Structural and morphological characterization of hemozoin produced by Schistosoma mansoni and Rhodnius prolixus

Hemozoin (Hz) is a heme crystal produced upon the digestion of hemoglobin (Hb) by blood-feeding organisms as a main mechanism of heme disposal. The structure of Hz consists of heme dimers bound by reciprocal iron-carboxylate interactions and stabilized by hydrogen bonds. We have recently described heme crystals in the blood fluke, Schistosoma mansoni, and in the kissing bug, Rhodnius prolixus. Here, we characterized the structures and morphologies of the heme crystals from those two organisms and compared them to synthetic β-hematin (βH). Synchrotron radiation X-ray powder diffraction showed that all heme crystals share the same unit cell and structure. The heme crystals isolated from S. mansoni and R. prolixus consisted of very regular units assembled in multicrystalline spherical structures exhibiting remarkably distinct surface morphologies compared to βH. In both organisms, Hz formation occurs inside lipid droplet-like particles or in close association to phospholipid membranes. These results show, for the first time, the structural and morphological characterization of natural Hz samples obtained from these two blood-feeding organisms. Moreover, Hz formation occurring in close association to a hydrophobic environment seems to be a common trend for these organisms and may be crucial to produce very regular shaped phases, allowing the formation of multicrystalline assemblies in the guts of S. mansoni and R. prolixus.     

Dealing with gene expression missing data

Compared evaluation of different methods is presented for estimating missing values in microarray data: weighted K-nearest neighbours imputation (KNNimpute), regression-based methods such as local least squares imputation (LLSimpute) and partial least squares imputation (PLSimpute) and Bayesian principal component analysis (BPCA). The influence in prediction accuracy of some factors, such as methods' parameters, type of data relationships used in the estimation process (i.e. row-wise, column-wise or both), missing rate and pattern and type of experiment [time series (TS), non-time series (NTS) or mixed (MIX) experiments] is elucidated. Improvements based on the iterative use of data (iterative LLS and PLS imputation--ILLSimpute and IPLSimpute), the need to perform initial imputations (modified PLS and Helland PLS imputation--MPLSimpute and HPLSimpute) and the type of relationships employed (KNNarray, LLSarray, HPLSarray and alternating PLS--APLSimpute) are proposed. Overall, it is shown that data set properties (type of experiment, missing rate and pattern) affect the data similarity structure, therefore influencing the methods' performance. LLSimpute and ILLSimpute are preferable in the presence of data with a stronger similarity structure (TS and MIX experiments), whereas PLS-based methods (MPLSimpute, IPLSimpute and APLSimpute) are preferable when estimating NTS missing data.     

Circadian Variation with a Diurnal Bimodal Profile on Scent-Marking Behavior in Captive Common Marmosets (Callitrhix jacchus)

Scent-marking behavior is associated with different behavioral contexts in callitrichids, including signalizing a territory, location of feeding resources, and social rank. In marmosets and tamarins it is also associated with intersexual communication. Though it appears very important for the daily routine of the individuals, very few researchers have investigated distribution through the 24-h cycle. In a preliminary report, we described a preferential incidence of this behavior 2 h before nocturnal rest in families of common marmosets. We expand the data using 8 family groups (28 subjects), 8 fathers, 6 mothers, 8 nonreproductive adults (4 sons and 4 daughters), and 6 juvenile (3 sons and 3 daughters) offspring that we kept in outdoor cages under natural environmental conditions. We recorded the frequency of anogenital scent marking for each group during the light phase, twice a wk, for 4 consecutive wks, from March 1998 to September 1999. Cosinor test detected 24- and 8-h variations in 89.3% and 85.7% of the subjects, respectively, regardless of sex or reproductive status. The 8-h component is a consequence of the 2 peaks for the behavior, at the beginning and end of the light phase. Daily distribution of scent marking is similar to that others described previously for motor activity in marmosets. The coincident rhythmical patterns for both behaviors seem to be associated with feeding behavior, as described for callitrichids in free-ranging conditions, involving an increase in foraging activities early in the morning and shortly before nocturnal rest.     

Occurrence of Lysiphlebus testaceipes (Cresson) (Hymenoptera: Aphidiidae) on aphids (Hemiptera: Aphididae) in wheat plantation in Medianeira, Parana State, Brazil

This paper records the occurrence of Lysiphlebus testaceipes (Cresson) attacking aphids in wheat plantation in Medianeira, in the west region of Paraná State, Brazil. This microhymenoptera was introduced and released by Embrapa Trigo, from 1978 to 1992 in the wheat production region at the state of Rio Grande do Sul, what suggests that individuals of this species may show high dispersal ability.     

The prognosis of acute and persistent low-back pain: a meta-analysis

Background:

Although low-back pain is a highly prevalent condition, its clinical course remains uncertain. Our main objective was to systematically review the literature on the clinical course of pain and disability in patients with acute and persistent low-back pain. Our secondary objective was to investigate whether pain and disability have similar courses.

Methods:

We performed a meta-analysis of inception cohort studies. We identified eligible studies by searching MEDLINE, Embase and CINAHL. We included prospective studies that enrolled an episode-inception cohort of patients with acute or persistent low-back pain and that measured pain, disability or recovery. Two independent reviewers extracted data and assessed methodologic quality. We used mixed models to determine pooled estimates of pain and disability over time.

Results:

Data from 33 discrete cohorts (11 166 participants) were included in the review. The variance-weighted mean pain score (out of a maximum score of 100) was 52 (95% CI 48–57) at baseline, 23 (95% CI 21–25) at 6 weeks, 12 (95% CI 9–15) at 26 weeks and 6 (95% CI 3–10) at 52 weeks after the onset of pain for cohorts with acute pain. Among cohorts with persistent pain, the variance-weighted mean pain score (out of 100) was 51 (95% CI 44–59) at baseline, 33 (95% CI 29–38) at 6 weeks, 26 (95% CI 20–33) at 26 weeks and 23 (95% CI 16–30) at 52 weeks after the onset of pain. The course of disability outcomes was similar to the time course of pain outcomes in the acute pain cohorts, but the pain outcomes were slightly worse than disability outcomes in the persistent pain cohorts.

Interpretation:

Patients who presented with acute or persistent low-back pain improved markedly in the first six weeks. After that time improvement slowed. Low to moderate levels of pain and disability were still present at one year, especially in the cohorts with persistent pain.Low-back pain is a highly prevalent condition associated with work absenteeism, disability and large health care costs; however, there is still disagreement about prognosis. For example, the European guidelines for the management of low-back pain states that 90% of patients with acute low-back pain recover in six weeks.¹ In contrast, some well-conducted cohort studies show a less optimistic picture, providing short-term estimates of recovery ranging from 39% to 76%.^2,3 This wide range of estimates of prognosis is likely explained by differences in cohorts and definitions used to define the onset or conclusion of an episode of low-back pain. Because very different definitions of recovery are often used, it is difficult to obtain pooled estimates of recovery rates. Instead, it might be more useful to describe the clinical course of low-back pain in terms of expected changes in pain or disability over time.A recent systematic review⁴ summarized the prognostic factors for persistent disabling low-back pain but did not describe the clinical course. The only meta-analysis to investigate the clinical course of acute low-back pain was published in 2003.⁵ This review concluded that both pain and disability improve rapidly within weeks (mean reduction of 58% of initial scores in the first month) and recurrences are common. A limitation of this review was that, although it retrieved 15 studies, only 5 were cohort studies; the remaining 10 were randomized controlled trials. Randomized trials often have narrow inclusion criteria and low rates of participation, which make them less suitable for inferring prognosis. The best design to describe the prognosis of a condition is a cohort study enrolling a representative sample of incident cases (i.e., by including patients at a similar early point in their condition).^6,7 Such studies are known as inception cohort studies. To the best of our knowledge, no review has yet investigated the clinical course of pain and disability among people with persistent low-back pain (subacute and chronic). Thus, the prognosis for people with persistent low-back pain is still uncertain.The aim of our study was to systematically review the clinical course of pain and disability in patients with acute and persistent low-back pain. We included only inception cohort studies. Our second aim was to investigate whether pain and disability have similar courses.     

Annotated list of demersal fishes occurring at Sedlo Seamount, Azores north-east central Atlantic Ocean

Several fish surveys were carried out in recent years at Sedlo Seamount, Azores, north-eastern central Atlantic Ocean. An objective of the surveys was to determine the species composition of the demersal fish species living in the area. Four types of sampling gears (bottom trawl and three types of longline) were used at Sedlo Seamount resulting in very different species composition by gear and a very complete coverage of the fish fauna of the area. A list of fishes caught with these sampling methods is presented, along with other specific auxiliary information. Altogether 78 species from 43 families were listed for Sedlo Seamount, and as far as is known, 15 species were recorded for the first time for Azorean waters.     

Anti-Trypanosoma cruzi and cytotoxic activities of Eugenia uniflora L

Chagas disease is caused by Trypanosoma cruzi, being considered a public health problem. An alternative to combat this pathogen is the use of natural products isolated from fruits such as Eugenia uniflora, a plant used by traditional communities as food and medicine due to its antimicrobial and biological activities. Ethanolic extract from E. uniflora was used to evaluate in vitro anti-epimastigote and cytotoxic activity. This is the first record of anti-Trypanosoma activity of E. uniflora, demonstrating that a concentration presenting 50% of activity (EC(50)) was 62.76 μg/mL. Minimum inhibitory concentration (MIC) was ≤ 1024 μg/mL. Our results indicate that E. uniflora could be a source of plant-derived natural products with anti-epimastigote activity with low toxicity.     

Associations of polymorphisms of folate cycle enzymes and risk of breast cancer in a Brazilian population are age dependent

Polymorphisms in genes involved in folate metabolism have been shown to be implicated in breast cancer risk but with contradictory results. In this case–control study, we investigated the association between MTHFR C677T and A1298C, TYMS 5′-UTR, MTR A2756G and cSHMT C1420T and also the folate carrier (RFC1 G80A) and breast cancer risk in a northeastern Brazilian population. The study included 183 women diagnosed with breast cancer and 183 controls volunteers without any history of cancer. Also a significant number of healthy individuals were included for allelic frequency in the population studied. Risk of breast cancer was estimated by conditional logistic regression. An association with risk was found for women carrying the MTR A2756G polymorphic allele (AG, P = 0.0036; AG/GG, P = 0.0040), and a protective effect in carriers of the RFC1 G80A polymorphic allele (GA, P = 0.0015; AA, P = 0.0042). Stratifying the data by age (cutoff point of 50 years old), different distributions were observed for breast cancer risk. For women ≤50 years, the risk observed in the presence of the polymorphic allele MTR 2756 (AG/GG) in the general analysis was, restricted to this age group (P = 0.0118). Conversely, for women over 50, the risk of breast cancer development was statistically associated with the MTHFR 677CT genotype, but especially significant was risk associated with the presence of the polymorphic allele of cSHMT C1420T (P = 0.0120) and the protective effect associated with the RFC1 G80A polymorphism allele (P = 0.0021), was restrict to this age group. These data indicate that the cutoff age used (50 years old) was appropriate, since it was able to discriminate risk in each age group in the population studied and also to point to the importance of age in the analyses of cancer-associated polymorphisms.