Biological and Genetic Determinants of Glycolysis: Phosphofructokinase Isoforms Boost Energy Status of Stored Red Blood Cells and Transfusion Outcomes

Mature red blood cells (RBCs) lack mitochondria, and thus exclusively rely on glycolysis to generate adenosine triphosphate (ATP) during aging in vivo and during storage in vitro in the blood bank. Here we identify an association between blood donor age, sex, ethnicity and end-of-storage levels of glycolytic metabolites in 13,029 volunteers from the Recipient Epidemiology and Donor Evaluation Study. Associations were also observed to ancestry-specific genetic polymorphisms in regions encoding phosphofructokinase 1, platelet (which we detected in mature RBCs), hexokinase 1, and ADP-ribosyl cyclase 1 and 2 (CD38/BST1). Gene-metabolite associations were validated in fresh and stored RBCs from 525 Diversity Outbred mice, and via multi-omics characterization of 1,929 samples from 643 human RBC units during storage. ATP levels, breakdown, and deamination into hypoxanthine were associated with hemolysis in vitro and in vivo, both in healthy autologous transfusion recipients and in 5,816 critically ill patients receiving heterologous transfusions.

Highlights

Blood donor age and sex affect glycolysis in stored RBCs from 13,029 volunteers;Ancestry, genetic polymorphisms in PFKP, HK1, CD38/BST1 influence RBC glycolysis;RBC PFKP boosts glycolytic fluxes when ATP is low, such as in stored RBCs;ATP and hypoxanthine are biomarkers of hemolysis in vitro and in vivo.

Graphical abstract

Genetic regulation of carnitine metabolism controls lipid damage repair and aging RBC hemolysis in vivo and in vitro

Recent large-scale multi-omics studies suggest that genetic factors influence the chemical individuality of donated blood. To examine this concept, we performed metabolomics analyses of 643 blood units from volunteers who donated units of packed red blood cells (RBCs) on two separate occasions. These analyses identified carnitine metabolism as the most reproducible pathway across multiple donations from the same donor. We also measured L-carnitine and acyl-carnitines in 13,091 packed RBC units from donors in the Recipient Epidemiology and Donor Evaluation (REDS) study. Genome wide association studies against 879,000 polymorphisms identified critical genetic factors contributing to inter-donor heterogeneity in end-of-storage carnitine levels, including common non-synonymous polymorphisms in genes encoding carnitine transporters (SLC22A16, SLC22A5, SLC16A9); carnitine synthesis (FLVCR1, MTDH) and metabolism (CPT1A, CPT2, CRAT, ACSS2), and carnitine-dependent repair of lipids oxidized by ALOX5. Significant associations between genetic polymorphisms on SLC22 transporters and carnitine pools in stored RBCs were validated in 525 Diversity Outbred mice. Donors carrying two alleles of the rs12210538 SLC22A16 Single Nucleotide Polymorphism exhibited the lowest L-carnitine levels, significant elevations of in vitro hemolysis, and the highest degree of vesiculation, accompanied by increases in lipid peroxidation markers. Separation of RBCs by age, via in vivo biotinylation in mice and Percoll density gradients of human RBCs, showed age-dependent depletions of L-carnitine and acyl-carnitine pools, accompanied by progressive failure of the reacylation process following chemically induced membrane lipid damage. Supplementation of stored murine RBCs with L-carnitine boosted post-transfusion recovery, suggesting this could represent a viable strategy to improve RBC storage quality.

Regulation of kynurenine metabolism by blood donor genetics and biology impacts red cell hemolysis in vitro and in vivo

ABSTRACT

In the field of transfusion medicine, the clinical relevance of the metabolic markers of the red blood cell (RBC) storage lesion is incompletely understood. Here, we performed metabolomics of RBC units from 643 donors enrolled in the Recipient Epidemiology and Donor Evaluation Study, REDS RBC Omics. These units were tested on storage days 10, 23, and 42 for a total of 1929 samples and also characterized for end-of-storage hemolytic propensity after oxidative and osmotic insults. Our results indicate that the metabolic markers of the storage lesion poorly correlated with hemolytic propensity. In contrast, kynurenine was not affected by storage duration and was identified as the top predictor of osmotic fragility. RBC kynurenine levels were affected by donor age and body mass index and were reproducible within the same donor across multiple donations from 2 to 12 months apart. To delve into the genetic underpinnings of kynurenine levels in stored RBCs, we thus tested kynurenine levels in stored RBCs on day 42 from 13 091 donors from the REDS RBC Omics study, a population that was also genotyped for 879 000 single nucleotide polymorphisms. Through a metabolite quantitative trait loci analysis, we identified polymorphisms in SLC7A5, ATXN2, and a series of rate-limiting enzymes (eg, kynurenine monooxygenase, indoleamine 2,3-dioxygenase, and tryptophan dioxygenase) in the kynurenine pathway as critical factors affecting RBC kynurenine levels. By interrogating a donor-recipient linkage vein-to-vein database, we then report that SLC7A5 polymorphisms are also associated with changes in hemoglobin and bilirubin levels, suggestive of in vivo hemolysis in 4470 individuals who were critically ill and receiving single-unit transfusions.

Modeling Red Blood Cell Metabolism in the Omics Era

Red blood cells (RBCs) are abundant (more than 80% of the total cells in the human body), yet relatively simple, as they lack nuclei and organelles, including mitochondria. Since the earliest days of biochemistry, the accessibility of blood and RBCs made them an ideal matrix for the characterization of metabolism. Because of this, investigations into RBC metabolism are of extreme relevance for research and diagnostic purposes in scientific and clinical endeavors. The relative simplicity of RBCs has made them an eligible model for the development of reconstruction maps of eukaryotic cell metabolism since the early days of systems biology. Computational models hold the potential to deepen knowledge of RBC metabolism, but also and foremost to predict in silico RBC metabolic behaviors in response to environmental stimuli. Here, we review now classic concepts on RBC metabolism, prior work in systems biology of unicellular organisms, and how this work paved the way for the development of reconstruction models of RBC metabolism. Translationally, we discuss how the fields of metabolomics and systems biology have generated evidence to advance our understanding of the RBC storage lesion, a process of decline in storage quality that impacts over a hundred million blood units transfused every year.

The Effect of beta-blockade on objectively measured physical fitness in patients with abdominal aortic aneurysms--A blinded interventional study

BACKGROUND

Perioperative beta-blockade is widely used, especially before vascular surgery; however, its impact on exercise performance assessed using cardiopulmonary exercise testing (CPET) in this group is unknown. We hypothesized that beta-blocker therapy would significantly improve CPET-derived physical fitness in this group.

METHODS

We recruited patients with abdominal aortic aneurysms (AAA) of <5.5 cm under surveillance. All patients underwent CPET on and off beta-blockers. Patients routinely prescribed beta-blockers underwent a first CPET on medication. Beta-blockers were stopped for one week before a second CPET. Patients not routinely taking beta-blockers underwent the first CPET off treatment, then performed a second CPET after commencement of bisoprolol for at least 48 h. Oxygen uptake (.VO2) at estimated lactate threshold and .VO2 at peak were primary outcome variables. A linear mixed-effects model was fitted to investigate any difference in adjusted CPET variables on and off beta-blockers.

RESULTS

Forty-eight patients completed the study. No difference was observed in .VO2 at estimated lactate threshold and .VO2 at peak; however, a significant decrease in .VE/.VCO2 at estimated lactate threshold and peak, an increase in workload at estimated lactate threshold., O2 pulse and heart rate both at estimated lactate threshold and peak was found with beta-blockers. Patients taking beta-blockers routinely (chronic group) had worse exercise performance (lower .VO2 ).

CONCLUSIONS

Beta blockade has a significant impact on CPET-derived exercise performance, albeit without changing .VO2 at estimated lactate threshold and.VO2 at peak. This supports performance of preoperative CPET on or off beta-blockers depending on local perioperative practice.

CLINICAL TRIAL REGISTRATION

NCT 02106286.

Psychosocial benefits of sentinel lymph node biopsy in the management of cutaneous malignant melanoma

Lymphoscintigraphy combined with sentinel lymph node biopsy has become a powerful and sensitive tool in establishing nodal spread in cutaneous melanoma, as well as in breast and other cancers. Although the technique is reliable and validated, there is, as yet, no proven clinical benefit. A suggested benefit of sentinel lymph node biopsy is that a negative biopsy may decrease the psychological morbidity associated with malignancy by reassuring the patient that he or she has localised disease. We studied a group of patients with cutaneous melanoma who underwent sentinel lymph node biopsy, and found that although they did gain some psychosocial benefit from the procedure, this was short term and they were still significantly concerned about their disease status.

Clinical reasoning of an experienced physiotherapist: insight into clinician decision-making regarding low back pain

BACKGROUND AND PURPOSE

Investigation of the clinical reasoning skills of experienced clinicians provides insight into decision-making in the practice of physiotherapy. The purpose of the present study was to analyse the clinical reasoning skills of an experienced physiotherapist during her assessment and treatment of clients with low back pain.

METHOD

Deconstruction of the physiotherapist's reasoning process was accomplished through observation of encounters between her and each of six patient subjects. Reconstruction and analysis of the physiotherapist's decision-making process was performed through retrospective interviews and reflective analysis of her clinical reasoning during each encounter.

RESULTS

A working model of the physiotherapist's clinical reasoning was created from an integration of theoretical elements in the literature and the data. Through analysis of this framework, two core dimensions of her clinical reasoning were revealed: the influence of clinical experience and the influence of advanced training in a specific philosophy of treating the spine.

CONCLUSIONS

The construction of these themes has contributed to the growing understanding of clinical reasoning strategies and skills used in orthopaedic physical therapy practice. Detailed description of the physiotherapist's reasoning process provides more meaningful understanding of physiotherapy treatments. In this case the physiotherapist employed a pattern recognition strategy and forward reasoning process in making a diagnosis. Further research is necessary to expand knowledge on the development of clinical reasoning skills.

Satisfaction with in-patient psychiatric services. Relationship to patient and treatment factors

BACKGROUND

There is growing concern about patient satisfaction with psychiatric in-patient provision. This paper measures satisfaction in psychiatric in-patients and its relationships with patient characteristics and ward experiences.

AIMS

To: (a) measure overall in-patient satisfaction; (b) examine its relationship to in-patient experiences; and (c) examine its relationship to patient factors.

METHOD

Four hundred and thirty-three patients were interviewed. Satisfaction was assessed by a single quest on, the Client Satisfaction Questionnaire (CSQ) and by a semistructured interview.

RESULTS

Over three-quarters of the patients were satisfied, but two-thirds reported adverse events. Females, younger patients and those detained were more dissatisfied. No significant relationship was found for ethnic group. Results were similar in the mental hospital and district general hospital.

CONCLUSIONS

There remain problems with satisfaction scales. Qualitative approaches to examine patients' experiences in hospital and the causes of dissatisfaction are recommended.

Gender issues in the management of multi-impulsive bulimia: a case-study

We describe the management of multi-impulsive bulimia nervosa in a 27-year-old man. Inpatient treatment was attempted using a standardized focal-interpretative (psychodynamic) and cognitive-behavioral approach, with an emphasis on ward milieu. The value of this approach has been proved for female patients in the past. To our knowledge, this is the first report of its usage for a male with multi-impulsive bulimia, and the problems encountered highlight the impact of gender on behavioral symptoms, ward culture, and the predominantly female patient group.

A perfusion system for in vitro measurement of human cilia beat frequency

We have designed and built a perfusion system and perfusion chamber to allow investigation of the effects of anaesthetic agents on human cilia in vitro. Using this system, samples of human respiratory cilia can be maintained in a stable and controlled environment for several hours. We measured cilia beat frequency of nasal respiratory epithelium from 10 healthy volunteers; cilia beat frequency was constant over a 4-h period, and measurements were found to be in good agreement with previously published work [1]. In a separate study we investigated the effect of a sleep dose of propofol on cilia beat frequency in samples from six patients undergoing minor surgery; samples were obtained before and immediately after induction of anaesthesia with propofol 2-3 mg kg-1. There was no statistically significant difference in cilia beat frequency between data obtained before and after induction with propofol.

Measurement of the sensitivity of upper airway reflexes

We describe a method for measurement of the sensitivity of upper airway reflexes. The technique is based upon delivery of an irritant chemical stimulus (dilute concentrations of ammonia vapour) to the upper airway. The technique is non-invasive and uses equipment which is portable, allowing measurements to be made in the clinical environment.

Comparison of the combined effects of atropine and neostigmine with atropine and edrophonium on the lower oesophageal sphincter

In two groups (n = 11) of healthy patients, we have measured gastric, lower oesophageal and barrier pressures before and after antagonism of neuromuscular block during anaesthesia with nitrous oxide and isoflurane. In one group, atropine 1.2 mg and neostigmine 2.5 mg were given and in the second group atropine 0.6 mg with edrophonium 1 mg/kg. One minute after administration of the reversal agents, there was a significantly greater reduction in barrier pressures in the neostigmine and atropine group than in the edrophonium and atropine group, but subsequently, there was no significant difference between the two groups. We conclude that there is no clinical difference between the two reversal mixtures in terms of the risk of regurgitation in the immediate period after reversal.

The effect of the Trendelenburg position on lower oesophageal sphincter tone

Measurements were made of gastric, lower oesophageal and barrier pressures in the supine, moderate and steep Trendelenburg positions in 10 healthy female patients during balanced anaesthesia. Adoption of the Trendelenburg position resulted in no significant changes in any measurement, with the exception of a small increase (0.1 kPa) in intragastric pressure in the steep head-down position. We conclude that the steep Trendelenburg position should not predispose to regurgitation in healthy patients.

Cervical spine dislocations with unilateral facet interlocking

From this series it would appear that 17-5 per cent (92 cases from a series of 525) of all cervical lesions associated with spinal cord trauma are dislocations with unilateral facet interlocking. This type of dislocation is often missed but nevertheless with suitable radiographs the very characteristic radiographic appearances are well demonstrated. Two-thirds of these cases are initially incomplete neurological lesions which carry a good neurological prognosis directly proportional to the degree of initial neurological escape. A significant percentage reduce easily on traction alone--51 per cent of the entire series. Taking the year 1973, with 17 cases on a standardised regime of treatment and disregarding the two cases reduced by immediate manipulation under general anaesthesia, ten out of 15 (66 per cent) reduced easily on skull traction alone-possibly a more realistic figure.