Triplet exciton diffusion and phosphorescence quenching in Iridium(III)-Centered dendrimers

A study of triplet-triplet exciton annihilation and nonradiative decay in films of iridium(III)-centered phosphorescent dendrimers is reported. The average separation of the chromophore was tuned by the molecular structure and also by blending with a host material. It was found that triplet exciton hopping is controlled by electron exchange interactions and can be over 600 times faster than phosphorescence quenching. Nonradiative decay occurs by weak dipole-dipole interactions and is independent of exciton diffusion, except in very thin films

Combining carbohydrate substitutions at bioinspired positions with multivalent presentation towards optimising lectin inhibitors: case study with calixarenes.

Carbohydrate derivatisation and glycocluster formation are both known to enhance avidity for lectin binding. Using a plant toxin and human adhesion/growth-regulatory lectins (inter- and intrafamily comparisons) the effect of their combination is examined. In detail, aromatic substituents were introduced at the 2-N or 30-positions of N-acetyllactosamine and the products conjugated to two types of calix[n]arenes (n=4, 6) via thiourealinker chemistry

High altitude respiratory physiology and patho- physiology

At high altitude, reduced atmospheric pressure causes the partial pressure of oxygen to decrease – creating an environment of hypobaric hypoxia which presents a unique set of challenges for the respiratory system. Pulmonary physiological responses such as the hypoxic ventilatory drive are essential for successful acclimatisation, whilst others such as hypoxic pulmonary vasoconstriction may be implicated in the development of altitude illnesses. Pulmonary conditions are some of the most common (e.g. high altitude cough) and also the most serious illnesses seen at altitude (e.g high altitude pulmonary oedema, HAPE). Minimising the chance of developing HAPE through planning an appropriate ascent profile should be strongly encouraged as HAPE can rapidly be fatal if left untreated. Whilst pharmacological agents such as nifedipine can help with the management of HAPE, rapid descent remains the single-most important treatment option once symptomatic. Given the increasing popularity of travelling to altitude, an awareness of how hypobaric hypoxia affects chronic respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD) is also becoming increasingly important for respiratory physician

Non-Glycosidically Linked Pseudodisaccharides: Thioethers, Sulfoxides, Sulfones, Ethers, Selenoethers, and Their Binding to Lectins

Hydrolytically stable non-glycosidically linked tail-to-tail pseudodisaccharides are linked by a single bridging atom remote from the anomeric centre of the constituent monosaccharides. Some such pseudodisaccharides with sulfur or oxygen bridges were found to act as disaccharide mimetics in their binding to the Banana Lectin and to Concanavalin A. A versatile synthetic route to a small library of such compounds is described.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69166/1/1951_ftp.pd

(Z)-1,2:5,6-Di-O-isopropyl­idene-α-d-ribo-hexofuranos-3-ulose O-benzyl­oxime

The title compound, C19H25NO6, is a Z diastereomer in which the phenyl ring of the 3-benzyl­oxime substituent and the 5,6-O-isopropyl­idene acetal are both located on the Si-face of the C=N double bond. Inter­molecular C—H⋯O inter­actions result in helical chains along the b axis of the monoclinic unit cell

Intensive care physicians' perceptions of the diagnosis & management of patients with acute hypoxic respiratory failure associated with COVID-19: A UK based survey.

BACKGROUND: Whilst the management of Coronavirus disease-2019 (COVID-19) has evolved in response to the emerging data, treating such patients remains a challenge, and many treatments lack robust clinical evidence. We conducted a survey to evaluate Intensive Care Unit (ICU) management of COVID-19 patients with acute hypoxic respiratory failure and compared the results with data from a similar survey focusing on Acute Respiratory Distress Syndrome (ARDS) that was conducted in 2013. METHODS: The questionnaire was refined from a previous survey of ARDS-related clinical practice using an online electronic survey engine (Survey Monkey®) and all UK intensivists were encouraged to participate. The survey was conducted between 16/05/2020 and 17/06/2020. RESULTS: There were 137 responses from 89 UK centres. Non-invasive ventilation was commonly used in the form of CPAP. The primary ventilation strategy was the ARDSnet protocol, with 63% deviating from its PEEP recommendations. Similar to our previous ARDS survey, most allowed permissive targets for hypoxia (94%), hypercapnia (55%) and pH (94%). The routine use of antibiotics was common, and corticosteroids were frequently used, usually in the context of a clinical trial (45%). Late tracheostomy (>7 days) was preferred (92%). Routine follow-up was offered by 66% with few centres providing routine dedicated rehabilitation programmes following discharge. Compared to the ARDS survey, there is an increased use of neuromuscular agents, APRV ventilation and improved provision of rehabilitation services. CONCLUSIONS: Similar to our previous ARDS survey, this survey highlights variations in the management strategies used for patients with acute hypoxic respiratory failure due to COVID-19

Oxygen targets in the intensive care unit during mechanical ventilation for acute respiratory distress syndrome: a rapid review

BACKGROUND: Supplemental oxygen is frequently administered to patients with acute respiratory distress syndrome (ARDS), including ARDS secondary to viral illness such as coronavirus disease 19 (COVID-19). An up-to-date understanding of how best to target this therapy (e.g. arterial partial pressure of oxygen (PaO2) or peripheral oxygen saturation (SpO2) aim) in these patients is urgently required.OBJECTIVES: To address how oxygen therapy should be targeted in adults with ARDS (particularly ARDS secondary to COVID-19 or other respiratory viruses) and requiring mechanical ventilation in an intensive care unit, and the impact oxygen therapy has on mortality, days ventilated, days of catecholamine use, requirement for renal replacement therapy, and quality of life.SEARCH METHODS: We searched the Cochrane COVID-19 Study Register, CENTRAL, MEDLINE, and Embase from inception to 15 May 2020 for ongoing or completed randomized controlled trials (RCTs).SELECTION CRITERIA: Two review authors independently assessed all records in accordance with standard Cochrane methodology for study selection. We included RCTs comparing supplemental oxygen administration (i.e. different target PaO2 or SpO2 ranges) in adults with ARDS and receiving mechanical ventilation in an intensive care setting. We excluded studies exploring oxygen administration in patients with different underlying diagnoses or those receiving non-invasive ventilation, high-flow nasal oxygen, or oxygen via facemask.DATA COLLECTION AND ANALYSIS: One review author performed data extraction, which a second review author checked. We assessed risk of bias in included studies using the Cochrane 'Risk of bias' tool. We used the GRADE approach to judge the certainty of the evidence for the following outcomes; mortality at longest follow-up, days ventilated, days of catecholamine use, and requirement for renal replacement therapy.MAIN RESULTS: We identified one completed RCT evaluating oxygen targets in patients with ARDS receiving mechanical ventilation in an intensive care setting. The study randomized 205 mechanically ventilated patients with ARDS to either conservative (PaO2 55 to 70 mmHg, or SpO2 88% to 92%) or liberal (PaO2 90 to 105 mmHg, or SpO2 ≥ 96%) oxygen therapy for seven days. Overall risk of bias was high (due to lack of blinding, small numbers of participants, and the trial stopping prematurely), and we assessed the certainty of the evidence as very low. The available data suggested that mortality at 90 days may be higher in those participants receiving a lower oxygen target (odds ratio (OR) 1.83, 95% confidence interval (CI) 1.03 to 3.27). There was no evidence of a difference between the lower and higher target groups in mean number of days ventilated (14.0, 95% CI 10.0 to 18.0 versus 14.5, 95% CI 11.8 to 17.1); number of days of catecholamine use (8.0, 95% CI 5.5 to 10.5 versus 7.2, 95% CI 5.9 to 8.4); or participants receiving renal replacement therapy (13.7%, 95% CI 5.8% to 21.6% versus 12.0%, 95% CI 5.0% to 19.1%). Quality of life was not reported.AUTHORS' CONCLUSIONS: We are very uncertain as to whether a higher or lower oxygen target is more beneficial in patients with ARDS and receiving mechanical ventilation in an intensive care setting. We identified only one RCT with a total of 205 participants exploring this question, and rated the risk of bias as high and the certainty of the findings as very low. Further well-conducted studies are urgently needed to increase the certainty of the findings reported here. This review should be updated when more evidence is available.</p