Identifying the most important data for research in the field of infectious diseases: thinking on the basis of artificial intelligence

OBJECTIVE

Clinical data on which artificial intelligence (AI) algorithms are trained and tested provide the basis to improve diagnosis or treatment of infectious diseases (ID). We aimed to identify important data for ID research to prioritise efforts being undertaken in AI programmes.

METHODS

We searched for 1,000 articlesfrom high-impact ID journals on PubMed, selecting 288 of the latest articles from 10 top journals. We classified them into structured or unstructured data. Variables were homogenised and grouped into the following categories: epidemiology, admission, demographics, comorbidities, clinical manifestations, laboratory, microbiology, other diagnoses, treatment, outcomes and other non-categorizable variables.

RESULTS

4,488 individual variables were collected, from the 288 articles. 3,670 (81.8%) variables were classified as structured data whilst 818 (18.2%) as unstructured data. From the structured data, 2,319 (63.2%) variables were classified as direct-retrievable from electronic health records-whilst 1,351 (36.8%) were indirect. The most frequent unstructured data were related to clinical manifestations and were repeated across articles. Data on demographics, comorbidities and microbiology constituted the most frequent group of variables.

CONCLUSIONS

This article identified that structured variables have comprised the most important data in research to generate knowledge in the field of ID. Extracting these data should be a priority when a medical centre intends to start an AI programme for ID. We also documented that the most important unstructured data in this field are those related to clinical manifestations. Such data could easily undergo some structuring with the use of semi-structured medical records focusing on a few symptoms.

Partial recovery of SARS-CoV-2 immunity after booster vaccination in renal transplant recipients

The pandemic caused by the SARS-CoV-2 coronavirus has been especially detrimental to patients with end-stage renal disease. History with other vaccines suggests that patients with renal disease may not respond adequately to the SARS-CoV-2 vaccine. The aim of this study is to evaluate the immunity to SARS-CoV-2 mRNA vaccines in renal patients. Post SARS-CoV-2 vaccination first, and after the booster dose, antibodies and cellular immunity were studied in patients on hemodialysis (N = 20), peritoneal dialysis (N = 10) and renal transplantation (N = 10). After the two doses of vaccine, there was an effective immunity in dialysis patients, with 100% seroconversion and 87% detection of cellular immunity (85% in hemodialysis and 90% in peritoneal dialysis). In contrast, in renal transplant recipients there was only 50% seroconversion and cellular immunity was detected in 30% of patients. After the booster dose, all dialysis patients achieved a cellular and antibody immunity, whereas in transplant patients, despite improvement, 20% did not produce antibodies and in 37.5% cellular immunity could not be detected. The mRNA vaccine plus booster performs excellently in dialysis patients, whereas in kidney transplant recipients, despite the booster, complete immunization is not achieved.

Transitions and empowerment theory: A framework for nursing interventions during intensive care unit patient transition

OBJECTIVES

1) To explore the main characteristics of intensive care unit transition according to patients' lived experience and 2) To identify nursing therapeutics to facilitate patients' transition from the intensive care unit to the inpatient unit.

METHODOLOGY

Secondary Analysis (SA) of the findings of a descriptive qualitative study on the experience of patients admitted to an ICU during the transition to the inpatient unit, based on the Nursing Transitions Theory. Data for the primary study were generated from 48 semi-structured interviews of patients who had survived critical illness in 3 tertiary university hospitals.

RESULTS

Three main themes were identified during the transition of patients from the intensive care unit to the inpatient unit: 1) nature of ICU transition, 2) response patterns and 3) nursing therapeutics. Nurse therapeutics incorporates information, education and promotion of patient autonomy; in addition to psychological and emotional support.

CONCLUSIONS

Transitions Theory as a theoretical framework helps to understand patients' experience during ICU transition. Empowerment nursing therapeutics integrates the dimensions aimed at meeting patients' needs and expectations during ICU discharge.

Risk scores' performance and their impact on operative decision-making in left-sided endocarditis: a cohort study

The accuracy of contemporary risk scores in predicting perioperative mortality in infective endocarditis (IE) remains controversial. The aim is to evaluate the performance of existent mortality risk scores for cardiovascular surgery in IE and the impact on operability at high-risk thresholds. A single-center retrospective review of adult patients diagnosed with acute left-sided IE undergoing surgery from May 2014 to August 2019 (n = 142) was done. Individualized risk calculation was obtained according to the available mortality risk scores: EuroScore I and II, PALSUSE, Risk-E, Costa, De Feo-Cotrufo, AEPEI, STS-risk, STS-IE, APORTEI, and ICE-PCS scores. A cross-validation analysis was performed on the score with the best area under the curve (AUC). The 30-day survival was 96.5% (95%CI 91-98%). The score with worse area under the curve (AUC = 0.6) was the STS-IE score, while the higher was for the RISK-E score (AUC = 0.89). The AUC of the majority of risk scores suggested acceptable performance; however, statistically significant differences in expected versus observed mortalities were common. The cross-validation analysis showed that a large number of survivors (> 75%) would not have been operated if arbitrary high-risk threshold estimates had been used to deny surgery. The observed mortality in our cohort is significantly lower than is predicted by contemporary risk scores. Despite the reasonable numeric performance of the analyzed scores, their utility in judging the operability of a given patient remains questionable, as demonstrated in the cross-validation analysis. Future guidelines may advise that denial of surgery should only follow a highly experienced Endocarditis Team evaluation.

Anticoagulation strategies and risk of bleeding events in critically ill COVID-19 patients

Objective

To evaluate the rate of thrombosis, bleeding and mortality comparing anticoagulant doses in critically ill COVID-19 patients.

Design

Retrospective observational and analytical cohort study.

Setting

COVID-19 patients admitted to the intensive care unit of a tertiary hospital between March and April 2020.

Patients

201 critically ill COVID-19 patients were included. Patients were categorized into three groups according to the highest anticoagulant dose received during hospitalization: prophylactic, intermediate and therapeutic.

Interventions

The incidence of venous thromboembolism (VTE), bleeding and mortality was compared between groups. We performed two logistic multivariable regressions to test the association between VTE and bleeding and the anticoagulant regimen.

Main variables of interest

VTE, bleeding and mortality.

Results

78 patients received prophylactic, 94 intermediate and 29 therapeutic doses. No differences in VTE and mortality were found, while bleeding events were more frequent in the therapeutic (31%) and intermediate (15%) dose group than in the prophylactic group (5%) (p < 0.001 and p < 0.05 respectively). The anticoagulant dose was the strongest determinant for bleeding (odds ratio 2.4, 95% confidence interval 1.26-4.58, p = 0.008) but had no impact on VTE.

Conclusions

Intermediate and therapeutic doses appear to have a higher risk of bleeding without a decrease of VTE events and mortality in critically ill COVID-19 patients.

COVID-19 on Pregnancy Outcomes, Mental Health and Placenta: Focus in Latin America

The COVID-19 pandemic has impacted many aspects of health and society worldwide. One vulnerable group that faced SARS-CoV-2 infection is pregnant women, who were considered to have potentiated risk factors. In physiological pregnancy, maternal systems have several changes and adaptations to support fetal development. These changes involve regulations of cardiovascular, respiratory, and immunologic systems, among others, which SARS-CoV-2 could severely alter. Furthermore, the systemic effects of viral infection could be associated with placental dysfunction and adverse pregnancy outcomes, which have been studied from the start of the pandemic to date. Additionally, pregnancy is a condition of more significant mental health vulnerability, especially when faced with highly stressful situations. In this chapter, we have collected information on the effect of COVID-19 on maternal mortality, the SARS-CoV-2 infection rate in pregnancy, and the impact on pregnancy outcomes, maternal mental health, and placental function, with a particular focus on studies that consider the Latin American population.

Intranasal disulfiram-induced encephalopathy: clinical and neuroimage findings

INTRODUCTION

Disulfiram-induced-encephalopathy is a rare complication that has been well described in adults. Although it usually occurs in acute intoxication with high doses of disulfiram, late onset encephalopathy has also been reported. Some authors propose the inhibition of dopamine beta-hydroxylase mediated by toxic metabolites of disulfiram as the main responsible, but the exact mechanism remains unclear. The aim of this report was to describe the clinical and neuroimaging findings in an unusual case of acute encephalitis due to disulfiram toxicity associated to chronic intranasal consume.

CASE REPORT

A chronic alcoholic who referred snorted use of a very high dose of disulfiram without simultaneous alcohol intake developed an acute encephalopathy with a rapidly progressive respiratory failure. A characteristic neuroimage finding consisting in extensive bilateral symmetric involvement of both pallidal nuclei was described. Recovery and neurologic improvement were slow. Two months after the intoxication, the patient still had slight intentional tremor and a scheduled magnetic resonance imaging. showed evolution of symmetrical areas of cytotoxic edema to necrosis.

CONCLUSION

Disulfiram-induced neurotoxicity must be suspect during chronic therapy with disulfiram or after acute ingestion of high doses. Symptoms such as symmetric sensory and motor neuropathy, confusion, catatonia, parkinsonism, ataxia, choreoathetosis, seizures and encephalopathy should make us rule out this disorder. A brain imaging test should be performed in these patients since a characteristic involvement of both nuclei pallidus has been described, but it is not present in all patients.

OP0299-HPR ANALYSIS OF THE ACCEPTANCE AND USEFULNESS OF A NON-PRESENTIAL CONSULTATION, IN PATIENTS WITH CHRONIC INFLAMMATORY JOINT DISEASES USING A DIGITAL PLATFORM

Background

The Covid-19 pandemic has meant a modification of the patterns of the doctor-patient relationship, favoring online visits and reducing face-to-face visits. Likewise, the implementation of Patient-Reported Outcomes (PROs) that do not require the intervention of the doctor in our clinical practice and that given their close relationship with the clinical activity of chronic inflammatory joint diseases (CIJD) has favored an empowerment of patients and can allow the development of the online visit.

Objectives

Know the use and acceptance of patients with CIJD: rheumatoid arthritis (RA), psoriatic arthritis (PsA) and spondyloarthropathies (SpA) of a non-face-to-face online visit, through a digital environment.

Methods

Patients were included in a platform called Rheumanet for access by username and passwords (https://www.laconsultacercadeti.com/). At the time of inclusion, demographic variables were collected: date of birth, sex, level of education (primary education, secondary education, vocational training, further education and higher education), distance from the hospital to the patient’s home, and clinical variables such as diagnosis: RA, PsA or SpA, as well as the duration of the disease. Prior to the appointment, patients were encouraged to complete a PRO survey to assess their clinical situation: Routine Assessment of Patient Index Data 3 (RAPID3) for RA, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) for SpA and RAPID3 and / or BASDAI for the PsA. Both the RAPID3 and BASDAI were scored for the patient’s knowledge and assigned to a color scale based on disease activity in green (remission or low activity), orange (moderate activity) or red (severe activity). Likewise, they were ordered to express through a free text what they would tell us as if they were in a face-to-face consultation. Complementary tests (analytical, radiological studies and others) are obtained simultaneously from the medical records and a joint assessment of the visit is carried out.

Results

Between September 1, 2020 and January 31, 2022, a total of 248 patients (113 RA, 53 SpA and 82 PsA) were included in the platform. 172 (69.3%) patients used the digital platform and made at least one non-face-to-face visit during follow-up. The number of online visits made by each patient ranged from 1 to a maximum of 13 visits. 80 patients (70.7%) suffered from RA, 40 (75.4%) from SpA and 52 (63.4%) from PsA. The number of patients who made non-face-to-face visits was 38 (72.3%) for a disease duration of <5 years and 137 (64.5%) for >5 years. When the ages of the patients were analyzed, the number of patients who made visits was 75 (73.5%) between 18 and 30 years old, 50 (67.7%) between 30 and 50 and 47 (66.4 %) from 50 years. According to the degree of activity of the disease, 75 patients were in remission or low activity at some point during the visits, 63 patients with moderate activity and 34 with severe activity. The distribution according to level of education was: 11 (6.3%) primary education, 21 (12.2%) secondary education, 37 (21.5%) vocational training, 63 (36.6%) further education and 40 (23.2%)higher education. The number of online visits was higher in patients who lived at a distance of 50 km or more from the hospital, reaching 100% of the visits in this subgroup of patients.

Conclusion

The online visit through a digital platform through PROs is well accepted by our population with CIJD, especially in the young population, with a higher cultural level and whose home is far from the hospital. The online visit was made by patients regardless of the severity of their disease activity. Speed and ease of use using PROs already known to the patient and clinician is an important consideration for rheumatologists working in healthcare systems where patient contact time is limited. It would be interesting to obtain this information in non-pandemic situations such as COVID-19, which would make it possible to assess actual acceptance and its use in this type of patient in circumstances in which fear of contagion is not a variable to consider.

Disclosure of Interests

None declared

Peripheral microcirculatory alterations are associated with the severity of acute respiratory distress syndrome in COVID-19 patients admitted to intermediate respiratory and intensive care units

Background

COVID-19 is primarily a respiratory disease; however, there is also evidence that it causes endothelial damage in the microvasculature of several organs. The aim of the present study is to characterize in vivo the microvascular reactivity in peripheral skeletal muscle of severe COVID-19 patients.

Methods

This is a prospective observational study carried out in Spain, Mexico and Brazil. Healthy subjects and severe COVID-19 patients admitted to the intermediate respiratory (IRCU) and intensive care units (ICU) due to hypoxemia were studied. Local tissue/blood oxygen saturation (StO₂) and local hemoglobin concentration (THC) were non-invasively measured on the forearm by near-infrared spectroscopy (NIRS). A vascular occlusion test (VOT), a three-minute induced ischemia, was performed in order to obtain dynamic StO₂ parameters: deoxygenation rate (DeO₂), reoxygenation rate (ReO₂), and hyperemic response (H_AUC). In COVID-19 patients, the severity of ARDS was evaluated by the ratio between peripheral arterial oxygen saturation (SpO₂) and the fraction of inspired oxygen (FiO₂) (SF ratio).

Results

Healthy controls (32) and COVID-19 patients (73) were studied. Baseline StO₂ and THC did not differ between the two groups. Dynamic VOT-derived parameters were significantly impaired in COVID-19 patients showing lower metabolic rate (DeO₂) and diminished endothelial reactivity. At enrollment, most COVID-19 patients were receiving invasive mechanical ventilation (MV) (53%) or high-flow nasal cannula support (32%). Patients on MV were also receiving sedative agents (100%) and vasopressors (29%). Baseline StO₂ and DeO₂ negatively correlated with SF ratio, while ReO₂ showed a positive correlation with SF ratio. There were significant differences in baseline StO₂ and ReO₂ among the different ARDS groups according to SF ratio, but not among different respiratory support therapies.

Conclusion

Patients with severe COVID-19 show systemic microcirculatory alterations suggestive of endothelial dysfunction, and these alterations are associated with the severity of ARDS. Further evaluation is needed to determine whether these observations have prognostic implications. These results represent interim findings of the ongoing HEMOCOVID-19 trial.

Trial registration ClinicalTrials.gov NCT04689477. Retrospectively registered 30 December 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03803-2.

Small vessel disease disrupts EEG postural brain networks in 'unexplained dizziness in the elderly'

•

Unexplained dizziness in the elderly may result from cerebral small vessel disease.

•

Dizzy elderly patients differed from controls in EEG power when standing.

•

EEG power when standing correlated with subjective (perceived) instability.

Objective

To examine the hypothesis that small vessel disease disrupts postural networks in older adults with unexplained dizziness in the elderly (UDE).

Methods

Simultaneous electroencephalography and postural sway measurements were undertaken in upright, eyes closed standing, and sitting postures (as baseline) in 19 younger adults, 33 older controls and 36 older patients with UDE. Older adults underwent magnetic resonance imaging to determine whole brain white matter hyperintensity volumes, a measure of small vessel disease. Linear regression was used to estimate the effect of instability on electroencephalographic power and connectivity.

Results

Ageing increased theta and alpha desynchronisation on standing. In older controls, delta and gamma power increased, and theta and alpha power reduced with instability. Dizzy older patients had higher white matter hyperintensity volumes and more theta desynchronisation during periods of instability. White matter hyperintensity volume and delta power during periods of instability were correlated, positively in controls but negatively in dizzy older patients. Delta power correlated with subjective dizziness and instability.

Conclusions

Neural resource demands of postural control increase with age, particularly in patients with UDE, driven by small vessel disease.

Significance

EEG correlates of postural control saturate in older adults with UDE, offering a neuro-physiological basis to this common syndrome.

Increased P2×2 receptors induced by amyloid-β peptide participates in the neurotoxicity in alzheimer's disease

Amyloid beta peptide (Aβ) is tightly associated with the physiopathology of Alzheimer's Disease (AD) as one of the most important factors in the evolution of the pathology. In this context, we previously reported that Aβ increases the expression of ionotropic purinergic receptor 2 (P2×2R). However, its role on the cellular and molecular Aβ toxicity is unknown, especially in human brain of AD patients. Using cellular and molecular approaches in hippocampal neurons, PC12 cells, and human brain samples of patients with AD, we evaluated the participation of P2×2R in the physiopathology of AD. Here, we reported that Aβ oligomers (Aβo) increased P2×2 levels in mice hippocampal neurons, and that this receptor increases at late Braak stages of AD patients. Aβo also increases the colocalization of APP with Rab5, an early endosomes marker, and decreased the nuclear/cytoplasmic ratio of Fe65 and PGC-1α immunoreactivity. The overexpression in PC12 cells of P2×2a, but not P2×2b, replicated these changes in Fe65 and PGC-1α; however, both overexpressed isoforms increased levels of Aβ. Taken together, these data suggest that P2×2 is upregulated in AD and it could be a key potentiator of the physiopathology of Aβ. Our results point to a possible participation in a toxic cycle that increases Aβ production, Ca²⁺ overload, and a decrease of PGC-1α. These novel findings put the P2×2R as a key novel pharmacological target to develop new therapeutic strategies to treat Alzheimer's Disease.

Integrated quality assessment for diabetes care in Portuguese primary health care using prevention quality indicators

AIMS

This study evaluates the prevention quality indicators (PQI) for Diabetes Mellitus (DM) in Portugal using contemporary data and explores their variability according to Primary Health Care (PHC) quality indicators.

METHODS

We conducted a retrospective observational analysis of secondary data comprising Portuguese PHC indicators by health centres group (ACES) and the National Hospital Morbidity Database. We calculated and analysed age-sex-adjusted rates for each PQI. Worse-performing ACES were identified using the 2017 median PQI values as an assessment cut-off. A multivariate logistic analysis was carried to find variables associated with the likelihood of being a worse-performing ACES for the biennium.

RESULTS

The median values of the indicator PQI93 - Prevention Quality Diabetes Composite were 79 and 65.2 hospitalizations per 100 000 pop, in 2016 and 2017 respectively. Diabetes long term complications (PQI 03) accounted for most of the hospitalizations. The quality indicator in PHC with greater influence on PQI93 was the proportion of DM patients with <65 years with test results for HbA1c < = 6.5%.

CONCLUSIONS

This study shows that some PHC quality indicators are closely related to DM care, and so their monitoring is of high importance. Diabetes long term complications (PQI 03) demand greater attention from PHC professionals.

Dosimetric impact of rectum and bladder anatomy and intrafractional prostate motion on hypofractionated prostate radiation therapy

OBJECTIVE

The objective of this study was to evaluate the dosimetric impact on hypofractionated prostate radiation therapy of two geometric uncertainty sources: rectum and bladder filling and intrafractional prostate motion.

MATERIALS AND METHODS

This prospective study included 544 images (375 pre-treatment cone-beam CT [CBCT] and 169 post-treatment CBCT) from 15 prostate adenocarcinoma patients. We recalculated the dose on each pre-treatment CBCT once the positioning errors were corrected. We also recalculated two dose distributions on each post-treatment CBCT, either using or not intrafractional motion correction. A correlation analysis was performed between CBCT-based dose and rectum and bladder filling as well as intrafraction prostate displacements.

RESULTS

No significant differences were found between administered and planned rectal doses. However, we observed an increase in bladder dose due to a lower bladder filling in 66% of treatment fractions. These differences were reduced at the end of the fraction since the lower bladder volume was compensated by the filling during the treatment session. A statistically significant reduction in target volume coverage was observed in 27% of treatment sessions and was correlated with intrafractional prostate motion in sagittal plane > 4 mm.

CONCLUSIONS

A better control of bladder filling is recommended to minimize the number of fractions in which the bladder volume is lower than planned. Fiducial mark tracking with a displacement threshold of 5 mm in any direction is recommended to ensure that the prescribed dose criteria are met.

Tocilizumab reduces the risk of ICU admission and mortality in patients with SARS-CoV-2 infection

Objectives

In some patients the immune response triggered by SARS-CoV-2 is unbalanced, presenting an acute respiratory distress syndrome which in many cases requires intensive care unit (ICU) admission. The limitation of ICU beds has been one of the major burdens in the management around the world; therefore, clinical strategies to avoid ICU admission are needed. We aimed to describe the influence of tocilizumab on the need of transfer to ICU or death in non-critically ill patients.

Material and methods

A retrospective study of 171 patients with SARS-CoV-2 infection that did not qualify as requiring transfer to ICU during the first 24h after admission to a conventional ward, were included. The criteria to receive tocilizumab was radiological impairment, oxygen demand or an increasing of inflammatory parameters, however, the ultimate decision was left to the attending physician judgement. The primary outcome was the need of ICU admission or death whichever came first.

Results

A total of 77 patients received tocilizumab and 94 did not. The tocilizumab group had less ICU admissions (10.3% vs. 27.6%, P=0.005) and need of invasive ventilation (0 vs 13.8%, P=0.001). In the multivariable analysis, tocilizumab remained as a protective variable (OR: 0.03, CI 95%: 0.007-0.1, P=0.0001) of ICU admission or death.

Conclusions

Tocilizumab in early stages of the inflammatory flare could reduce an important number of ICU admissions and mechanical ventilation. The mortality rate of 10.3% among patients receiving tocilizumab appears to be lower than other reports. This is a non-randomized study and the results should be interpreted with caution.

The Ω-3 fatty acid docosahexaenoic acid selectively induces apoptosis in tumor-derived cells and suppress tumor growth in gastric cancer

Despite current achievements and innovations in cancer treatment, conventional chemotherapy has several limitations, such as unsatisfactory long-term survival, cancer drug resistance and toxicity against non-tumoral cells. In the search for safer therapeutic alternatives, docosahexaenoic acid (DHA) has shown promising effects inhibiting tumor growth without significant side effects in several types of cancer, but in gastric cancer (GC) its effects have not been completely described. In this study, we characterized the effects of DHA in GC using in vivo and in vitro models. Among all of the evaluated Ω-3 and Ω-6 fatty acids, DHA showed the highest antiproliferative potency and selectivity against the GC-derived cell line AGS. 10-100 μM DHA decreased AGS cell viability in a concentration-dependent manner but had no effect on non-tumoral GES-1 cells. To evaluate if the effects of DHA were due to apoptosis induction, cells were stained with Annexin V-PI, observing that 75 and 100 μM DHA increased apoptosis in AGS, but not in GES-1 cells. Additionally, levels of several proapoptotic and antiapoptotic regulators were assessed by qPCR, western blot and activity assays, showing similar results. In order to evaluate DHA efficacy in vivo, xenografts in an immunodeficient mouse model (BALB/cNOD-SCID) were used. In these experiments, DHA treatment for six weeks consistently reduced subcutaneous tumor size, ascitic fluid volume and liver metastasis. In summary, we found that DHA has a selective antiproliferative effect on GC, being this effect driven by apoptosis induction. Our investigation provides promising features for DHA as potential therapeutic agent in GC.

Real-life use of remdesivir in hospitalized patients with COVID-19

Objective

Controversial results on remdesivir efficacy have been reported. We aimed to report our real-life experience with the use of remdesivir from its availability in Spain.

Methods

We performed a descriptive study of all patients admitted for ≥48 hours with confirmed COVID-19 who received remdesivir between the 1st of July and the 30th of September 2020.

Results

A total of 123 patients out of 242 admitted with COVID-19 at our hospital (50.8%) received remdesivir. Median age was 58 years, 61% were males and 56.9 % received at least one anti-inflammatory treatment. No adverse events requiring remdesivir discontinuation were reported. The need of intensive care unit admission, mechanical ventilation and 30-days mortality were 19.5%, 7.3% and 4.1%, respectively.

Conclusion

In our real-life experience, the use of remdesivir in hospitalized patients with COVID-19 was associated with a low mortality rate and good safety profile.

Stereospecific Inhibition of Ethanol Potentiation on Glycine Receptor by M554 Stereoisomers

Blocking the interaction between the Gβγ protein and the glycine receptor (GlyR) has emerged as a promising pharmacological strategy to treat acute alcohol intoxication by inhibiting ethanol potentiation on GlyR. M554 is a recently discovered small molecule capable of binding to Gβγ with potent in vitro and in vivo inhibitory activity. This compound has been tested as a mixture of diastereomers, and no information is available concerning the stereospecific activity of each species, which is critical to pursue efforts on lead optimization and drug development. In this work, we explored the differential activity of four M554 stereoisomers by in silico molecular dynamics simulations and electrophysiological experiments. Our results revealed that the (R,R)-M554 stereoisomer is a promising lead compound that inhibits ethanol potentiation of GlyR.

Patient characteristics, clinical course and factors associated to ICU mortality in critically ill patients infected with SARS-CoV-2 in Spain: A prospective, cohort, multicentre study

Background

The clinical course of COVID-19 critically ill patients, during their admission in the intensive care unit (UCI), including medical and infectious complications and support therapies, as well as their association with in-ICU mortality has not been fully reported.

Objective

This study aimed to describe clinical characteristics and clinical course of ICU COVID-19 patients, and to determine risk factors for ICU mortality of COVID-19 patients.

Methods

Prospective, multicentre, cohort study that enrolled critically ill COVID-19 patients admitted into 30 ICUs from Spain and Andorra. Consecutive patients from March 12th to May 26th, 2020 were enrolled if they had died or were discharged from ICU during the study period. Demographics, symptoms, vital signs, laboratory markers, supportive therapies, pharmacological treatments, medical and infectious complications were reported and compared between deceased and discharged patients.

Results

A total of 663 patients were included. Overall ICU mortality was 31% (203 patients). At ICU admission non-survivors were more hypoxemic [SpO₂ with non-rebreather mask, 90 (IQR 83–93) vs 91 (IQR 87–94); p < 0.001] and with higher sequential organ failure assessment score [SOFA, 7 (IQR 5–9) vs 4 (IQR 3–7); p < 0.001]. Complications were more frequent in non-survivors: acute respiratory distress syndrome (ARDS) (95% vs 89%; p = 0.009), acute kidney injury (AKI) (58% vs 24%; p < 10⁻¹⁶), shock (42% vs 14%; p < 10⁻¹³), and arrhythmias (24% vs 11%; p < 10⁻⁴). Respiratory super-infection, bloodstream infection and septic shock were higher in non-survivors (33% vs 25%; p = 0.03, 33% vs 23%; p = 0.01 and 15% vs 3%, p = 10⁻⁷), respectively. The multivariable regression model showed that age was associated with mortality, with every year increasing risk-of-death by 1% (95%CI: 1–10, p = 0.014). Each 5-point increase in APACHE II independently predicted mortality [OR: 1.508 (1.081, 2.104), p = 0.015]. Patients with AKI [OR: 2.468 (1.628, 3.741), p < 10⁻⁴)], cardiac arrest [OR: 11.099 (3.389, 36.353), p = 0.0001], and septic shock [OR: 3.224 (1.486, 6.994), p = 0.002] had an increased risk-of-death.

Conclusions

Older COVID-19 patients with higher APACHE II scores on admission, those who developed AKI grades II or III and/or septic shock during ICU stay had an increased risk-of-death. ICU mortality was 31%.

Local policy for managing the risk of the proliferation and spread of Legionella in the Girona area

Issue

The towns in the Girona area are mostly small (70% have fewer than 1.500 inhabitants) and employ few public health technicians. Difficulties exist in municipal facilities when it comes to carrying out self-assessment tests and fulfilling regulatory requirements.

Description

In 2009, Dipsalut designed a programme to offer support to local councils in the management and control of the sanitation of municipal facilities at risk of transmitting Legionella.

Main Objectives

To improve the control of the health risk, to ensure the technical capacitation of personnel and to achieve territorial equity in health protection. The programme methodology comprised: a service provision programme with structured actions, a network of public health stakeholders and an information system shared between the stakeholders. The programme includes the structural description of the facilities, the study of the risk factors for the proliferation and spread of Legionella, the drawing up of control plans based on the HACCP system, analyses to determine and quantify Legionella, preventive cleaning and disinfection, on-site advice for workers, and training courses.

Results

Regarding the improvement in the control of the health risk: - In 2019, 905 facilities were controlled in 105 towns. In the last 8 years, the refurbishment of 239 facilities has been carried out, involving a total investment of 2,075.857€.Reduction in the concentration of Legionella where more exhaustive sampling is carried out.

Regarding the technical capacitation of personnel: 2.012 people on courses and 10.121 people in visits on-site.

Lessons

Realising the importance of ensuring the co-responsibility of facility managers. Adapting actions to be carried out in facilities according to risk: the greater the risk, the greater the effort.

Key messages

The application of an area-wide programme improves facility risk management. Ensuring technical capacitation, incorporating improvements based on common experiences and optimising resources.

Patient characteristics, clinical course and factors associated to ICU mortality in critically ill patients infected with SARS-CoV-2 in Spain: A prospective, cohort, multicentre study

Antecedentes

No se ha reportado plenamente la evolución clínica de los pacientes críticos de COVID-19 durante su ingreso en la unidad de cuidados intensivos (UCI), incluyendo las complicaciones médicas e infecciosas y terapias de soporte, así como su asociación con la mortalidad en UCI.

Objetivo

El objetivo de este estudio es describir las características clínicas y la evolución de los pacientes ingresados en UCI por COVID-19 y determinar los factores de riesgo de la mortalidad en UCI de dichos pacientes.

Métodos

Estudio prospectivo, multicéntrico y de cohorte, que incluyó a los pacientes críticos de COVID-19 ingresados en 30 UCI de España y Andorra. Se incluyó a los pacientes consecutivos del 12 de marzo al 26 de mayo del 2020 si habían fallecido o habían recibido el alta de la UCI durante el periodo de estudio. Se reportaron los datos demográficos, los síntomas, los signos vitales, los marcadores de laboratorio, las terapias de soporte, terapias farmacológicas y las complicaciones médicas e infecciosas, realizándose una comparación entre los pacientes fallecidos y los pacientes dados de alta.

Resultados

Se incluyó a un total de 663 pacientes. La mortalidad general en UCI fue del 31% (203 pacientes). Al ingreso en UCI los no supervivientes eran más hipoxémicos (SpO₂ con mascarilla de no reinhalación, de 90 [RIC 83-93] vs. 91 [RIC 87-94]; p < 0,001] y con mayor puntuación en la escala SOFA-Evaluación de daño orgánico secuencial (SOFA, 7 [RIC 5-9] vs. 4 [RIC 3-7]; p <0,001]). Las complicaciones fueron más frecuentes en los no supervivientes: síndrome de distrés respiratorio agudo (SDRA) (95% vs. 89%; p = 0,009), insuficiencia renal aguda (IRA) (58% vs. 24%; p < 10^–6), shock (42% vs. 14%; p < 10^–13) y arritmias (24% vs. 11%; p < 10^–4). Las superinfecciones respiratorias, infecciones del torrente sanguíneo y los shock sépticos fueron más frecuentes en los no supervivientes (33% vs. 25%; p = 0,03, 33% vs. 23%; p = 0,01 y 15% vs. 3%, p = 10^–7, respectivamente). El modelo de regresión multivariable reflejó que la edad estaba asociada a la mortalidad y que cada año incrementaba el riesgo de muerte en un 1% (IC del 95%: 1-10, p = 0,014). Cada incremento de 5 puntos en la escala APACHE II predijo de manera independiente la mortalidad (odds ratio [OR]: 1,508 [1,081, 2,104], p = 0,015). Los pacientes con IRA (OR: 2,468 [1,628, 3,741], p < 10^–4)], paro cardiaco (OR: 11,099 [3,389, 36,353], p = 0,0001] y shock séptico [OR: 3,224 [1,486, 6,994], p= 0,002) tuvieron un riesgo de muerte incrementado.

Conclusiones

Los pacientes mayores de COVID-19 con puntuaciones APACHE II más altas al ingreso, que desarrollaron IRA en grados ii o iii o shock séptico durante la estancia en UCI tuvieron un riesgo de muerte incrementado. La mortalidad en UCI fue del 31%.

AB1150 ECONOMIC IMPACT ASSOCIATED TO BIOLOGICAL THERAPY / SYNTHETIC FAME OPTIMIZATION IN A COHORT OF PATIENTS WITH CHRONIC INFLAMMATORY RHEUMATIC DISEASES TREATED BY OBJECTIVES

Background:

Therapeutic decision-making for biologic-therapies/ synthetic FAME (BT/SD) dose optimization, should be based on optimal disease activity results according to a treatment strategy by objectives. The goal of BT optimization is to guarantee long-term effectiveness and safety, maximising economic savings

Objectives:

To evaluate BT optimization patterns in patients with rheumatic diseases (RD) and associated economic savings.

Methods:

An observational and prospective study, which included a cohort of patients with rheumatoid arthritis (RA), spondyloarthropathies (SA) and psoriatic arthritis (PsA) treated with BT from January 2014 to December 2019. BT optimization, achieved by reducing or prolonging the interval at least one dose, was indicated when patients have more than 6 months of treatment and are in clinical remission (DAS28 <2.6 for RA and PsA, and BASDAI<2 for SA) or minimal clinical activity (DAS28<3.2 for RA and PsA, and BASDAI<4 for SA).

Variables were described as frequencies and means. Diagnosis, BT (abatacept, adalimumab, apremilast, baricitinib, certolizumab, etanercept, golimumab, ixekizumab, secukinumab, tocilizumab, tofacitinib, and ustekinumab), dose regimens, total treatment duration, time on BT optimization (TO) and treatment costs were collected.

Cost savings were calculated per patient by comparing optimization treatment costs to conventional treatment and globally by comparing real cost to theoretical conventional doses cost.

Results:

A total of 260 patients were included in the study. Switching were observed in 32.7%. From all patients, 53% were candidates for BT optimization (according to diagnosis: 60.9% with RA, followed by 52.2% with SA and 43.4% with PsA)

A 40% of patients with BT optimization were treated with adalimumab and etanercept being also the most common BT used in RD treatment

BT optimization allowed a pharmaceutical saving of€ 177,539.40per year against the use of conventional therapy, resulting in a reduction of the total cost of€1,065,236.40in the last 6 years. The saving per patient / year was € 707.63 for RA; € 850,40 for SA and of €493,21 for the PsA.

Conclusion:

Therapeutic decision-making based on validated disease activity scales has allowed the BT optimization in approximately 53% of patients with RD.

BT optimization allowed a pharmaceutical saving of € 177,539.40 per year being higher in the SA (€ 850.40) followed by the RA (€ 707.63) and finally the PsA (€ 493.21)

The BT optimization allows to reduce costs maintaining the effectiveness and safety.

Disclosure of Interests:

None declared

THU0168 GESTATIONAL DESIRE AND CERTOLIZUMAB PEGOL IN PATIENTS WITH CHRONIC INFLAMMATORY RHEUMATIC DISEASE. PRELIMINARY RESULTS OF THE GESTAMAD COHORT

Background:

The use of biological therapies during pregnancy has been contraindicated since the beginning of the use of these drugs. In recent years several studies have demonstrated the minimal-to-no transfer of certolizumab pegol (CZP) to the placenta and breast milk, which has allowed its approval for use in pregnancy and breastfeeding if clinically necessary. However, there are no studies evaluating the use of CZP during this period in real life or the characteristics of this subgroup of patients.

Objectives:

To describe the profile of women of childbearing age diagnosed with chronic inflammatory rheumatic disease (CIRD): Rheumatoid Arthritis (RA), Psoriatic Arthritis (PsA) and axial Spondyloarthritis (axSpA), who initiate CZP by gestational desire using the GESTAMAD registry (multicenter study of women with chronic inflammatory rheumatic disease of childbearing age who are initiated on CPZ by gestational desire from the Madrid community).

Methods:

Prospective multicenter study that aims to know the characteristics of women of childbearing age diagnosed with CIRD and gestational desire to which CZP is initiated for this reason. The comorbidities of the patients such as hypertension, diabetes and cardiovascular disease were collected. Disease activity was measured by DAS28 using CRP in RA and PsA and BASDAI in axSpA. The present study presents preliminary data from the initial cohort and will be followed prospectively for 24 months to assess the efficacy and safety of the drug during pre-conception, pregnancy and lactation.

Results:

A total of 45 patients have been recruited in 6 Madrid hospitals from June to December 2019. Patients had a mean age of 35.9, (36.6 in RA, 35.2 in PA and 35.1 in SPA). Fifty-one percent had RA, 20.0 percent had PA and 28.8 percent had SPA. The mean disease duration for RA, PA and SPA was 9.5, 7.3 and 6.9 years, respectively. 48.9% of women were nulliparous. The abortion rate of patients diagnosed with spondyloarthropathy was upper of 25%. 33.3% of the patients had been treated with previous biologicals, with gestational desire/pregnancy being the reason for the change.

75.5% of the patients had been treated with synthetic disease modifying antirheumatic drugs (DMARD) previously. With regard to disease activity, the mean DAS 28 at the start of treatment was 4.5 in RA and 3.8 in PA and BASDAI 7.0 in axSPA.

In RA the highest values of CRP and ESR were found prior to initiation with CZP, but this difference was not statistically significant (p=0.644 and 0.605, respectively). 22.2% of patients had previous comorbidities.

Conclusion:

The mean age of patients with gestational desire in CIRD is high. Women diagnosed with PsA and axSpA have a high rate of previous abortions, upper than 25%. The duration of the disease is equally long at the time of manifesting gestational desire. The use of treatments such as CZP, compatible with pregnancy and lactation would allow a better control of inflammatory joint disease in this period of life, encouraging patients not to postpone their gestational desire.

Disclosure of Interests:

None declared

INFOMATAS multi-center systematic review and meta-analysis individual patient data of dynamic cerebral autoregulation in ischemic stroke

Rationale

Disturbances in dynamic cerebral autoregulation after ischemic stroke may have important implications for prognosis. Recent meta-analyses have been hampered by heterogeneity and small samples.

Aim and/or hypothesis

The aim of study is to undertake an individual patient data meta-analysis (IPD-MA) of dynamic cerebral autoregulation changes post-ischemic stroke and to determine a predictive model for outcome in ischemic stroke using information combined from dynamic cerebral autoregulation, clinical history, and neuroimaging.

Sample size estimates

To detect a change of 2% between categories in modified Rankin scale requires a sample size of ∼1500 patients with moderate to severe stroke, and a change of 1 in autoregulation index requires a sample size of 45 healthy individuals (powered at 80%, α = 0.05). Pooled estimates of mean and standard deviation derived from this study will be used to inform sample size calculations for adequately powered future dynamic cerebral autoregulation studies in ischemic stroke.

Methods and design

This is an IPD-MA as part of an international, multi-center collaboration (INFOMATAS) with three phases. Firstly, univariate analyses will be constructed for primary (modified Rankin scale) and secondary outcomes, with key co-variates and dynamic cerebral autoregulation parameters. Participants clustering from within studies will be accounted for with random effects. Secondly, dynamic cerebral autoregulation variables will be validated for diagnostic and prognostic accuracy in ischemic stroke using summary receiver operating characteristic curve analysis. Finally, the prognostic accuracy will be determined for four different models combining clinical history, neuroimaging, and dynamic cerebral autoregulation parameters.

Study outcome(s)

The outcomes for this study are to determine the relationship between clinical outcome, dynamic cerebral autoregulation changes, and baseline patient demographics, to determine the diagnostic and prognostic accuracy of dynamic cerebral autoregulation parameters, and to develop a prognostic model using dynamic cerebral autoregulation in ischemic stroke.

Discussion

This is the first international collaboration to use IPD-MA to determine prognostic models of dynamic cerebral autoregulation for patients with ischemic stroke.

CD8 infiltration is associated with disease control and tobacco exposure in intermediate-risk oropharyngeal cancer

Oropharyngeal squamous cell carcinoma (OPSCC) incidence is increasing at a nearly epidemic rate, largely driven by the human papillomavirus (HPV). Despite the generally favorable clinical outcomes of patients with HPV driven (HPV+) OPSCC, a significant subset of HPV tumors associated with tobacco exposure have diminished treatment response and worse survival. The tumor immune microenvironment (TIME) has been shown to be a critical driver of treatment response and oncologic outcomes in OPSCC generally and HPV+ OPSCC more specifically. However, the impact of tobacco exposure on the TIME in OPSCC patients remains unclear. We analyzed the relationship between TIME, tobacco exposure and clinical outcomes in OPSCC patients (n = 143) with extensive tobacco exposure (median pack-years = 40). P16 overexpression, a surrogate marker of HPV association, was a strong predictor of relapse-free (RFS) and overall survival (OS) (p < 0.001, p < 0.001 respectively) regardless of tobacco exposure and associated strongly with differential infiltration of the tumor by both CD3 and CD8 lymphocytes measured via immunohistochemistry (p < 001, p < 0.001 respectively). CD3 and CD8 infiltration was a strong predictor of RFS and OS and associated strongly with disease stage (AJCC 8th Edition Staging Manual). Tobacco exposure correlated significantly (p < 0.001) with decreased CD8 infiltration in p16+ OPSCC tumors. Our findings demonstrate that the HPV+ OPSCC clinical outcomes are strongly correlated with the TIME, which is potentially modulated by tobacco exposure. Immunomodulatory strategies targeting this disease in smokers must take into consideration the potential modifying effects of tobacco exposure on treatment effectiveness and clinical outcomes.

P4421Increased circulating levels of VCAM-1 correlate with left atrial remodeling in highly trained athletes

Introduction

Reports have shown increased risk of atrial fibrillation (AF) in athletes. Vascular cell adhesion molecule-1 (VCAM1) is associated with new onset AF in general population. VCAM1 and its relation with left atrial (LA) remodeling have not been investigated in athletes.

Purpose

To study VCAM1 and LA remodeling in marathon runners.

Methods

Study of 36 male marathon runners in the training period previous to race (42 km) and 18 sedentary controls with no risk factors. Athletes were divided in two groups according to highest training intensity reached (group 1, >100 km/week; group 2, 50–100 km/week). Previous to race in all subjects, VCAM1 serum levels were measured by ELISA and an echocardiogram was performed. In athletes, VCAM1 was measured immediately post-race. Wilcoxon and Spearman were used.

Results

See table. Group 1 showed a significant increment in VCAM1 post-race (651±350 to 905±373 ng/mL; p=0.002) as compared to group 2 with no increment (533±133 to 651±138 ng/mL; p=0.117). In athletes, a moderate correlation between LA volume and VCAM1 was found (rho: 0.483; p=0.007).

Baseline characteristics Group 1 (n=18) Group 2 (n=18) Controls (n=18) p value Age (years) 37±6 38±5 36±4 0.373 Heart rate (bpm) 53±8 57±7 69±6 * 0.001 Body surface area (m2) 1.8±0.1 1.8±0.1 1.9±0.1 0.075 LV diastolic diameter (mm) 49±5 48±5 46±4 0.404 LV systolic diameter (mm) 29±5 30±5 30±4 0.879 Septal wall (mm) 9.1±1.2† 8.2±1.1 8.1±0.8 0.005 Posterior wall (mm) 9.3±2.1† 8.5±1.2 7.6±0.8 0.001 Ejection fraction (%) 55±3 55±6 57±4 0.110 LV mass index (g/m2) 106±27† 78±18 58±11 0.001 LA volume (mL/m2) 42±8† 30±11 25±9 0.001 E wave (cm/sec) 78±13 84±12 77±15 0.217 A wave (cm/sec) 50±12 53±10 48±16 0.438 DT (msec) 233±65 229±65 221±66 0.184 VCAM1 (ng/mL) 651±350† 533±133 440±98 0.022 Mean ± SD. *p<0.05 vs group 1 and 2 post Kruskall-Wallis; †p<0.05 vs other groups post Kruskall-Wallis. LV, left ventricle; LA, left atrium; DT, deceleration time.

Conclusions

Most trained athletes had increased levels of VCAM1 as compared to controls and less trained athletes. They also showed an increment post-effort. VCAM1 is related to LA remodeling in athletes. VCAM1 could be a potential biomarker of AF in athletes which should be confirmed.

Acknowledgement/Funding

FONDECYT 1170963 (LG); FONDAP 15130011 (LG,SL)

Evidence of epistatic suppression of repeat fruiting in cultivated strawberry

BACKGROUND

Consumers purchase fresh strawberries all year long. Extending the fruiting season for new strawberry cultivars is a common breeding goal. Understanding the inheritance of repeat fruiting is key to improving breeding efficiency. Several independent research groups using multiple genotypes and analytic approaches have all identified a single genomic region in strawberry associated with repeat fruiting. Markers mapped to this region were used to evaluate breeding parents from the United States Department of Agriculture - Agricultural Research Service (USDA-ARS) strawberry breeding program at Beltsville, Maryland.

RESULTS

Markers mapped to repeat fruiting identified once-fruiting genotypes but not repeat-fruiting genotypes. Eleven of twenty-three breeding parents with repeat-fruiting marker profiles were actually once fruiting, indicating at least one additional locus acting epistatically to suppress repeat fruiting. Family segregation ratios could not be predicted reliably by the combined use of parental phenotypes and marker profiles, when using a single-gene model. Expected segregation ratios were calculated for all phenotypic and marker-profile combinations possible from the mapped locus combined with a hypothetical dominant or recessive suppressor locus. Segregation ratios specific to an epistatic suppressor acting on the mapped locus were observed in four families. The segregation ratios for two families were best explained by a dominant suppressor acting on the mapped locus, and, for the other two, by a recessive suppressor. Not all of the observed ratios could be explained by one model or the other, and when multiple families with a common parent were compared, there was no predicted genotype for the common parent that would lead to all of the observed segregation ratios.

CONCLUSIONS

Considering all lines of evidence in this study and others, repeat-fruiting in commercial strawberry is controlled primarily by a dominant allele at a single locus, previously mapped by multiple groups. At least two additional genes, one dominant and one recessive, exist that act epistatically to suppress repeat fruiting. Environmental effects and/or incomplete penetrance likely affect phenotype through the suppressor loci, rather than the primary mapped locus. One of the dominant suppressors acts only in the first year, the year the plant is germinated from seed, and not after the plant has experienced a winter.

Differential Effects of Purinergic Signaling in Gastric Cancer-Derived Cells Through P2Y and P2X Receptors

Gastric cancer (GC) is the one of the most prevalent cancers and one of the leading causes of cancer-induced deaths. Previously, we found that the expression of purinergic P2Y₂ receptor (P2Y₂R) is increased in GC samples as compared to adjacent healthy mucosa taken from GC-diagnosed patients. In this work, we studied in detail purinergic signaling in the gastric adenocarcinoma-derived cell lines: AGS, MKN-45, and MKN-74, and compared them to a nontumoral epithelial cell line: GES-1. In GC-derived cells, we detected the expression of several purinergic receptors, and found important differences as compared to GES-1 cells. Functional studies revealed a strong contribution of P2Y₂Rs in intracellular calcium increases, elicited by adenosine-triphosphate (ATP), uridine-triphosphate (UTP), and the P2Y₂R agonist MRS2768. Responses were preserved in the absence of extracellular calcium and inhibited by P2Y₂R antagonists. In GES-1 cells, ATP and UTP induced similar responses and the combination of P2X and P2Y receptor antagonists was able to block them. Proliferation studies showed that ATP regulates AGS and MKN-74 cells in a biphasic manner, increasing cell proliferation at 10–100 μM, but inhibiting at 300 μM ATP. On the other hand, 1–300 μM UTP, a P2Y₂R agonist, increased concentration-dependent cell proliferation. The effects of UTP and ATP were prevented by both wide-range and specific purinergic antagonists. In contrast, in GES-1 cells ATP only decreased cell proliferation in a concentration-dependent manner, and UTP had no effect. Notably, the isolated application of purinergic antagonists was sufficient to change the basal proliferation of AGS cells, indicating that nucleotides released by the cells can act as paracrine/autocrine signals. Finally, in tumor-derived biopsies, we found an increase of P2Y₂R and a decrease in P2X4R expression; however, we found high variability between seven different biopsies and their respective adjacent healthy gastric mucosa. Even so, we found a correlation between the expression levels of P2Y₂R and P2X4R and survival rates of GC patients. Taken together, these results demonstrate the involvement of different purinergic receptors and signaling in GC, and the pattern of expression changes in tumoral cells, and this change likely directs ATP and nucleotide signaling from antiproliferative effects in healthy tissues to proliferative effects in cancer.

Characterization and simulation of noise in PET images reconstructed with OSEM: Development of a method for the generation of synthetic images

INTRODUCTION

The goals of the study are to characterize imaging properties in 2D PET images reconstructed with the iterative algorithm ordered-subset expectation maximization (OSEM) and to propose a new method for the generation of synthetic images.

MATERIAL AND METHODS

The noise is analyzed in terms of its magnitude, spatial correlation, and spectral distribution through standard deviation, autocorrelation function, and noise power spectrum (NPS), respectively. Their variations with position and activity level are also analyzed. This noise analysis is based on phantom images acquired from ¹⁸F uniform distributions. Experimental recovery coefficients of hot spheres in different backgrounds are employed to study the spatial resolution of the system through point spread function (PSF). The NPS and PSF functions provide the baseline for the proposed simulation method: convolution with PSF as kernel and noise addition from NPS.

RESULTS

The noise spectral analysis shows that the main contribution is of random nature. It is also proven that attenuation correction does not alter noise texture but it modifies its magnitude. Finally, synthetic images of 2 phantoms, one of them an anatomical brain, are quantitatively compared with experimental images showing a good agreement in terms of pixel values and pixel correlations. Thus, the contrast to noise ratio for the biggest sphere in the NEMA IEC phantom is 10.7 for the synthetic image and 8.8 for the experimental image.

CONCLUSIONS

The properties of the analyzed OSEM-PET images can be described by NPS and PSF functions. Synthetic images, even anatomical ones, are successfully generated by the proposed method based on the NPS and PSF.

Opposing Roles of Calcium and Intracellular ATP on Gating of the Purinergic P2X2 Receptor Channel

P2X2 receptors (P2X2R) exhibit a slow desensitization during the initial ATP application and a progressive, calcium-dependent increase in rates of desensitization during repetitive stimulation. This pattern is observed in whole-cell recordings from cells expressing recombinant and native P2X2R. However, desensitization is not observed in perforated-patched cells and in two-electrode voltage clamped oocytes. Addition of ATP, but not ATPγS or GTP, in the pipette solution also abolishes progressive desensitization, whereas intracellular injection of apyrase facilitates receptor desensitization. Experiments with injection of alkaline phosphatase or addition of staurosporine and ATP in the intracellular solution suggest a role for a phosphorylation-dephosphorylation in receptor desensitization. Mutation of residues that are potential phosphorylation sites identified a critical role of the S363 residue in the intracellular ATP action. These findings indicate that intracellular calcium and ATP have opposing effects on P2X2R gating: calcium allosterically facilitates receptor desensitization and ATP covalently prevents the action of calcium. Single cell measurements further revealed that intracellular calcium stays elevated after washout in P2X2R-expressing cells and the blockade of mitochondrial sodium/calcium exchanger lowers calcium concentrations during washout periods to basal levels, suggesting a role of mitochondria in this process. Therefore, the metabolic state of the cell can influence P2X2R gating.