Lifetime of peroxyl radicals of poly(U), poly(A) and single-and double-stranded DNA and the rate of their reaction with thiols

Peroxyl radicals of poly(U), poly(A), and single- and double-stranded DNA have been produced by photolysing H2O2 in oxygenated aqueous solution in presence of the substrates. The peroxyl radicals are formed by the reaction of OH radicals with the polynucleotides followed by addition of oxygen. The lifetime of the peroxyl radicals and the rate constant of their reactions with the thiols cysteamine, glutathione and dithiothreithol have been measured by time-resolved e.s.r. spectroscopy. The unusually long lifetimes range from 0.2 to 3.3 s. The activation energy for the decay for all four substrates is 10.3 +/- 1 kcal/mol (43 kJ mol-1). The reaction rate constants with the thiols range from k = 0.8 X 10(4) to 1.3 X 10(5) dm3 mol-1 s-1. The reactions of the thiols with the peroxyl radical of poly(U) are known to prevent strand break formation. This shows that the peroxyl radicals of poly(U) observed by e.s.r. are intermediates in the pathway leading to strand break formation.     

Respiratory muscle interaction during NREM sleep in patients with occlusive apnea

To study respiratory muscle interaction in patients with occlusive apnea, diaphragmatic electromyogram (EMGdi) and gastric, pleural, and transdiaphragmatic pressures (Pga, Ppl, and Pdi, respectively) were studied in seven patients during non-rapid-eye-movement (NREM) sleep. Diaphragmatic force output, as assessed by Pdi, followed the periodic changes in EMGdi but during the occlusive phase the increase in Pdi was more than the increase in EMGdi. This increase in Pdi was essentially due to an increase in Ppl, since Pga and EMGdi had a linear relationship (r = 0.98, P less than 0.001) that did not change during the occlusive and ventilatory phases. Abdominal muscle recruitment evident in Pga and abdominal motion tracings during the occlusive phase when paradoxical rib cage motion was observed suggested that this increase in diaphragmatic efficiency was likely due to a change in diaphragmatic length-tension characteristics. These results demonstrate that, in patients with occlusive apneas, the diaphragm is the predominant respiratory muscle during NREM sleep and that its function is supported by abdominal muscle recruitment.     

Alternative allosteric mechanisms can regulate the substrate and E2 in SUMO conjugation

Sumoylation is the covalent attachment of small ubiquitin-like modifier (SUMO) to a target protein. Similar to other ubiquitin-like pathways, three enzyme types are involved that act in succession: an activating enzyme (E1), a conjugating enzyme (E2), and a ligase (E3). To date, unlike other ubiquitin-like mechanisms, sumoylation of the target RanGAP1 (Target^RanGAP1) does not absolutely require the E3 of the system, RanBP2 (E3^RanBP2), since the presence of E2 (E2^Ubc9) is enough to sumoylate Target^RanGAP1. However, in the presence of E3, sumoylation is more efficient. To understand the role of the target specificity of E3^RanBP2 and E2^Ubc9, we carried out molecular dynamics simulations for the structure of E2^Ubc9-SUMO-Target^RanGAP1 with and without the E3^RanBP2 ligase. Analysis of the dynamics of E2^Ubc9-SUMO-Target^RanGAP1 in the absence and presence of E3^RanBP2 revealed that two different allosteric sites regulate the ligase activity: (i) in the presence of E3^RanBP2, the E2^Ubc9's loop 2; (ii) in the absence of E3^RanBP2, the Leu65-Arg70 region of SUMO. These results provide a first insight into the question of how E3^RanBP2 can act as an intrinsic E3 for E2^Ubc9 and why, in its absence, the activity of E2^Ubc9-SUMO-Target^RanGAP1 could still be maintained, albeit at lower efficiency.     

Ultrafast liquid chromatographic analysis of erdosteine in human plasma based on fluorimetric detection and precolumn derivatization with 4‐bromomethyl‐7‐methoxycoumarin: Application to pharmacokinetic studies

In this study, a new analytical method for erdosteine (ERD) in plasma based on high‐performance liquid chromatography and a fluorimetric detector, is presented. Precolumn derivatization of ERD with 4‐bromomethyl‐7‐methoxy coumarin (BrMmC) and dibenzo‐18‐crown‐6‐ether as a reaction catalyst led to the production of a fluorescent compound. ERD was monitored by fluorescence with an excitation wavelength λ_ext. = 325 nm and emission wavelength λ_em. = 390 nm. Optimum reaction conditions were carefully studied and optimized. A chromatographic procedure was performed using a C18 column of 150 × 4.6 mm and 3 μm particle size and a mobile phase consisting of methanol:acetonitrile:water (30:30:40, v/v/v) under a flow rate of 0.5 ml min^?1. A calibration plot was established covering analyte concentration range 0.2–3.0 μg ml^?1; the detection limit was 0.015 μg ml^?1 and quantification limit was 0.05 μg ml^?1. Mean recovery was 87.33% and relative standard deviation was calculated to be less than 4.4%. The developed method was successfully used to determine pharmacokinetic preparations of ERD subsequent to administration of a 900 mg dose capsule to a healthy 40‐year‐old woman volunteer.     

Effect of melatonin and gibberellic acid foliar application on the yield and quality of Jumbo blackberry species

Not many chemical hormone studies does exist in our country especially in berry fruits. Foliar application of melatonin and gibberellic acid hormones was performed in 2016 and 2017 in order to analyze the effects of different doses of hormone applications on fruit quality and yield. Pheonologic, pomological and some bioactive content analyses of these hormones were studied. According to the research results, while M?+?GA10 ppm (240.50; 3.9) and M?+?GA 5?ppm (226.50; 3.6) applications have the highest fruit number and weight (g), the highest fruit size was obtained from GA 5?ppm (21.21?mm fruit length, 16.56?mm fruit width) and M 10?ppm (21.10?mm fruit length, 16.20?mm fruit width) chemical applications in Jumbo blackberry species. The highest values in Ph, soluble solid content (SSC) and titratable acidity averages were obtained from GA 5?ppm (3.69; 10.80; 2.42) and GA 10?ppm (3.68; 10.70; 2.40) applications; the highest total antioxidant activity in bioactive characteristics averages was found in G 10?ppm 143.21?mg/g, the highest total phenolics was identified in G 5?ppm 72.68?ppm/GAE and the highest total flavonoids was determined in G 10?ppm 4925.75?ppm/QE.     

Protection by Edaravone,a Radical Scavenger,against Manganese‐Induced Neurotoxicity in Rats

Manganese (Mn) is a required element for biological systems; however, its excessive exposure may lead to a neurological syndrome known as manganism. The aim of the present study was to assess the toxic effects of subacute exposure of Mn by measuring weight gain, motor performance, and biochemical parameters (complex I activity, lipid peroxides, and protein carbonyls) in brain mitochondria in rats. We also examined whether edaravone (EDA), a radical scavenger, exerts protective effects against Mn‐induced neurotoxicity. In addition, we evaluated the accumulation of Mn in brain regions using magnetic resonance imaging. Mn‐exposed rats revealed significantly impaired motor performance, weight loss, and Mn accumulation in particular brain area. Lipid peroxides and protein carbonyls were significantly increased in Mn‐exposed rats, whereas complex I activity was found to be decreased. EDA treatment significantly prevented mitochondrial oxidative damage and improved motor performance. These findings suggested that EDA might serve as a clinically effective agent against Mn‐induced neurotoxicity.     

Isolated jejunal metastasis in a patient with cervical cancer: A case report

Background

In approximately 8% of cervical carcinoma patients, gastrointestinal tract is involved, most commonly the rectosigmoid portion, because of local extension. Isolated metastases to small bowel are exceedingly rare.

Case report

We present a case of a 63-year-old woman with cervical cancer who developed isolated jejunal metastasis 8 months after postoperative chemoradiotherapy. The patient was alive with no evidence of disease 6 months after resection of metastasis. Very few cases have been reported concerning squamous cell carcinoma of the cervix with documented metastases to the small bowel. There is only one published case report of cervical cancer with multiple metastases to the small intestine and jejunum. To our knowledge, this is the first case of cervical cancer with isolated jejunal metastasis, which was initially demonstrated with positron emission tomography and confirmed histopathologically.

Conclusion

Although the exact mechanism underlying the isolated metastasis is unknown, hematogenous spread or tumor seeding during surgery may play a role.     

Comparative studies on the adsorption of Cr(VI) ions on to various sorbents

The adsorption of Cr(VI) ions onto various sorbents (chitin, chitosan, ion exchangers; Purolite CT-275 (Purolite I), Purolite MN-500 (Purolite II) and Amberlite XAD-7) was investigated. Batch adsorption experiments were carried out as a function of pH, agitation period and concentration of Cr(VI) ions. The optimum pH for Cr(VI) adsorption was found as 3.0 for chitin and chitosan. The Cr(VI) uptake by ion exchangers was not very sensitive to changes in the pH of the adsorption medium. The maximum chromium sorption occurred at approximately 50 min for chitin, 40 min for Purolite II and 30 min for chitosan, Purolite I and Amberlite XAD-7. The suitability of the Freundlich and Langmuir adsorption models were also investigated for each chromium-sorbent system. Adsorption isothermal data could be accurately interpreted by the Langmuir equation for chitosan, chitin, Purolite I and Purolite II and by the Freundlich equation for chitosan, chitin and Amberlite XAD-7. The chromium(VI) ions could be removed from the sorbents rapidly by treatment with an aqueous EDTA solution and at the same time the sorbent regenerated and also could be used again to adsorb by heavy metal ions. The results showed that, chitosan, which is a readily available, economic sorbent, was found suitable for removing chromium from aqueous solution.