, 327.3 ± 20.1 and 315.8 ± 20.9 pg.mL-1 vs. 242.1 ± 24.8 and 217.5 ± 21 pg.mL-1, respectively, at 20 and 24 hours, P < 0.05). The results obtained showed that the administration of LHTP reduced the nocturnal melatonin release, possibly by bringing about an increase in serotonin synthesis and synaptic release in the pineal. Therefore, the serotoninergic transmission from the raphe towards the pineal would constitute a mechanism of modulation of the synthesis and melatonin release in quails.

Hepatitis B and C virus markers among patients with hepatosplenic mansonic schistosomiasis

PURPOSE

To evaluate the frequency and the consequences of the co-infection of hepatitis B and C viruses in patients with hepatosplenic schistosomiasis (HSS).

METHODS

B and C serologic markers, exposure to risk factors, biochemical assays, upper gastrointestinal endoscopies, and abdominal ultrasonograms were evaluated in 101 patients with HSS from 1994 to 1997. Whenever possible, PCR was tested and histopathological studies were reviewed.

RESULTS

At least one HBV virus marker was found in 15.8%, and anti-HCV was detected in 12.9% of the subjects. The seropositive subjects tended to be older than the seronegative ones. A history of blood transfusion was significantly related to the presence of anti-HCV. Three (18.75%) out of 16 subjects exposed to B virus were HBsAg positive. Eleven (84.6%) out of thirteen patients who were anti-HCV positive demonstrated viral activity. Patients with ongoing viral infection presented a higher average level of liver aminotransferases, a higher frequency of cell decompensation and a higher rate of chronic hepatitis. Portal hypertension parameters were not influenced by viral exposure.

CONCLUSIONS

The rate of hepatitis B and C viruses serologic markers observed in the patients with HSS was higher than the control group. The co-infection was responsible for a higher frequency of cell decompensation.

[Vaccination coverage in the first year of life in 4 cities of the state of São Paulo, Brazil]

Immunization is an important disease prevention measure, and evaluating the effectiveness of immunization programs is crucial to ensuring their success. This study describes the results of a household survey in four cities in the state of São Paulo, Brazil: Francisco Morato, Guarulhos, Osasco, and São Paulo. The survey was done in order to estimate immunization coverage for the cohort of children born in 1996. The city of São Paulo was divided into five strata, according to socioeconomic and living conditions. The survey followed the methodology that the Pan American Health Organization recommends for immunization coverage surveys. The proportion of children who had received a complete set of the recommended vaccinations at the time of the interview, taking into account both oral reports and information recorded on the children's immunization cards, was above 90% for all the cities except Francisco Morato, which had the worst living conditions. In the city of São Paulo, the worst coverage was found in the lowest and highest strata. When only the doses received during the first year of life were considered, the coverage was not adequate to produce herd immunity. The use of private vaccination services was higher in the areas with better living conditions. The difference between the coverage calculated based on data from health services and the coverage calculated based on the survey was inversely proportional to living conditions. Our results suggest that surveys similar to the one described here should be carried out in other cities. Employees who provide vaccination services should be trained to correctly record vaccination data. In addition, it is important to make health professionals aware of the official immunization calendar, and to facilitate the public's access to health services.

[Correlation between homicide rates and economic indicators in São Paulo, Brazil, 1996]

Around 30% of the deaths due to violent causes in Brazil result from homicides. Violence has traditionally been related to larger social problems, such as poverty. Recently, however, a positive correlation has been observed between higher incomes and an increase in the homicide rate, so that some researchers have begun to consider inequality, rather than poverty, as an explanation for the epidemic of violence. The objective of this study was to investigate the correlation between urbanization, poverty, and economic inequality and homicide rates in the state of São Paulo, Brazil, in 1996. Information regarding population size, average monthly income of household heads, income distribution, and Gini index was obtained for each municipality, based on the demographic census. Homicide rates were calculated based on official data. Data were analyzed in terms of correlation and relative risk with 95% confidence intervals. Homicide rates rose in direct proportion to city population and ranged from 6.96 (per 100,000 inhabitants) in municipalities with a population smaller than 10,000 inhabitants, to 55.54 in municipalities with more than 1 million inhabitants. Relative risk ranged from 1.35 to 7.98. A significant correlation with population size was found only for incomes above 3.11 times the minimum wage and a Gini index greater than 0.50. There was a strong, direct, and significant correlation between homicide rates and the income ratio between the ninetieth and the twentieth percentiles of the population. It is necessary to probe more deeply into the macrosocial determinants of homicide rates in order to identify indicators of inequality that can generate meaningful data for developing public health strategies.

[Time trends in death rates from homicides in the city of Sao Paulo, Brazil, 1979-1994]

To study homicide trends by gender and age, 1979-1994, São Paulo, Brazil, cubic polynomials were used to determine the best model for adjusting to time trends in homicide mortality rates by age and gender in the city of São Paulo, Brazil, 1979-1994. The model best adjusted to each group was selected considering the regression coefficient (Beta) , R2 value, residual analysis, and model's simplicity. The results show linear growth for total rates and rates by gender due to behavior of rates in the 20-29 and 30-39 year age groups. The reciprocal model adjusted best to rates for the 40-49 and 50-59 year age groups, while rates for adolescents followed the multiplicative model. There was no significant relationship between homicide rates and time for the remaining groups (under 10 and over 59 years). Rates for males were considerably higher in all age groups. The remarkably steady growth in homicide rates among adolescents and young adults is consistent with trends observed in other urban areas in developing and developed countries and denotes deteriorating living conditions and increased poverty.

[Nursing and the environmental question: proposal of a theoretical model for the professional practice]

Considering the side effects of environmental changes over the population's health, a theoretical model is proposed in this study in order to incorporate ecologic matters into the nursing practices. The reference for this work is the eco-socialist-marxist theory. The model is based on the analysis of the capitalist economic process, its production technologies and consumption. It is known that this economic model generates ecoinequalities and anthropogenic impacts that rebound on the health-disease profile of the population. The nursing action, permeated by ecological awareness, can prevent and also combat ecoinequalities and destructive human actions on the environment.

Prenatal diagnosis of mosaicism for tetrasomy 18p: cytogenetic, fish and morphological findings

A case of mosaicism for tetrasomy 18p detected prenatally is reported. We believe this is the second case where fetal anomalies were found at autopsy.

Pharmacological evidence for GABAergic and glutamatergic involvement in the convulsant and behavioral effects of glutaric acid

The effect of intrastriatal administration of glutaric acid (GTR), a metabolite that accumulates in glutaric acidemia type I (GA-I), on the behavior of adult male rats was investigated. After cannula placing, rats received unilateral intrastriatal injections of GTR buffered to pH 7.4 with NaOH or NaCl. GTR induced rotational behavior toward the contralateral side of injection and clonic convulsions in a dose-dependent manner. Rotational behavior was prevented by intrastriatal preadministration of DNQX and muscimol, but not by the preadministration of MK-801. Convulsions were prevented by intrastriatal preinjection of muscimol. This study provides evidence for a participation of glutamatergic non-NMDA and GABAergic mechanisms in the GTR-induced behavioral alterations. These findings may be of value in understanding the physiopathology of the neurological dysfunction in glutaric acidemia.

[Perceptions of the nursing staff after a death: the ritual of post mortem preparation of the body]

This paper intends verificated the significance of the patients' death in nursing professionals and the emotions during the prepare of his bodies. The dispositions were collected with 23 professionals at UTI service in a hospital of São Paulo city. The results shows some sad during the prepare of the body and the comprehension that the time of the experience and the type of relationship make the different in this procedure.

Intra-urban differentials in death rates from homicide in the city of São Paulo, Brazil, 1988-1994

The objective of this research was to analyze the relationship between socioeconomic statistics and homicide mortality rates in the city of São Paulo between 1988 and 1994. City districts were grouped into five geographic areas. A socioeconomic indicator (ISE) was constructed with census information combining average income of the family head, illiteracy rate for the population over 5 yr of age, average number of rooms and number of persons per household. The higher the score, the better the socioeconomic situation (possible values: 4 to 384). Deaths from homicide were grouped by residential areas, and the rates for these areas were calculated. The association between homicide rates and the socioeconomic situation was analyzed with Spearman correlation coefficients. Average ISE scores varied from 291 in the Central area (homicide rate = 27.96 deaths per 100000) to 119.9 in the East area (homicide rate = 40.38). The Spearman coefficient between ISEs and homicide rates was -0.98 (p < 0.05). Due to the heterogeneity inside the areas, the median ISE is a better indicator of the socioeconomic conditions yielding an rs = -1.0. Almost half the population resides in areas with the highest risk of homicide mortality (East and South). Taking the Central area as a reference, we found risks of 1.36 in the Western, 1.37 in the Northern, 1.44 in the Eastern and 2.67 in the Southern areas.

Properties of chicken lens MIP channels reconstituted into planar lipid bilayers

Membrane fractions highly enriched in chicken lens MIP (MIP28) were found to form ion channels when incorporated into planar lipid bilayers. The channels displayed prominent unitary conductances of about 60 and 290 pS in symmetric 150 mm KCl solution and were slightly anion selective. For both depolarizing and hyperpolarizing voltages, voltage sensitivity of the MIP28-induced conductance could be fit by a Boltzmann relation, symmetric around zero mV, with V0 = 18.5 mV, n = 4.5 and gmin/gmax = 0.17. Channel properties were not appreciably altered by pH in the range of 5.8 to 7, although channel incorporation was observed to occur more frequently at lower pH values. Calcium, at millimolar concentrations, decreased the channel mean open time. Partial proteolysis of MIP28 to yield MIP21 did not appreciably affect single-channel conductance or voltage sensitivity of the reconstituted channels. MIP28 was not phosphorylated by cAMP dependent protein kinase (PKA). Although unitary conductance and selectivity of the chicken MIP channel are similar to those reported for the bovine MIP (MIP26), the voltage sensitivity of MIP28 was higher than that of the bovine homologue, and voltage sensitivity of MIP28 was not modulated by treatments previously shown to affect MIP26 voltage gating (partial proteolysis and protein phosphorylation by PKA: (Ehring et al., 1990). The existence of such strikingly different functional properties in highly homologous channel isoforms may provide a useful system for exploration of the structure-function relations of MIP channels.

Comparative characterization of a human large cell lung carcinoma cell line and the xenograft derived cell line

The HK-1 cell line established from a human large cell lung carcinoma shows a high transformed phenotype and undifferentiated characteristics. This cell line grows as an adherent monolayer in fetal calf serum-supplemented medium, shows a high proliferation index, is able to grow in semi-solid agar and is tumorigenic in athymic nude rats. The cell line HK-2 derived from the HK-1 xenograft in athymic nude rats shows basically the same features found in the original HK-1 cell line, which include aneuploid nuclear DNA content, abnormal chromosomal number. rearranged marker chromosomes and abnormally localised nucleolar organizer regions. Cytokeratin and vimentin intermediary-sized filaments were found in both cell lines as well as in the original and induced tumour, while neither oncofetal antigens (alphafeto-protein, carcinoembryonic antigen, chorionic gonatropin and human placental lactogen) nor neural differentiation markers (neurofilament and neural specific enolase) were expressed. Analysis of sulphated glycosaminoglycans in the cell cultures and in the nude rat induced tumour showed high expression of chondroitin sulphate.

Bilateral retinoblastoma associated with 13q-mosaicism. Possible manifestation of a germinal mutation

Fifteen retinoblastoma patients were studied cytogenetically using G- and R-banding techniques. One patient showed 13q-mosaicism. It is suggested that a postzygotic deficiency in mosaic cases and in tumoral cells may be secondary to germinal mutation.

Sister chromatid exchange frequency in a retinoblastoma mosaic patient with del(13)

The frequencies of sister chromatid exchange (SCE) were investigated in different cell populations derived from a patient with retinoblastoma and 46,XY/46,XY,del(13) (q12.3q21.2) mosaicism. No differences in spontaneous or mitomycin C-induced SCE were detected between cell populations.

Duchenne muscular dystrophy in a girl with an (X;15) translocation

This is a report of a girl with Duchenne muscular dystrophy (DMD) associated with an 46,X,t (X;15) (p21; q 26) chromosome constitution. Although in the eight published cases of girls with DMD and a t(X;aut) different autosomes were involved in the translocation, the breakpoint was always at Xp21. The present case supports the hypothesis that the DMD gene must be located at Xp21. In this study, involvement of the father's chromosomes in the translocation was detected.

Length dependence of activation studied in the isovolumic blood-perfused dog heart

In studies utilizing the isolated isovolumic blood-perfused canine heart, left ventricular pressure was measured following a sudden expansion of ventricular volume. An increase in performance occurred in two phases: first, there was an instantaneous rise of developed pressure simultaneous with ventricular distension; in the second phase, developed pressure continued to increase for several minutes until a final steady state was reached. The immediate increase in developed pressure occurred with a prolongation of the time-to-peak pressure, and there was no further change of time-to-peak pressure during the time-dependent increase of developed pressure. In another series of experiments, systolic pressure was elevated without changing resting volume, and mechanical performance changed in a different manner: after an increase in systolic load, there was a modest and transient decrease of developed pressure; thereafter, ventricular pressure recovered only to original values. The influence of different degrees of ventricular expansion, calcium, and verapamil were studied. Under higher ventricular dilations the immediate as well as the slow increase of contraction were heightened and the time to reach half of the slow increase was shortened. When ventricular dilation was induced during an infusion of calcium chloride, higher values for the immediate pressure increase were observed, whereas the time-dependent increase and the time to reach half of the slow increase did not change in comparison with control studies. Verapamil decreased the immediate and the time-dependent enhancement of contraction. The time-dependent increase in developed pressure occurs more slowly with verapamil.(ABSTRACT TRUNCATED AT 250 WORDS)