Radiation damage by extensive local water ionization from two-step electron-transfer-mediated decay of solvated ions

Biomolecular radiation damage is largely mediated by radicals and low-energy electrons formed by water ionization rather than by direct ionization of biomolecules. It was speculated that such an extensive, localized water ionization can be caused by ultrafast processes following excitation by core-level ionization of hydrated metal ions. In this model, ions relax via a cascade of local Auger-Meitner and, importantly, non-local charge- and energy-transfer processes involving the water environment. Here, we experimentally and theoretically show that, for solvated paradigmatic intermediate-mass Al3+ ions, electronic relaxation involves two sequential solute-solvent electron transfer-mediated decay processes. The electron transfer-mediated decay steps correspond to sequential relaxation from Al5+ to Al3+ accompanied by formation of four ionized water molecules and two low-energy electrons. Such charge multiplication and the generated highly reactive species are expected to initiate cascades of radical reactions.

1290 CAN P1NP LEVELS INFLUENCE MANAGEMENT PLANNING FOR PATIENTS WITH A FRAGILITY HIP FRACTURE RECEIVING ANTI-RESORPTIVE MEDICATIONS?

Introduction

Procollagen-N-terminal-peptide (P1NP) is a bone formation marker. Bisphosphonates lead to a reduction in P1NP levels and levels are significantly elevated shortly after fracture. In older patients taking bisphosphonates who have had a further osteoporotic fracture there is a lack of evidence to guide ongoing osteoporotic management.

Objectives

To assess if measuring P1NP in patients receiving Bisphosphonates treatment who develop neck of femur fractures helps guide further management in regards to long term bone protection treatment.

Method

Retrospective descriptive cohort study of P1NP levels for the patients who presented with NOF# (>60yrs) and who were taking anti-resorptive medications. Cases were discussed in our complex bone health MDM and patient specific plans made accordingly.

Results

60 patients were identified between March 2017 and Sept 2021 had P1NP tested (2.6 % of the 2,303 total fractures in this time). Mean age 83 years (F:M – 54:6 / # type - IC:EC – 34:26). Overall: 17 (28%) patients had significantly elevated PINP with identifiable reasons. 39 (65%) patients had supressed P1NP levels (< 35mcg/L) and 5(7 %) between 36-39 mcg/L. Of those with supressed P1NP: Patients taking treatment >5 years (n=9) – Treatment stopped for 6 patients, 2 changed treatment following DXA and 1 continued. On treatment 3-5 years (n=8) – 5 continued with treatment, 1 had further ix and 2 treatments changed On treatment 1-3 years (n=17) – 14 continued treatment, 2 treatments stopped, 1 treatment changed On treatment <1 year (n=16) – all continued the same treatment

Conclusion

The measurement of P1NP has been helpful in making patient centred decisions in this cohort. It has added to the detailed discussions in the hip fracture bone health MDM and for 23% of patients with supressed bone turnover contributed to a change in management. Most changes occurred in those patients taking treatment for more than 5 years where the evidence of bone turnover suppression gives confidence to stop or change treatment.

The association between central ambulatory blood pressure and end-organ damage

Background/Introduction

Central blood pressure (BP) measured in the clinic relates more strongly to end-organ damage and may be superior to brachial BP in predicting cardiovascular events. Measurement of central ambulatory BP (ABP) is now possible and emerging data suggest that central ABP is better correlated with left ventricular mass index (LVMI) than brachial ABP.1,2 However, the association between central ABP and other measures of end-organ damage remains unclear.

Purpose

We investigated the association between brachial or central ABP and end-organ damage, in a large community-based population of untreated individuals.

Method

1091 participants (mean age 45±18 years; 589 females) had simultaneous measurements of brachial and central ABP over 24 hours, using the Mobil-O-Graph device. Central ABP was derived using two waveform calibration methods (1: mean/diastolic BP; 2: systolic/diastolic BP). Participants also underwent measurement of aortic pulse wave velocity (aPWV; SphygmoCor device) in the clinic. In a subset of 675 individuals, LVMI was assessed by echocardiography and in 610 individuals, carotid intima-media thickness (CIMT) was measured, using ultrasound. 24-hour and daytime brachial and central ambulatory systolic BP (ASBP) and pulse pressure (APP) were considered.

Results

The Pearson's coefficient for each correlation is listed in Table 1. LVMI was most strongly correlated with 24-hour central ASBP, using calibration method 1 (MAP/DBP; r=0.403, P<0.001). CIMT was most strongly correlated with daytime central ASBP, again derived from calibration method 1 (r=0.341, p<0.001), whereas aPWV measured in the clinic, was most strongly correlated with 24-hour central ASBP, derived from calibration method 2 (SBP/DBP; r=0.441, P<0.001). Based on z statistics, all correlations reported above were significantly stronger than equivalent correlations using brachial ASBP (P<0.001 for all three comparisons of correlation coefficients).

Conclusion

Measurement of central ABP relates more closely to end-organ damage than equivalent measures based on brachial ABP. Central ABP may provide valuable additional information concerning cardiovascular risk above and beyond brachial ABP.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): British Heart Foundation

475 DEVELOPING A VIRTUAL CARE HOME SUPPORT FORUM DURING THE COVID-19 PANDEMIC

Introduction

COVID-19 has had a devastating effect on care homes, increasing both morbidity and mortality of residents and staff. Between 2 March and 12 June 2020, COVID-19 was the main cause of death in male care home residents (33.5%) and second for female (26.6%).1 By 1 May 2020, the death rate from all causes in care homes exceeded that in hospital (6,409 versus 6,397).2 Thus, care homes had to rapidly adapt to facilitate safe care of patients and staff.

Method

An expert outreach team visited a number of care homes in Surrey and Sussex to explore COVID-19 issues in care homes. Key themes were identified that informed topics for the Virtual Care Home Forum, where a series of virtual teaching, training and peer support sessions were hosted either live or on-demand, accessible for all care home staff.

Results

12 sessions were held with an average attendance of 25 people, predominantly care home managers and community healthcare professionals. Real time qualitative feedback was collected and an electronic survey was completed at the end of the series which showed 100% felt the sessions had improved their understanding of the topic, 100% felt the knowledge and skills obtained from the sessions would be useful in their job, 87.5% agreed the sessions would impact or change their practise and 100% felt more supported during the pandemic.

Conclusion

It has been an unprecedented year for the NHS, and the care home sector has suffered significantly. In order to provide the best level of care for patients and support for our community colleagues, we must work collaboratively, including provision of education and training. To ensure equal access for all, maintaining user-safety and compliance with government legislation, virtual webinars proved to be an excellent modality. We plan to continue providing training, teaching and support through this means in the future.

P373 Left atrial mechanics and aortic stiffness following high intensity interval training: a randomised controlled study

Background

Physical inactivity is associated with an increased risk of cardiovascular disease. High intensity interval training (HIIT) has been shown to improve important health parameters, including aerobic capacity, arterial blood pressure, cardiac autonomic modulation and left ventricular mechanics. However, adaptations in left atrial (LA) mechanics and aortic stiffness remain unclear. Therefore, the aim of the present study was to assess any left atrial and aortic adaptations to HIIT.

Methods

Forty-one physically inactive males and females (aged 23 ± 2.7 years) volunteered for the study. Participants were randomised to either a 4-week HIIT intervention (n = 21) or 4-week control period (n = 20). The HIIT protocol consisted of 3 x 30-second maximal cycle ergometer sprints with a resistance of 7.5% body weight, interspersed with 2-minutes of active unloaded recovery. Speckle tracking imaging of the left atrium and M-Mode tracing of the aorta was performed pre and post HIIT and control period using commercially available software (EchoPac; GE Medical Systems). Analysis of covariance, with baseline measures as the covariate, was used to explore any differences in left atrial mechanics and aortic stiffness between the intervention and control groups. Stepwise linear regression analysis using LA stiffness as the dependent variable was conducted.

Results

Following 4-weeks of HIIT, there was significant improvement in LA mechanics, including LA reservoir (13.9 ± 13.4%, p = 0.033) and LA stiffness (-0.05 ± 0.04%-1, p = 0.032) compared to the control condition. In addition, improvements were observed in aortic distensibility (2.1 ± 2.7 cm2 × dyn×-1 × 103, p = 0.031) and aortic stiffness index (-2.6 ± 4.6, p = 0.041) compared to the control condition. In stepwise linear regression analysis, aortic distensibility change was significantly associated with LA stiffness change (p = 0.002), with an R2 of 0.613.

Conclusion

A short-term programme of HIIT was associated with a significant improvement in LA mechanics and aortic stiffness. These adaptations may have important health implications and contribute to the improved left ventricular diastolic and systolic mechanics, aerobic capacity and reduced arterial blood pressure previously documented following HIIT.

Methods and considerations concerning cardiac output measurement in pregnant women: recommendations of the International Working Group on Maternal Hemodynamics

Cardiac output (CO), along with blood pressure and vascular resistance, is one of the most important parameters of maternal hemodynamic function. Substantial changes in CO occur in normal pregnancy and in most obstetric complications. With the development of several non-invasive techniques for the measurement of CO, there is a growing interest in the determination of this parameter in pregnancy. These techniques were initially developed for use in critical-care settings and were subsequently adopted in obstetrics, often without appropriate validation for use in pregnancy. In this article, methods and devices for the measurement of CO are described and compared, and recommendations are formulated for their use in pregnancy, with the aim of standardizing the assessment of CO and peripheral vascular resistance in clinical practice and research studies on maternal hemodynamics. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Multi-channel electronic and vibrational dynamics in polyatomic resonant high-order harmonic generation

High-order harmonic generation in polyatomic molecules generally involves multiple channels of ionization. Their relative contribution can be strongly influenced by the presence of resonances, whose assignment remains a major challenge for high-harmonic spectroscopy. Here we present a multi-modal approach for the investigation of unaligned polyatomic molecules, using SF6 as an example. We combine methods from extreme-ultraviolet spectroscopy, above-threshold ionization and attosecond metrology. Fragment-resolved above-threshold ionization measurements reveal that strong-field ionization opens at least three channels. A shape resonance in one of them is found to dominate the signal in the 20-26 eV range. This resonance induces a phase jump in the harmonic emission, a switch in the polarization state and different dynamical responses to molecular vibrations. This study demonstrates a method for extending high-harmonic spectroscopy to polyatomic molecules, where complex attosecond dynamics are expected.

Neural basis of auditory expectation within temporal cortex

Predictive coding frameworks of perception propose that neural networks form predictions of expected input and generate prediction errors when the external input does not match expectation. We therefore investigated the processing of unexpected sounds and silence in the auditory cortex using fMRI. Unexpected sounds, when compared to expected sounds, evoked greater activation in large areas of the left temporal and insular cortices. Additionally the left middle temporal gyrus exhibited greater activation to unexpected events in general, whether sounds or silence, when compared to the corresponding expected events. These findings support predictive coding models of perception, which suggest that regions of the temporal cortex function to integrate sensory information with predictive signals during auditory perception.

Cytological recognition of herpes simplex virus infection in bronchoscopic samples from the respiratory tract

Cytological features suggesting herpes simplex virus (HSV) infection in samples obtained at bronchoscopy have been described only very rarely in routinely processed samples. We report four cases where evidence of HSV infection was identified morphologically in samples processed using thin-layer techniques, with polymerase chain reaction confirmation of the presence of virus in three cases. We suggest that the increased morphological clarity provided by this technique for processing these cytology samples may result in the morphological features of viral infection being seen more frequently. Pathologists reporting such samples need to be aware of this possibility in order to avoid potential misinterpretations. In addition, however, respiratory and intensive care physicians unused to receiving cytology reports indicating 'HSV infection' need to be aware that the significance is uncertain and in most cases it is likely to indicate the reactivation of a latent infection.

Membrane reinsertion of a myristoyl-peptidyl anchored extracellular domain growth hormone receptor

The actions of GH are mediated through a cell surface cytokine receptor. We previously demonstrated that naturally occurring truncated membrane bound GH receptors (GHRs) can block GH receptor signaling. We have now investigated whether recombinant extracellular GHR can be conjugated to a myristoylated-peptide (mp) tail and inserted into cell membranes to modulate GHR signaling. Recombinant human extracellular domain (1-241) GHR was expressed in Escherichia coli, purified, and refolded from cell lysate. The free C-terminal cysteine was then reduced and conjugated to an activated preformed mp tail. The properties of the purified tailed GHR (GHR-mp) were then compared with those of the untailed purified GHR 1-241. Fluorescence-activated cell sorter analysis and cell surface binding assays demonstrated that GHR-mp inserted into the cell surface membranes of CHO cells, whereas untailed GHR 1-241 showed no insertion. In a cell-based bioassay GHR-mp partially inhibited wild-type GHR signaling, whereas GHR 1-241 had no effect. Truncated extracellular domain GHR can, when specifically modified with a membrane-localizing mp unit, insert into cell surface membranes and modulate GHR signaling.

PEHO and PEHO-like syndromes: report of five Australian cases

PEHO syndrome is a rare progressive infantile encephalopathy with onset within the first few months of life. Few patients fulfilling the diagnostic criteria for PEHO syndrome have been reported outside Finland. Affected infants have facial dysmorphism and suffer from severe hypotonia, profound mental retardation, convulsions (often with a hypsarrhythmic EEG pattern), transient or persistent peripheral oedema, and optic atrophy. Cerebellar and brainstem atrophy are usually present on neuroimaging. A PEHO-like syndrome has been described, in which the affected individuals have neither optic atrophy nor the typical neuroradiological findings. We report five Australian patients, the first with classical features of PEHO syndrome, and four who have a PEHO-like disorder. We compare their features with other published cases. We suggest that PEHO or a PEHO-like syndrome may affect more patients than are currently identified, based on the original diagnostic criteria for this disorder.

New Zealand sea lion (Phocarctos hookeri) epidemic 2002 (abstract)

The New Zealand sea lion is a threatened species and two unusual events contributed to a decrease in recruitment in 2002. The first was a marked reduction (20%) in the number of pups born at the principal Auckland Island rookeries. Secondly, the mortality rate for pups was significantly elevated and was 33% by the end of February, almost three times the mean for that time of the year. Counts of females at rookeries indicated that the lowered fecundity was possibly due to a scarcity of food resources, supported by the fact that male pups (n=50) in 2002 grew poorly with the lightest recorded liveweights for the previous 8 years. Lowered fecundity may also have resulted from infection leading to foetal death, seen in an adult by-catch female, or abortion. Necropsies were conducted on 126/133 pups that died at Sandy Bay and for many the cause of death was multifactorial and included stillbirth, trauma, malnutrition, and severe anaemia caused by hookworm (Uncinaria spp) infection. An unusual disease presentation seen for the first time in 2002 was characterised by systemic bacterial infection that caused suppurative polyarthritis, severe necrotising fasciitis, myositis and osteomyelitis, suppurative peritonitis, pleuritis, or meningitis. For 41 pups, this syndrome was the primary cause of death and for an additional 16 it was a contributing factor along with hookworm infection or trauma. A consistent isolate has been Klebsiella pneumoniae with frequent isolations of Salmonella spp.

Pegvisomant: structure and function

Pegvisomant is the pegylated form of mutant growth hormone (B2036). B2036 has increased affinity in one binding site and lowered affinity in its second binding site, it has been shown that this molecule still enables dimerisation of the growth hormone receptor at the cell surface but does not allow the necessary conformational changes for signalling. Pegylation decreases the antagonistic activity of B2036, however the rate of clearance of the pegylated B2036 is greatly reduced compared to the unpegylated form. Even though the antagonistic activity of pegvisomant is lower than B2036, the reduced rate of clearance makes it an effective clinical drug for the treatment of conditions such as acromegaly.