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1.
Epidemiol Prev ; 47(1-2): 34-46, 2023.
Article En | MEDLINE | ID: mdl-36971236

BACKGROUND: because of different human behaviours, SARS-CoV-2 spread may be lower in spring/summer. On the contrary, it is not clearly known whether the clinical course/severity of hospitalized patients infected by SARS-CoV-2 can be different in the various seasons.. OBJECTIVES: to understand whether there were differences in severity of COVID-19 in patients who had contracted the infection in winter versus those infected in spring/summer. DESIGN: observational retrospective cohort study. SETTING AND PARTICIPANTS: from the administrative database of the SARS-CoV-2 surveillance system and that of hospital discharge, a cohort of patients (8,221, 653 of which were hospitalized) who tested positive to the RT-PCR test for SARS-CoV-2 between 01.12.2020 and 31.07.2021 in the Grosseto province (Tuscany Region, Central Italy) was selected and analysed. MAIN OUTCOME MEASURES: hospitalization rate and length, continuous positive airway pressure (CPAP) or non-invasive ventilation (NIV) use, Intensive Care Unite (ICU) admissions, intra-hospital mortality and PaO2/FiO2 values were measured and compared between subjects infected in winter and those who developed COVID-19 in spring/summer. Viral load (cycle threshold, Ct), vitamin D, serum ferritin, IL-6, procalcitonin, D-dimer, and C-reactive protein measured in the two periods were also compared. RESULTS: in the considered months, the hospitalization rate among 8,221 patients with COVID-19 was 8%: 370 (8.5%) individuals were hospitalized in winter and 283 (7,3%; p=0.31) in spring/summer; 62 (16.8%), 88 (23.8%), and 63 (17%) in winter and 28 (9.9%), 40 (14.1%), and 36 (12.7%) in spring/summer were admitted in ICU (p=0.01), used CPAP/NIV (p=0.002) and died (p=0.13), respectively. Hospitalization days were 14.5±11.6 in winter and 10.3±8.84 in spring/summer (p=0.001), while minimum PaO2/FiO2, measured during hospital stays was 123.2±38.6 in spring/summer and 112.6±40.8 in winter (p=0.054). Multivariate analysis (adjusted for all confounding factors) also confirmed reduced risks of having ICU admissions (0.53; 95%CI 0.32;0.88; p=0.01) and of using CPAP/NIV (0.48; 95%CI 0.32;0.75; p=0.001) in spring/summer when compared to winter. Hospitalization days and minimum PaO2/FiO2 were also lower in spring/summer (ß= -3.9; 95%CI -5.5;-2.2; p=0.001) and winter (ß= -17; 95%CI -0.93;35; p=0.06), respectively. The adjusted hazard ratio of mortality in winter, obtained with a Cox model, was higher of about 38% compared to spring/summer. No Ct values (viral load) differences were found either in winter (19.45±6.18) or spring/summer (20.3±6.7; p=0.343). IL-6, ferritin, procalcitonin, D-dimer were similar. Conversely, CRP was lower whereas vitamin D was higher in the warmer seasons. CONCLUSIONS: COVID-19 may be less severe during spring/summer in hospitalized patients. This does not seem to be influenced by different SARS-CoV-2 viral load in the different periods considered. C-reactive protein was found to be lower whereas vitamin D higher in the warmer months. It can be hypothesized that higher levels of vitamin D in spring/summer, compared to winter, may be associated to a positive modulation of COVID-19 induced inflammation with a possible disease severity reduction during spring/summer.


COVID-19 , Respiratory Distress Syndrome , Humans , COVID-19/epidemiology , SARS-CoV-2 , Retrospective Studies , C-Reactive Protein , Seasons , Interleukin-6 , Procalcitonin , Italy/epidemiology , Vitamin D , Ferritins
2.
Nutrients ; 15(2)2023 Jan 10.
Article En | MEDLINE | ID: mdl-36678208

This real-world analysis evaluated the clinical and economic burden of non-dialysis-dependent CKD patients with and without secondary hyperparathyroidism (sHPT) in Italy. An observational retrospective study was conducted using administrative databases containing a pool of healthcare entities covering 2.45 million health-assisted individuals. Adult patients with hospitalization discharge diagnoses for CKD stages 3, 4, and 5 were included from 1 January 2012 to 31 March 2015 and stratified using the presence/absence of sHPT. Of the 5710 patients, 3119 were CKD-only (62%) and 1915 were CKD + sHPT (38%). The groups were balanced using Propensity Score Matching (PSM). Kaplan-Meier curves revealed that progression to dialysis and cumulative mortality had a higher incidence in the CKD + sHPT versus CKD-only group in CKD stage 3 patients and the overall population. The total direct healthcare costs/patient at one-year follow-up were significantly higher in CKD + sHPT versus CKD-only patients (EUR 8593 vs. EUR 5671, p < 0.001), mostly burdened by expenses for drugs (EUR 2250 vs. EUR 1537, p < 0.001), hospitalizations (EUR 4628 vs. EUR 3479, p < 0.001), and outpatient services (EUR 1715 vs. EUR 654, p < 0.001). These findings suggest that sHPT, even at an early CKD stage, results in faster progression to dialysis, increased mortality, and higher healthcare expenditures, thus indicating that timely intervention can ameliorate the management of CKD patients affected by sHPT.


Hyperparathyroidism, Secondary , Renal Insufficiency, Chronic , Adult , Humans , Retrospective Studies , Financial Stress , Renal Dialysis/adverse effects , Renal Insufficiency, Chronic/complications , Renal Insufficiency, Chronic/therapy , Hyperparathyroidism, Secondary/epidemiology , Hyperparathyroidism, Secondary/therapy , Hyperparathyroidism, Secondary/complications
3.
Minerva Med ; 114(5): 642-651, 2023 Oct.
Article En | MEDLINE | ID: mdl-34269554

BACKGROUND: We know that excessive short-acting ß2-agonists (SABA) use in asthma may be associated to high exacerbation risks. We studied whether such excessive SABA consumption is connected with different higher oral corticosteroid (OC) prescriptions in the two sexes. METHODS: In our prescribing database, we searched subjects aged 18-40 years that were prescribed at least one SABA package/year and/or at least two ICS or two ICS/LABA boxes/year to identify asthmatics. Their OC prescriptions/year were also examined. Subjects were divided into 4 groups according to SABA packages/year prescribed (0, 1-2,3-6 and ≥7), considering sexes separately. RESULTS: Individuals recruited were 9,102. Subjects with at least one OC prescription were higher in each group and were females (P<0.001). The OC packages/year number was also more elevated in women especially those with >7 SABA prescriptions/year (0.96 in males vs. 2.64 in females, P<0.001). 94.7%/93.6% males/females, who never used SABA, took at least one ICS/LABA (mean 5.84/5.48 packages/year), while the subject percentage adhering to ICS/LABA dropped to 28-47% (mean 0.94-3.82 packages/year) in those who used SABA (P<0.001). Higher SABA prescriptions were associated with an increasing OC dispensation (ß=0.057, P<0.0001). We observed also a greater risk of using >3 OC packages/year in subjects with 3-6 (OR: 2.98 [95% CI: 2.19-4.06], P<0.001) and ≥7 (OR: 3.49 [95% CI: 2.39-5.10], P<0.001) SABA prescriptions compared to those that never used SABA. Besides, we found that using ICS (OR:0.51 [95% CI: 0.35-0.75], P<0.001) or ICS/LABA (OR:0.07 [95% CI: 0.05-0.09], P<0.001) may significantly reduce SABA prescriptions. CONCLUSIONS: Poor adherence to maintenance treatment appears to associated with excessive SABA prescriptions that may lead to a higher OC consumption particularly noticeable in women.


Anti-Asthmatic Agents , Asthma , Adult , Female , Humans , Male , Sex Characteristics , Adrenergic beta-Agonists/adverse effects , Administration, Inhalation , Asthma/drug therapy , Adrenal Cortex Hormones/adverse effects , Anti-Asthmatic Agents/adverse effects
4.
Clin Epidemiol ; 14: 1327-1337, 2022.
Article En | MEDLINE | ID: mdl-36387930

Purpose: A retrospective analysis of real-world data was performed to assess the epidemiology and economic burden of multiple sclerosis (MS), relapsing-remitting MS (RRMS), and secondary-progressive MS (SPMS) in Italy. Patients and Methods: An observational study on administrative databases from a sample of Italian entities was carried-out. Between 01/2010-12/2017, patients with ≥1 MS diagnosis code (ICD-9-CM:340 and/or exemption code:046) and/or ≥1 disease-modifying therapies (DMTs) prescription, were included. Among MS-cohort, SPMS patients were identified by ≥2 hospitalizations or by ≥2 drug prescriptions related to MS progression. MS patients not fulfilling SPMS criteria were included as RRMS. Mean annual healthcare costs were reported during follow-up and stratified by DMT treatment/untreatment. Results: Overall, 9543 MS patients were included; 8397 with RRMS and 1146 with SPMS. Estimated prevalence of MS was 141.6/100,000 inhabitants (RRMS 124.4/100,000 and SPMS 17.2/100,000). Mean annual cost for untreated and treated patient was respectively: €3638 and €11796 (MS-cohort), €3183 and €11486 (RRMS-cohort), €6317 and €15511 (SPMS-cohort). The first-line DMT treatment duration averaged 27.4 ± 22.8 months; the mean cost was 19004€ for the whole period. The second-line DMT treatment lasted on average 31.1 ± 24.5 months; the mean cost was 47293€ for the whole period. Conclusion: This study provided insights into the MS epidemiology in Italy and its economic burden. Healthcare costs associated with MS management were mainly driven by DMTs expenditure. A trend of higher healthcare-resource consumption was observed among SPMS-cohort.

6.
Adv Respir Med ; 2022 Jan 31.
Article En | MEDLINE | ID: mdl-35099058

INTRODUCTION: Many uncontrolled severe asthmatics are not on biologic therapy. We hypothesized that using a prescription database could help us identify them. MATERIAL AND METHODS: 3,309 patients who received at least one Montelukast prescription in 2019 were extracted from our prescription database. Number of packages/year, types and dosages of ICS, LABA, ICS/LABA, LAMA and monoclonal antibodies were considered for each patient. In our analysis, for subjects that took > 7 packages of ICS/LABA + LTRA +/- LAMA (high adherent) the number of oral corticosteroids (OC) packets prescribed for each of them was also looked upon. RESULTS: Patients that took ICS/LABA or ICS/LABA + LAMA continuously with high ICS doses were 188 (25.6%) and 117 (39.3%) respectively (total: 305 - 29.5%). Among them, 58 (30.9%) and 53 (45.3%) (total: 111 - 36.4%) were prescribed more than 2 OC packages. Whereas, 21 (11.2%) and 24 (20.5%) patients (total: 45 - 14.75%) received at least 4 OC package prescriptions. CONCLUSION: Approximately 36% of patients in continuous step-4/5 of GINA guidelines treatment may have severe uncontrolled asthma (overusing OC) which needed biologic treatment. In our opinion, a prescription archiving database may be a tool that can help us identify such uncontrolled asthma patients.

7.
Pulm Pharmacol Ther ; 71: 102076, 2021 12.
Article En | MEDLINE | ID: mdl-34530132

BACKGROUND: Given COPD heterogeneity, we do not know if some LABA/LAMAs are more suitable for some COPD phenotypes. This real-life database study aimed to evaluate retrospectively the 4 LABA/LAMA effectiveness and highlight possible specificities that could better guide us in choosing the right LABA/LAMA to be used. METHODS: We searched for subjects (1,779) adherent to umeclidinium/vilanterol (UM/VI), indacaterol/glycopyrronium (IND/GLY), aclidinium/formoterol (ACLI/FOR) and tiotropium/olodaterol (TIO/OLO) treatments in our prescribing/dispensing database. Prescriptions for systemic corticosteroids (SC), antibiotics and salbutamol during one year of LABA/LAMA treatment were analyzed. RESULTS: A better adherence was found in individuals taking IND/GLY (10.42 ± 1.86 packages/year) compared with UM/VI (10.09 ± 1.9; p = 0.008), ACLI/FOR (9.8 ± 1.8; p = 0.001) and TIO/OLO (10.1 ± 2.1; p = 0.047). The number of patients that were prescribed at least one package of SC/year and their package numbers/year were similar in males/females, across age groups and in "non-frequent exacerbators" with the 4 LABA/LAMAs. More SC were taken by frequent exacerbators, whereas fewer SC/antibiotic packages were prescribed to subjects aged >80 years with all treatments. In patients treated with ACLI/FOR or TIO/OLO, lower risks to having antibiotic prescriptions were observed when UM/VI (0.698[0.516-0.945] and 0.696[0.491-0.985; p = 0.020 and p = 0.041) and IND/GLY (0.597[0.445-0.802] and 0.595[0.423-0.836]; p = 0.001 and p = 0.003) were considered as landmarks. Lower risks for salbutamol prescriptions were detected with UM/VI (0.678[0.480-0.958]; p = 0.027) and TIO/OLO (0.585[0.365-0.937]; p = 0.026) when ACLI/FOR was used as a reference. CONCLUSION: According to our retrospective database study, each LABA/LAMA could have a specific efficacy profile in COPD that might be considered for personalized therapy. However, head-to-head targeted trials aimed to assess the impact of different LABA/LAMAs on COPD are needed to confirm/disprove such results.


Adrenergic beta-2 Receptor Agonists , Pulmonary Disease, Chronic Obstructive , Administration, Inhalation , Adrenergic beta-2 Receptor Agonists/therapeutic use , Bronchodilator Agents/therapeutic use , Drug Combinations , Female , Glycopyrrolate/therapeutic use , Humans , Male , Muscarinic Antagonists/therapeutic use , Pulmonary Disease, Chronic Obstructive/drug therapy , Retrospective Studies , Treatment Outcome
8.
Sci Adv ; 7(1)2021 01.
Article En | MEDLINE | ID: mdl-33187978

Using AI, we identified baricitinib as having antiviral and anticytokine efficacy. We now show a 71% (95% CI 0.15 to 0.58) mortality benefit in 83 patients with moderate-severe SARS-CoV-2 pneumonia with few drug-induced adverse events, including a large elderly cohort (median age, 81 years). An additional 48 cases with mild-moderate pneumonia recovered uneventfully. Using organotypic 3D cultures of primary human liver cells, we demonstrate that interferon-α2 increases ACE2 expression and SARS-CoV-2 infectivity in parenchymal cells by greater than fivefold. RNA-seq reveals gene response signatures associated with platelet activation, fully inhibited by baricitinib. Using viral load quantifications and superresolution microscopy, we found that baricitinib exerts activity rapidly through the inhibition of host proteins (numb-associated kinases), uniquely among antivirals. This reveals mechanistic actions of a Janus kinase-1/2 inhibitor targeting viral entry, replication, and the cytokine storm and is associated with beneficial outcomes including in severely ill elderly patients, data that incentivize further randomized controlled trials.


Antiviral Agents/pharmacology , Azetidines/pharmacology , COVID-19/mortality , Enzyme Inhibitors/pharmacology , Janus Kinases/antagonists & inhibitors , Liver/virology , Purines/pharmacology , Pyrazoles/pharmacology , SARS-CoV-2/pathogenicity , Sulfonamides/pharmacology , Adult , Aged , Aged, 80 and over , COVID-19/metabolism , COVID-19/virology , Cytokine Release Syndrome , Cytokines/metabolism , Drug Evaluation, Preclinical , Female , Gene Expression Profiling , Humans , Interferon alpha-2/metabolism , Italy , Janus Kinases/metabolism , Liver/drug effects , Male , Middle Aged , Patient Safety , Platelet Activation , Proportional Hazards Models , RNA-Seq , Spain , Virus Internalization/drug effects , COVID-19 Drug Treatment
9.
Curr Med Res Opin ; 36(12): 1991-1998, 2020 12.
Article En | MEDLINE | ID: mdl-33044088

OBJECTIVE: This study aimed to describe the demographic and clinical characteristics of migraineurs prescribed ≥1 migraine prophylactic therapy, and to analyze their therapeutic pathways, healthcare resource consumption, and related costs. METHODS: This retrospective analysis was based on administrative databases from two regions and three local health units in Italy. Adult patients with ≥1 discharge diagnosis for migraine or ≥1 prescription for migraine-specific drugs, or ≥1 emergency room visit for migraine from 1 January 2010 to 31 December 2016 were included if they had received ≥1 migraine prophylactic therapy between 1 January 2011 and 31 December 2015 (enrollment period). The first date of the last migraine prophylactic treatment was considered as the index date (ID). Patients were characterized 1-year prior ID and followed-up for 1 year afterwards. RESULTS: Of the 166,362 identified migraineurs, 32,794 (mean age: 45.9 ± 13.9 years, 19.2% male) who received migraine prophylaxis were included in the analysis. At ID, 31,629 patients had received 1 prophylactic treatment with antidepressants (51.2%), neuromodulators (28.1%), beta blockers (12.4%), other migraine preparations (7.8%), and botulinum toxin A (0.5%). Focusing on patients with one prophylactic treatment at ID, 85.4% did not have any previous therapeutic failures whereas 14.6% had ≥1 previous failure. During follow-up, 5% of patients made a therapeutic switch after a mean period of 103.4 ± 97.9 days. Total mean annual cost for patients receiving migraine prophylaxis was 1193.64€ during characterization and 1303.86€ during follow-up periods. CONCLUSION: This real-world study gave insights on the characterization of migraineurs and patterns of prophylaxis utilization in Italian clinical settings, showing an underuse of prophylactic agents.


Migraine Disorders/economics , Migraine Disorders/prevention & control , Patient Acceptance of Health Care/statistics & numerical data , Adrenergic beta-Antagonists/therapeutic use , Adult , Antidepressive Agents/therapeutic use , Botulinum Toxins, Type A/therapeutic use , Drug Costs , Female , Health Care Costs , Hospitalization/economics , Humans , Italy , Male , Middle Aged , Migraine Disorders/drug therapy , Retrospective Studies
10.
J Clin Med ; 9(8)2020 Aug 18.
Article En | MEDLINE | ID: mdl-32824861

The combination of atrial fibrillation (AF) and acute coronary syndrome (ACS) is a complex situation in which a three-dimensional risk-cardioembolic, coronary, and hemorrhagic-has to be carefully managed. Triple antithrombotic therapy (TAT) is burdened with a high risk of serious bleeding, while dual antithrombotic therapy with an anticoagulant (DAT) likely provides only suboptimal coronary protection early after stent implantation. Moreover, TAT precludes the advantages provided by the use of the latest and more potent P2Y12 inhibitors in ACS patients. Here, we aimed to simulate and compare the expected coronary, cardioembolic, and hemorrhagic outcomes offered by DAT, TAT, or modern dual antiplatelet therapy (DAPT) with aspirin plus one of the latest P2Y12 inhibitors in AF patients early after an ACS. The comparison of numbers needed to treat to prevent major adverse events with the various antithrombotic regimens suggests that AF-ACS patients at high ischemic and hemorrhagic risk and at moderately low embolic risk (CHA2DS2VASc score 2-4) might safely withhold anticoagulation after revascularization for one month taking advantage of a modern DAPT, with a favorable risk-to-benefit ratio. In conclusion, this strategy, not sufficiently addressed in recent European and North American guidelines or consensus documents, adds to the spectrum of treatment options in these difficult patients; it might be the best choice in a substantial number of patients; and should be prospectively tested in a randomized controlled trial.

11.
J Diabetes Res ; 2019: 3174654, 2019.
Article En | MEDLINE | ID: mdl-31976334

BACKGROUND: This study is aimed at estimating the proportion of type 2 diabetes mellitus (T2DM) patients treated with basal insulin (insulin glargine U100) and at evaluating daily insulin dose, treatment pattern, and adherence to treatment of these patients. METHODS: Data from administrative and laboratory databases of 3 Italian Local Health Units were retrospectively collected and analyzed. All patients with a diagnosis of T2DM between 01/01/2012 and 31/12/2012 were considered, and those with at least a prescription of insulin glargine between 01/01/2013 and 31/12/2014 were included and followed up for one year. For each patient, we evaluated HbA1c levels both at baseline and during the follow-up period and the daily average dose of insulin. Medication adherence was defined by using medication possession ratio (MPR) and reported as proportion of patients with MPR ≥ 80%. RESULTS: 7,422 T2DM patients were available for the study. According to the antidiabetic medication prescribed, patients were categorized into four groups: insulin glargine only, insulin glargine plus oral glucose-lowering drugs, insulin glargine plus rapid-acting insulin, and insulin glargine plus DPP-4 inhibitors. Median daily dose of insulin among insulin glargine only patients was higher than in other groups (35 IU vs. 20 IU, p < 0.05), and a higher percentage of them achieved a target HbA1c value of less than 7.0% (53.8% vs. 30%, p < 0.001). Adherence to insulin treatment was lowest (41%) in the insulin glargine only group compared to other groups (ranging from 58.4% to 64.4%), p < 0.001. CONCLUSIONS: A large proportion of T2DM patients treated with insulin fail in achieving the glycemic target of HbA1c level < 7%, irrespective of treatment regimen; however, basal insulin only is associated with lower therapeutic unsuccess. Adherence to antidiabetes medications is also suboptimal in these patients and should be addressed to improve long-term outcomes of reducing and preventing microvascular and macrovascular complications.


Diabetes Mellitus, Type 2/drug therapy , Hypoglycemic Agents/therapeutic use , Insulin Glargine/therapeutic use , Aged , Aged, 80 and over , Diabetes Mellitus, Type 2/blood , Female , Glycated Hemoglobin/analysis , Humans , Male , Medication Adherence , Middle Aged , Retrospective Studies
12.
Eur J Pharm Biopharm ; 107: 180-90, 2016 Oct.
Article En | MEDLINE | ID: mdl-27368749

Beyond the therapeutic purpose, the impact of drug delivery microparticles on the local tissue and inflammatory responses remains to be further elucidated specifically for reactions mediated by the host immune cells. Such immediate and prolonged reactions may adversely influence the release efficacy and intended therapeutic pathway. The lack of suitable in vitro platforms limits our ability to gain insight into the nature of immune responses at a single cell level. In order to establish an in vitro 3D system mimicking the connective host tissue counterpart, we utilized reproducible, compressed, rat-tail collagen polymerized matrices. THP1 cells (human acute monocytic leukaemia cells) differentiated into macrophage-like cells were chosen as cell model and their functionality was retained in the dense rat-tail collagen matrix. Placebo microparticles were later combined in the immune cell seeded system during collagen polymerization and secreted pro-inflammatory factors: TNFα and IL-8 were used as immune response readout (ELISA). Our data showed an elevated TNFα and IL-8 secretion by macrophage THP1 cells indicating that Placebo microparticles trigger certain immune cell responses under 3D in vivo like conditions. Furthermore, we have shown that the system is sensitive to measure the differences in THP1 macrophage pro-inflammatory responses to Active Pharmaceutical Ingredient (API) microparticles with different API release kinetics. We have successfully developed a tissue-like, advanced, in vitro system enabling selective "readouts" of specific responses of immune-related cells. Such system may provide the basis of an advanced toolbox enabling systemic evaluation and prediction of in vivo microparticle reactions on human immune-related cells.


Collagen/chemistry , Drug Carriers , Animals , Cell Line , Humans , Lactic Acid , Polyglycolic Acid , Polylactic Acid-Polyglycolic Acid Copolymer , Rats , Reproducibility of Results , Rheology
13.
J Mater Chem B ; 2(23): 3567-3577, 2014 Jun 21.
Article En | MEDLINE | ID: mdl-32263793

This article presents a critical overview of the most significant developments in the use of polymers as hemostatic agents. The materials have been divided into two groups, which are, naturally occurring and synthetic. Remarkable examples include collagen, chitosan, bovine serum albumin/glutaraldehyde hydrogels, poly(cyanoacrylate)s and poly(alkylene oxide)s. The different mechanisms for their modes of action as well as the structural features that are believed to induce hemostasis are discussed. Finally, an overview of the future challenges is given.

14.
Chem Commun (Camb) ; 47(22): 6464-6, 2011 Jun 14.
Article En | MEDLINE | ID: mdl-21552589

The preparation of acrylic polymers with predetermined molecular weights using metalloenzymes as catalysts, ascorbic acid as reducing agent and alkyl halides as initiators is reported. The mechanism of polymerization resembles an ARGET ATRP process.


Catalase/metabolism , Laccase/metabolism , Peroxidase/metabolism , Polyethylene Glycols/chemistry , Polymethacrylic Acids/chemistry , Water/chemistry , Animals , Armoracia/enzymology , Ascorbic Acid/chemistry , Biocatalysis , Cattle , Halogens/chemistry , Liver/enzymology , Polymerization , Reducing Agents/chemistry , Trametes/enzymology
16.
Dalton Trans ; (41): 8878-84, 2009 Nov 07.
Article En | MEDLINE | ID: mdl-19826719

An electrospray ionization mass spectrometer equipped with a quadrupole ion trap as the mass analyzer provided a powerful tool for the investigation of metal ligand affinities of catalysts for atom transfer radical polymerization. It allowed, in particular, (i) the identification, in a library of ligands, of the most stable, and thus active, copper catalysts; (ii) the assessment of the effects of the reaction medium on the relative stabilities of the catalyst complexes; and (iii) the evaluation of the influence of the nature of the ligand on both the complex halogenophilicity and the metal-ligand stabilities in the gas-phase.

17.
Chem Commun (Camb) ; (47): 6306-8, 2008 Dec 21.
Article En | MEDLINE | ID: mdl-19048137

An ESI-MS-based methodology allows for a rapid assay of ATRP catalyst performance without prior polymerization experiments.

18.
J Am Chem Soc ; 129(10): 2796-802, 2007 Mar 14.
Article En | MEDLINE | ID: mdl-17302412

Fourier transform ion mobility spectrometry is used to determine the branching in mass-selected, chemically trapped oligomers produced in the polymerization of ethylene by a metallocene catalyst activated by methylalumoxane. The measured branching is included in a kinetic analysis to extract the activation energies for the elementary steps in polyethylene formation. Propagation, chain transfer, and chain walking have activation energies of 4.1, 11, and 11 kcal/mol.

19.
Chem Commun (Camb) ; (41): 4309-11, 2006 Nov 04.
Article En | MEDLINE | ID: mdl-17047850

Chemical trapping of metal-bound oligomeric chains during the MAO-activated, metallocene-catalyzed polymerization of ethylene identify the two observed chain-bearing species to be alkylzirconocenium species and higher alkyl aluminiums, consistent with a proposed mechanism.

20.
Chem Commun (Camb) ; (46): 5757-9, 2005 Dec 14.
Article En | MEDLINE | ID: mdl-16307136

Electrospray ionization mass spectrometry (ESI-MS) of MAO-activated metallocene-catalyzed polymerizations quenched with carbodiimides provides a method for the determination of rate constants in Ziegler-Natta polymerizations.

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