Transfusion of incompatible blood to a patient with alloanti-Sc1

Sc1 is a high-prevalence blood group antigen that is part of the Scianna blood group system. The clinical significance of Scianna antibodies is not well understood because of their rarity; there are only a handful of cases in the literature. This scarcity of information can make it difficult to decide on the best course of action when transfusing a patient with alloantibodies to Scianna blood group antigens. We describe a case of an 85-year-old woman presenting with melena and a hemoglobin of 66 g/L. Upon request for crossmatched blood, a panreactive antibody was found, later elucidated to be alloanti-Sc1. Because of the urgent nature of the transfusion, the patient was transfused with 2 incompatible, presumed Sc1+, red blood cell units with no evidence of an acute or delayed transfusion reaction. This case has been shared with the International Society of Blood Transfusion Rare Donor Working Party, via their Outcome of Incompatible Transfusion form, and adds to the body of evidence on clinical significance of antibodies to the antigens of the Scianna blood group system.

Highly Conductive and Solution-Processable n-Doped Transparent Organic Conductor

Transparent conductors (TCs) play a vital role in displays, solar cells, and emerging printed electronics. Here, we report a solution-processable n-doped organic conductor from copper-catalyzed cascade reactions in the air, which involves oxidative polymerization and reductive doping in one pot. The formed polymer ink is shelf-stable over 20 days and can endure storage temperatures from -20 to 65 °C. The optimized n-doped thin-film TC exhibits a low sheet resistance of 45 Ω/sq and a high transmittance (T₅₅₀ > 80%), which can rival indium tin oxide. The transparent organic conductor exhibits excellent durability under accelerated weathering tests (85 °C/85% RH). Furthermore, the n-doped polymer film can also function as an electrode material with a high volumetric capacity. When it is paired with p-doped PEDOT:PSS, a record-high coloration efficiency is obtained in a dual-polymer electrochromic device.

Radical Polymer-Based Organic Electrochemical Transistors

Organic electrochemical transistors (OECTs) are an emerging platform for bioelectronic applications. Significant effort has been placed in designing advanced polymers that simultaneously transport both charge and ions (i.e., macromolecules that are mixed conductors). However, the considerations for mixed organic conductors are often different from the established principles that are well-known in the solid-state organic electronics field; thus, the discovery of new OECT macromolecular systems is highly desired. Here, we demonstrate a new materials system by blending a radical polymer (i.e., a macromolecule with a nonconjugated backbone and with stable open-shell sites at its pendant group) with a frequently used conjugated polymer. Specifically, poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl) (PTEO) was blended with poly(3-hexylthiophene) (P3HT) to create thin films with distinct closed-shell and open-shell domains. Importantly, the sharp and unique oxidation-reduction (redox) potential associated with the radical moieties of the PTEO chain provided a distinct actuation feature to the blended films that modulated the ionic transport of the OECT devices. In turn, this led to controlled regulation of the doping of the P3HT phase in the composite film. By decoupling the ionic and electronic transport into two distinct phases and by using an ion transport phase with well-controlled redox activity, never-before-seen performance for a P3HT-based OECT was observed. That is, at loadings as low as 5% PTEO (by weight) OECTs achieved figure-of-merit (i.e., μC*) values >150 F V^-1 cm^-1 s^-1, which place the performance on the same order as state-of-the-art conjugated polymers despite the relatively common conjugated macromolecular moiety implemented. As such, this effort presents a design platform by which to readily create a tailored OECT response through strategic macromolecular selection and polymer processing.

Vaccine-induced thrombosis and thrombocytopenia (VITT) in Ireland: A review of cases and current practices

Since the beginning of the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS CoV-2) virus pandemic, several highly effective and safe vaccines have been produced at remarkable speed. Following global implementation of vaccination programmes, cases of thrombosis with thrombocytopenia following administration of adenoviral vector-based vaccines started being reported. In this review we discuss the known pathogenesis and epidemiology of so-called vaccine induced thrombocytopenia and thrombosis (VITT). We consider the available guidelines, diagnostic laboratory tests and management options for these patients. Finally, we discuss important unanswered questions and areas for future research in this novel pathoclinical entity.

Curative-Intent Radiotherapy for Squamous Cell Carcinoma of the Head and Neck in Sri Lanka: The Impact of Radiotherapy Technique on Survival

AIMS

We conducted a retrospective analysis of patients with squamous cell carcinoma of the head and neck (SCCHN) treated with curative-intent radiotherapy at the National Cancer Institute of Sri Lanka to determine the impact of the treatment technique on disease-free survival (DFS).

MATERIALS AND METHODS

SCCHN patients treated with radical radiotherapy or adjuvant postoperative radiotherapy from 2016 to 2017 were included in the study. Data on the following variables were collected by reviewing clinical and radiotherapy treatment records: age, gender, tumour site, stage, time to delivery of radiotherapy, use of neoadjuvant chemotherapy, use of concurrent radiosensitising chemotherapy and treatment technique. DFS, defined as the time to death, tumour recurrence or loss to follow-up, was the primary end point and outcomes were compared between patients treated with intensity-modulated radiotherapy (IMRT) in linear accelerators and those treated with conventional radiotherapy in cobalt teletherapy units. Univariate and multivariate analyses were carried out on known prognostic variables.

RESULTS

In total, 408 patients were included in the study, with 138 (34%) being treated with IMRT in the linear accelerator. More than 75% of patients were of stage III or IV at diagnosis. The 2-year DFS of the whole cohort was 25% (95% confidence interval 21-30%). Patients treated with IMRT in the linear accelerator had a superior DFS in comparison with those treated with conventional radiotherapy in the cobalt teletherapy units (P < 0.001, hazard ratio 0.64, 95% confidence interval 0.5-0.82). Higher stage, cobalt treatment and use of neoadjuvant chemotherapy were adversely associated with DFS on multivariate analysis.

CONCLUSION

A large proportion of patients with SCCHN treated with curative-intent radiotherapy in Sri Lanka had locally advanced disease and DFS was superior in patients treated with IMRT in the linear accelerator.

Designing Donor-Acceptor Copolymers for Stable and High-Performance Organic Electrochemical Transistors

Organic electrochemical transistors (OECTs) are oft-used for bioelectronic applications, and a variety of OECT channel materials have been developed in recent years. However, the majority of these materials are still limited by long-term performance and stability challenges. To resolve these issues, we implemented a next-generation design of polymers for OECTs. Specifically, diketopyrrolopyrrole (DPP) building blocks were copolymerized with propylene dioxythiophene-based (Pro-based) monomers to create a donor-acceptor-type conjugated polymer (PProDOT-DPP). These PProDOT-DPP macromolecules were synthesized using a straightforward direct arylation polymerization synthetic route. The PProDOT-DPP polymer thin film exhibited excellent electrochemical response, low oxidation potential, and high crystallinity, as evidenced by spectroelectrochemical measurements and grazing incidence wide-angle X-ray scattering measurements. Thus, the resultant polymer thin films had high charge mobility and volumetric capacitance values (i.e., μC* as high as 310 F cm^-1 V^-1 s^-1) when they were used as the active layer materials in OECT devices, which places PProDOT-DPP among the highest performing accumulation-mode OECT polymers reported to date. The performance of the PProDOT-DPP thin films was also retained for 100 cycles and over 2000 s of ON-OFF cycling, indicating the robust stability of the materials. Therefore, this effort provides a clear roadmap for the design of electrochemically active macromolecules for accumulation-mode OECTs, where crystalline acceptor cores are incorporated into an all-donor polymer. We anticipate that this will ultimately inspire future polymer designs to enable OECTs with both high electrical performance and operational stability.

In Situ Measurement of Breathing Strain and Mechanical Degradation in Organic Electrochromic Polymers

Organic mixed ionic-electronic conductors (OMIECs) are an emerging family of materials crucial in the development of flexible, bio-, and optoelectronics. In electrochromic polymers, the cyclic redox reaction is associated with a mechanical breathing strain, which deforms the OMIECs and degrades the device reliability. We set forth an in situ nanoindentation approach to measure the breathing strain of a poly(3,4-propylenedioxythiophene) (PProDOT) thin film in a customized liquid cell during electrochromic cycles. A breathing volumetric strain of 12-25% is persistent in different sets of electrolytes of various solvents, salts, and salt molarities. The electrochemical conditioning, intermittence time, and cyclic protocol have minor effects on the mechanical response of PProDOT. The mechanical behavior and anion diffusivity measurement further infer the redox kinetics. Heavily cycled PProDOT films show reduced volumetric strain and accumulated mechanical damage of channel cracks and dysfunctional regions of slow and inhomogeneous electrochromic switching. This work is a systematic characterization of mechanical deformation and damage in a model OMIEC and informs the mechanical reliability of organic electrochromic devices.

Statin treatment and accrual of covert cerebral ischaemia on neuroimaging: a systematic review and meta-analysis of randomized trials

BACKGROUND AND PURPOSE

Prevention of ischaemic stroke and cardiovascular events is an established benefit of statin therapy, but the effects of statin treatment on the accrual of magnetic resonance imaging (MRI) markers of ischaemic cerebral injury remain unknown. A systematic review was performed to identify all studies that randomized patients with cardiovascular risk factors to statin treatment and assessed the effect of statin treatment on covert infarcts (asymptomatic, evident only on neuroimaging) and white matter hyperintensity (WMH) accrual on MRI.

METHODS

A systematic review in MEDLINE and Scopus from inception to 23 October 2019 was performed. A random-effects model was used to calculate the pooled estimates of the crude risk ratios and standardized mean differences.

RESULTS

Data from three randomized controlled trials (1430 participants) were included evaluating the effect of rosuvastatin (10 mg/day) in 668 hypertensive patients older than 60 years of age over 5 years, pravastatin (40 mg/day) in 554 elderly people more than 70 years of age over 3 years and simvastatin (20 mg/day) in 208 patients with asymptomatic middle cerebral artery stenosis over 2 years. Patients randomized to statin treatment had decreased accrual of new covert infarcts (risk ratio 0.63, 95% confidence interval 0.46-0.88) during a mean follow-up of 2-6 years. Only one study reported WMH decreased volume change in patients randomized to statin treatment compared to patients randomized to non-statin treatment (standardized mean difference -1.17; 95% confidence interval -1.33, -1.00).

CONCLUSION

Our findings suggest that, in addition to stroke prevention, statin treatment can reduce the accrual of covert MRI markers of ischaemic cerebral injury.

Combination of single-molecule magnet behaviour and luminescence properties in a new series of lanthanide complexes with tris(pyrazolyl)borate and oligo(β-diketonate) ligands

Mono-, di- & trinuclear ternary complexes of Dy³⁺ & Tb³⁺ with pyrazole & oligo-diketonates are both luminescent and single molecule magnets. Quantum yields & U_eff values decrease with higher nuclearity & reduced intramolecular Ln–Ln distance.

Conjugated electrochromic polymers with amide-containing side chains enabling aqueous electrolyte compatibility

This work illustrates an effective side-chain modification approach using amide functional groups to induce aqueous electroactivity to ProDOT-based electrochromic polymers.

Percentage of small platelets on peripheral blood smear and Child-Turcott-Pugh class can predict the presence of oesophageal varices in newly diagnosed patients with cirrhosis: development of a prediction model for resource limited settings

Background

In cirrhosis upper-gastrointestinal-endoscopy (UGIE) identifies oesophageal varices (OV). UGIE is unavailable in most resource-limited settings. Therefore, we assessed prediction of presence of OV using hematological parameters (HP) and Child-Turcott-Pugh (CTP) class.

Methods

A prospective study was carried out on consecutive, consenting, newly-diagnosed patients with cirrhosis, in the University Medical Unit, Colombo North Teaching Hospital, Ragama, Sri Lanka from April 2014–April 2016. All patients had UGIE to evaluate presence and degree of OV, prior to appropriate therapy. HP (full blood count with indices using automated analyzer and peripheral blood smear using Leishmann stain) and CTP class were assessed on admission. Linear logistic regression model was developed to predict OV using HP and CTP class.

Results

54-patients with cirrhosis were included [14(26%), 24(44%) and 16(30%) belonged to CTP class A, B and C respectively]. 37 had varices [CTP-A 4/14(26.6%), CTP-B 19/24(79.2%), CTP-C 14/16(87.5%)] on UGIE. Generalized linear model fitting showed decreasing percentage of small platelets (%SP) (P = 0.002), CTP-B (P = 0.003) and CTP-C (P = 0.003) compared to CTP-A had higher probability of having OV. The model predicts the log odds for having OV = − 0.189 – (0.046*%SP) + 2.9 [if CTP-B] + 3.7 [if CTP-C]. Based on receiver operating characteristic (ROC) analysis, a model value > − 0.19 was selected as the cutoff point to predict OV with 89%-sensitivity, 76%-specificity, 89%-positive predictive value and 76%-negative predictive value.

Conclusions

We constructed a model using %SP on peripheral blood smear and CTP class. This model may be used to predict the presence of OV, in newly diagnosed patients with cirrhosis, with acceptable sensitivity and specificity, to prioritize the patients who deserve early UGIE in limited resource settings.

Electronic supplementary material

The online version of this article (10.1186/s12876-019-1054-5) contains supplementary material, which is available to authorized users.

Warfarin prevalence, indications for use and haemorrhagic events

Warfarin, the standard oral anticoagulant drug used in Ireland, is a widely prescribed medication, particularly in the elderly. A HSE Mid-Western Area wide audit was undertaken over a 12-month period to examine the prevalence and indications for warfarin use and haemorrhagic complications associated with the drug. Every patient receiving warfarin therapy over a 13-week period was included (2564). The age standardised rate varied from 0.09% of 35-39 year olds to 6.1% of 80-84 year olds. Atrial fibrillation was the most common indication (54%) in patients attending the Mid-Western Regional Hospital anticoagulation clinic. The annual cumulative incidence of adverse haemorrhagic events in patients with a recorded INR > or = 5.0 episode was 16.6%. The incidence of major and minor haemorrhagic events per INR > or = 5.0 episode was 1.3% and 15.3% respectively. The most common sites of haemorrhage were genitourinary (39%) and gastrointestinal (27%). No fatal or intracranial haemorrhage relating to episodes of over-anticoagulation were reported during the audit period. The most frequent reason for over-anticoagulation was drug interaction (43%). In 74% of patients, the elevated INR was reversed by omitting or reducing warfarin dose. In 17% of cases, vitamin K was administered. Only 3% of incidents were treated with fresh frozen plasma or prothrombin complex concentrates.

Spontaneous hydrolysis of 4-trifluoromethylphenol to a quinone methide and subsequent protein alkylation

4-Trifluoromethylphenol (4-TFMP) was cytotoxic to precision-cut rat liver slices as indicated by loss of intracellular potassium. Intracellular glutathione levels decreased and fluoride ion levels increased in a time and concentration-dependent manner. The cytotoxicity of 4-TFMP did not appear to be due to the release of fluoride, however, since equimolar concentrations of sodium fluoride or potassium fluoride were not toxic. The ortho isomer (2-TFMP), which had a threefold slower rate of fluoride release, was much less toxic to liver slices. In incubations without slices, 4-TFMP spontaneously hydrolyzed in aqueous buffer at physiological pH to form 4-hydroxybenzoic acid via a quinone methide intermediate. The quinone methide was trapped by the addition of glutathione. Analysis of the glutathione adduct indicated that all of the fluorine atoms were lost during the hydrolysis, yielding a cresol derivative with the glutathione moiety attached to a benzylic carbonyl group. The glutathione conjugate was the primary product formed at low alkylphenol/glutathione ratios; however, at higher 4-TFMP concentrations additional unidentified products were observed. 4-TFMP also inhibited the in vitro enzyme activity of purlfied glyceraldehyde-3-phosphate dehydrogenase, a sulfhydryl-dependent enzyme, in a time and concentration-dependentmanner. Loss of thiol residues closely paralleled the loss in enzyme activity. The coaddition of glutathione prevented 4-TFMP-induced loss of enzyme activity. The cytotoxicity of 4-TFMP therefore appears to be due to spontaneous quinone methide formation and subsequent alkylation of cellular macromolecules.

Metabolism and toxicity of 4-hydroxyphenylacetone in rat liver slices: comparison with acetaminophen

Acetaminophen is oxidized by cytochrome P450 to a reactive quinone imine, N-acetyl-p-benzoquinone imine, which is thought to be responsible for its hepatotoxic effects. 4-Hydroxyphenylacetone (4-HPA) is a structural analog of acetaminophen in which the amine group is replaced by a methylene group. Following a similar metabolic pathway, 4-HPA would be oxidized to form a reactive quinone methide intermediate. We compared the metabolism and toxicity of 4-HPA and acetaminophen in liver microsomes and precision-cut liver slices from male Sprague-Dawley rats. Both 4-HPA and acetaminophen formed glutathione conjugates in microsomal incubations. 4-HPA formed diastereomeric glutathione conjugates, which is consistent with the formation of an intermediate quinone methide. The rate of conjugate formation with 4-HPA was 8.5-fold greater than that with acetaminophen. In rat liver slices a concentration of 5 mM 4-HPA killed approximately 50% of hepatocytes after 6 hr of incubation, whereas acetaminophen was not toxic at concentrations up to 50 mM. N-Acetylcysteine protected slices from 4-HPA-induced toxicity, whereas phenobarbital enhanced metabolism and toxicity. In summary, 4-HPA is more hepatotoxic than acetaminophen, and this may be the result of differences in the metabolic rate and/or the type of reactive intermediate formed.

Studies on the mechanism of hepatotoxicity of 4-methylphenol (p-cresol): effects of deuterium labeling and ring substitution

We recently observed that 4-methylphenol (p-cresol) is toxic to rat liver tissue slices. A possible mechanism involves biotransformation of 4-methylphenol to a reactive quinone methide intermediate which covalently binds to cellular macromolecules and elicits cytotoxicity. In order to obtain further evidence for this proposed mechanism, we studied the effects of deuterium-labeled 4-methylphenol (4-[alpha, alpha, alpha-d3]-methylphenol), and the presence of various ring substituents, on the metabolism and toxicity of 4-methylphenol in precision cut liver slices prepared from male Sprague-Dawley rats. Deuterium-labeled 4-methylphenol was significantly less toxic than the parent compound in rat liver slices (LC50 = 3.36 vs. 1.31 mM, respectively). In addition, the deuterium-labeled compound was metabolized to a reactive intermediate (measured as glutathione conjugate formation) at a slower rate than that of 4-methylphenol in both liver slices and liver microsomal incubations. The presence of electron withdrawing substituents (2-chloro or 2-bromo) markedly enhanced both metabolism and toxicity, with the exception of 2,6-dibromocresol, which was similar to cresol in terms of rate of metabolism and toxicity. Conversely, the presence of electron donating substituents (2-methoxy, 2-methyl or 2,6-dimethyl) diminished metabolism and toxicity. In addition, methylation of the hydroxyl group to form 4-methylanisole, greatly reduced toxicity. These results support the hypothesis that the toxicity of 4-methylphenol is dependent on the formation of a reactive quinone methide intermediate.

Inhibition of mitochondrial respiration by a para-quinone methide

A relatively stable para quinone methide was prepared from 4-allyl-2,6-dimethoxyphenol. In aqueous solution the quinone methide had a half-life of 52 min, yet reacted rapidly with thiols such as glutathione or cysteine. The unusual stability of this quinone methide allowed us to directly test its effects on mitochondrial respiration. The quinone methide was a potent inhibitor of succinate-dependent mitochondrial respiration (IC50 = 47 microM). The inhibition appeared to be due to the depletion of protein thiols, since its effects were comparable to 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB, Ellman's reagent). This quinone methide may prove a useful tool in the investigation of the specific effects of quinone methides on cells which lead to cytotoxicity.

o-Methoxy-4-alkylphenols that form quinone methides of intermediate reactivity are the most toxic in rat liver slices

The effects of p-alkyl substituents on the relative cytotoxicity of 4-alkyl-2-methoxyphenols were investigated in isolated rat liver slices. The derivatives of 4-alkyl-2-methoxyphenol studied were 4-methyl- (creosol), 4-ethyl-, 4-propyl-, 4-isopropyl-, 4-allyl-2-methoxyphenol (eugenol), as well as 4-allyl-2,6-dimethoxyphenol. The data were correlated with previous microsomal experiments which showed that all of the 4-alkyl-2-methoxyphenols were converted to quinone methides (QMs; 4-methylene-2,5-cyclohexadien-1-ones) via a cytochrome P450-catalyzed process [Bolton, J. L. Comeau, E., and Vukomanovic, V. (1995) Chem.-Biol. Interact., in press]. The present investigation showed little correlation between the rate of QM formation in microsomes and the relative toxicities of the alkylphenols, unless the QMs formed were of similar reactivity. In contrast, a plot of alkylphenol toxicity versus the relative hydrolysis rates of QMs derived from these phenols fit a parabolic equation with a minimum at the data for 4-isopropyl-2-methoxyphenol. These data suggest that in vivo oxidation of phenols to QMs which have lifetimes in the 10 s-10 min range results in cytotoxicity. QMs with reactivities outside this window are less toxic since the electrophile is either too stable for reaction with cellular nucleophiles or too reactive for nucleophilic cellular macromolecules to compete with solvent. These data suggest that a reactivity window exists for QMs which is a primary determinant of the extent of cytotoxic injury caused by these reactive electrophiles.

Quinone methide formation from para isomers of methylphenol (cresol), ethylphenol, and isopropylphenol: relationship to toxicity

The oxidative metabolism and toxicity of the para isomers of methylphenol (cresol), ethylphenol, and isopropylphenol were studied using male Sprague-Dawley rat liver microsomes and precision-cut liver slices. Reactive intermediates from each compound were trapped using radiolabeled glutathione and were detected and quantified by HPLC. Conjugates were collected and their structures determined by fast atom bombardment mass spectrometry and proton nuclear magnetic resonance. During microsomal incubations each test compound formed monoglutathione conjugates with structures which are consistent with the formation of quinone methide intermediates. In each case the glutathione moiety was attached to the benzylic carbon on the alkyl side chain of the phenol. With ethylphenol, which has a prochiral benzylic carbon, two isomeric conjugates were detected. The rate of formation of the glutathione conjugates in liver slice incubations was 4-isopropylphenol > 4-ethylphenol > 4-methylphenol. This correlated with the toxicity of the three compounds in liver slices. At equimolar concentrations 4-isopropylphenol was the most toxic while 4-methylphenol was the least toxic. Depletion of intracellular glutathione was observed in the presence of each test compound which preceded cell death. Enhancement of cellular thiol levels with N-acetylcysteine protected cells from the toxic effects of all three compounds as did inhibition of cytochrome P450 activity with metyrapone. These results suggest the formation of quinone methide intermediates from three alkylphenols during oxidative metabolism and demonstrate a correlation between the amount of reactive intermediate formed and toxicity observed in liver slices.

Cresol isomers: comparison of toxic potency in rat liver slices

A comparison of the toxicity of cresol isomers (o-, m-, and p-methylphenol) was carried out using precision-cut rat liver slices as a test system. At equimolar concentrations p-cresol was the most toxic isomer. A 5- to 10-fold higher concentration of either the o- or m-isomers was required to observe the same degree of cell killing as p-cresol. The toxicity of p-cresol was inhibited by the thiol precursor N-acetylcysteine and was enhanced by pretreatment of liver slices with diethyl maleate to deplete glutathione. These treatments, however, had little effect on either o- or m-cresol toxicity. p-Cresol rapidly depleted intracellular glutathione levels, while the o- and m-isomers depleted glutathione to a lesser extent. [14C]p-cresol was metabolized to a reactive intermediate which covalently bound to slice protein and was inhibited by N-acetylcysteine. In microsomal incubations covalent binding of [14C]p-cresol metabolites was also observed. This binding was inhibited by glutathione and resulted in the formation of a glutathione conjugate. In the absence of glutathione, p-hydroxybenzyl alcohol was the major microsomal metabolite formed from p-cresol, but this compound was not toxic to liver slices at a concentration of 2 mM. These results demonstrate that p-cresol is the most toxic cresol isomer in rat liver tissue and that its toxicity is dependent on the formation of a reactive intermediate. The results also suggest that the mechanism(s) of toxicity of the o- and m-isomers may differ from that of p-cresol.