The inability of the yeast
Saccharomyces cerevisiae
to produce ethanol from xylose has hampered the biofuel production from lignocellulosic biomass. However, prior studies reveal that functional ...expression of xylose isomerase (XI) from
Burkholderia cenocepacia
(XylA
Bc
) in
S. cerevisiae
has remarkably improved xylose consumption and ethanol productivity. Yet, little is known about kinetic and structural properties of this enzyme. Hereby, a purified recombinant XylA was assayed in vitro, showing optimal enzyme activity at 37 °C and pH 7.2. The K
m
of XylA for
d
-xylose was at least threefold lower than the K
m
results for any XI published to date (e.g. XylA from
Piromyces
sp.). In addition, oligomerization behavior as a tetramer was observed for XylA in solution. Functional and structural comparative analyses amongst three microbial XIs were further performed as theoretical models, showing that xylose orientation at the active site was highly conserved among the XIs. Mg
2+
ions anchor the sugar and guide its pyranoside oxygen towards a histidine residue present at the active site, allowing an acid–base reaction, linearizing xylose. Electrostatic surface analyses showed that small variations in the net charge distribution and dipole moment could directly affect the way the substrate interacts with the protein, thus altering its kinetic properties. Accordingly, in silico modeling suggested the tetramer may be the major functional form. These analyses and the resulting model promote a better understanding of this protein family and pave the way to further protein engineering and application of XylA in the ethanol industry.
We investigated the kinetics of parasite replication, leukocyte migration, and cytokine/chemokine mRNA expression in the heart tissue from animals infected with the Colombiana strain of
Trypanosoma
...cruzi. Cardiac tissue parasitism was noticeable at 15 days, peaked around 30 days and was dramatically reduced at 120 days postinfection (p.i.). Kinetic studies showed that the inflammatory infiltrate was dominated by the presence of αβT CD3
+ CD4
+ CD8
–, αβT CD3
+ CD4
–CD8
+ lymphocytes and macrophages. The mRNA expression of the monokines IL-1β and IL-12(p40) was elevated at 15 days p.i. and controlled at later time points. In contrast, TNF-α mRNA was expressed throughout the infection. Interestingly, we found that at 15 and 30 days p.i. cytokine expression was dominated by the presence of IFN-γ mRNA, whereas at 60 days or later time points the balance of type 1 and type 2 cytokines was switched in favor of IL-4 and IL-10 mRNAs. The chemokine mRNAs encoding JE, MIP-1α, MIP-1β, KC, and MIP-2 were all mainly expressed at 15 and/or 30 days p.i. and diminished thereafter. In contrast, the expression of RANTES, MIG and IP-10 mRNAs was augmented at 15 days p.i. and persisted at high levels up to 120 days p.i. Taken together, our results indicate that regulation of IFN-γ and chemokine expression, associated with decreased tissue parasitism, may be largely responsible for the control of inflammation and immunopathology observed in the cardiac tissue of animals infected with
T. cruzi.
The ocean is considered to be a great reservoir of biodiversity. Microbial communities in marine environments are ecologically relevant as intermediaries of energy, and play an important role in ...nutrient regeneration cycles as decomposers of dead and decaying organic matter. In this sense, marine-derived fungi can be considered as a source of enzymes of industrial and/or environmental interest. Fungal strains isolated from different substrates, such as invertebrates, decaying wood, seawater, sediments, and mangrove detritus, have been reported to be producers of hydrolytic and/or oxidative enzymes, with alginate lyase, amylase, cellulase, chitinase, glucosidase, inulinase, keratinase, ligninase, lipase, nuclease, phytase, protease, and xylanase being among the enzymes produced by fungi of marine origin. These enzymes present temperature and pH optima ranging from 35 to 70(∘)C, and 3.0 to 11.0, respectively. High-level production in bioreactors is mainly performed using submerged-state fermentation. Certain marine-derived fungal strains present enzymes with alkaline and cold-activity characteristics, and salinity is considered an important condition in screening and production processes. The adaptability of marine-derived fungi to oceanic conditions can be considered an attractive point in the field of fungal marine biotechnology. In this review, we focus on the advances in discovering enzymes from marine-derived fungi and their biotechnological relevance.
•Esketamine 0.25 mg/kg was noninferior to ketamine 0.5 mg/kg in promoting remission of major depression symptoms 24 h after a single intravenous administration in subjects with treatment-resistant ...depression.•Esketamine and ketamine demonstrated a similar safety pattern and were well tolerated by most participants.•This is the first head-to-head randomized clinical trial comparing racemic ketamine and esketamine in patients with treatment-resistant depression.
Ketamine and its enantiomers have recently been highlighted as one of the most effective therapeutic options in refractory depression. However, racemic ketamine and esketamine have not been directly compared. The aim of this study is to assess the efficacy and safety of esketamine compared to ketamine in patients with treatment-resistant depression (TRD).
This is a randomized, double-blind, active-controlled, bicentre, non-inferiority clinical trial, with two parallel groups. Participants were randomly assigned to a 40-min single intravenous infusion of ketamine 0.5 mg/kg or esketamine 0.25 mg/kg. The primary outcome was the difference in remission rates for depression 24 h following intervention using the Montgomery-Åsberg Depression Rating Scale (MADRS), with a non-inferiority margin of 20%.
63 subjects were included and randomly assigned (29 to receive ketamine and 34 to receive esketamine). At 24 h, 24.1% of participants in the ketamine group and 29.4% of participants in the esketamine group showed remission, with a difference of 5.3% (95% CILB -13.6%), confirming non-inferiority. MADRS scores improved from 33 (SD 9.3) to 16.2 (SD 10.7) in the ketamine group and from 33 (SD 5.3) to 17.5 (SD 12.2) in the esketamine one, with a difference of -5.27% (95% CILB, -13.6). Both groups presented similar mild side effects.
Esketamine was non-inferior to ketamine for TRD 24 h following infusion. Both treatments were effective, safe, and well tolerated.
Registered in Japan Primary Registries Network: UMIN000032355.
Type 1 diabetes is characterized by the destruction of pancreatic β cells, and generating new insulin-producing cells from other cell types is a major aim of regenerative medicine. One promising ...approach is transdifferentiation of developmentally related pancreatic cell types, including glucagon-producing α cells. In a genetic model, loss of the master regulatory transcription factor Arx is sufficient to induce the conversion of α cells to functional β-like cells. Here, we identify artemisinins as small molecules that functionally repress Arx by causing its translocation to the cytoplasm. We show that the protein gephyrin is the mammalian target of these antimalarial drugs and that the mechanism of action of these molecules depends on the enhancement of GABAA receptor signaling. Our results in zebrafish, rodents, and primary human pancreatic islets identify gephyrin as a druggable target for the regeneration of pancreatic β cell mass from α cells.
Display omitted
•Artemisinins inhibit ARX function and impair α cell identity•Compounds act by stabilizing gephyrin, thus enhancing GABAA receptor signaling•Artemisinins increase β cell mass in zebrafish and rodent models•Functional and transcriptional data indicate a conserved phenotype in human islets
The anti-malarial drug Artemisinin can drive the in vivo conversion of pancreatic α cells into functional β-like cells through enhanced GABA signaling and may have potential as a therapeutic for diabetes.
The placenta is a temporary organ that plays critical roles at the maternal-fetal interface. Normal development and function of the placenta is dependent on hormonal signaling pathways that make the ...placenta a target of endocrine disrupting chemical (EDC) action. Studies showing association between prenatal exposure, hormone disruption, and reproductive damage indicate that EDCs are developmentally toxic and can impact future generations. In this context, new placental models (trophoblast-derived cell lines, organotypic or 3D cell models, and physiologically based kinetic models) have been developed in order to create new approach methodology (NAM) to assess and even prevent such disastrous toxic harm in future generations. With the widespread discouragement of conducting animal studies, it has become irrefutable to develop in vitro models that can serve as a substitute for in vivo models. The goal of this review is to discuss the newest in vitro models to understand the maternal-fetal interface and predict placental development, physiology, and dysfunction generated by failures in molecular hormone control mechanisms, which, consequently, may change epigenetic programming to increase susceptibility to metabolic and other disorders in the offspring. We summarize the latest placental models for developmental toxicology studies, focusing mainly on three-dimensional (3D) culture models.
•New placental models are available for in vitro maternal-fetal interface studies.•Developmental toxicity is an emerging growth area and needs to be addressed.•In vitro studies to assess risk of developmental damage can reduce disease development in adulthood.
Trypanosoma cruzi is the causative agent of the life-threatening Chagas disease, in which increased platelet aggregation related to myocarditis is observed. Platelet-activating factor (PAF) is a ...potent intercellular lipid mediator and second messenger that exerts its activity through a PAF-specific receptor (PAFR). Previous data from our group suggested that T. cruzi synthesizes a phospholipid with PAF-like activity. The structure of T. cruzi PAF-like molecule, however, remains elusive.
Here, we have purified and structurally characterized the putative T. cruzi PAF-like molecule by electrospray ionization-tandem mass spectrometry (ESI-MS/MS). Our ESI-MS/MS data demonstrated that the T. cruzi PAF-like molecule is actually a lysophosphatidylcholine (LPC), namely sn-1 C18:1(delta 9)-LPC. Similar to PAF, the platelet-aggregating activity of C18:1-LPC was abrogated by the PAFR antagonist, WEB 2086. Other major LPC species, i.e., C16:0-, C18:0-, and C18:2-LPC, were also characterized in all T. cruzi stages. These LPC species, however, failed to induce platelet aggregation. Quantification of T. cruzi LPC species by ESI-MS revealed that intracellular amastigote and trypomastigote forms have much higher levels of C18:1-LPC than epimastigote and metacyclic trypomastigote forms. C18:1-LPC was also found to be secreted by the parasite in extracellular vesicles (EV) and an EV-free fraction. A three-dimensional model of PAFR was constructed and a molecular docking study was performed to predict the interactions between the PAFR model and PAF, and each LPC species. Molecular docking data suggested that, contrary to other LPC species analyzed, C18:1-LPC is predicted to interact with the PAFR model in a fashion similar to PAF.
Taken together, our data indicate that T. cruzi synthesizes a bioactive C18:1-LPC, which aggregates platelets via PAFR. We propose that C18:1-LPC might be an important lipid mediator in the progression of Chagas disease and its biosynthesis could eventually be exploited as a potential target for new therapeutic interventions.
In this work, chemical and structural properties of various biochars were analyzed and compared with those from a highly stable anthropic soil, Terra Preta de Índio (TPI). TPI is believed to be ...responsible for the fertility of Amazonian soils and their stability; therefore, the production of a synthetic TPI would be of great interest for agricultural applications. Biochar produced from different raw biomasses were comprehensively characterized and, based on the obtained results, a preliminary study was performed testing three different routes of chemical activation using nitric acid, phosphoric acid, and potassium hydroxide as activating agents. After chemical activations, metal contents in the biochars decreased, as expected, and high degrees of carbonization were observed. In the case of the activation performed with HNO3, intense signals related to carboxylic groups in TG-MS analysis and in potentiometric titrations point out to a highly oxygenated biochar. Structural analysis showed that activations generated point defects in sp2-carbon structures of biochar, with the material obtained after KOH activation showing a high surface area (569 m2 g−1), an important feature for the use as soil amendment.
Display omitted
•Synthetic production of a material similar to a fertile anthropic soil (TPI).•Characterization and comparison of biochars from different raw biomasses with TPI.•Chemical activations of biochars with HNO3, H3PO4, and KOH as a path to mimetize TPI.
Dissociative symptoms are common, possibly severe, side effects associated with the use of ketamine and esketamine in depression. We investigated the relationship between trait dissociation and ...dissociation induced by ketamine and esketamine used as augmentation therapy in treatment-resistant depression (TRD). Adults with TRD were randomly assigned to receive a single intravenous infusion, with a duration of 40 min, of either esketamine 0.25 mg/kg or ketamine 0.5 mg/kg. We assessed trait dissociation with the Dissociative Experience Scale (DES) and, to evaluate induced dissociation, the Clinician-Administered Dissociative States Scale (CADSS) was used. Thirty-two subjects received esketamine and 29 received ketamine. The groups had similar median DES scores (p = 0.26). More than 30% of the patients in both groups had DES scores ≥30 points. The median CADSS score in the esketamine group was equivalent to that in the ketamine group (p = 0.40). Every 5 points increment in the DES was associated with a 10.9% (95% CI 4.5–17.8%) increase in the CADSS, in an exponential fashion when the two groups were pooled together. Subjects with high trait dissociation had a higher risk of induced dissociation state (relative risk RR 1.41, 95% CI 1.11–1.78) and very high induced dissociation (RR 3.05, 95% CI 1.14–8.15). Induced dissociation was not a serious adverse effect. The findings suggest that trait dissociation is a predictor of induced dissociation by Ketamine or Esketamine in TRD subjects. Screening for trait dissociation and counseling patients with high trait dissociation on the risks of dissociation by these drugs are recommended.
•Trait dissociation values were similar among ketamine and esketamine groups.•More than 30% of patients in both groups had high levels of trait dissociation.•Daily dissociation experiences correlated to dissociation induced by both drugs.•High trait dissociation subjects had a higher risk of induced dissociation.•Induced dissociation was not reported as a serious effect.
PDF
