Effects of maternal leptin treatment during lactation on the body weight and leptin resistance of adult offspring

We investigate whether leptin treatment to lactating rats affects food intake, body weight and leptin serum concentration and its anorectic effect on their adult offspring. Lactating rats were divided into 2 groups: Lep-single injected with recombinant rat leptin (8 microg/100 g of body weight, daily for the last 3 consecutive days of lactation) and control group (C) that received the same volume of saline. After weaning all pups had free access to the control diet, their body weight and food intake were monitored at each 4 days until 180 days of age, when they were tested for its food intake and response to either leptin (0.5 mg/kg body wt, ip) or saline vehicle. The offspring of the leptin-treated dams gained more weight and had higher food intake from day 37 onward (p<0.05), higher amount of retroperitoneal white adipose tissue (RPWAT) (37%, p<0.05) and higher leptin serum concentration (40%, p<0.05) at 180 days of age compared to control group. The food intake at 2, 4, 6 and 24 h was unaffected after acute injection of leptin in these animals, suggesting resistance to the anorectic effect of leptin. The maternal leptin treatment during lactation makes their adult offspring more susceptible to overweight with resistance to the anorectic effect of leptin.     

TGF-beta-associated enhanced susceptibility to leishmaniasis following intramuscular vaccination of mice with Leishmania amazonensis antigens

Leishmania amazonensis and Leishmania braziliensis are the main causal agents of anergic diffuse cutaneous leishmaniasis and hyperergic mucosal leishmaniasis in man, respectively. In this work we demonstrate that intramuscular vaccination of BALB/c mice with whole antigens of L. amazonensis (LaAg) but not L. braziliensis (LbAg) results in increased susceptibility to cutaneous leishmaniasis. LaAg vaccination resulted in an increased capacity of the draining lymph nodes to produce IL-10 and TGF-beta during antigen recall responses. In vitro cultivation with LaAg but not LbAg induced increased apoptosis of CD8+ T cells. Following infection with L. amazonensis, LaAg-vaccinated mice produced significantly more TGF-beta and a higher serum IgG1/IgG2a antibody ratio compared with LbAg-vaccinated and non-vaccinated animals. The association of TGF-beta with enhanced susceptibility to infection was confirmed in mice co-vaccinated with LaAg and neutralizing anti-TGF-beta antibodies. Upon parasite challenge, these animals developed much smaller lesion sizes and parasite burdens, comparable with non-vaccinated controls. The disease-promoting effect of LaAg vaccination is not a general event, as in contrast to BALB/c, the disease outcome in C57Bl/6 mice was unaltered. Together, these findings indicate that species-specific components of L. amazonensis activate overt TGF-beta production that predisposes more susceptible individuals to aggravated disease following vaccination.     

Identification of multiple HLA-A*0201-restricted cruzipain and FL-160 CD8+ epitopes recognized by T cells from chronically Trypanosoma cruzi-infected patients

Chronic Chagas disease occurs in 16 million individuals chronically infected by the protozoan Trypanosoma cruzi in Latin America, and may lead to a dilated cardiomyopathy in 10-30% of patients. A vigorous cellular immune response holds parasitism in check. However, up to now, few T. cruzi proteins have been shown to be recognized by CD8+ T cells from Chagas disease patients. In this study, we designed 94 peptides derived from T. cruzi proteins cruzipain and FL-160, predicted to bind to HLA-A2 molcules. After in vitro binding assays to HLA-A*0201, 26 peptides were selected, and their recognition by PBMC from Chagas disease patients was tested with the IFN-gamma ELISPOT assay. All 26 peptides were recognized by PBMC from at least one patient. Furthermore, a tetrameric HLA-A*0201 complex built with the cruzipain 60-68 peptide that was frequently recognized in the periphery also bound to CD8+ T cells from a heart-infiltrating T cell line obtained from a single patient with Chagas disease cardiomyopathy. Thus, our results suggest that the recognition of CD8+ T cell epitopes in cruzipain and FL-160 may have a pathogenic or protective role in chronic Chagas disease.     

Antioxidant activity of new ruthenium compounds

Many biological properties have been attributed to ruthenium complexes including anti-tumor activity and the attenuation of reperfusion damage and infarct size. In this work, we characterize the antioxidant activity of trans-[RuCl2(nic)4] where nic is 3-pyridinecarboxylic acid and trans-[RuCl2(i-nic)4] where i-nic is 4-pyridinecarboxylic acid by (i) evaluation of total antioxidant potential (TRAP); (ii) prevention of DNA damage induced by hydrogen peroxide using the alkaline comet assay; and (iii) the prevention of lipid peroxidation and cell death induced by iron in liver slices. Our results suggest that nic has stronger antioxidant potential when compared to the i-nic. Higher doses (above 200 microM) of these compounds gave genotoxic effects, but the antioxidant potential could be obtained with the use lower doses (0.1-10 microM).     

Death rates reflect accumulating brain damage in arthropods

We present the results of the first quantitative, whole-lifespan study of the relationship between age-specific neurolipofuscin concentration and natural mortality rate in any organism. In a convenient laboratory animal, the African migratory locust, Locusta migratoria, we find an unusual delayed-onset neurolipofuscin accumulation pattern that is highly correlated with exponentially accelerating age-specific Gompertz-Makeham death rates in both males (r=0.93, p=0.0064) and females (r=0.97, p=0.0052). We then test the conservation of this association by aggregating the locust results with available population-specific data for a range of other terrestrial, freshwater, marine, tropical and temperate arthropods whose longevities span three orders of magnitude. This synthesis shows that the strong association between neurolipofuscin deposition and natural mortality is a phylogenetically and environmentally widespread phenomenon (r=0.96, p < 0.0001). These results highlight neurolipofuscin as a unique and outstanding integral biomarker of ageing. They also offer compelling evidence for the proposal that, in vital organs like the brain, either the accumulation of toxic garbage in the form of lipofuscin itself, or the particular molecular reactions underlying lipofuscinogenesis, including free-radical damage, are the primary events in senescence.     

Applicability of RAPD markers on silver-stained polyacrylamide gels to ascertain genetic diversity in Peripatus acacioi (Peripatidae; Onychophora)

RAPD (random amplification of polymorphic DNA) molecular markers can be utilized for analyzing genetic variability in populations for which only a few or no molecular markers are available. They were used in a study of an endangered species, Peripatus acacioi, found in the Tripuí Ecological Station, in Ouro Preto, MG, Brazil. The ecological station was specifically created to protect this velvet worm species, the first of this group found in Brazil. For an initial evaluation of the genetic diversity of this species, DNA samples from the lobopods of four individuals, collected at random, were analyzed using RAPD. Each reaction was run with a different primer (Operon RAPD 10-mer Kits), totaling 13 primers (OPC2, OPC3, OPC4, OPC6, OPC8, OPC10, OPC11, OPL2, OPL7, OPL11, OPL13, OPL18, and OPL19). Due to the low amplification yield, RAPD fragments were separated in polyacrylamide gels and stained with silver nitrate. Numerous bands were observed. Fifty-five of the amplified bands proved to be reproducible, both in terms of presence and intensity. Among these, 27 were variable and 28 were constant. The average number of bands per gel was 4.2. Nine of the 13 primers tested allowed the identification of constant and variable bands among these four individuals. RAPD analysis of genetic variation using silver-stained polyacrylamide gel electrophoresis provided measures of band sharing among the individuals, and therefore could be used in population genetics studies of P. acacioi.     

Ouabain-insensitive Na+-ATPase of proximal tubules is an effector for urodilatin and atrial natriuretic peptide

In the present paper we studied the effect of urodilatin and atrial natriuretic peptide (ANP) on the proximal tubule Na+-ATPase and (Na+K+)ATPase activities. Urodilatin and ANP inhibit the Na+-ATPase activity but not the (Na+K+)ATPase activity. Maximal effect was observed at a concentration of 10(-11) M for both peptides. In this condition, the enzyme activity decreases from 10.8 +/- 1.6 (control) to 5.7 +/- 0.9 or 6.1 +/- 0.7 nmol Pi mg(-1) min(-1) in the presence of urodilatin or ANP, respectively. This effect was completely reversed by 10(-6) M LY83583, a guanylyl cyclase inhibitor, and mimicked by 10 nM cGMP. Furthermore, both ANP and urodilatin increase cGMP production by 33% and 49%, respectively. This is the first demonstration that it was shown that urodilatin and ANP directly modulate primary active sodium transport in the proximal tubule. The data obtained indicate that this effect is mediated by the activation of the NPR-A/guanylate cyclase/cGMP pathway.     

Intracellular lithium and cyclic AMP levels are mutually regulated in neuronal cells

In this work, we studied the effect of intracellular 3',5'-cyclic adenosine monophosphate (cAMP) on Li+ transport in SH-SY5Y cells. The cells were stimulated with forskolin, an adenylate cyclase activator, or with the cAMP analogue, dibutyryl-cAMP. It was observed that under forskolin stimulation both the Li+ influx rate constant and the Li+ accumulation in these cells were increased. Dibutyryl-cAMP also increased Li+ uptake and identical results were obtained with cortical and hippocampal neurons. The inhibitor of the Na+/Ca2+ exchanger, KB-R7943, reduced the influx of Li+ under resting conditions, and completely inhibited the effect of forskolin on the accumulation of the cation. Intracellular Ca2+ chelation, or inhibition of N-type voltage-sensitive Ca2+ channels, or inhibition of cAMP-dependent protein kinase (PKA) also abolished the effect of forskolin on Li+ uptake. The involvement of Ca2+ on forskolin-induced Li+ uptake was confirmed by intracellular free Ca2+ measurements using fluorescence spectroscopy. Exposure of SH-SY5Y cells to 1 mm Li+ for 24 h increased basal cAMP levels, but preincubation with Li+, at the same concentration, decreased cAMP production in response to forskolin. To summarize, these results demonstrate that intracellular cAMP levels regulate the uptake of Li+ in a Ca(2+)-dependent manner, and indicate that Li+ plays an important role in the homeostasis of this second messenger in neuronal cells.     

Remnant populations of the regal fritillary (Speyeria idalia) in Pennsylvania: Local genetic structure in a high gene flow species

The Regal Fritillary butterfly, Speyeria idalia (Drury) (Lepidoptera: Nymphalidae), has been described as a high gene flow species. Supporting this assertion, previous studies in the Great Plains, where it is still relatively widespread, have found evidence of gene flow across hundreds of kilometers. Using mitochondrial and microsatellite loci, we examined the spatial genetic structure of a very isolated Pennsylvania population of these butterflies that occupies three separate meadows located within ten kilometers of each other. We found restricted gene flow and a distinct structure, with each meadow having a unique genetic signature. Our findings indicate that even a species that normally exhibits high gene flow may show fine-scale genetic subdivision in areas where populations have been largely extirpated.Authors contributed equally.     

Personalized diagnosis by cached solutions with hypertension as a study model

Statistical modeling of links between genetic profiles with environmental and clinical data to aid in medical diagnosis is a challenge. Here, we present a computational approach for rapidly selecting important clinical data to assist in medical decisions based on personalized genetic profiles. What could take hours or days of computing is available on-the-fly, making this strategy feasible to implement as a routine without demanding great computing power. The key to rapidly obtaining an optimal/nearly optimal mathematical function that can evaluate the "disease stage" by combining information of genetic profiles with personal clinical data is done by querying a precomputed solution database. The database is previously generated by a new hybrid feature selection method that makes use of support vector machines, recursive feature elimination and random sub-space search. Here, to evaluate the method, data from polymorphisms in the renin-angiotensin-aldosterone system genes together with clinical data were obtained from patients with hypertension and control subjects. The disease "risk" was determined by classifying the patients' data with a support vector machine model based on the optimized feature; then measuring the Euclidean distance to the hyperplane decision function. Our results showed the association of renin-angiotensin-aldosterone system gene haplotypes with hypertension. The association of polymorphism patterns with different ethnic groups was also tracked by the feature selection process. A demonstration of this method is also available online on the project's web site.