A Common Active Intermediate in the Oxidation of Alkenes, Alcohols and Alkanes with H2O2 and a Mn(II)/Pyridin-2-Carboxylato Catalyst.

The mechanism and the reactive species involved in the oxidation of alkenes, and alcohols with H2O2, catalysed by an in situ prepared mixture of a MnII salt, pyridine-2-carboxylic acid and a ketone is elucidated using substrate competition experiments, kinetic isotope effect (KIE) measurements, and atom tracking with 18O labelling. The data indicate that a single reactive species engages in the oxidation of both alkenes and alcohols. The primary KIE in the oxidation of benzyl alcohols is ca. 3.5 and shows the reactive species to be selective despite a zero order dependence on substrate concentration, and the high turnover frequencies (up to 30 s-1) observed. Selective 18O labelling identifies the origin of the oxygen atoms transferred to the substrate during oxidation, and is consistent with a highly reactive, e. g., [MnV(O)(OH)] or [MnV(O)2], species rather than an alkylperoxy or hydroperoxy species.

[Ocular manifestations in patients with COVID-19]. / Okuläre Manifestationen bei COVID-19-Patienten.

BACKGROUND: There are only few reports on ocular symptoms and manifestations in association with coronavirus disease 2019 (COVID-19). OBJECTIVE: The aim of this study is to describe ocular manifestations in the anterior and posterior segments of the eye and to analyze viral prevalence in tears of patients with COVID-19. METHODS: Hospitalized COVID-19 patients treated from 16 April 2020 to 7 January 2021 at this hospital were screened for ocular manifestations in the anterior and posterior segments. Conjunctival swabs were analyzed for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA. RESULTS: A total of 37 patients were enrolled in this study. In the anterior segment we found chemosis of the conjunctiva (5), hyposphagma (2) and conjunctivitis (1). In 11 patients vascular alterations and potentially disease-specific manifestations of the fundus were found in one or both eyes: retinal hemorrhages (5), cotton wool spots (5) and tortuosity (5). One patient demonstrated branch artery occlusion, one had branch retinal vein occlusion and two patients had positive conjunctival swab results in one or both eyes. CONCLUSION: Our findings of the anterior segment are commonly known, although not specific for COVID-19. Various vascular fundus abnormalities were found in the study; however, it is unclear whether these were correlated to systemic comorbidities or whether they were caused or exacerbated by COVID-19. This study suggests that the risk of viral transmission via tears is low.

Off-line analysis in the manganese catalysed epoxidation of ethylene-propylene-diene rubber (EPDM) with hydrogen peroxide.

The epoxidation of ethylene-propylene-diene rubber (EPDM) with 5-ethylidene-2-norbornene (ENB) as the diene to epoxidized EPDM (eEPDM) creates additional routes to cross-linking and reactive blending, as well as increasing the polarity and thereby the adhesion to polar materials, e.g., mineral fillers such as silica. The low solubility of apolar, high molecular weight polymers in the polar solvents constrains the catalytic method for epoxidation that can be applied. Here we have applied an in situ prepared catalyst comprising a manganese(ii) salt, sodium picolinate and a ketone to the epoxidation of EPDM rubber with hydrogen peroxide (H2O2) as the oxidant in a solvent mixture, that balances the need for polymer and catalyst/oxidant miscibility and solubility. Specifically, a mixture of cyclohexane and cyclohexanone is used, where cyclohexanone functions as a co-solvent as well as the ketone reagent. Reaction progress was monitored off-line through a combination of Raman and ATR-FTIR spectroscopies, which revealed that the reaction profile and the dependence on the composition of the catalyst are similar to those observed with low molar mass alkene substrates, under similar reaction conditions. The combination of spectroscopies offers a reliable method for off-line reaction monitoring of both the extent of the conversion of unsaturation (Raman) and the extent of epoxidation (FTIR) as well as determining side reactions, such as epoxide ring opening and further, aerobic oxidation. The epoxidation of EPDM described, in contrast to currently available methods, uses a non-scarce manganese catalyst and H2O2, and avoids side reactions, such as those that can occur with peracids.

Correction to "Oxidative Cleavage of Cellobiose by Lytic Polysaccharide Monooxygenase (LPMO)-Inspired Copper Complexes".

[This corrects the article DOI: 10.1021/acsomega.9b00785.].

Oxidative Cleavage of Cellobiose by Lytic Polysaccharide Monooxygenase (LPMO)-Inspired Copper Complexes.

The potentially tridentate ligand bis[(1-methyl-2-benzimidazolyl)ethyl]amine (2BB) was employed to prepare copper complexes [(2BB)CuI]OTf and [(2BB)CuII(H2O)2](OTf)2 as bioinspired models of lytic polysaccharide copper-dependent monooxygenase (LPMO) enzymes. Solid-state characterization of [(2BB)CuI]OTf revealed a Cu(I) center with a T-shaped coordination environment and metric parameters in the range of those observed in reduced LPMOs. Solution characterization of [(2BB)CuII(H2O)2](OTf)2 indicates that [(2BB)CuII(H2O)2]2+ is the main species from pH 4 to 7.5; above pH 7.5, the hydroxo-bridged species [{(2BB)CuII(H2O) x }2(µ-OH)2]2+ is also present, on the basis of cyclic voltammetry and mass spectrometry. These observations imply that deprotonation of the central amine of Cu(II)-coordinated 2BB is precluded, and by extension, amine deprotonation in the histidine brace of LPMOs appears unlikely at neutral pH. The complexes [(2BB)CuI]OTf and [(2BB)CuII(H2O)2](OTf)2 act as precursors for the oxidative degradation of cellobiose as a cellulose model substrate. Spectroscopic and reactivity studies indicate that a dicopper(II) side-on peroxide complex generated from [(2BB)CuI]OTf/O2 or [(2BB)CuII(H2O)2](OTf)2/H2O2/NEt3 oxidizes cellobiose both in acetonitrile and aqueous phosphate buffer solutions, as evidenced from product analysis by high-performance liquid chromatography-mass spectrometry. The mixture of [(2BB)CuII(H2O)2](OTf)2/H2O2/NEt3 results in more extensive cellobiose degradation. Likewise, the use of both [(2BB)CuI]OTf and [(2BB)CuII(H2O)2](OTf)2 with KO2 afforded cellobiose oxidation products. In all cases, a common Cu(II) complex formulated as [(2BB)CuII(OH)(H2O)]+ was detected by mass spectrometry as the final form of the complex.

Diagnosing adenomyosis with MRI: a prospective study revisiting the junctional zone thickness cutoff of 12 mm as a diagnostic marker.

OBJECTIVES: To assess the diagnostic accuracy of a junctional zone (JZ) thickness of ≥ 12 mm and morphological features of the JZ in MRI in diagnosing adenomyosis in a premenopausal study population. METHODS: This single-center, prospective observational study consecutively enrolled 93 premenopausal women suffering from a benign gynecological condition, from September 2014 to August 2016. Institutional review board approval and written consent were obtained. All participants underwent MRI and hysterectomy with a histopathological examination. MR images were evaluated in a blinded fashion by two independent readers. The maximum junctional zone thickness (JZmax), presence of JZmax ≥ 12 mm, and any irregular appearance of the JZ (defined as irregular outer or inner borders, focal thickening, presence of high-intensity signal foci, or fingerlike indentations at the inner border) were documented, and the diagnostic performance was evaluated with the AUC, chi-square test, and multiple regression. RESULTS: Adenomyosis was histopathologically confirmed in 57 (61%) of the women. JZmax was not positively correlated with adenomyosis diagnosis (AUC = 0.57, p = 0.26) and did not differ significantly between those with and without adenomyosis (10.3 vs 10.1 mm, p = 0.88), nor was a cutoff of JZmax ≥ 12 mm (n = 30/57 (53%) vs n = 16/36 (44%), p = 0.29). The presence of an irregular JZ showed the best association with adenomyosis among the evaluated signs (sensitivity 74% (95% CI, 60, 85); specificity 83% (95% CI, 67, 94) (p < 0.001)). CONCLUSIONS: JZmax was not correlated with adenomyosis in the present premenopausal study population, but direct signs of adenomyosis such as irregularities of the JZ provided a good diagnostic accuracy. KEY POINTS: • Measuring the junctional zone thickness is of limited value for diagnosing adenomyosis with MRI and should not be used for diagnosing adenomyosis in premenopausal women with moderate disease severity. • An irregular appearance of the junctional zone, the presence of myometrial cysts, and adenomyoma appear to provide the highest specificity for diagnosing adenomyosis. • A consensus for the definition and reading of the junctional zone is needed.

Origins of Catalyst Inhibition in the Manganese-Catalysed Oxidation of Lignin Model Compounds with H2 O2.

The upgrading of complex bio-renewable feedstock, such as lignocellulose, through depolymerisation benefits from the selective reactions at key functional groups. Applying homogeneous catalysts developed for selective organic oxidative transformations to complex feedstock such as lignin is challenged by the presence of interfering components. The selection of appropriate model compounds is essential in applying new catalytic systems and identifying such interferences. Here, it was shown by using as an example the oxidation of a model substrate containing a ß-O-4 linkage with H2 O2 and an in situ-prepared manganese-based catalyst, capable of efficient oxidation of benzylic alcohols, that interference from compounds liberated during the reaction can prevent its application to lignocellulose depolymerisation.

Immobilization during anesthesia for vitrectomy using a laryngeal mask without neuromuscular blockade versus endotracheal intubation and neuromuscular blockade.

BACKGROUND: For intraocular surgery, most authors recommend general anesthesia including intubation and neuromuscular blockade to avoid complications by patient movements. However, anesthesia using a laryngeal mask and avoidance of muscle relaxants is common clinical practice. Purpose of this prospective observational study was to compare the incidence of eye movement and deviation of the eye axis during general anesthesia adjusted to minimal alveolar concentration (MAC) for pars plana-vitrectomy (PPV) using a laryngeal mask without neuromuscular blockade (LM) versus endotracheal intubation and neuromuscular blockade (INT). METHODS: The patients (N.=148) who underwent PPV for vitreoretinal disorders received MAC adjusted general anesthesia by volatile anesthetics. Seventy-four patients were subjected to LM and 74 to INT. In both groups the patient's lungs were mechanically ventilated without allowing spontaneous ventilation. Eye movements and upward deviations were judged and documented during surgery. Postoperatively quality of immobilization was assessed by a standardized questionnaire. RESULTS: Intraoperative movements were not observed in either group. Upward eye deviation was observed in nine (12%) patients in the LM group, but not in patients in the INT group (0%; P=0.003). The standardized questionnaire revealed no clinically relevant difference in quality of immobilization between groups, especially eye deviations did not lead to any relevant surgical complications or difficulties. CONCLUSIONS: For PPV, MAC adjusted balanced anesthesia using a laryngeal mask without neuromuscular blockade was associated with more, but clinically irrelevant upward eye deviations and may be an alternative to intubation with neuromuscular blockade. However, adequate depth of anesthesia must be assured to avoid unwanted injuries during surgery.

Reversible photochromic switching in a Ru(II) polypyridyl complex.

Fully reversible photoswitching of the coordination mode of the ligand MeN4Py (1,1-di(pyridin-2-yl)-N,N'-bis(pyridin-2-yl-methyl)-ethan-1-amine) in its ruthenium(II) complex with visible light is reported. Irradiation with visible light results in dissociation of a pyridyl moiety, which is reversed by irradiation at 355 nm.

Different kinetics of HBV and HCV during haemodialysis and absence of seronegative viral hepatitis in patients with end-stage renal disease.

BACKGROUND: Hepatitis C virus (HCV) and hepatitis B virus (HBV) infections are common in haemodialysis units. Moreover, some studies reported seronegative cases of viral hepatitis. We and others have previously shown an HCV RNA decline during haemodialysis; however, limited data on HBV viraemia during haemodialysis are available. METHODS: A total of 142 haemodialysis patients participated in this study, 11 were anti-HCV positive and 7 were HBsAg positive. HCV RNA and HBV DNA were determined in all patients irrespective of hepatitis serology. HBV DNA, HCV RNA, HBsAg and HCV core antigen (HCVcoreAg) were quantified repeatedly in anti-HCV- and HBsAg-positive patients before and after haemodialysis. RESULTS: No case of seronegative viral hepatitis could be identified. HCV RNA was detected in 9 of the 11 anti-HCV-positive patients, while HBV DNA tested positive in all 7 HBsAg-positive patients. A decrease of HCVcoreAg was observed during four dialysis sessions in 8/9 patients (-24.4 ± 22.7%, P < 0.001) parallelled by HCV RNA decline in most individuals (-10.1 ± 48.6%, P = 0.22). In contrast, HBV DNA and HBsAg declined only in 1/7 patients during all four independent measurements. The remaining six patients showed heterogeneous patterns of HBV DNA and HBsAg before and after haemodialysis without a significant change in mean HBV DNA and HBsAg levels (+14 ± 60.6% and -0.2 ± 25.3%, P > 0.05, respectively). HCVcoreAg correlated strongly with HCV RNA (r = 0.937; P < 0.001, n = 72), while there was no correlation between HBV DNA and HBsAg (r = -0.234; P = 0.131, n = 43). CONCLUSIONS: Seronegative viral hepatitis is rare in German maintenance haemodialysis patients. HCV RNA and HCVcoreAg decline during haemodialysis indicating a potential beneficial effect of haemodialysis during antiviral therapy of hepatitis C, which does not apply to HBV infection.

Anterior chamber depth and iridocorneal angle in healthy White subjects: effects of age, gender and refraction.

PURPOSE: Prior to phakic intraocular lens implantation, it is important to obtain precise knowledge of the anterior chamber depth (ACD). Accurate topographic evaluation of the iridocorneal angle is helpful in estimating risk for angle-closure glaucoma. This study investigated the use of the Orbscan II system to measure ACD and the iridocorneal angle in healthy subjects and assessed the influences of age, gender and spherical equivalent on these parameters. METHODS: The Orbscan II system was used to determine the ACD and iridocorneal angle in eight different positions in 390 healthy White subjects with a mean age of 41± 16years (range 10-80 years). The sample included 242 male and 148 female subjects. The influences of age, gender and spherical equivalent were assessed using multiple regression analysis. RESULTS: Mean ACD was 2.87 ± 0.04 mm in male subjects and 2.81±0.37mm in female subjects. The explanatory variables relevant to the ACD were age (partial regression coefficient B = -0.0115, p < 0.0001), spherical equivalent (B = - 0.0562, p< 0.0001) and gender (B = 0.0996, p=0.0036). The mean iridocorneal angle (MIA) was 30.7 ± 2.0 ° in male and 31.6 ± 2.1° in female subjects. The variables relevant to the MIA were gender (B =- 0.865, p < 0.0001), age (B =- 0.017, p = 0.0007) and spherical equivalent (B = - 0.121, p = 0.001). The superior iridocorneal angle displayed the strongest negative correlation with age, whereas the temporal angle exhibited the least correlation with age. CONCLUSIONS: The decline in ACD appears to be linear with age, amounting to a mean of 0.58 mm over 50 years. This may become clinically relevant in the use of phakic intraocular lenses. In addition, the angle is more severely constricted in the superior quadrant than in the temporal quadrant.

Efficacy of plain radiography and computer tomography in localizing the site of pelvic arterial bleeding in trauma patients.

BACKGROUND: Immediate angiography is warranted in pelvic trauma patients with suspected arterial injury (AI) in order to stop ongoing bleeding. Prior to angiography, plain pelvic radiography (PPR) and abdominopelvic computer tomography (CT) are performed to identify fracture and hematoma sites. PURPOSE: To investigate if PPR and CT can identify the location of AI in trauma patients undergoing angiography. MATERIAL AND METHODS: 95 patients with pelvic fractures on PPR (29 women, 66 men), at a mean age of 44 (9-92) years, underwent pelvic angiography for suspected AI. Fifty-six of them underwent CT additionally. Right and left anterior and posterior fractures on PPR were registered, and fracture displacement was recorded for each quadrant. Arterial blush on CT was registered, and the size of the hematoma in each region was measured in cm(2). AIs were registered for anterior and posterior segments of both internal iliac arteries. Presence of fractures, arterial blush, and hematomas were correlated with AI. RESULTS: Presence of fracture in the corresponding skeletal segment on PPR showed sensitivity and specificity of 0.86 and 0.58 posteriorly, and 0.87 and 0.44 anteriorly. The area under the curve (AUC) was 0.77 and 0.69, respectively. Fracture displacement on PPR >0.9 cm posteriorly and >1.9 cm anteriorly revealed specificity of 0.84. Sensitivities of arterial blush and hematoma on CT were 0.38 and 0.82 posteriorly, and 0.24 and 0.82 anteriorly. The specificities were 0.96 and 0.58 posteriorly, and 0.79 and 0.53 anteriorly, respectively. For hematomas, the AUC was 0.79 posteriorly and 0.75 anteriorly. Size of hematoma >22 cm(2) posteriorly and >29 cm(2) anteriorly revealed specificity of 0.85 and 0.86, respectively. CONCLUSION: CT findings of arterial blush and hematoma predicted site of arterial bleeding on pelvic angiography. Also, PPR predicted the site of bleeding using location of fracture and size of displacement. In the hemodynamically unstable patient, PPR may contribute equally to effective assessment of injured arteries.

Kinetics of hepatitis C viral RNA and HCV-antigen during dialysis sessions: evidence for differential viral load reduction on dialysis.

Hepatitis C infection is a common problem in dialysis units. The prevalence ranges from 3% to more than 50%. Several reports have described a variable reduction of HCV-RNA during hemodialysis treatment sessions. But so far nothing is known about the HCV antigenemia or the kinetics of the reduction of HCV-RNA and HCV antigenemia during these sessions. HCV-RNA was monitored using the VERSANT HCV bDNA assay 3.0 (Bayer Healthcare Diagnostics, Leverkusen, Germany) or the HCV-Monitor TaqMan (Roche Diagnostics). HCV antigenemia was tested by using Ortho-trac-C assay (Ortho Clinical Diagnostics, Neckargemünd, Germany). Kinetics of HCV-RNA were available in 15 dialysis sessions measured by bDNA assay and in 5 dialysis sessions measured by rt-PCR. Quantitative HCV-antigenemia was available in fourteen dialysis sessions. Not only HCV-RNA but as expected also the HCV-antigenemia fell during the dialysis session. However, while the average reduction of HCV-antigen appears steady and linear, the level of HCV-RNA seems to be stable during the first 3 hr of dialysis, and decreases rapidly during the last 2 hr. The results seem to be independent of the HCV-RNA detection method. The different kinetics of HCV RNA and HCV antigen load suggest that there are different mechanisms responsible for the reduction of the HCV antigen and HCV-RNA, respectively. Reduction of viral load during dialysis session indicates a potential benefit of dialysis in case of HCV associated antiviral therapy.

Intraparenchymal Doppler ultrasound after proximal embolization of the splenic artery in trauma patients.

We studied the changes in proximal embolization of the splenic artery to the intraparenchymal blood flow with Doppler ultrasound. Seventeen trauma patients with spleen injury OIS grade 2-5 underwent embolization of the splenic artery. Peak-systolic velocity (PSV) and end-diastolic velocity (EDV) were measured in intrasplenic arteries initially 1 day after embolization, at early follow-up after 7 days, at intermediate follow-up after 10 weeks, and at late follow-up after 10 months. Resistance index (RI), systolic/diastolic ratio (S/D ratio), acceleration (AC), and acceleration time (AT) were calculated. The results were compared to values from 17 volunteers. RI increased from 0.39 initially to 0.49 (P = 0.002) at intermediate and to 0.52 (P < 0.001) at late follow-up. S/D ratio increased from 1.68 initially to 1.99 (P = 0.002) and to 2.10 (P < 0.001) at intermediate and late follow-up, respectively. Follow-up results of RI and S/D ratio differed significantly from the reference group. AC increased from 1.06 m/s(2) initially to 1.89 m/s(2) at late follow-up (P = 0.01). AC at late follow-up was not different from reference group (2.33 m/s(2)). In conclusion, Doppler ultrasound is a useful tool in the evaluation of improvable intraparenchymal blood flow over time after central splenic artery embolization.

Nonoperative management of pediatric splenic injury with angiographic embolization.

A 12-year-old girl was admitted after a bicycle accident, and a grade 4 splenic injury was diagnosed. She became hemodynamically unstable within the first hours after arrival and remained so despite fluid resuscitation and transfusions. As an alternative to laparotomy, splenic artery embolization was performed. The patient had an uneventful recovery without the need for further transfusions. Nonoperative management of blunt splenic trauma remains the gold standard in pediatric trauma care. In hemodynamically unstable patients, splenic artery embolization should be considered as an adjunct to that strategy.

Design and application of an assessment protocol for electromagnetic tracking systems.

This paper defines a simple protocol for competitive and quantified evaluation of electromagnetic tracking systems such as the NDI Aurora (A) and Ascension microBIRD with dipole transmitter (B). It establishes new methods and a new phantom design which assesses the reproducibility and allows comparability with different tracking systems in a consistent environment. A machined base plate was designed and manufactured in which a 50 mm grid of holes was precisely drilled for position measurements. In the center a circle of 32 equispaced holes enables the accurate measurement of rotation. The sensors can be clamped in a small mount which fits into pairs of grid holes on the base plate. Relative positional/orientational errors are found by subtracting the known distances/ rotations between the machined locations from the differences of the mean observed positions/ rotation. To measure the influence of metallic objects we inserted rods made of steel (SST 303, SST 416), aluminum, and bronze into the sensitive volume between sensor and emitter. We calculated the fiducial registration error and fiducial location error with a standard stylus calibration for both tracking systems and assessed two different methods of stylus calibration. The positional jitter amounted to 0.14 mm(A) and 0.08 mm(B). A relative positional error of 0.96 mm +/- 0.68 mm, range -0.06 mm; 2.23 mm(A) and 1.14 mm +/- 0.78 mm, range -3.72 mm; 1.57 mm(B) for a given distance of 50 mm was found. The relative rotation error was found to be 0.51 degrees (A)/0.04 degrees (B). The most relevant distortion caused by metallic objects results from SST 416. The maximum error 4.2 mm(A)/ > or = 100 mm(B) occurs when the rod is close to the sensor(20 mm). While (B) is more sensitive with respect to metallic objects, (A) is less accurate concerning orientation measurements. (B) showed a systematic error when distances are calculated.

Design and application of an assessment protocol for electromagnetic tracking systems.

This paper defines a simple protocol for competitive and quantified evaluation of electromagnetic tracking systems such as the NDI Aurora (A) and Ascension microBIRD with dipole transmitter (B). It establishes new methods and a new phantom design which assesses the reproducibility and allows comparability with different tracking systems in a consistent environment. A machined base plate was designed and manufactured in which a 50 mm grid of holes was precisely drilled for position measurements. In the center a circle of 32 equispaced holes enables the accurate measurement of rotation. The sensors can be clamped in a small mount which fits into pairs of grid holes on the base plate. Relative positional/orientational errors are found by subtracting the known distances/rotations between the machined locations from the differences of the mean observed positions/rotation. To measure the influence of metallic objects we inserted rods made of steel (SST 303, SST 416), aluminum, and bronze into the sensitive volume between sensor and emitter. We calculated the fiducial registration error and fiducial location error with a standard stylus calibration for both tracking systems and assessed two different methods of stylus calibration. The positional jitter amounted to 0.14 mm(A) and 0.08 mm(B). A relative positional error of 0.96mm±0.68mm, range -0.06 mm; 2.23 mm(A) and 1.14mm±0.78mm, range -3.72 mm; 1.57 mm(B) for a given distance of 50 mm was found. The relative rotation error was found to be 0.51° (A)/0.04° (B). The most relevant distortion caused by metallic objects results from SST 416. The maximum error 4.2mm(A)∕⩾100mm(B) occurs when the rod is close to the sensor(20 mm). While (B) is more sensitive with respect to metallic objects, (A) is less accurate concerning orientation measurements. (B) showed a systematic error when distances are calculated.