Development and validation of a predictive model to determine the level of care in patients confirmed with COVID-19.

BACKGROUND: The COVID-19 pandemic has imposed significant challenges on hospital capacity. While mitigating unnecessary crowding in hospitals is favourable to reduce viral transmission, it is more important to prevent readmissions with impaired clinical status due to initially inappropriate level of care. A validated predictive tool to assist clinical decisions for patient triage and facilitate remote stratification is of critical importance. METHODS: We conducted a retrospective study in patients with confirmed COVID-19 stratified into two levels of care, namely ambulatory care and hospitalization. Data on socio-demographics, clinical symptoms, and comorbidities were collected during the first (N = 571) and second waves (N = 174) of the pandemic in Belgium (2 March to 6 December 2020). Univariate and multivariate logistic regressions were performed to build and validate the prediction model. RESULTS: Significant predictors of hospitalization were old age (OR = 1.08, 95%CI:1.06-1.10), male gender (OR = 4.41, 95%CI: 2.58-7.52), dyspnoea (OR 6.11, 95%CI: 3.58-10.45), dry cough (OR 2.89, 95%CI: 1.54-5.41), wet cough (OR 4.62, 95%CI: 1.93-11.06), hypertension (OR 2.20, 95%CI: 1.17-4.16) and renal failure (OR 5.39, 95%CI: 1.00-29.00). Rhinorrhea (OR 0.43, 95%CI: 0.24-0.79) and headache (OR 0.36, 95%CI: 0.20-0.65) were negatively associated with hospitalization. A receiver operating characteristic (ROC) curve was constructed and the area under the ROC curve was 0.931 (95% CI: 0.910-0.953) for the prediction model (first wave) and 0.895 (95% CI: 0.833-0.957) for the validated dataset (second wave). CONCLUSION: With a good discriminating power, the prediction model might identify patients who require ambulatory care or hospitalization and support clinical decisions by Emergency Department staff and general practitioners.

Clinical decision support tool for diagnosis of COVID-19 in hospitals.

BACKGROUND: The coronavirus infectious disease 19 (COVID-19) pandemic has resulted in significant morbidities, severe acute respiratory failures and subsequently emergency departments' (EDs) overcrowding in a context of insufficient laboratory testing capacities. The development of decision support tools for real-time clinical diagnosis of COVID-19 is of prime importance to assist patients' triage and allocate resources for patients at risk. METHODS AND PRINCIPAL FINDINGS: From March 2 to June 15, 2020, clinical patterns of COVID-19 suspected patients at admission to the EDs of Liège University Hospital, consisting in the recording of eleven symptoms (i.e. dyspnoea, chest pain, rhinorrhoea, sore throat, dry cough, wet cough, diarrhoea, headache, myalgia, fever and anosmia) plus age and gender, were investigated during the first COVID-19 pandemic wave. Indeed, 573 SARS-CoV-2 cases confirmed by qRT-PCR before mid-June 2020, and 1579 suspected cases that were subsequently determined to be qRT-PCR negative for the detection of SARS-CoV-2 were enrolled in this study. Using multivariate binary logistic regression, two most relevant symptoms of COVID-19 were identified in addition of the age of the patient, i.e. fever (odds ratio [OR] = 3.66; 95% CI: 2.97-4.50), dry cough (OR = 1.71; 95% CI: 1.39-2.12), and patients older than 56.5 y (OR = 2.07; 95% CI: 1.67-2.58). Two additional symptoms (chest pain and sore throat) appeared significantly less associated to the confirmed COVID-19 cases with the same OR = 0.73 (95% CI: 0.56-0.94). An overall pondered (by OR) score (OPS) was calculated using all significant predictors. A receiver operating characteristic (ROC) curve was generated and the area under the ROC curve was 0.71 (95% CI: 0.68-0.73) rendering the use of the OPS to discriminate COVID-19 confirmed and unconfirmed patients. The main predictors were confirmed using both sensitivity analysis and classification tree analysis. Interestingly, a significant negative correlation was observed between the OPS and the cycle threshold (Ct values) of the qRT-PCR. CONCLUSION AND MAIN SIGNIFICANCE: The proposed approach allows for the use of an interactive and adaptive clinical decision support tool. Using the clinical algorithm developed, a web-based user-interface was created to help nurses and clinicians from EDs with the triage of patients during the second COVID-19 wave.

Extending Abdominal Aortic Aneurysm Detection to Older Age Groups: Preliminary Results from the Liège Screening Programme.

BACKGROUND: There is evident benefit in terms of reduced aneurysm-related mortality from screening programs of abdominal aortic aneurysm (AAA) in men aged 65 years and more. Recent studies in the United Kingdom and Sweden have shown a decline of the prevalence of AAA in the general population. Current screening policies (e.g., men aged 65-74 years), however, do not account for aging and increased life expectancy of Western populations. This study investigated AAA detection by extending the target population to older age groups (75-85 years). METHODS: AAA screening was conducted in the County of Chaudfontaine (Liège, Belgium) on the population of elderly (n = 3,054). The participation rate was 36%. The 1,101 participants (722 men aged 65-85 years and 379 women aged 74-85 years) were examined by ultrasound scan. AAA was defined as an infrarenal aortic outer-outer diameter of at least 3 cm. Demographics, clinical parameters, and risk factors were also recorded. AAA prevalence was estimated, and patients with and without AAA were compared by logistic regression. RESULTS: The overall AAA prevalence was 3.6% (n = 40). In female participants, AAA prevalence was low (1.3%). In men, it amounted 2.7% in the 65-74 age group but rose to 7.3% in the age-extended group (75-85 years). Further in addition to age, height, current smoking, history of coronary artery disease, hypercholesterolemia, peripheral artery disease of the lower limbs, and varicose veins were significantly associated with the presence of AAA. CONCLUSIONS: These preliminary findings, based on a representative sample of the elderly population of the Liège region, support the idea that current AAA screening policies should be updated to cover an increasingly aging population. The presence of varicose veins as a potential risk factor for AAA should also be considered during screening.

An alternative role of FoF1-ATP synthase in Escherichia coli: synthesis of thiamine triphosphate.

In E. coli, thiamine triphosphate (ThTP), a putative signaling molecule, transiently accumulates in response to amino acid starvation. This accumulation requires the presence of an energy substrate yielding pyruvate. Here we show that in intact bacteria ThTP is synthesized from free thiamine diphosphate (ThDP) and P(i), the reaction being energized by the proton-motive force (Δp) generated by the respiratory chain. ThTP production is suppressed in strains carrying mutations in F(1) or a deletion of the atp operon. Transformation with a plasmid encoding the whole atp operon fully restored ThTP production, highlighting the requirement for F(o)F(1)-ATP synthase in ThTP synthesis. Our results show that, under specific conditions of nutritional downshift, F(o)F(1)-ATP synthase catalyzes the synthesis of ThTP, rather than ATP, through a highly regulated process requiring pyruvate oxidation. Moreover, this chemiosmotic mechanism for ThTP production is conserved from E. coli to mammalian brain mitochondria.

Thiamine status in humans and content of phosphorylated thiamine derivatives in biopsies and cultured cells.

BACKGROUND: Thiamine (vitamin B1) is an essential molecule for all life forms because thiamine diphosphate (ThDP) is an indispensable cofactor for oxidative energy metabolism. The less abundant thiamine monophosphate (ThMP), thiamine triphosphate (ThTP) and adenosine thiamine triphosphate (AThTP), present in many organisms, may have still unidentified physiological functions. Diseases linked to thiamine deficiency (polyneuritis, Wernicke-Korsakoff syndrome) remain frequent among alcohol abusers and other risk populations. This is the first comprehensive study on the distribution of thiamine derivatives in human biopsies, body fluids and cell lines. METHODOLOGY AND PRINCIPAL FINDINGS: Thiamine derivatives were determined by HPLC. In human tissues, the total thiamine content is lower than in other animal species. ThDP is the major thiamine compound and tissue levels decrease at high age. In semen, ThDP content correlates with the concentration of spermatozoa but not with their motility. The proportion of ThTP is higher in humans than in rodents, probably because of a lower 25-kDa ThTPase activity. The expression and activity of this enzyme seems to correlate with the degree of cell differentiation. ThTP was present in nearly all brain and muscle samples and in ∼60% of other tissue samples, in particular fetal tissue and cultured cells. A low ([ThTP]+[ThMP])/([Thiamine]+[ThMP]) ratio was found in cardiovascular tissues of patients with cardiac insufficiency. AThTP was detected only sporadically in adult tissues but was found more consistently in fetal tissues and cell lines. CONCLUSIONS AND SIGNIFICANCE: The high sensitivity of humans to thiamine deficiency is probably linked to low circulating thiamine concentrations and low ThDP tissue contents. ThTP levels are relatively high in many human tissues, as a result of low expression of the 25-kDa ThTPase. Another novel finding is the presence of ThTP and AThTP in poorly differentiated fast-growing cells, suggesting a hitherto unsuspected link between these compounds and cell division or differentiation.

Thiamine triphosphate synthesis in rat brain occurs in mitochondria and is coupled to the respiratory chain.

In animals, thiamine deficiency leads to specific brain lesions, generally attributed to decreased levels of thiamine diphosphate, an essential cofactor in brain energy metabolism. However, another far less abundant derivative, thiamine triphosphate (ThTP), may also have a neuronal function. Here, we show that in the rat brain, ThTP is essentially present and synthesized in mitochondria. In mitochondrial preparations from brain (but not liver), ThTP can be produced from thiamine diphosphate and P(i). This endergonic process is coupled to the oxidation of succinate or NADH through the respiratory chain but cannot be energized by ATP hydrolysis. ThTP synthesis is strongly inhibited by respiratory chain inhibitors, such as myxothiazol and inhibitors of the H(+) channel of F(0)F(1)-ATPase. It is also impaired by disruption of the mitochondria or by depolarization of the inner membrane (by protonophores or valinomycin), indicating that a proton-motive force (Deltap) is required. Collapsing Deltap after ThTP synthesis causes its rapid disappearance, suggesting that both synthesis and hydrolysis are catalyzed by a reversible H(+)-translocating ThTP synthase. The synthesized ThTP can be released from mitochondria in the presence of external P(i). However, ThTP probably does not accumulate in the cytoplasm in vivo, because it is not detected in the cytosolic fraction obtained from a brain homogenate. Our results show for the first time that a high energy triphosphate compound other than ATP can be produced by a chemiosmotic type of mechanism. This might shed a new light on our understanding of the mechanisms of thiamine deficiency-induced brain lesions.

Thiaminylated adenine nucleotides. Chemical synthesis, structural characterization and natural occurrence.

Thiamine and its three phosphorylated derivatives (mono-, di- and triphosphate) occur naturally in most cells. Recently, we reported the presence of a fourth thiamine derivative, adenosine thiamine triphosphate, produced in Escherichia coli in response to carbon starvation. Here, we show that the chemical synthesis of adenosine thiamine triphosphate leads to another new compound, adenosine thiamine diphosphate, as a side product. The structure of both compounds was confirmed by MS analysis and 1H-, 13C- and 31P-NMR, and some of their chemical properties were determined. Our results show an upfield shifting of the C-2 proton of the thiazolium ring in adenosine thiamine derivatives compared with conventional thiamine phosphate derivatives. This modification of the electronic environment of the C-2 proton might be explained by a through-space interaction with the adenosine moiety, suggesting U-shaped folding of adenosine thiamine derivatives. Such a structure in which the C-2 proton is embedded in a closed conformation can be located using molecular modeling as an energy minimum. In E. coli, adenosine thiamine triphosphate may account for 15% of the total thiamine under energy stress. It is less abundant in eukaryotic organisms, but is consistently found in mammalian tissues and some cell lines. Using HPLC, we show for the first time that adenosine thiamine diphosphate may also occur in small amounts in E. coli and in vertebrate liver. The discovery of two natural thiamine adenine compounds further highlights the complexity and diversity of thiamine biochemistry, which is not restricted to the cofactor role of thiamine diphosphate.

Benfotiamine, a synthetic S-acyl thiamine derivative, has different mechanisms of action and a different pharmacological profile than lipid-soluble thiamine disulfide derivatives.

BACKGROUND: Lipid-soluble thiamine precursors have a much higher bioavailability than genuine thiamine and therefore are more suitable for therapeutic purposes. Benfotiamine (S-benzoylthiamine O-monophosphate), an amphiphilic S-acyl thiamine derivative, prevents the progression of diabetic complications, probably by increasing tissue levels of thiamine diphosphate and so enhancing transketolase activity. As the brain is particularly sensitive to thiamine deficiency, we wanted to test whether intracellular thiamine and thiamine phosphate levels are increased in the brain after oral benfotiamine administration. RESULTS: Benfotiamine that is practically insoluble in water, organic solvents or oil was solubilized in 200 mM hydroxypropyl-beta-cyclodextrin and the mice received a single oral administration of 100 mg/kg. Though thiamine levels rapidly increased in blood and liver to reach a maximum after one or two hours, no significant increase was observed in the brain. When mice received a daily oral administration of benfotiamine for 14 days, thiamine derivatives were increased significantly in the liver but not in the brain, compared to control mice. In addition, incubation of cultured neuroblastoma cells with 10 muM benfotiamine did not lead to increased intracellular thiamine levels. Moreover, in thiamine-depleted neuroblastoma cells, intracellular thiamine contents increased more rapidly after addition of thiamine to the culture medium than after addition of benfotiamine for which a lag period was observed. CONCLUSION: Our results show that, though benfotiamine strongly increases thiamine levels in blood and liver, it has no significant effect in the brain. This would explain why beneficial effects of benfotiamine have only been observed in peripheral tissues, while sulbutiamine, a lipid-soluble thiamine disulfide derivative, that increases thiamine derivatives in the brain as well as in cultured cells, acts as a central nervous system drug. We propose that benfotiamine only penetrates the cells after dephosphorylation by intestinal alkaline phosphatases. It then enters the bloodstream as S-benzoylthiamine that is converted to thiamine in erythrocytes and in the liver. Benfotiamine, an S-acyl derivative practically insoluble in organic solvents, should therefore be differentiated from truly lipid-soluble thiamine disulfide derivatives (allithiamine and the synthetic sulbutiamine and fursultiamine) with a different mechanism of absorption and different pharmacological properties.

Discovery of a natural thiamine adenine nucleotide.

Several important cofactors are adenine nucleotides with a vitamin as the catalytic moiety. Here, we report the discovery of the first adenine nucleotide containing vitamin B1: adenosine thiamine triphosphate (AThTP, 1), or thiaminylated ATP. We discovered AThTP in Escherichia coli and found that it accumulates specifically in response to carbon starvation, thereby acting as a signal rather than a cofactor. We detected smaller amounts in yeast and in plant and animal tissues.