Age-related worm load and worm fecundity patterns in human populations, as indicated by schistosome circulating antigens

Recently, our group determined the relationship between serum CAA levels and fecal egg counts in two foci with very intense Schistosoma mansoni transmission: Maniema (Zaire), an area endemic for S. mansoni since several decades, and Ndombo (Senegal), where transmission has only been established since a few years. The objective was to study and compare age-related worm load and worm fecundity patterns in these two different endemic settings. Here, we will summarize the most important findings and conclusions of this study.

Unconditioned responses and functional fear networks in human classical conditioning.

Human imaging studies examining fear conditioning have mainly focused on the neural responses to conditioned cues. In contrast, the neural basis of the unconditioned response and the mechanisms by which fear modulates inter-regional functional coupling have received limited attention. We examined the neural responses to an unconditioned stimulus using a partial-reinforcement fear conditioning paradigm and functional MRI. The analysis focused on: (1) the effects of an unconditioned stimulus (an electric shock) that was either expected and actually delivered, or expected but not delivered, and (2) on how related brain activity changed across conditioning trials, and (3) how shock expectation influenced inter-regional coupling within the fear network. We found that: (1) the delivery of the shock engaged the red nucleus, amygdale, dorsal striatum, insula, somatosensory and cingulate cortices, (2) when the shock was expected but not delivered, only the red nucleus, the anterior insular and dorsal anterior cingulate cortices showed activity increases that were sustained across trials, and (3) psycho-physiological interaction analysis demonstrated that fear led to increased red nucleus coupling to insula but decreased hippocampus coupling to the red nucleus, thalamus and cerebellum. The hippocampus and the anterior insula may serve as hubs facilitating the switch between engagement of a defensive immediate fear network and a resting network.

Methicillin-resistant Staphylococcus aureus in human milk

We collected and analyzed 500 samples of human milk, from five Brazilian cities (100 from each) to detect methicillin-resistant strains of Staphylococcus aureus (MRSA) producing enterotoxins. We found 57 strains of MRSA, and the mecA gene, responsible for resistance, was detected in all of them using a specific molecular probe. We examined 40 strains for the presence of four enterotoxins, after selecting a subset that included all strains from each region, except for the largest sample, from which 10 were randomly selected. Among these two presented enterotoxin B, and growth in human colostrum and trypicase soy broth. After 5 h of incubation at 37°C, population sizes were already higher than 9.4 x 105 UFC/ml and enterotoxin was released into culture medium and colostrum. Our results stress the importance of hygiene, sanitary measures, and appropriate preservation conditions to avoid the proliferation of S. aureus in human milk.

Cytotoxic effects of combination of oxidosqualene cyclase inhibitors with atorvastatin in human cancer cells.

Ten oxidosqualene cyclase inhibitors with high efficacy as cholesterol-lowering agents and of different chemical structure classes were evaluated as potential anticancer agents against human cancer cells from various tissue origins and nontumoral human-brain-derived endothelial cells. Inhibition of cancer cell growth was demonstrated at micromolar concentrations, comparable to the concentrations of statins necessary for antitumor effect. Human glioblastoma cells were among the most sensitive cells. These compounds were also able to decrease the proliferation of angiogenic brain-derived endothelial cells, as a model of tumor-induced neovasculation. Additive effects in human glioblastoma cells were also demonstrated for oxidosqualene cyclase inhibitors in combination with atorvastatin while maintaining selectivity against endothelial cells. Thus, not only statins targeting the 3-hydroxy-3-methylglutaryl coenzyme A reductase but also inhibitors of oxidosqualene cyclase decrease tumor growth, suggesting new therapeutic opportunities of combined anti-cholesterol agents for dual treatment of glioblastoma.

Frequency of CCR5 Delta-32 Mutation in Human Immunodeficiency Virus (HIV)-seropositive and HIV-exposed Seronegative Individuals and in General Population of Medellin, Colombia

Repeated exposure to human immunodeficiency virus (HIV) does not always result in seroconversion. Modifications in coreceptors for HIV entrance to target cells are one of the factors that block the infection. We studied the frequency of Delta-32 mutation in ccr5 gene in Medellin, Colombia. Two hundred and eighteen individuals distributed in three different groups were analyzed for Delta-32 mutation in ccr5 gene by polymerase chain reaction (PCR): 29 HIV seropositive (SP), 39 exposed seronegative (ESN) and 150 individuals as a general population sample (GPS). The frequency of the Delta-32 mutant allele was 3.8% for ESN, 2.7% for GPS and 1.7% for SP. Only one homozygous mutant genotype (Delta-32/Delta-32) was found among the ESN (2.6%). The heterozygous genotype (ccr5/Delta-32) was found in eight GPS (5.3%), in one SP (3.4%) and in one ESN (2.6%). The differences in the allelic and genotypic frequencies among the three groups were not statistically significant. A comparison between the expected and the observed genotypic frequencies showed that these frequencies were significantly different for the ESN group, which indirectly suggests a protective effect of the mutant genotype (Delta-32/Delta-32). Since this mutant genotype explained the resistance of infection in only one of our ESN persons, different mechanisms of protection must be playing a more important role in this population.

Hepatitis B virus exposure in human immunodeficiency virus seropositive Cuban patients

In order to estimate the prevalence of serological markers of exposure to Hepatitis B Virus (HBV), 295 subjects were selected at random from the National Registry of human immunodeficiency virus positive subjects. Evidence of exposure to HBV was defined as: testing Hepatitis B surface antigen (HBsAg) and anti-Hepatitis B core antigen (anti-HBc) positive or anti-HBc positive only. Overall, 133 (45.5%) were positive for anti-HBc and 15 (5.1%) resulted positive to HBsAg. Significant statistical association was found between male sex and exposure to HBV (p<0.01). Homosexual or bisexual behavior was found to be strongly associated to HBV exposure (p<0.001). In conclusion, the prevalence of HBV serological markers is higher in Cuban HIV positive subjects compared to the Cuban general population.

Comparison of dengue infection in human mononuclear leukocytes with mosquito C6/36 and mammalian Vero cells using flow cytometry to detect virus antigen

Fluorescent activated cell sorter (FACS) analysis is useful for the detection of cellular surface antigens and intracellular proteins. We used this methodology in order to detect and quantify dengue antigens in highly susceptible cells such as clone C6/36 (Aedes albopictus) and Vero cells (green monkey kidney). Additionally, we analyzed the infection in vitro of human peripheral blood mononuclear leukocytes (PBML). FACS analysis turned out to be a reliable technique to quantify virus growth in traditional cell cultures of C6/36 as well as Vero cells. High rates of infection were achieved with a good statistical correlation between the virus amount used in infection and the percentage of dengue antigen containing cells detected in infected cultures. We also showed that human monocytes (CD14+) are preferred target cells for in vitro dengue infection among PBML. Monocytes were much less susceptible to virus infection than cell lines but they displayed dengue antigens detected by FACS five days after infection. In contrast, lymphocytes showed no differences in their profile for dengue specific immunofluorescence. Without an animal model to reproduce dengue disease, alternative assays have been sought to correlate viral virulence with clinical manifestations and disease severity. Study of in vitro interaction of virus and host cells may highlight this relationship.

Analysis of stop-gain and frameshift variants in human innate immunity genes.

Loss-of-function variants in innate immunity genes are associated with Mendelian disorders in the form of primary immunodeficiencies. Recent resequencing projects report that stop-gains and frameshifts are collectively prevalent in humans and could be responsible for some of the inter-individual variability in innate immune response. Current computational approaches evaluating loss-of-function in genes carrying these variants rely on gene-level characteristics such as evolutionary conservation and functional redundancy across the genome. However, innate immunity genes represent a particular case because they are more likely to be under positive selection and duplicated. To create a ranking of severity that would be applicable to innate immunity genes we evaluated 17,764 stop-gain and 13,915 frameshift variants from the NHLBI Exome Sequencing Project and 1,000 Genomes Project. Sequence-based features such as loss of functional domains, isoform-specific truncation and nonsense-mediated decay were found to correlate with variant allele frequency and validated with gene expression data. We integrated these features in a Bayesian classification scheme and benchmarked its use in predicting pathogenic variants against Online Mendelian Inheritance in Man (OMIM) disease stop-gains and frameshifts. The classification scheme was applied in the assessment of 335 stop-gains and 236 frameshifts affecting 227 interferon-stimulated genes. The sequence-based score ranks variants in innate immunity genes according to their potential to cause disease, and complements existing gene-based pathogenicity scores. Specifically, the sequence-based score improves measurement of functional gene impairment, discriminates across different variants in a given gene and appears particularly useful for analysis of less conserved genes.

Distribution of the monocarboxylate transporter MCT2 in human cerebral cortex: an immunohistochemical study

The monocarboxylate transporter MCT2 belongs to a large family of membrane proteins involved in the transport of lactate, pyruvate and ketone bodies. Although its expression in rodent brain has been well documented, the presence of MCT2 in the human brain has been questioned on the basis of low mRNA abundance. In this study, the distribution of the monocarboxylate transporter MCT2 has been investigated in the cortex of normal adult human brain using an immunohistochemical approach. Widespread neuropil staining in all cortical layers was observed by light microscopy. Such a distribution was very similar in three different cortical areas investigated. At the cellular level, the expression of MCT2 could be observed in a large number of neurons, in fibers both in grey and white matter, as well as in some astrocytes, mostly localized in layer I and in the white matter. Double staining experiments combined with confocal microscopy confirmed the neuronal expression but also suggested a preferential postsynaptic localization of synaptic MCT2 expression. A few astrocytes in the grey matter appeared to exhibit MCT2 labelling but at low levels. Electron microscopy revealed strong MCT2 expression at asymmetric synapses in the postsynaptic density and also within the spine head but not in the presynaptic terminal. These data not only demonstrate neuronal MCT2 expression in human, but since a portion of it exhibits a distinct synaptic localization, it further supports a putative role for MCT2 in adjustment of energy supply to levels of activity.

Mycobacterium bovis BCG but not Mycobacterium leprae induces TNF-alpha secretion in human monocytic THP-1 cells

In this study, we compared the level of TNF-alpha secretion induced in monocytic THP-1 cells after phagocytosis of Mycobacterium leprae, the causative agent of leprosy, and M. bovis BCG, an attenuated strain used as a vaccine against leprosy and tuberculosis. The presence of M. leprae and BCG was observed in more than 80% of the cells after 24 h of exposure. However, BCG but not M. leprae was able to induce TNF-alpha secretion in these cells. Moreover, THP-1 cells treated simultaneously with BCG and M. leprae secreted lower levels of TNF-alpha compared to cells incubated with BCG alone. M. leprae was able, however, to induce TNF-alpha secretion both in blood-derived monocytes as well as in THP-1 cells pretreated with phorbol myristate acetate. The inclusion of streptomycin in our cultures, together with the fact that the use of both gamma-irradiated M. leprae and heat-killed BCG gave similar results, indicate that the differences observed were not due to differences in viability but in intrinsic properties between M. leprae and BCG. These data suggest that the capacity of M. leprae to induce TNF-alpha is dependent on the stage of cell maturation and emphasize the potential of this model to explore differences in the effects triggered by vaccine strain versus pathogenic species of mycobacteria on the host cell physiology and metabolism.

Preliminary results on the effects of CD40/CD40L interactions and SAC-induction on IFN-gamma expression in human schistosomiasis

In this communication the authors analyzed the pattern of expression of IFN-gamma as a surrogate type 1 response in different clinical forms of schistosomiasis in response to stimulation involving T-cell dependent and T-cell independent pathways, to investigate which pathways were functional in human schistosomiasis, and to further characterize the nature of Th1 response impairment in this parasitic disease.

Adaptive filtering methods for identifying cross-frequency couplings in human EEG.

Oscillations have been increasingly recognized as a core property of neural responses that contribute to spontaneous, induced, and evoked activities within and between individual neurons and neural ensembles. They are considered as a prominent mechanism for information processing within and communication between brain areas. More recently, it has been proposed that interactions between periodic components at different frequencies, known as cross-frequency couplings, may support the integration of neuronal oscillations at different temporal and spatial scales. The present study details methods based on an adaptive frequency tracking approach that improve the quantification and statistical analysis of oscillatory components and cross-frequency couplings. This approach allows for time-varying instantaneous frequency, which is particularly important when measuring phase interactions between components. We compared this adaptive approach to traditional band-pass filters in their measurement of phase-amplitude and phase-phase cross-frequency couplings. Evaluations were performed with synthetic signals and EEG data recorded from healthy humans performing an illusory contour discrimination task. First, the synthetic signals in conjunction with Monte Carlo simulations highlighted two desirable features of the proposed algorithm vs. classical filter-bank approaches: resilience to broad-band noise and oscillatory interference. Second, the analyses with real EEG signals revealed statistically more robust effects (i.e. improved sensitivity) when using an adaptive frequency tracking framework, particularly when identifying phase-amplitude couplings. This was further confirmed after generating surrogate signals from the real EEG data. Adaptive frequency tracking appears to improve the measurements of cross-frequency couplings through precise extraction of neuronal oscillations.

Prevalence of Chlamydia trachomatis in human immunodeficiency virus-infected women in Cuba

To determine the prevalence rates and serovar distribution of Chlamydia trachomatis cervical infections in Cuban women, two different groups were selected. Group I consisted of 60 human immunodeficiency virus (HIV-1) seropositive women from different regions of Cuba and group II of 60 randomly selected women HIV seronegative and apparently healthy. C. trachomatis was detected in cervical scrapes by mean of nested polymerase chain reaction (PCR) specific for major out membrane protein. The overall prevalence rate of C. trachomatis in cervical scrapes determined by nested PCR was 10% in group I and the estimated prevalence was 6.6% for group II; 83.3% of HIV seropositive women with C. trachomatis infection reported history of pelvic inflammatory disease followed by cervicitis (50%). The control group C. trachomatis-infected women referred a history of cervicitis in 75% of cases. Other reports in the latter group included infertility and pelvic inflamatory disease in 50%. The present study is the first report of C. trachomatis prevalence in Cuba. It showed that there was not significantly difference in the prevalence rate of C. trachomatis between both groups.