Anti-toxoplasma,antioxidant and cytotoxic activities of Pleopeltis crassinervata (Fée) T. Moore hexane fraction

The apicomplexan parasite Toxoplasma gondii (T. gondii) causes toxoplasmosis in humans. Pyrimethamine and sulfadiazine that are the drugs of choice to treat the disease, produce severe side effects as well as failure treatments because of drug resistance; thus, novel anti-Toxoplasma compounds are needed and natural compounds can be a good source to obtain them, as medicinal plants have been used to control other apicomplexan parasites. Pleopeltis crassinervata (P. crassinervata) is a fern used in some rural areas of Mexico to treat among other malaises, mouth ulcers, gastrointestinal problems and parasites. Therefore, the efficacy of extracts and fractions obtained from P. crassinervata fronds was evaluated on the viability of T. gondii RH strain tachyzoites by the Stytox green method. RH is the prototypical type 1 Toxoplasma strain, isolated for the first time from the brain of a patient boy named R. H. Its phytochemical profile, MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, Hep-2 cytotoxicity and antioxidant activity by ABTS (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) and DPPH (2,2-diphenyl-1-picrylhydrazyl) methods, were also assessed. Hexane fraction exhibited the highest anti-Toxoplasma activity with an IC₅₀ of 16.90 µg/mL. This fraction did not show antioxidant activity and contained at least 2 terpenoid type compounds with retention factor (Rf) of 0.75 and 0.86. The fraction was not toxic to the host cells in doses up to 50 µg/mL. P. crassinervata frond hexane fraction seems to be a good candidate to obtain possible anti-Toxoplasma compounds. This study is the first to report the biological, antioxidant and cytotoxic activity of P. crassinervata fern.     

Sequential monitoring of randomization tests: stratified randomization

In many clinical trials, it is desirable to establish a sequential monitoring plan, whereby the test statistic is computed at an interim point or points in the trial and a decision is made whether to stop early due to evidence of treatment efficacy. In this article, we will set up a sequential monitoring plan for randomization-based inference under the permuted block design, stratified block design, and stratified urn design. We will also propose a definition of information fraction in these settings and discuss its calculation under these different designs.     

Developing a diagnostic model for estimating terrestrial vegetation gross primary productivity using the photosynthetic quantum yield and Earth Observation data

This article develops a new carbon exchange diagnostic model [i.e. Southampton CARbon Flux (SCARF) model] for estimating daily gross primary productivity (GPP). The model exploits the maximum quantum yields of two key photosynthetic pathways (i.e. C₃ and C₄) to estimate the conversion of absorbed photosynthetically active radiation into GPP. Furthermore, this is the first model to use only the fraction of photosynthetically active radiation absorbed by photosynthetic elements of the canopy (i.e. FAPAR_ps) rather than total canopy, to predict GPP. The GPP predicted by the SCARF model was comparable to in situ GPP measurements (R² > 0.7) in most of the evaluated biomes. Overall, the SCARF model predicted high GPP in regions dominated by forests and croplands, and low GPP in shrublands and dry‐grasslands across USA and Europe. The spatial distribution of GPP from the SCARF model over Europe and conterminous USA was comparable to those from the MOD17 GPP product except in regions dominated by croplands. The SCARF model GPP predictions were positively correlated (R² > 0.5) to climatic and biophysical input variables indicating its sensitivity to factors controlling vegetation productivity. The new model has three advantages, first, it prescribes only two quantum yield terms rather than species specific light use efficiency terms; second, it uses only the fraction of PAR absorbed by photosynthetic elements of the canopy (FAPAR_ps) hence capturing the actual PAR used in photosynthesis; and third, it does not need a detailed land cover map that is a major source of uncertainty in most remote sensing based GPP models. The Sentinel satellites planned for launch in 2014 by the European Space Agency have adequate spectral channels to derive FAPAR_ps at relatively high spatial resolution (20 m). This provides a unique opportunity to produce global GPP operationally using the Southampton CARbon Flux (SCARF) model at high spatial resolution.     

基于遥感信息的黄土高原主要灌溉农业分布区生态安全特征

生态安全是区域经济社会可持续发展的重要保证.本研究基于2000-2018年间的遥感数据,系统分析了黄土高原4个主要灌溉农业分布区(银川平原、河套平原、汾河谷地和渭河平原)植被覆盖度(FVC)和遥感生态指数(RSEI)的变化特征.结果 表明:2000-2018年间,研究区FVC整体呈下降趋势,但4个不同灌溉农业分布区FV...     

Biochemical modifications of gliadins induced by microbial transglutaminase on wheat flour

Background

Celiac disease (CD) is an immune-mediated disorder caused by the ingestion of wheat gluten. A lifelong, gluten-free diet is required to normalize the intestinal mucosa. We previously found that transamidation by microbial transglutaminase (mTGase) suppressed the gliadin-specific immune response in intestinal T-cell lines from CD patients and in models of gluten sensitivity.

Methods

SDS-PAGE, Western blot, ELISA, tissue transglutaminase (tTGase) assay and nano-HPLC–ESI-MS/MS experiments were used to analyze prolamins isolated from treated wheat flour.

Results

Gliadin and glutenin yields decreased to 7.6 ± 0.5% and 7.5 ± 0.3%, respectively, after a two-step transamidation reaction that produced a water-soluble protein fraction (spf). SDS-PAGE, Western blot and ELISA analyses confirmed the loss of immune cross-reactivity with anti-native gliadin antibodies in residual transamidated gliadins (K-gliadins) and spf as well as the occurrence of neo-epitopes. Nano-HPLC–ESI-MS/MS experiments identified some native and transamidated forms of celiacogenic peptides including p31–49 and confirmed that mTGase had similar stereo-specificity of tTGase. Those peptides resulted to be 100% and 57% modified in spf and K-gliadins, respectively. In particular, following transamidation p31–49 lost its ability to increase tTGase activity in Caco-2 cells. Finally, bread manufactured with transamidated flour had only minor changes in baking characteristics.

Conclusions

The two-step transamidation reaction modified the analyzed gliadin peptides, which are known to trigger CD, without influencing main technological properties.

General significance

Our data shed further light on a detoxification strategy alternative to the gluten free diet and may have important implications for the management of CD patients.     

The water-soluble fraction of bee venom produces antinociceptive and anti-inflammatory effects on rheumatoid arthritis in rats

We recently demonstrated that bee venom (BV) injection into the Zusanli acupoint produced a significantly more potent anti-inflammatory and antinociceptive effect than injection into a non-acupoint in a Freund's adjuvant induced rheumatoid arthritis (RA) model. However, the precise BV constituents responsible for these antinociceptive and/or anti-inflammatory effects are not fully understood. In order to investigate the possible role of the soluble fraction of BV in producing the anti-arthritic actions of BV acupuncture, whole BV was extracted into two fractions according to solubility (a water soluble fraction, BVA and an ethylacetate soluble fraction, BVE) and the BVA fraction was further tested.Subcutaneous BVA injection (0.9 mg/kg/day) into the Zusanli acupoint was found to dramatically inhibit paw edema and radiological change (i.e. new bone proliferation and soft tissue swelling) caused by Freund's adjuvant injection. BVA treatment also reduced the increase in serum interleukin-6 caused by RA induction to levels observed in non-arthritic animals. In addition, BVA therapy significantly reduced arthritis-induced nociceptive behaviors (i.e. nociceptive scores for mechanical hyperalgesia and thermal hyperalgesia). Finally, BVA treatment significantly suppressed adjuvant-induced Fos expression in the lumbar spinal cord at 3 weeks post-adjuvant injection. In contrast, BVE treatment (0.05 mg/kg/day) failed to show any anti-inflammatory or antinociceptive effects on RA.The results of the present study demonstrate that BVA is the effective fraction of whole BV responsible for the antinociception and anti-inflammatory effects of BV acupuncture treatment. Thus it is recommended that this fraction of BV be used for long-term treatment of RA-induced pain and inflammation. However, further study is necessary to clarify which constituents of the BVA fraction are directly responsible for these anti-arthritis effects.     

Mass-Based Fraction Collection of Crude Synthetic Peptides in Analytical and Preparative Scale

Synthetic peptides become more and more important as drug candidates in the treatment of a variety of diseases. A particular therapeutic focus for synthetic peptides is cancer treatment.^1,2 In order to keep pace with the growing number of newly synthesized peptides, peptide purification should not represent the bottleneck in the drug discovery process. Since the target masses of synthetic peptides are well known, mass-based fraction collection represents an efficient technique for their purification. In contrast to fraction triggering with less specific detectors, employing a mass selective detector leads in each run only to the purification of the target mass. Consequently, it is not necessary to pick the compound of interest out of a series of redundant fractions. In this article we demonstrate mass-based purification of a variety of crude synthetic peptides by reversed phase high-performance liquid chromatography. The peptides were in the mass range from less than 1 kDa to more than 10 kDa and covered a pI range from 4 to 13. We particularly focused on some technical aspects of the system that were prerequisite for reliable compound purification with high recoveries.     

Trypanosoma cruzi: distinct patterns of infection in the sibling caviomorph rodent species Thrichomys apereoides laurentius and Thrichomys pachyurus (Rodentia, Echimyidae)

Thrichomys apereoides, a caviomorph rodent species common in a highly endemic area for Chagas disease in Brazil, may act as reservoir of the parasite. However, no information is available concerning its sibling species Thrichomys pachyurus, found in the Pantanal region, where Trypanosoma cruzi is found only in the enzootic cycle. We followed up the cross infection of these cryptic species with two isolates derived from naturally infected T. pachyurus and Thrichomys apereoides laurentius. No regional co-adaptation between Thrichomys species and the regional isolates were noticed. However, significant differences in the outcome of the infection were observed. T. a. laurentius was more resistant than T. pachyurus, as expressed by lower parasitemia and less histopathological damage. The routine biochemical markers used for laboratory rodents were unsuitable for follow up of infection in Thrichomys spp, since they did not correlate with the histopathological findings or allowed the kinetic follow-up of tissue colonization by the parasite.     

Climate warming alters subsoil but not topsoil carbon dynamics in alpine grassland

Subsoil contains more than half of soil organic carbon (SOC) globally and is conventionally assumed to be relatively unresponsive to warming compared to the topsoil. Here, we show substantial changes in carbon allocation and dynamics of the subsoil but not topsoil in the Qinghai‐Tibetan alpine grasslands over 5 years of warming. Specifically, warming enhanced the accumulation of newly synthesized (¹⁴C‐enriched) carbon in the subsoil slow‐cycling pool (silt‐clay fraction) but promoted the decomposition of plant‐derived lignin in the fast‐cycling pool (macroaggregates). These changes mirrored an accumulation of lipids and sugars at the expense of lignin in the warmed bulk subsoil, likely associated with shortened soil freezing period and a deepening root system. As warming is accompanied by deepening roots in a wide range of ecosystems, root‐driven accrual of slow‐cycling pool may represent an important and overlooked mechanism for a potential long‐term carbon sink at depth. Moreover, given the contrasting sensitivity of SOC dynamics at varied depths, warming studies focusing only on surface soils may vastly misrepresent shifts in ecosystem carbon storage under climate change.