Effects of Osmotic Therapy on Pupil Reactivity: Quantification Using Pupillometry in Critically Ill Neurologic Patients

BACKGROUND

Osmotic therapy is a critical component of medical management for cerebral edema. While up to 90% of neurointensivists report using these treatments, few quantitative clinical measurements guide optimal timing, dose, or administration frequency. Its use is frequently triggered by a qualitative assessment of neurologic deterioration and/or pupil size, and anecdotally appears to improve pupil asymmetry suggestive of uncal herniation. However, subjective pupil assessment has poor reliability, making it difficult to detect or track subtle changes. We hypothesized that osmotic therapy reproducibly improves quantitative pupil metrics.

METHODS

We included patients at two centers who had recorded quantitative pupil measurements within 2 h before and after either 20% mannitol or 23.4% hypertonic saline in the neurosciences intensive care unit. The primary outcome was the Neurologic Pupil Index (NPi), a composite metric ranging from 0 to 5 in which > 3 is considered normal. Secondary outcomes included pupil size, percent change, constriction and dilation velocity, and latency. Results were analyzed with Wilcoxon signed-rank tests, Chi-square and multi-level linear regression to control for other edema-reducing interventions.

RESULTS

Out of 72 admissions (403 paired pupil observations), NPi significantly differed within 2 h of osmotic therapy when controlling for other commonly used interventions in our whole cohort (β = 0.08, p = 0.0168). The effect was most pronounced (β = 0.57) in patients with abnormal NPi prior to intervention (p = 0.0235).

CONCLUSIONS

Pupil reactivity significantly improves after osmotic therapy in a heterogenous critically ill population when controlling for various other interventions. Future work is necessary to determine dose-dependent effects and clinical utility.

Myocardial protection in the arterial switch operation: Custodiol versus cold blood cardioplegia

OBJECTIVES

The optimal myocardial protective solution in the neonatal arterial switch operation remains controversial. The aim of this study was to demonstrate that Bretschneider's histidine-tryptophan-ketoglutarate crystalloid solution (Custodiol) offers protection at least similar to that of cold blood cardioplegia.

METHODS

Patients who underwent the neonatal arterial switch operation with Custodiol between January 2016 and December 2018 (n = 23) were compared with an historical cohort from August 2010 to December 2015 in which cold blood cardioplegia was used (n = 41). A linear mixed-effect model for repeated measures was performed to test the recovery of myocardial function based on inotropic and vasoactive inotropic scores, cardiac enzyme release and left ventricular ejection fraction.

RESULTS

Patients in the cold blood cardioplegia group had higher inotropic scores in the first 24 h (0 h, P = 0.001 and 24 h, P = 0.006) and higher vasoactive inotropic scores in the first 72 h (0 h, 24 h and 48 h, P < 0.001; 72 h, P = 0.012). Cardiac troponin-I concentrations were higher in the cold blood cardioplegia group at postoperative hours 1-72 (1 h, 6 h, 12 h and 24 h, P < 0.001; 48 h, P = 0.001 and 72 h, P = 0.003). Creatinine-kinase-MB concentrations were higher in the cold blood cardioplegia group at postoperative hours 1-24 (1 h, 6 h and 12 h, P < 0.001; 24 h, P = 0.042). The left ventricular ejection fraction was higher in the Custodiol group just after the operation (P = 0.005), at 24 h (P = 0.001) and on the first day without inotropic support (P = 0.011).

CONCLUSIONS

Neonatal myocardium protected with Custodiol during the arterial switch operation presented optimal ventricular function recovery with less inotropic support and less myocardial damage compared with cold blood cardioplegia.

Metabolic responses of wheat seedlings to osmotic stress induced by various osmolytes under iso-osmotic conditions

Many environmental stresses cause osmotic stress which induces several metabolic changes in plants. These changes often vary depending on the genotype, type and intensity of stress or the environmental conditions. In the current experiments, metabolic responses of wheat to osmotic stress induced by different kinds of osmolytes were studied under iso-osmotic stress conditions. A single wheat genotypes was treated with PEG-6000, mannitol, sorbitol or NaCl at such concentrations which reduce the osmotic potential of the culture media to the same level (-0.8MPa). The metabolic changes, including the accumulation of proline, glycine betaine (GB) and sugar metabolites (glucose, fructose, galactose, maltose and sucrose) were studied both in the leaves and roots together with monitoring the plant growth, changes in the photosynthetic activity and chlorophyll content of the leaves. In addition, the polyamine metabolism was also investigated. Although all osmolytes inhibited growth similarly, they induced different physiological and metabolic responses: the CO2 assimilation capacity, RWC content and the osmotic potential (ψπ) of the leaves decreased intensively, especially after mannitol and sorbitol treatments, followed by NaCl treatment, while PEG caused only a slight modification in these parameters. In the roots, the most pronounced decrease of ψπ was found after salt-treatments, followed by PEG treatment. Osmotic stress induced the accumulation of proline, glycine betaine and soluble sugars, such as fructose, glucose, sucrose and galactose in both the root and leaf sap. Specific metabolic response of roots and leaves under PEG included accumulation of glucose, fructose and GB (in the roots); sucrose, galactose and proline synthesis were dominant under NaCl stress while exposure to mannitol and sorbitol triggered polyamine metabolism and overproduction of maltose. The amount of those metabolites was time-dependent in the manner that longer exposure to iso-osmotic stress conditions stimulated the sugar metabolic routes. Our results showed that the various osmolytes activated different metabolic processes even under iso-osmotic stress conditions and these changes also differed in the leaves and roots.

Examining Mannitol Use in Kidney Cancer Surgery: A Cautionary Tale of Extrapolated Surgical Data

Mannitol for renal protection during partial nephrectomy is common but unsupported by evidence from clinical trials. The impact of mannitol on renal physiology includes both beneficial and harmful effects. Current understanding of renal ischemia reperfusion injury suggests potentially targetable processes that have a lower potential risk.

Inhaled nebulized glatiramer acetate against Gram-negative bacteria is not associated with adverse pulmonary reactions in healthy, young adult female pigs

The developmental speed of new antimicrobials does not meet the emergence of multidrug-resistant bacteria sufficiently. A potential shortcut is assessing the antimicrobial activity of already approved drugs. Intrudingly, the antibacterial action of glatiramer acetate (GA) has recently been discovered. GA is a well-known and safe immunomodulatory drug particular effective against Gram-negative bacteria, which disrupts biological membranes by resembling the activity of antimicrobial peptides. Thus, GA can potentially be included in treatment strategies used to combat infections caused by multidrug-resistant Gram-negatives. One potential application is chronic respiratory infections caused by Pseudomonas aeruginosa, however the safety of GA inhalation has never been assessed. Here, the safety of inhaling nebulized GA is evaluated in a preclinical pig model. The potential side effects, i.e., bronchoconstriction, respiratory tract symptoms and systemic- and local inflammation were assessed by ventilator monitoring, clinical observation, biochemistry, flowcytometry, and histopathology. No signs of bronchoconstriction assessed by increased airway peak pressure, Ppeak, or decreased oxygen pressure were observed. Also, there were no signs of local inflammation in the final histopathology examination of the pulmonary tissue. As we did not observe any potential pulmonary side effects of inhaled GA, our preliminary results suggest that GA inhalation is safe and potentially can be a part of the treatment strategy targeting chronic lung infections caused by multidrug-resistant Gram-negative bacteria.

Knockdown of the chitin-binding protein family gene CaChiIV1 increased sensitivity to Phytophthora capsici and drought stress in pepper plants

Phytophthora capsici has been the most destructive pathogen of pepper plants (Capsicum annuum L.), possessing the ability to quickly overcome the host defense system. In this context, the chitin-binding protein (CBP) family member CaChiIV1 regulates the response to P. capsici and abiotic stresses. The relevance of functional characterization and regulation of CaChiIV1 has not been explored in horticultural crops, especially pepper plants. The target gene (CaChiIV1) was isolated from pepper plants and cloned; the encoded protein carries a chitin-binding domain (CBD) that is rich in cysteine residues and has a hinge region with an abundance of proline and glycine residues. Additionally, the conserved regions in the promoter have a remarkable motif, "TTGACC". The expression of CaChiIV1 was markedly regulated by methyl-jasmonate (MeJA), hydrogen peroxide (H₂O₂), melatonin, mannitol and P. capsici (PC and HX-9) infection. Knockdown of CaChiIV1 in pepper plants increased sensitivity to P. capsici (PC strain). Higher malondialdehyde (MDA) content and relative electrolyte leakage (REL) but lower antioxidant enzyme activities, chlorophyll content, root activity, and proline content were observed in CaChiIV1-silenced plants than in control plants. In conclusion, CaChiIV1-silenced pepper plants displayed increased susceptibility to P. capsici infection due to changes in expression of defense-related genes, thus showing its coregulation affect in particular conditions. Furthermore, antioxidant enzymes and proline content were largely diminished in CaChiIV1-silenced plants. Therefore, this evidence suggests that the CaChiIV1 gene plays a prominent role in the defense mechanism of pepper plants against P. capsici infection. In the future, the potential role of the CaChiIV1 gene in defense regulatory pathways and its coregulation with other pathogen-related genes should be identified.

Identification of variable lymphocyte receptors that can target therapeutics to pathologically exposed brain extracellular matrix

Diseases that lead to blood-brain barrier (BBB) disruption will pathologically expose normally inaccessible brain extracellular matrix (ECM) to circulating blood components. Therefore, we hypothesized that brain ECM-targeting moieties could specifically target the disrupted BBB and potentially deliver therapies. Variable lymphocyte receptors (VLRs) that preferentially associate with brain ECM were identified from an immune VLR library via yeast surface display biopanning coupled with a moderate throughput ECM screen. Brain ECM binding of VLR clones to murine and human brain tissue sections was confirmed. After systemic administration, P1C10, the lead brain ECM-targeting VLR candidate, specifically accumulated in brains with mannitol-disrupted BBB and at disrupted BBB regions in two different intracranial glioblastoma models. We also demonstrate P1C10's ability to deliver doxorubicin-loaded liposomes, leading to significantly improved survival in glioblastoma-bearing mice. Thus, VLRs can be used to selectively target pathologically exposed brain ECM and deliver drug payloads.

Phase III Trial of Intravenous Mannitol Versus Placebo During Nephron-sparing Surgery: Post Hoc Analysis of 3-yr Outcomes

Our recently reported phase III trial demonstrated that patients undergoing nephron-sparing surgery (NSS) with an estimated glomerular filtration rate (eGFR) of ≥45 ml/min/1.73 m² who received mannitol had no improvement in renal function at 6 mo compared with those who received placebo. Some authors have suggested that benefit is restricted to subgroups, such as those with comorbidities. We assessed whether preoperative eGFR, or other patient and surgical factors modified the effect of mannitol on postoperative outcomes at 6 mo and with extended follow-up. We also assessed whether mannitol was associated with differences in long-term GFR years after surgery. No significant difference between the mannitol or placebo groups (mean eGFR difference: 1.4; 95% confidence interval: -2.6, 5.3; p = 0.5) was found in the 134 patients with known eGFR at 3 yr after NSS. At both 6 mo and 3 yr, the effect of mannitol was not significantly modified by patient or surgical factors including preoperative eGFR. In summary, we validated our original trial conclusions by finding that intraoperative use of mannitol does not improve either short- or long-term renal function in patients undergoing NSS. Specifically, there is no evidence that comorbidities, including lower preoperative eGFR, modify the effect of mannitol. PATIENT SUMMARY: Use of mannitol at the time of partial nephrectomy does not improve either short- or long-term renal function even in patients with comorbidities, including lower preoperative renal function. The routine use of intraoperative mannitol should be discontinued.

In silico screening of sugar alcohol compounds to inhibit viral matrix protein VP40 of Ebola virus

Ebola virus is a virulent pathogen that causes highly lethal hemorrhagic fever in human and non-human species. The rapid growth of this virus infection has made the scenario increasingly complicated to control the disease. Receptor viral matrix protein (VP40) is highly responsible for the replication and budding of progeny virus. The binding of RNA to VP40 could be the crucial factor for the successful lifecycle of the Ebola virus. In this study, we aimed to identify the potential drug that could inhibit VP40. Sugar alcohols were enrich with antiviral properties used to inhibit VP40. Virtual screening analysis was perform for the 48 sugar alcohol compounds, of which the following three compounds show the best binding affinity: Sorbitol, Mannitol and Galactitol. To understand the perfect binding orientation and the strength of non-bonded interactions, individual molecular docking studies were perform for the best hits. Further molecular dynamics studies were conduct to analyze the efficacy between the protein-ligand complexes and it was identify that Sorbitol obtains the highest efficacy. The best-screened compounds obtained drug-like property and were less toxic, which could be use as a potential lead compound to develop anti-Ebola drugs.

Visualization of the intrarenal distribution of capillary blood flow

This study describes a modified technique to fill the renal vasculature with a silicon rubber (Microfil) compound and obtain morphologic information about the intrarenal distribution of capillary blood flow under a variety of conditions. Kidneys and cremaster muscles of rats were perfused in vivo with Microfil using a perfusion pressure equal to the animal's mean arterial pressure at body temperature. Microfil did not alter arteriolar diameter or the pattern of flow in the microcirculation of the cremaster muscle. The modified protocol reproducibly filled the renal vasculature, including; glomerular, peritubular, and vasa recta capillaries. We compared the filling of the renal circulation in control rats with that seen in animals subjected to maneuvers reported to alter the intrarenal distribution of blood flow. Infusion of angiotensin II, hypotension, volume expansion, and mannitol- or furosemide-induced diuresis redistributed flow between renal cortical and medullary capillaries. The advantage of the current technique is that it provides anatomical information regarding the number, diameter, and branching patterns of capillaries in the postglomerular circulation critical in determining the intrarenal distribution of cortical and medullary blood flow.

A B-box zinc finger protein, MdBBX10, enhanced salt and drought stresses tolerance in Arabidopsis

The expression of MdBBX10 was significantly induced by different stresses and ABA treatments. Overexpression of MdBBX10 in Arabidopsis significantly enhanced abiotic stresses tolerance by ABA signalling. The roles of B-box domain(s) containing proteins (BBXs) in regulation of flowering and light morphogenesis of plants were intensively studied. However, the roles of plant BBXs in abiotic stresses are poorly understood. A B-box protein encoding gene from apple (MdBBX10) was found to be up-regulated from gene expression profile under salt stress. qRT-PCR analysis indicated that the expression of MdBBX10 was significantly induced by different stresses and exogenous abscisic acid (ABA) in apple roots and leaves. The β-glucuronidase activity driven by the promoter of MdBBX10 was also strongly induced by NaCl, H₂O₂, polyethylene glycol and exogenous ABA, which was consistent to the existence of rich cis-acting elements related to the abiotic stresses in the promoter sequence. Over-expression of MdBBX10 in Arabidopsis significantly enhanced tolerance to abiotic stresses, with higher germination ratio and longer length of roots than the wild type plants. Transgenic plants of over-expressing MdBBX10 lines were more sensitive to exogenous ABA than the wild type plants. Under abiotic stress treatments, the transcript levels of ABA- and stress-related genes were higher in MdBBX10-overexpressing plants than wild type plants. Over-expression of MdBBX10 could enhance plant's ability to scavenge reactive oxygen species (ROS) under stresses, which is correlated with the expression of ROS-scavenging genes. These results provided the evidences that MdBBX10 plays an important role in enhanced plant tolerance to abiotic stresses, which were involved in ABA-mediated response and ROS response.

Loss of Arabidopsis Halotolerance 2-like (AHL), a 3'-phosphoadenosine-5'-phosphate phosphatase, suppresses insensitive response of Arabidopsis thaliana ring zinc finger 1 (atrzf1) mutant to abiotic stress

Destruction of PAP phosphatase AHL suppresses atrzf1 phenotype in abiotic stress responses. AHL plays an intermediate role in the regulation of proline accumulation by PAP nucleotidase. Proline (Pro) metabolism is important for environmental responses, plant development, and growth. However, the role of Pro in abiotic stress process is unclear. Using atrzf1 (Arabidopsis thaliana ring zinc finger 1) mutant as a parental line for T-DNA tagging mutagenesis, we identified a suppressor mutant designated as proline content alterative 17 (pca17) that suppressed insensitivity of atrzf1 to abiotic stresses during early seedling growth. Pro content of pca17 was lower than that in both wild type (WT) and atrzf1 while complementary lines were less sensitive to abscisic acid (ABA) and abiotic stresses compared to WT. Thermal Asymmetric Interlaced (TAIL)-PCR of pca17 showed that T-DNA was inserted at site of At5g54390 (AHL for Arabidopsis Halotolerance 2-like) encoding 3'-phosphoadenosine-5'-phosphate (PAP) phosphatase. Under drought stress condition, products of sulfate metabolism such as PAP and adenosine monophosphate were significantly lower in pca17 than those in WT and atrzf1. Furthermore, pca17 showed significantly higher levels of several important drought parameters including malondialdehyde, ion leakage, and water loss than WT and atrzf1. Fluorescence signal of green fluorescent protein (GFP)-tagged AHL was quite strong in nuclei of the root and guard cells of transgenic seedlings. Additionally, AHL promoter-β-glucuronidase (GUS) construct revealed substantial gene expression in vasculature tissues and pollen. Collectively, these findings demonstrate that pca17 acts as a dominant suppressor mutant of atrzf1 in abiotic stress response by modulating proline and sulfate metabolism.

Alleviative role of exogenously applied mannitol in maize cultivars differing in chromium stress tolerance

A pot experiment was performed to examine the role of foliar applied mannitol (M) in chromium (Cr) stress alleviation in different maize cultivars. Two maize cultivars, one tolerant (6103) and one sensitive (9108) to chromium stress, were grown in soil treated with three concentrations of Cr (0, 5, and 10 mg kg^-1) and three levels of mannitol (0, 50, and 100 mg L^-1). Chromium stress decreased the overall growth of plants by reducing the plant height, root/shoot dry weight, chlorophyll contents, and enzymatic activities, while exacerbated the severity of reactive oxygen species in both maize cultivars. Chromium-induced reduction in growth attributes of maize plants was relatively higher in sensitive cultivar than that of tolerant one. Uptake of Cr by the plants and its translocation from roots to shoots increased with increasing concentration in the soil. However, foliar application of mannitol significantly alleviated the Cr stress and improved growth, biomass, and photosynthetic pigments of maize plants. Mannitol also considerably reduced Cr contents in leaves and roots of both cultivars. Hence, it is concluded that mannitol can be helpful for crops grown on heavy metal, especially Cr, contaminated soils for remediation purpose.

Mannitol decreases neocortical epileptiform activity during early brain development via cotransport of chloride and water

Seizures and brain injury lead to water and Cl^- accumulation in neurons. The increase in intraneuronal Cl^- concentration ([Cl^-]_i) depolarizes the GABA_A reversal potential (E_GABA) and worsens seizure activity. Neocortical neuronal membranes have a low water permeability due to the lack of aquaporins necessary to move free water. Instead, neurons use cotransport of ions including Cl^- to move water. Thus, increasing the extracellular osmolarity during seizures should result in an outward movement of water and salt, reducing [Cl^-]_i and improving GABA_A receptor-mediated inhibition. We tested the effects of hyperosmotic therapy with a clinically relevant dose of mannitol (20 mM) on epileptiform activity, spontaneous multiunit activity, spontaneous inhibitory post-synaptic currents (sIPSCs), [Cl^-]_i, and neuronal volume in layer IV/V of the developing neocortex of C57BL/6 and Clomeleon mice. Using electrophysiological techniques and multiphoton imaging in acute brain slices (post-natal day 7-12) and organotypic neocortical slice cultures (post-natal day 14), we observed that mannitol: 1) decreased epileptiform activity, 2) decreased neuronal volume and [Cl^-]_i through CCCs, 3) decreased spontaneous multi-unit activity frequency but not amplitude, and 4) restored the anticonvulsant efficacy of the GABA_A receptor modulator diazepam. Increasing extracellular osmolarity by 20 mOsm with hypertonic saline did not decrease epileptiform activity. We conclude that an increase in extracellular osmolarity by mannitol mediates the efflux of [Cl^-]_i and water through CCCs, which results in a decrease in epileptiform activity and enhances benzodiazepine actions in the developing neocortex in vitro. Novel treatments aimed to decrease neuronal volume may concomitantly decrease [Cl^-]_i and improve seizure control.

Effect of a single dose of mannitol on hydration status and electrolyte concentrations in patients with tick-borne encephalitis

OBJECTIVE

This study was performed to assess the effect of a single dose of 15% mannitol on the hydration status and electrolyte balance in patients with tick-borne encephalitis (TBE).

METHODS

Forty-one patients with TBE were treated with 0.25 g/kg of 15% mannitol. The electrolyte concentrations (Na, K, and Cl), creatinine concentration, and hydration status were measured before and after mannitol infusion.

RESULTS

After mannitol administration, 7 patients had hyponatremia, 3 had hypokalemia, 1 had hyperkalemia, and 17 had hypochloremia. The total body water volume (TBW) changed by 0.44% ± 0.55%, the external body water volume (EBW) changed by 0.12% ± 0.15%, and the internal body water volume (IBW) changed by 0.19% ± 0.40%. The mean ECW/ICW ratio was 0.7694 ± 0.07 before treatment and 0.7699 ± 0.07 after treatment. Age was correlated with the TBW change in men (R = 0.42, p < 0.05) and with the potassium change in women (R = 0.66, p < 0.05).

CONCLUSIONS

Patients with TBE should receive mannitol two to four times daily depending on the clinical manifestation. Administration of a single dose of mannitol (0.25 g/kg) requires at least 300 mL of fluid supplementation. Bioimpedance might be useful for individual evaluation of dehydration. Additionally, patients require monitoring for potential hyponatremia. Older men may be more prone to dehydration after receiving mannitol.

Novel osmotic stress control strategy for improved pneumocandin B0 production in Glarea lozoyensis combined with a mechanistic analysis at the transcriptome level

Pneumocandin B₀, the precursor of the antifungal drug caspofungin, is a secondary metabolite of the fungus Glarea lozoyensis. In this study, we investigated the effects of mannitol as the sole carbon source on pneumocandin B₀ production by G. lozoyensis. The osmotic pressure is more important in enhancing pneumocandin B₀ production than is the substrate concentration. Based on the kinetic analysis, an osmotic stress control fed-batch strategy was developed. This strategy led to a maximum pneumocandin B₀ concentration of 2711 mg/L with a productivity of 9.05 mg/L/h, representing 34.67 and 6.47% improvements, respectively, over the best result achieved by the one-stage fermentation. Furthermore, G. lozoyensis accumulated glutamate and proline as compatible solutes to resist osmotic stress, and these amino acids also provided the precursors for the enhanced pneumocandin B₀ production. Osmotic stress also activated ROS (reactive oxygen species)-dependent signal transduction by upregulating the levels of related genes and increasing intracellular ROS levels by 20%. We also provided a possible mechanism for pneumocandin B₀ accumulation based on signal transduction. These findings will improve our understanding of the regulatory mechanisms of pneumocandin B₀ biosynthesis and may be applied to improve secondary metabolite production.

Renal tubular epithelial cells injury induced by mannitol and its potential mechanism

Administration of mannitol with high dose could induce extensive isometric renal proximal tubular vacuolization and acute renal failure in clinic. We previously demonstrated that mannitol-induced human kidney tubular epithelial cell (HK-2) injury. The objective of our present work was to further study the cytotoxicity of mannitol in HK-2 cells and its potential mechanism. Cell viability was assessed by an MTT method. Cell morphological changes were observed. Furthermore, levels of malondialdehyde (MDA) and glutathione (GSH) were measured. Flow cytometry was performed to determine cell apoptosis by using Annexin V-FITC and PI. In addition, the F-actin of cells was labeled by FITC-Phalloidin for observation of cytoskeleton. The MTT assay displayed that the cell viability decreased significantly in a dose- and time-dependent manner. The morphological changes were observed, including cell membrane rapture and cell detachment. The GSH concentration in HK-2 cells decreased dramatically in mannitol treatment group, while MDA content increased significantly. The results of flow cytometry indicated that apoptotic percentages of HK-2 cells increased in 250 mmol/L mannitol treatment group. After treatment with 250 mmol/L mannitol for 48 h, HK-2 cells showed disorganization of cytoskeleton and even exhibited a totally destroyed cytoskeleton. Therefore, high dose of mannitol has a toxic effect on renal tubular epithelial cells, which might be attributed to oxidative stress, destroyed cellular cytoskeleton and subsequent cell apoptosis.

A tomato ERF transcription factor, SlERF84, confers enhanced tolerance to drought and salt stress but negatively regulates immunity against Pseudomonas syringae pv. tomato DC3000

ERF proteins are plant-specific transcription factors that play significant roles in plant defense against various stresses. However, only little information regarding stress-related ERF genes is available in tomato (Solanum lycopersicum, Sl). In this study, a tomato ERF gene, SlERF84, was cloned and functionally characterized. The nucleus localization of SlERF84-sGFP was confirmed through a transient expression assay. Transactivation assays in yeast demonstrated that SlERF84 functions as a transcriptional activator. Real-time PCR analysis revealed that SlERF84 could be markedly induced by drought, salt and by several phytohormones (ABA, MeJA and ACC). Overexpression of SlERF84 in Arabidopsis endows transgenic plants with ABA hypersensitivity and enhanced tolerance to drought and salt stress. Histochemical staining assay showed that SlERF84 renders transgenic plants better ROS-scavenging capability. Pathogen inoculation assay revealed that SlERF84 might negatively modulate plant defense response to Pseudomonas syringae pv. tomato DC3000. Moreover, the transcript levels of pathogenesis-related genes AtPR1 and AtPR3 were compromised in transgenic Arabidopsis, as compared to that in Col-0 plants when inoculated with Pseudomonas syringae pv. tomato DC3000. These results suggest that SlERF84 functions as a stress-responsive transcription factor in differentially modulation of abiotic and biotic stress tolerance, and may have applications in the engineering of economically important crops.

13C Pyruvate Transport Across the Blood-Brain Barrier in Preclinical Hyperpolarised MRI

Hyperpolarised MRI with Dynamic Nuclear Polarisation overcomes the fundamental thermodynamic limitations of conventional magnetic resonance, and is translating to human studies with several early-phase clinical trials in progress including early reports that demonstrate the utility of the technique to observe lactate production in human brain cancer patients. Owing to the fundamental coupling of metabolism and tissue function, metabolic neuroimaging with hyperpolarised [1-13C]pyruvate has the potential to be revolutionary in numerous neurological disorders (e.g. brain tumour, ischemic stroke, and multiple sclerosis). Through the use of [1-13C]pyruvate and ethyl-[1-13C]pyruvate in naïve brain, a rodent model of metastasis to the brain, or porcine brain subjected to mannitol osmotic shock, we show that pyruvate transport across the blood-brain barrier of anaesthetised animals is rate-limiting. We show through use of a well-characterised rat model of brain metastasis that the appearance of hyperpolarized [1-13C]lactate production corresponds to the point of blood-brain barrier breakdown in the disease. With the more lipophilic ethyl-[1-13C]pyruvate, we observe pyruvate production endogenously throughout the entire brain and lactate production only in the region of disease. In the in vivo porcine brain we show that mannitol shock permeabilises the blood-brain barrier sufficiently for a dramatic 90-fold increase in pyruvate transport and conversion to lactate in the brain, which is otherwise not resolvable. This suggests that earlier reports of whole-brain metabolism in anaesthetised animals may be confounded by partial volume effects and not informative enough for translational studies. Issues relating to pyruvate transport and partial volume effects must therefore be considered in pre-clinical studies investigating neuro-metabolism in anaesthetised animals, and we additionally note that these same techniques may provide a distinct biomarker of blood-brain barrier permeability in future studies.

PtDRG1, a Desiccation Response Gene from Pyropia tenera (Rhodophyta), Exhibits Chaperone Function and Enhances Abiotic Stress Tolerance

Pyropia are commercially valuable marine red algae that grow in the intertidal zone. They are extremely tolerant to desiccation stress. We have previously identified and reported desiccation response genes (DRGs) based on transcriptome analysis of P. tenera. Among them, PtDRG1 encodes a polypeptide of 22.6 kDa that is located in the chloroplast. PtDRG1 does not share sequence homology with any known gene deposited in public database. Transcription of PtDRG1 gene was upregulated by osmotic stress induced by mannitol or H₂O₂ as well as desiccation stress, but not by heat. When PtDRG1 was overexpressed in Escherichia coli or Chlamydomonas, transformed cells grew much better than control cells under high temperature as well as osmotic stress induced by mannitol and NaCl. In addition, PtDRG1 significantly reduced thermal aggregation of substrate protein under heat stress condition. These results demonstrate that PtDRG1 has a chaperone function and plays a role in tolerance mechanism for abiotic stress. This study shows that red algae have unknown stress proteins such as PtDRG1 that contributes to stress tolerance.

Modulation of synaptic inputs in magnocellular neurones in a rat model of cancer cachexia

In cancer cachexia, abnormal metabolism and neuroendocrine dysfunction cause anorexia, tissue damage and atrophy, which can in turn alter body fluid balance. Arginine vasopressin, which regulates fluid homeostasis, is secreted by magnocellular neurosecretory cells (MNCs) of the hypothalamic supraoptic nucleus. Arginine vasopressin secretion by MNCs is regulated by both excitatory and inhibitory synaptic activity, alterations in plasma osmolarity and various peptides, including angiotensin II. In the present study, we used whole-cell patch-clamp recordings of brain slices to determine whether hyperosmotic stimulation and/or angiotensin II potentiate excitatory synaptic input in a rat model of cancer cachexia, similar to their effects in normal (control) rats. Hyperosmotic (15 and 60 mmol L^-1   mannitol) stimulation and angiotensin II (0.1 μmol L^-1 ) increased the frequency, but not the amplitude, of miniature excitatory postsynaptic currents in normal rats; in model rats, both effects were significantly attenuated. These results suggest that cancer cachexia alters supraoptic MNC sensitivity to osmotic and angiotensin II stimulation.

The AtMYB44 promoter is accessible to signals that induce different chromatin modifications for gene transcription

AtMYB44 transcripts accumulate non-specifically under diverse stress conditions and with various phytohormone treatments in Arabidopsis thaliana. We investigated the chromatin modifications caused by various signals to uncover the induction mechanism of AtMYB44 transcription. Bisulfite sequencing confirmed a previous database illustrating that the AtMYB44 promoter and gene-body regions are completely DNA methylation-free. Chromatin immunoprecipitation (ChIP) assays revealed that the nucleosome density is remarkably low at the AtMYB44 promoter region. Thus, the promoter region appears to be highly accessible for various trans-acting factors. ChIP assays revealed that osmotic stress (mannitol treatment) lowered the nucleosome density at the gene-body regions, while abscisic acid (ABA) or jasmonic acid (JA) treatment did so at the proximal transcription start site (TSS) region. In response to mannitol treatment, histone H3 lysine 4 trimethylation (H3K4me3) and H3 acetylation (H3ac) levels within the promoter, TSS, and gene-body regions of AtMYB44 were significantly increased. However, occupancy of histone variant H2A.Z was not affected by the mannitol treatment. We previously reported that salt stress triggered a significant decrease in H2A.Z occupation without affecting the H3K4me3 and H3ac levels. In combination, our data suggest that each signal transduced to the highly accessible promoter induces a different chromatin modification for AtMYB44 transcription.

Early mannitol-triggered changes in the Arabidopsis leaf (phospho)proteome reveal growth regulators

Leaf growth is a complex, quantitative trait, controlled by a plethora of regulatory mechanisms. Diverse environmental stimuli inhibit leaf growth to cope with the perceived stress. In plant research, mannitol is often used to impose osmotic stress and study the underlying growth-repressing mechanisms. In growing leaf tissue of plants briefly exposed to mannitol-induced stress, a highly interconnected gene regulatory network is induced. However, early signalling and associated protein phosphorylation events that probably precede part of these transcriptional changes and that potentially act at the onset of mannitol-induced leaf size reduction are largely unknown. Here, we performed a proteome and phosphoproteome analysis on growing leaf tissue of Arabidopsis thaliana plants exposed to mild mannitol-induced stress and captured the fast (within the first half hour) events associated with this stress. Based on this in-depth data analysis, 167 and 172 differentially regulated proteins and phosphorylated sites were found. We provide these data sets as a community resource and we flag differentially phosphorylated proteins with described growth-regulatory functions, but we also illustrate potential novel regulators of shoot growth.

Euclidean distance can identify the mannitol level that produces the most remarkable integral effect on sugarcane micropropagation in temporary immersion bioreactors

Plant scientists usually record several indicators in their abiotic factor experiments. The common statistical management involves univariate analyses. Such analyses generally create a split picture of the effects of experimental treatments since each indicator is addressed independently. The Euclidean distance combined with the information of the control treatment could have potential as an integrating indicator. The Euclidean distance has demonstrated its usefulness in many scientific fields but, as far as we know, it has not yet been employed for plant experimental analyses. To exemplify the use of the Euclidean distance in this field, we performed an experiment focused on the effects of mannitol on sugarcane micropropagation in temporary immersion bioreactors. Five mannitol concentrations were compared: 0, 50, 100, 150 and 200 mM. As dependent variables we recorded shoot multiplication rate, fresh weight, and levels of aldehydes, chlorophylls, carotenoids and phenolics. The statistical protocol which we then carried out integrated all dependent variables to easily identify the mannitol concentration that produced the most remarkable integral effect. Results provided by the Euclidean distance demonstrate a gradually increasing distance from the control in function of increasing mannitol concentrations. 200 mM mannitol caused the most significant alteration of sugarcane biochemistry and physiology under the experimental conditions described here. This treatment showed the longest statistically significant Euclidean distance to the control treatment (2.38). In contrast, 50 and 100 mM mannitol showed the lowest Euclidean distances (0.61 and 0.84, respectively) and thus poor integrated effects of mannitol. The analysis shown here indicates that the use of the Euclidean distance can contribute to establishing a more integrated evaluation of the contrasting mannitol treatments.

Prevention of alcohol-induced DNA damage by a proprietary glycyrrhizin/D-mannitol product: A randomized, placebo-controlled, cross-over human study

OBJECTIVES

The purpose of the present study was to evaluate the ability of a proprietary combination of glycyrrhizin and D-mannitol to protect against oxidative damage to DNA associated with acute alcohol consumption by human subjects in a randomized, placebo-controlled cross-over designed study. Excessive alcohol consumption is associated with numerous diseases. Alcohol has been shown to generate reactive oxygen species that can result in DNA damage, leading to genetic and epigenetic changes.

METHODS

A total of 25 subjects (13 male and 12 female) were enrolled. Alcohol intake in the form of vodka (40% ethanol) was adjusted based on 1.275 g of 100% ethanol/kg body weight for men and 1.020 g/kg body weight for women, which was consumed with and without the study product. Blood samples were drawn at 2 h after alcohol consumption, lymphocytes were isolated, and were subjected to DNA comet electrophoresis on a blinded basis.

RESULTS

Acute alcohol consumption increased lymphocyte DNA damage by approximately 8.36%. Co-consumption of the glycyrrhizin/D-mannitol study product with alcohol reduced DNA damage to baseline levels. No adverse effects were associated with use of the study product, and no differences were observed in blood alcohol concentrations in the presence or absence of the study product in males and females.

CONCLUSIONS

Acute alcohol ingestion resulted in measurable increases in DNA damage, which were prevented by the addition of the proprietary glycyrrhizin/D-mannitol (NTX^®) study product to the alcohol, suggesting that the tissue-damaging effects of alcohol consumption can be ameliorated.