One substrate many enzymes virtual screening uncovers missing genes of carnitine biosynthesis in human and mouse.

The increasing availability of experimental and computational protein structures entices their use for function prediction. Here we develop an automated procedure to identify enzymes involved in metabolic reactions by assessing substrate conformations docked to a library of protein structures. By screening AlphaFold-modeled vitamin B6-dependent enzymes, we find that a metric based on catalytically favorable conformations at the enzyme active site performs best (AUROC Score=0.84) in identifying genes associated with known reactions. Applying this procedure, we identify the mammalian gene encoding hydroxytrimethyllysine aldolase (HTMLA), the second enzyme of carnitine biosynthesis. Upon experimental validation, we find that the top-ranked candidates, serine hydroxymethyl transferase (SHMT) 1 and 2, catalyze the HTMLA reaction. However, a mouse protein absent in humans (threonine aldolase; Tha1) catalyzes the reaction more efficiently. Tha1 did not rank highest based on the AlphaFold model, but its rank improved to second place using the experimental crystal structure we determined at 2.26 Å resolution. Our findings suggest that humans have lost a gene involved in carnitine biosynthesis, with HTMLA activity of SHMT partially compensating for its function.

Identification of the pyridoxal 5'-phosphate allosteric site in human pyridox(am)ine 5'-phosphate oxidase.

Adequate levels of pyridoxal 5'-phosphate (PLP), the catalytically active form of vitamin B6 , and its proper distribution in the body are essential for human health. The PLP recycling pathway plays a crucial role in these processes and its defects cause severe neurological diseases. The enzyme pyridox(am)ine 5'-phosphate oxidase (PNPO), whose catalytic action yields PLP, is one of the key players in this pathway. Mutations in the gene encoding PNPO are responsible for a severe form of neonatal epilepsy. Recently, PNPO has also been described as a potential target for chemotherapeutic agents. Our laboratory has highlighted the crucial role of PNPO in the regulation of PLP levels in the cell, which occurs via a feedback inhibition mechanism of the enzyme, exerted by binding of PLP at an allosteric site. Through docking analyses and site-directed mutagenesis experiments, here we identified the allosteric PLP binding site of human PNPO. This site is located in the same protein region as the allosteric site we previously identified in the Escherichia coli enzyme homologue. However, the identity and arrangement of the amino acid residues involved in PLP binding are completely different and resemble those of the active site of PLP-dependent enzymes. The identification of the PLP allosteric site of human PNPO paves the way for the rational design of enzyme inhibitors as potential anti-cancer compounds.

Functional and structural properties of pyridoxal reductase (PdxI) from Escherichia coli: a pivotal enzyme in the vitamin B6 salvage pathway.

Pyridoxine 4-dehydrogenase (PdxI), a NADPH-dependent pyridoxal reductase, is one of the key players in the Escherichia coli pyridoxal 5'-phosphate (PLP) salvage pathway. This enzyme, which catalyses the reduction of pyridoxal into pyridoxine, causes pyridoxal to be converted into PLP via the formation of pyridoxine and pyridoxine phosphate. The structural and functional properties of PdxI were hitherto unknown, preventing a rational explanation of how and why this longer, detoured pathway occurs, given that, in E. coli, two pyridoxal kinases (PdxK and PdxY) exist that could convert pyridoxal directly into PLP. Here, we report a detailed characterisation of E. coli PdxI that explains this behaviour. The enzyme efficiently catalyses the reversible transformation of pyridoxal into pyridoxine, although the reduction direction is thermodynamically strongly favoured, following a compulsory-order ternary-complex mechanism. In vitro, the enzyme is also able to catalyse PLP reduction and use NADH as an electron donor, although with lower efficiency. As with all members of the aldo-keto reductase (AKR) superfamily, the enzyme has a TIM barrel fold; however, it shows some specific features, the most important of which is the presence of an Arg residue that replaces the catalytic tetrad His residue that is present in all AKRs and appears to be involved in substrate specificity. The above results, in conjunction with kinetic and static measurements of vitamins B6 in cell extracts of E. coli wild-type and knockout strains, shed light on the role of PdxI and both kinases in determining the pathway followed by pyridoxal in its conversion to PLP, which has a precise regulatory function.

Structural insights into the DNA recognition mechanism by the bacterial transcription factor PdxR.

Specificity in protein-DNA recognition arises from the synergy of several factors that stem from the structural and chemical signatures encoded within the targeted DNA molecule. Here, we deciphered the nature of the interactions driving DNA recognition and binding by the bacterial transcription factor PdxR, a member of the MocR family responsible for the regulation of pyridoxal 5'-phosphate (PLP) biosynthesis. Single particle cryo-EM performed on the PLP-PdxR bound to its target DNA enabled the isolation of three conformers of the complex, which may be considered as snapshots of the binding process. Moreover, the resolution of an apo-PdxR crystallographic structure provided a detailed description of the transition of the effector domain to the holo-PdxR form triggered by the binding of the PLP effector molecule. Binding analyses of mutated DNA sequences using both wild type and PdxR variants revealed a central role of electrostatic interactions and of the intrinsic asymmetric bending of the DNA in allosterically guiding the holo-PdxR-DNA recognition process, from the first encounter through the fully bound state. Our results detail the structure and dynamics of the PdxR-DNA complex, clarifying the mechanism governing the DNA-binding mode of the holo-PdxR and the regulation features of the MocR family of transcription factors.

Cuticle Modifications and Over-Expression of the Chitin-Synthase Gene in Diflubenzuron-Resistant Phenotype.

Insecticide resistance is a major threat challenging the control of harmful insect species. The study of resistant phenotypes is, therefore, pivotal to understand molecular mechanisms underpinning insecticide resistance and plan effective control and resistance management strategies. Here, we further analysed the diflubenzuron (DFB)-resistant phenotype due to the point-mutation I1043M in the chitin-synthase 1 gene (chs1) in the mosquito Culex pipiens. By comparing susceptible and resistant strains of Cx. pipiens through DFB bioassays, molecular analyses and scanning electron microscopy, we showed that the I1043M-resistant mosquitoes have: (i) a striking level of DFB resistance (i.e., resistance ratio: 9006); (ii) a constitutive 11-fold over-expression of the chs1 gene; (iii) enhanced cuticle thickness and cuticular chitin content. Culex pipiens is one of the most important vector species in Europe and the rapid spread of DFB resistance can threaten its control. Our results, by adding new data about the DFB-resistant phenotype, provide important information for the control and management of insecticide resistance.

Brain and lower body protection during aortic arch surgery.

BACKGROUND: Deep hypothermic circulatory arrest (DHCA) at ≤20°C for aortic arch surgery has been widely used for decades, with or without cerebral perfusion (CP), antegrade (antegrade cerebral perfusion [ACP]), or retrograde. In recent years nadir temperature progressively increased to 26°C-28°C (moderately hypothermic circulatory arrest [MHCA]), adding ACP. Aim of this multicentric study is to evaluate early results of aortic arch surgery and if DHCA with 10 min of cold reperfusion at the same nadir temperature of the CA before rewarming (delayed rewarming [DR]) can provide a neuroprotection and a lower body protection similar to that provided by MHCA + ACP. METHODS: A total of 210 patients were included in the study. DHCA + DR was used in 59 patients and MHCA + ACP in 151. Primary endpoints were death, neurologic event (NE), temporary (TNE), or permanent (permanent neurologic deficit [PND]), and need of renal replacement therapy (RRT). RESULTS: Operative mortality occurred in 14 patients (6.7%), NEs in 17 (8.1%), and PNDs in 10 (4.8%). A total of 23 patients (10.9%) needed RRT. Death + PND occurred in 21 patients (10%) and composite endpoint in 35 (19.2%). Intergroup weighed logistic regression analysis showed similar prevalence of deaths, NDs, and death + PND, but need of RRT (odds ratio [OR]: 7.39, confidence interval [CI]: 1.37-79.1) and composite endpoint (OR: 8.97, CI: 1.95-35.3) were significantly lower in DHCA + DR group compared with MHCA + ACP group. CONCLUSIONS: The results of our study demonstrate that DHCA + DR has the same prevalence of operative mortality, NE and association of death+PND than MHCA + ACP. However, the data suggests that DHCA + DR when compared with MHCA + ACP provides better renal protection and reduced prevalence of composite endpoint.

Characterization of the Escherichia coli pyridoxal 5'-phosphate homeostasis protein (YggS): Role of lysine residues in PLP binding and protein stability.

The pyridoxal 5'-phosphate (PLP) homeostasis protein (PLPHP) is a ubiquitous member of the COG0325 family with apparently no catalytic activity. Although the actual cellular role of this protein is unknown, it has been observed that mutations of the PLPHP encoding gene affect the activity of PLP-dependent enzymes, B6 vitamers and amino acid levels. Here we report a detailed characterization of the Escherichia coli ortholog of PLPHP (YggS) with respect to its PLP binding and transfer properties, stability, and structure. YggS binds PLP very tightly and is able to slowly transfer it to a model PLP-dependent enzyme, serine hydroxymethyltransferase. PLP binding to YggS elicits a conformational/flexibility change in the protein structure that is detectable in solution but not in crystals. We serendipitously discovered that the K36A variant of YggS, affecting the lysine residue that binds PLP at the active site, is able to bind PLP covalently. This observation led us to recognize that a number of lysine residues, located at the entrance of the active site, can replace Lys36 in its PLP binding role. These lysines form a cluster of charged residues that affect protein stability and conformation, playing an important role in PLP binding and possibly in YggS function.

Distribution of Cerebrovascular Phenotypes According to Variants of the ENG and ACVRL1 Genes in Subjects with Hereditary Hemorrhagic Telangiectasia.

Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal dominant disorder caused, in more than 80% of cases, by mutations of either the endoglin (ENG) or the activin A receptor-like type 1 (ACVRL1) gene. Several hundred variants have been identified in these HHT-causing genes, including deletions, missense and nonsense mutations, splice defects, duplications, and insertions. In this study, we have analyzed retrospectively collected images of magnetic resonance angiographies (MRA) of the brain of HHT patients, followed at the HHT Center of our University Hospital, and looked for the distribution of cerebrovascular phenotypes according to specific gene variants. We found that cerebrovascular malformations were heterogeneous among HHT patients, with phenotypes that ranged from classical arteriovenous malformations (AVM) to intracranial aneurysms (IA), developmental venous anomalies (DVA), and cavernous angiomas (CA). There was also wide heterogeneity among the variants of the ENG and ACVRL1 genes, which included known pathogenic variants, variants of unknown significance, variants pending classification, and variants which had not been previously reported. The percentage of patients with cerebrovascular malformations was significantly higher among subjects with ENG variants than ACVRL1 variants (25.0% vs. 13.1%, p < 0.05). The prevalence of neurovascular anomalies was different among subjects with different gene variants, with an incidence that ranged from 3.3% among subjects with the c.1231C > T, c.200G > A, or c.1120C > T missense mutations of the ACVRL1 gene, to 75.0% among subjects with the c.1435C > T missense mutation of the ACVRL1 gene. Further studies and larger sample sizes are required to confirm these findings.

Combined Treatment With Carotid Endoarterectomy and Coronary Artery Bypass Grafting: A Single-Institutional Experience in 222 Patients.

INTRODUCTION: Carotid atherosclerotic disease is a known independent risk factor of post operative stroke after coronary artery bypass grafting (CABG). The best management of concomitant coronary artery disease and carotid artery disease remains debated. Current strategies include simultaneous carotid endoarterectomy (CEA) and CABG, staged CEA followed by CABG, staged CABG followed by CEA, staged transfemoral carotid artery stenting (TF-CAS) followed by CABG, simultaneous TF-CAS and CABG and transcarotid artery stenting. METHODS: We report our experience based on a cohort of 222 patients undergoing combined CEA and CABG surgery who come to our observation from 2004 to 2020. All patients with >70% carotid stenosis and severe multivessel or common truncal coronary artery disease underwent combined CEA and CABG surgery at our instituion. 30% of patients had previously remote neurological symptoms or a cerebral CT-scan with ischemic lesions. Patients with carotid stenosis >70%, either asymptomatic or symptomatic, underwent CT-scan without contrast media to assess ischemic brain injury, and in some cases, if necessary, CT-angiography of the neck and intracranial vessels. RESULTS: The overall perioperative mortality rate was 4.1% (9/222 patients). Two patients (.9%) had periprocedural ipsilateral transient ischemic attack (TIA) which completely resolved by the second postoperative day. Two patients (.9%) had an ipsilateral stroke, while 7 patients (3.2%) had a stroke of the controlateral brain hemisphere. Two patients (.9%) patients were affected by periprocedural coma caused by cerebral hypoperfusion due to perioperative heart failure. There were no statistically significant differences between patients in Extracorporeal Circulation (ECC) and Off-pump patients in the onset of perioperative stroke. CONCLUSION: Our experience reported that combined surgical treatment of CEA and CABG, possibly Off-Pump, is a feasible treatment procedure, able to minimize the risk of post-operative stroke and cognitive deficits.

Thiamine-dependent regulation of mammalian brain pyridoxal kinase in vitro and in vivo.

Vitamins B1 (thiamine) and B6 (pyridox (al/ine/amine)) are crucial for central nervous system (CNS) function and neurogenesis due to the coenzyme action of their phosphorylated derivatives in the brain metabolism of glucose and neurotransmitters. Here, the non-coenzyme action of thiamine on the major mammalian producers of pyridoxal-5'-phosphate (PLP), such as pyridoxal kinase (PdxK) and pyridoxine 5'-phosphate oxidase (PNPO), is characterized. Among the natural thiamine compounds, thiamine triphosphate (ThTP) is the best effector of recombinant human PdxK (hPdxK) in vitro, inhibiting hPdxK in the presence of Mg2+ but activating the Zn2+ -dependent reaction. Inhibition of hPdxK by thiamine antagonists decreases from amprolium to pyrithiamine to oxythiamine, highlighting possible dysregulation of both the B1 - and B6 -dependent metabolism in the chemical models of thiamine deficiency. Compared with the canonical hPdxK, the D87H and V128I variants show a twofold increase in Kapp of thiamine inhibition, and the V128I and H246Q variants show a fourfold and a twofold decreased Kapp of thiamine diphosphate (ThDP), respectively. Thiamine administration changes diurnal regulation of PdxK activity and phosphorylation at Ser213 and Ser285, expression of the PdxK-related circadian kinases/phosphatases in the rat brain, and electrocardiography (ECG). In contrast to PdxK, PNPO is not affected by thiamine or its derivatives, either in vitro or in vivo. Dephosphorylation of the PdxK Ser285, potentially affecting mobility of the ATP-binding loop, inversely correlates with the enzyme activity. Dephosphorylation of the PdxK Ser213, which is far away from the active site, does not correlate with the activity. The correlations analysis suggests the PdxK Ser213 to be a target of kinase MAP2K1 and phosphatase Ppp1ca. Diurnal effects of thiamine administration on the metabolically linked ThDP- and PLP-dependent enzymes may support the brain homeostatic mechanisms and physiological fitness.

Effects of Sodium-Glucose Transporter 2 Inhibitors (SGLT2-I) in Patients With Ischemic Heart Disease (IHD) Treated by Coronary Artery Bypass Grafting via MiECC: Inflammatory Burden, and Clinical Outcomes at 5 Years of Follow-Up.

Introduction: Minimally invasive extracorporeal circulation (MiECC) reduced inflammatory burden, leading to best clinical outcomes in patients treated with coronary artery bypass grafting (CABG). Despite this, the patients with type 2 diabetes mellitus (T2DM) vs those without T2DM (non-T2DM) have a worse prognosis, caused by over-inflammation and modulated by sodium-glucose transporter 2 receptors. However, we evaluated the inflammatory burden and clinical outcomes in non-T2DM vs T2DM patients under sodium-glucose transporter 2 inhibitors (SGLT2-I users) vs non-SGLT2-I users at 5 years of follow-up post-CABG via MiECC. Materials and methods: In a multicenter study, we screened consecutive patients with indications to receive CABG. The study endpoints were the inflammatory burden (circulating serum levels of tumor necrosis factor-alpha (TNF-α), interleukin 1 and 6 (IL-1 and IL-6), C-reactive protein (CRP), and leucocytes count) and the clinical outcomes at follow-up of 5 years in non-T2DM vs SGLT2-I users, in non-T2DM vs non-SGLT2-I users, and SGLT2-I users vs non-SGLT2-I users. Results: At baseline, and at one year and 5 years of follow-up, the non-T2DM vs SGLT2-I users, non-T2DM vs non-SGLT2-I users, and SGLT2-I users vs non-SGLT2-I users had the lowest values of IL-1, IL-6, and TNF-α (p < 0.05). At one year of follow-up, SGLT2-I users vs non-T2DM and non-SGLT2-I users vs non-T2DM users had a higher rate of all deaths, cardiac deaths, re-myocardial infarction, repeat revascularization, and stroke, and of the composite endpoint (p < 0.05). In a multivariate Cox regression analysis, the composite endpoint was predicted by IL-1 [2.068 (1.367-3.129)], TNF-α [1.989 (1.081-2.998)], and SGLT2-I [0.504 (0.078-0.861)]. Conclusion: In T2DM patients, the SGLT2-I significantly reduced the inflammatory burden and ameliorated clinical outcomes at 5 years of follow-up post-CABG via MiECC.

Beneficial Effects of Remote Medical Care for Patients with Hereditary Hemorrhagic Telangiectasia during the COVID-19 Pandemic.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) needs high-quality care and multidisciplinary management. During the COVID-19 pandemic, most non-urgent clinical activities for HHT outpatients were suspended. We conducted an analytical observational cohort study to evaluate whether medical and psychological support, provided through remote consultation during the COVID-19 pandemic, could reduce the complications of HHT. METHODS: A structured regimen of remote consultations, conducted by either video-calls, telephone calls, or e-mails, was provided by a multidisciplinary group of physicians to a set of patients of our HHT center. The outcomes considered were: number of emergency room visits/hospitalizations, need of blood transfusions, need of iron supplementation, worsening of epistaxis, and psychological status. RESULTS: The study included 45 patients who received remote assistance for a total of eight months. During this period, 9 patients required emergency room visits, 6 needed blood transfusions, and 24 needed iron supplementation. This was not different from what was registered among the same 45 patients in the same period of the previous year. Remote care also resulted in better management of epistaxis and improved quality of life, with the mean epistaxis severity score and the Euro-Quality of Life-Visual Analogue Scale that were significantly better at the end than at the beginning of the study. DISCUSSION: Remote medical care might be a valid support for HHT subjects during periods of suspended outpatient surveillance, like the COVID-19 pandemic.

Identification and characterization of the pyridoxal 5'-phosphate allosteric site in Escherichia coli pyridoxine 5'-phosphate oxidase.

Pyridoxal 5'-phosphate (PLP), the catalytically active form of vitamin B6, plays a pivotal role in metabolism as an enzyme cofactor. PLP is a very reactive molecule and can be very toxic unless its intracellular concentration is finely regulated. In Escherichia coli, PLP formation is catalyzed by pyridoxine 5'-phosphate oxidase (PNPO), a homodimeric FMN-dependent enzyme that is responsible for the last step of PLP biosynthesis and is also involved in the PLP salvage pathway. We have recently observed that E. coli PNPO undergoes an allosteric feedback inhibition by PLP, caused by a strong allosteric coupling between PLP binding at the allosteric site and substrate binding at the active site. Here we report the crystallographic identification of the PLP allosteric site, located at the interface between the enzyme subunits and mainly circumscribed by three arginine residues (Arg23, Arg24, and Arg215) that form an "arginine cage" and efficiently trap PLP. The crystal structure of the PNPO-PLP complex, characterized by a marked structural asymmetry, presents only one PLP molecule bound at the allosteric site of one monomer and sheds light on the allosteric inhibition mechanism that makes the enzyme-substrate-PLP ternary complex catalytically incompetent. Site-directed mutagenesis studies focused on the arginine cage validate the identity of the allosteric site and provide an effective means to modulate the allosteric properties of the enzyme, from the loosening of the allosteric coupling (in the R23L/R24L and R23L/R215L variants) to the complete loss of allosteric properties (in the R23L/R24L/R21L variant).

Structural dynamics in the La-module of La-related proteins.

The La-related proteins (LaRPs) are a superfamily of eukaryotic RNA-binding proteins with important and varied roles. To understand LaRP functions it is essential to unravel the divergent features responsible for their RNA target selectivity, which underlie their distinct identities and cellular roles. LaRPs are built on a common structural module called the 'La-module' that acts as a main locus for RNA recognition. The La-module is comprised of two tethered domains whose relative structural and dynamic interplay has been proposed to regulate RNA-target selection, albeit the mechanistic underpinning of this recognition remains to be elucidated. A main unsolved conundrum is how conserved La-modules across LaRPs are able to bind to extremely diverse RNA ligands.In this work, we employed Small Angle X-ray Scattering (SAXS) to investigate several human LaRP La-modules in the absence and, where applicable, in the presence of their RNA target, with the aim to explore the structural dynamics of their RNA recognition and provide information on the architectural landscape accessible to these proteins. Integration of these SAXS experiments with prior X-ray crystallography and NMR data suggests that RNA binding is generally accompanied by a compaction and loss of flexibility of the La-module. Nonetheless, the La-modules appear to experience a considerably different degree of inherent flexibility in their apo state. Furthermore, although they all exist in discrete subsets of accessible populations in equilibrium, these vary from LaRP to LaRP and can be either extended or compact. We propose that these divergent features may be critical for RNA substrate discrimination.

QTc Interval Prolongation and Life-Threatening Arrhythmias During Hospitalization in Patients With Coronavirus Disease 2019 (COVID-19): Results From a Multicenter Prospective Registry.

BACKGROUND: Prolonged QTc intervals and life-threatening arrhythmias (LTA) are potential drug-induced complications previously reported with antimalarials, antivirals, and antibiotics. Our objective was to evaluate the prevalence and predictors of QTc interval prolongation and incidences of LTA during hospitalization for coronavirus disease 2019 (COVID-19) among patients with normal admission QTc. METHODS: We enrolled 110 consecutive patients in a multicenter international registry. A 12-lead electrocardiograph was performed at admission, after 7, and at 14 days; QTc values were analyzed. RESULTS: After 7 days, 15 (14%) patients developed a prolonged QTc (pQTc; mean QTc increase 66 ± 20 msec; +16%; P < .001); these patients were older and had higher basal heart rates, higher rates of paroxysmal atrial fibrillation, and lower platelet counts. The QTc increase was inversely proportional to the baseline QTc level and leukocyte count and directly proportional to the basal heart rate (P < .01).We conducted a multivariate stepwise analysis including age, male gender, paroxysmal atrial fibrillation, basal QTc values, basal heart rate, and dual antiviral therapy; age (odds ratio [OR], 1.06; 95% confidence interval [CI], 1.00-1.13; P < .05), basal heart rate (OR, 1.07; 95% CI, 1.02-1.13; P < .01), and dual antiviral therapy (OR, 12.46; 95% CI, 2.09-74.20; P < .1) were independent predictors of QT prolongation.The incidence rate of LTA during hospitalization was 3.6%. There was 1 patient who experienced cardiac arrest and 3 with nonsustained ventricular tachycardia. LTAs were recorded after a median of 9 days from hospitalization and were associated with 50% of the mortality rate. CONCLUSIONS: After 7 days of hospitalization, 14% of patients with COVID-19 developed pQTc; age, basal heart rate, and dual antiviral therapy were found to be independent predictors of pQTc. Life-threatening arrhythmias have an incidence rate of 3.6%, and were associated with a poor outcome.

An Engineered Escherichia coli Strain with Synthetic Metabolism for in-Cell Production of Translationally Active Methionine Derivatives.

In the last decades, it has become clear that the canonical amino acid repertoire codified by the universal genetic code is not up to the needs of emerging biotechnologies. For this reason, extensive genetic code re-engineering is essential to expand the scope of ribosomal protein translation, leading to reprogrammed microbial cells equipped with an alternative biochemical alphabet to be exploited as potential factories for biotechnological purposes. The prerequisite for this to happen is a continuous intracellular supply of noncanonical amino acids through synthetic metabolism from simple and cheap precursors. We have engineered an Escherichia coli bacterial system that fulfills these requirements through reconfiguration of the methionine biosynthetic pathway and the introduction of an exogenous direct trans-sulfuration pathway. Our metabolic scheme operates in vivo, rescuing intermediates from core cell metabolism and combining them with small bio-orthogonal compounds. Our reprogrammed E. coli strain is capable of the in-cell production of l-azidohomoalanine, which is directly incorporated into proteins in response to methionine codons. We thereby constructed a prototype suitable for economic, versatile, green sustainable chemistry, pushing towards enzyme chemistry and biotechnology-based production.

Antithrombotic Therapy in Hereditary Hemorrhagic Telangiectasia: Real-World Data from the Gemelli Hospital HHT Registry.

Although Hereditary Hemorrhagic Telangiectasia (HHT) is characterized by an overwhelming bleeding propensity, patients with this disease may also present medical conditions that require antithrombotic therapy (AT). However, precise information on indications, dosage, duration, effectiveness, and safety of AT in HHT patients is lacking. We performed a retrospective analysis of the HHT Registry of our University Hospital and found 26 patients who received AT for a total of 30 courses (19 courses of anticoagulant therapy and 11 courses of antiplatelet therapy). Indications to treatments included: atrial fibrillation, venous thrombosis and pulmonary embolism, heart valve replacement, retinal artery occlusion, secondary prevention after either stroke or myocardial infarction, and thromboprophylaxis for surgery. The total time of exposure to antiplatelet therapy was 385 months and to anticoagulant therapy 169 months. AT was generally well tolerated, with no fatal bleedings and no significant changes in hemoglobin levels. However, we found three major bleedings, with an incidence rate of 6.5 per 100 patients per year. When only patients treated with anticoagulants were considered, the incidence rate of major bleedings increased to 21.6 per 100 patients per year. Our study indicates that major bleeding may occur in HHT patients receiving AT, with a substantially increased rate in those treated with anticoagulants. Further studies are needed to fully estimate the tolerability of antithrombotic drugs in HHT.

The multifaceted role of vitamin B6 in cancer: Drosophila as a model system to investigate DNA damage.

A perturbed uptake of micronutrients, such as minerals and vitamins, impacts on different human diseases, including cancer and neurological disorders. Several data converge towards a crucial role played by many micronutrients in genome integrity maintenance and in the establishment of a correct DNA methylation pattern. Failure in the proper accomplishment of these processes accelerates senescence and increases the risk of developing cancer, by promoting the formation of chromosome aberrations and deregulating the expression of oncogenes. Here, the main recent evidence regarding the impact of some B vitamins on DNA damage and cancer is summarized, providing an integrated and updated analysis, mainly centred on vitamin B6. In many cases, it is difficult to finely predict the optimal vitamin rate that is able to protect against DNA damage, as this can be influenced by a given individual's genotype. For this purpose, a precious resort is represented by model organisms which allow limitations imposed by more complex systems to be overcome. In this review, we show that Drosophila can be a useful model to deeply understand mechanisms underlying the relationship between vitamin B6 and genome integrity.

Safety of antithrombotic therapy in subjects with hereditary hemorrhagic telangiectasia: prospective data from a multidisciplinary working group.

Subjects with the rare autosomal dominant disease Hereditary Hemorrhagic Telangiectasia (HHT) may develop medical conditions that require antithrombotic therapy (AT). However, safety of AT is uncertain in these patients and the only data currently available derive from retrospective analyses of registries and/or databases. At the HHT Centre of the 'Fondazione Policlinico Universitario A. Gemelli IRCCS' (Rome, Italy), a prospective study is currently ongoing to evaluate the safety of AT in subjects affected by HHT. The study is enrolling subjects with a definite diagnosis of HHT who receive an AT prescription by one of the physicians of the HHT Centre. The primary outcome is the number of hemorrhagic events, distinguished in major, clinically relevant non-major (CRNM), and minor bleedings, according to the criteria of the International Society on Thrombosis and Hemostasis (ISTH). Another primary outcome is worsening of epistaxis upon initiation of AT, assessed using the internationally accepted Epistaxis Severity Score (ESS). Additional outcomes are changes in hemoglobin levels and changes in the need of blood transfusion after initiation of AT. Here, we present the results of an interim analysis, conducted on the 12 HHT subjects that have been enrolled so far. After a mean follow-up of 6.5 ± 0.8 months, no major bleedings, no CRNM bleedings, and no minor bleedings different from epistaxis were recorded. Worsening of epistaxis upon initiation of AT was documented only in one patient, but did not require discontinuation of AT. There were no significant changes in the mean ESS measured before and after initiation of AT. There were no significant changes in hemoglobin levels and need for blood transfusion after initiation of AT. Although preliminary, these are the first prospective data on the safety of AT in HHT patients. Our interim analysis suggests that, when prescribed by experienced physicians in a multidisciplinary setting, AT is well tolerated by HHT patients. More patients and a longer follow-up are needed to confirm these findings.