The behaviour of poly(2,3-epoxypropyl methacrylate) in dilute solution

Homopolymers of 2,3-epoxypropyl methacrylate with various molecular masses were prepared by solution polymerization with 2,2′-azoisobutyronitrile as initiator. The effect of polymerization conditions on the molecular parameters (weight- and number-average molecular masses M_W and M_n intrinsic viscosity [η]) and the tacticity of the resulting poly (2,3-epoxypropyl methacrylate)s was investigated. For unfractionated polymers, the constants of the Mark-Houwink equation for 1,4-dioxane and tetrahydrofuran were determined. Gel permeation chromatography was tested as a tool for the determination of the M_w and M_n values.     

Poly(oxyethylene) terminated with tertiary amino or quaternary ammonium groups

α-(3-Dimethylaminopropyl)-ω-dimethylaminomethylpoly(oxyethylene)s (2a–e) were prepared from α-(3-aminopropyl)-ω-aminomethylpoly(oxyethylene)s (1a–e) (M?_n = 430–2300 g·mol^?1), by the Wallach-Leuckart reaction, with a degree of transformation of ? NH₂ into ? N(CH₃)₂ groups of 70–98%. The samples were characterized by means of IR spectrometry and Siggia's acylation method, adjusted for microdetermination. The polymers terminated with 3-dimethylaminopropoxy groups were transformed into the corresponding derivatives bearing quaternary ammonium end groups, and characterized both as dihydroxides and dichlorides. The content of the quaternary ammonium groups was found to differ considerably for the individual samples in the range of 19–97%. The reason for this variability was found not to be a low efficiency of the quaternization reaction, but the Hofmann-degradation giving rise to terminal vinyl groups of the polyether chain.     

Minimisation of priming volume and blood saving in paediatric cardiac surgery.

We started a programme of donor blood reduction for open heart surgery in children in 1983. At first, only meticulous surgical and perfusion techniques were used. Later, increased haemodilution was added. Miniaturisation of the perfusion circuit and introduction of blood taken prior from the patient further decreased donor blood requirements. In 1989, we used 0.89 l per patient compared to 3.2 l per patient in 1983. Miniaturisation of the circuit was tested in a pilot study on 30 children undergoing the Senning operation in 1988. Priming volume was reduced from 661 +/- 72 ml to 421 +/- 62 ml. In 1989, 167 out of 194 children (86%) received a clear prime. Ninety-seven of 100 children whose weight was over 15 kg received a clear prime: 55 did not require subsequent transfusion. Prime miniaturisation and autotransfusion can considerably reduce blood requirements for open heart surgery.     

Diffusion and Reaction of Methylaluminoxane (MAO) within a Silica Membrane

Summary: The self‐diffusion coefficient of MAO confined within a silica membrane is not experimentally accessible by traditional PFG NMR measurements, probably due to a susceptibility effect resulting in rather broad, unobservable resonance lines. A more indirect approach was therefore applied to probe the diffusivity of MAO within a silica membrane. MAO confined in a bulk toluene solution on one side of the membrane was free to diffuse through the membrane (saturated with toluene) and into a corresponding deuterated toluene solution on the other side of the membrane where its proton NMR signal intensity was monitored as a function of time. By introducing a relevant diffusion model, the diffusivities of both toluene and MAO were derived by model‐fitting. By refining the diffusion model, the formation of methane within the silica was explained, and its diffusivity estimated. The results suggest a significant reduction in diffusivities of both MAO and toluene within the silica as compared to the corresponding diffusivities in bulk solution.

¹H NMR spectra as a function of time within the shift region δ = 2.0–2.5 ppm (toluene) acquired during the first 40 h of the diffusion process.     

NMR evidence of the block structure of poly(methyl methacrylate)-block-poly(ethyl acrylate) prepared by group transfer polymerization

The structure of poly(methyl methacrylate)-block-poly(ethyl acrylate) prepared by group transfer polymerization was studied by ¹H and ¹³C 1 D and 2D NMR methods including SINEPT, COSY, LR H-H-C RELAY and COLOC using model homopolymers of methyl methacrylate (MMA) and ethyl acrylate (EA) of a length equal to that of the blocks and prepared under the same conditions. The ¹H and ¹³C spectra of the copolymer are shown to be a superposition of the respective spectra of the homopolymers, with the exception that the copolymer lacks the terminal group present in the MMA homopolymer and the initiating group of the EA polymer. Moreover, a new minor signal is found in the CH₂ region of the copolymer which is shown to belong to the link of the blocks. The existence of a direct link between the blocks is further supported by the results of 1D and 2D coherence transfer methods, especially, those using the newly modified DS INEPT and H-C-C RELAY pulse sequences.     

Cost-effectiveness of adding oseltamivir to primary care for influenza-like-illness: economic evaluation alongside the randomised controlled ALIC4E trial in 15 European countries

Background

Oseltamivir is usually not often prescribed (or reimbursed) for non-high-risk patients consulting for influenza-like-illness (ILI) in primary care in Europe. We aimed to evaluate the cost-effectiveness of adding oseltamivir to usual primary care in adults/adolescents (13 years +) and children with ILI during seasonal influenza epidemics, using data collected in an open-label, multi-season, randomised controlled trial of oseltamivir in 15 European countries.

Methods

Direct and indirect cost estimates were based on patient reported resource use and official country-specific unit costs. Health-Related Quality of Life was assessed by EQ-5D questionnaires. Costs and quality adjusted life-years (QALY) were bootstrapped (N = 10,000) to estimate incremental cost-effectiveness ratios (ICER), from both the healthcare payers’ and the societal perspectives, with uncertainty expressed through probabilistic sensitivity analysis and expected value for perfect information (EVPI) analysis. Additionally, scenario (self-reported spending), comorbidities subgroup and country-specific analyses were performed.

Results

The healthcare payers’ expected ICERs of oseltamivir were €22,459 per QALY gained in adults/adolescents and €13,001 in children. From the societal perspective, oseltamivir was cost-saving in adults/adolescents, but the ICER is €8,344 in children. Large uncertainties were observed in subgroups with comorbidities, especially for children. The expected ICERs and extent of decision uncertainty varied between countries (EVPI ranged €1–€35 per patient).

Conclusion

Adding oseltamivir to primary usual care in Europe is likely to be cost-effective for treating adults/adolescents and children with ILI from the healthcare payers’ perspective (if willingness-to-pay per QALY gained > €22,459) and cost-saving in adults/adolescents from a societal perspective.

     

Prevalence and sociodemographic determinants of uninvestigated dyspepsia in the Czech Republic

OBJECTIVE: There are no data on the epidemiology of dyspepsia in Central Europe. The aim of this study was to evaluate the prevalence of uninvestigated dyspepsia in a representative sample of the Czech population. METHODS: A total of 2509 persons, aged 5-100 years, randomly selected from 30 012 individuals in the general population, entered this multicentre, prospective, questionnaire-based epidemiological study. RESULTS: We found a 17% prevalence of long-lasting (>12 months) dyspeptic symptoms in the general population. Two subgroups were distinguished: (i) persons with dyspepsia as the only one long-lasting symptom and themselves feeling otherwise healthy (9%), mostly among younger patients (subgroup A); and (ii) patients with dyspepsia as part of the complex of previously recognized diseases (8%), mostly in older patients (subgroup B). The prevalence of dyspepsia was significantly higher among women. The excess cases of dyspepsia among the highly educated seemed to be cases of dyspepsia of subgroup A, and the higher prevalence of dyspepsia among the lower social classes was largely dyspepsia of subgroup B. Being a widow/widower had a significant effect on the risk of self-reported dyspepsia among 25-64-year-olds. No association between Helicobacter pylori infection and dyspepsia was found. CONCLUSION: The prevalence of uninvestigated dyspepsia in the Czech Republic is comparable with data from other European countries. Clearly distinct subgroups of dyspeptic patients exist that should be further studied.