Beneficial role of methyl jasmonate on morphological, physiological and phytochemical responses of Calendula officinalis L. under Chromium toxicity

Contamination of soil with chromium (Cr) is a rising problem in terms of agricultural sustainability and food safety. Here, the effects of methyl jasmonate (MJ; 0, 5, and 10 µM) on alleviating Cr stress (0, 100, and 200 µM) were surveyed in pot marigold (Calendula officinalis L.). The results showed that Cr stress significantly reduced photosynthetic pigments and leaf accumulation of total soluble sugars, total starch, and mineral nutrients and, consequently, lowered the height and biomass of pot marigold plants. Chromium toxicity also increased the leaf levels of oxidative stress markers and induced oxidative stress, which was associated with damage to bio-membranes and increased levels of malondialdehyde. However, MJ supplementation reduced the leaf accumulation of Cr, increased the content of photosynthetic pigments, and improved the performance of the photosynthetic machinery in Cr-stressed plants. MJ supplementation boosted the antioxidant defense system by upregulating antioxidant enzymes, glyoxalase enzymes, and the ascorbate-glutathione (AsA-GSH) pool redox, which significantly diminished Cr-induced oxidative stress. Hence, MJ supplementation might be a practicable approach for reducing Cr absorption and its negative impacts on pot marigold plants growing under Cr-contaminated conditions. Clinical trials registration Not applicable.

Effects of silicon and titanium dioxide nanoparticles on arsenic accumulation, phytochelatin metabolism, and antioxidant system by rice under arsenic toxicity

Arsenic (As) is known to be one of the most toxic metalloids for humans and plants; however, little is known about the use of silicon (Si) and titanium dioxide (TiO₂) nanoparticles (NPs) in reducing As toxicity in rice (Oryza sativa L.). The experiment was conducted to examine the effects of Si-NPs (50 and 100 mg/L), TiO₂-NPs (25 and 50 mg/L) and As (50 µM) on growth, photosynthetic pigments, antioxidant defense system, glyoxalase system, expression of Si/As transporters, and genes involved in As sequestration in rice under hydroponic conditions. The results revealed that Si- and TiO₂-NPs by upregulating the activity of antioxidant enzymes and glyoxalase cycle reduced hydrogen peroxide, methylglyoxal, malondialdehyde, and electrolyte leakage, and thus protected the photosynthetic apparatus and improved plant growth under As stress. By increasing the expression of GSH1, PCS, and ABC1 genes, Si- and TiO₂-NPs increased leaf and root accumulation of glutathione and phytochelatins and sequestered As in vacuoles, which protected plant cells from As toxicity. Si-NPs diminished As uptake and increased Si uptake in As-exposed rice plants by modulating the expression of Si/As transporters (Lsi1, Lsi2, and Lsi6). The results depicted that 100 mg/L Si-NPs treatment had the highest positive effect on plant growth and tolerance under As stress compared to other treatments. In general, Si- and TiO₂-NPs augmented the growth of rice under As stress through different strategies, which can be used to design effective fertilizers to enhance the crop growth and yield in areas contaminated with toxic metals.

Phytotoxicity of green synthesized silver nanoparticles on Camelina sativa L

Due to the increased production and release of silver nanoparticles (AgNPs) in the environment, the concerns about the possibility of toxicity and oxidative damage to plant ecosystems should be considered. In the present study, the effects of different concentrations of AgNPs (0, 0.5, 1, 2, 3 and 4 g/L) synthesized using the extract of camelina (Camelina sativa) leaves on the growth and the biochemical traits of camelina seedlings were investigated. The results showed that AgNPs significantly increased Ag accumulation in the roots and shoots which decreased the growth and photosynthetic pigments of camelina seedlings. The highest decrease in the height and total dry weight was observed by 53.1 and 61.8% under 4 g/L AgNPs, respectively over control plants. AgNPs application over 2 g/L enhanced the accumulation of proline, malondialdehyde, hydrogen peroxide and methylglyoxal, and up-regulated the activity of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase) and glyoxalase (glyoxalase I and II) system which indicates oxidative stress induction in camelina seedlings. Moreover, AgNPs reduced ASA and GSH contents and increased DHA and GSSG contents, hence disrupting the redox balance. These results showed that AgNPs at 4 g/L had the most toxic effects on the camelina growth. Therefore, increasing oxidative stress markers and the activity of antioxidant enzymes and enzymes involved in glyoxalase system indicated the oxidative stress induced by AgNPs treatments over 2 g/L as well as the induction of antioxidant defense systems to combat AgNPs-induced oxidative stress.

Naloxone added to bupivacaine or bupivacaine-fentanyl prolongs motor and sensory block during supraclavicular brachial plexus blockade: a randomized clinical trial

BACKGROUND

In this study, the effect of naloxone on duration of supraclavicular brachial plexus block was evaluated. It was hypothesized that naloxone can increase the duration of neural blockade.

METHODS

Sixty-eight patients scheduled for surgery under supraclavicular brachial plexus block were randomly assigned to receive 30 ml bupivacaine (Group C); 30 ml bupivacaine with 100 μg of fentanyl (Group F); 30 ml bupivacaine with 100 ng naloxone (Group N); or 30 ml bupivacaine with 100 μg of fentanyl and 100 ng naloxone (Group N + F). Sensory and motor blockade were recorded at 5, 15, and 30 min following the block, and every 10 min following the end of surgery. Duration of sensory and motor block was considered to be the time interval between the complete block and the first postoperative pain and complete recovery of motor functions.

RESULTS

Sensory and motor onset times were the same in all groups. The duration of sensory and motor block in Group C (11.3 ± 1.7 h and 4.56 ± 1.0 h) and Group F (12.8 ± 3.3 h and 5.1 ± 2.0 h) were less than in the other groups (18.1 ± 2.2 h and 6.18 ± 1.0 h in Group N, and 15.8 ± 2.9 h and 6.53 ± 1.1 h in Group N + F, P < 0.0001).

CONCLUSION

Addition of naloxone to bupivacaine in supraclavicular brachial plexus block prolonged the duration of the neural blockade.

Comparing omeprazole with fluoxetine for treatment of patients with heartburn and normal endoscopy who failed once daily proton pump inhibitors: double-blind placebo-controlled trial

BACKGROUND

Patients with heartburn but without esophageal erosion respond less well to proton pump inhibitors (PPIs). There is a growing body of evidence implicating the role of psychological comorbidities in producing reflux symptoms. Pain modulators improve symptoms in patients with other functional gastrointestinal disorders. We aimed to compare the efficacy of fluoxetine with omeprazole and placebo to achieve symptomatic relief in patients with heartburn and normal endoscopy who failed once daily PPIs.

METHODS

Endoscopy-negative patients with heartburn who failed once daily PPIs were randomly allocated to receive 6 weeks treatment of fluoxetine, omeprazole, or placebo. Random allocation was stratified according to ambulatory pH monitoring study. Percentage of heartburn-free days and symptom severity was assessed.

KEY RESULTS

Sixty patients with abnormal and 84 patients with normal pH test were randomized. Subjects receiving fluoxetine experienced more improvement in percentage of heartburn-free days (median 35.7, IQR 21.4-57.1) than those on omeprazole (median 7.14, IQR 0-50, p < 0.001) or placebo (median 7.14, IQR 0-33.6, p < 0.001). In normal pH subgroup, fluoxetine was superior to both omeprazole and placebo regarding percentage of heartburn-free days (median improvement, 57.1, IQR 35.7-57.1 vs 13.9, IQR, 0-45.6 and 7.14, 0-23.8, respectively, p < 0.001), but no significant difference was observed between medications in abnormal pH subgroup.

CONCLUSIONS & INFERENCES

Fluoxetine was superior to omeprazole for improving the symptoms of patients with heartburn and normal endoscopy who failed once daily PPIs. The superiority of fluoxetine was mostly attributed to those with normal esophageal pH rather than those with abnormal pH (ClinicalTrials.gov, number NCT01269788).