High resolution NMR analysis of the stereochemistry of poly(methyl methacrylate)

Ferguson, Raymond C.; Ovenall, Derick W.

doi:10.1021/ma00172a014

Cited by 71 publications

(34 citation statements)

References 4 publications

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“…The peak corresponding to mm (isotactic) diad could not be seen in the 13 C NMR spectrum. The PMMA prepared by the conventional radical polymerization39 (using AIBN and BPO) also results in a predominantly syndiotactic PMMA (53 to 63%), and our results indicate that the ( R )‐BBiBN bifunctional initiator behaves as a typical ATRP initiator with no specific effect on polymer stereochemistry. The resulting polymer showed [α] D = 10.3 (c = 0.50 g/dL in THF at 25 °C), indicating that racemization was not taking place during the period of polymerization.…”

Section: Resultsmentioning

confidence: 64%

“…The 13 C NMR spectrum of PMMA prepared using ( R )‐BBiBN/CuCl/PMDETA/50% (v/v) anisole as the initiation system is shown in Figure 8. The tacticity of PMMA was calculated from the signal corresponding to the quaternary carbon group (C2) 39. According to the integral area of the peaks of rr (syndiotactic 44.52 ppm) and rm(mr) (atactic 44.86 ppm) diads, the stereochemistry of PMMA is observed to be predominately syndiotactic ( rr, 67.2%) with the remaining being atatctic (32.6%).…”

Section: Resultsmentioning

confidence: 99%

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Long‐term anti–tumor necrosis factor antibody therapy in rheumatoid arthritis patients sensitizes the pituitary gland and favors adrenal androgen secretion

Straub

Pongratz

Schölmerich

et al. 2003

Arthritis & Rheumatism

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Objective. New insights into the role of tumor necrosis factor (TNF) in the pathogenesis of rheumatoid arthritis (RA) have expanded our understanding about the possible mechanisms by which anti-TNF antibody therapy reduces local synovial inflammation. Beyond local effects, anti-TNF treatment may modulate systemic antiinflammatory pathways such as the hypothalamic-pituitary-adrenal (HPA) axis. This longitudinal anti-TNF therapy study was designed to assess these effects in RA patients.Methods. RA patients were given 5 infusions of anti-TNF at weeks 0, 2, 6, 10, and 14, with followup observation until week 16. We measured serum levels of interleukin-6 (IL-6), adrenocorticotropic hormone (ACTH), 17-hydroxyprogesterone (17[OH]progesterone), cortisol, cortisone, androstenedione (ASD), dehydroepiandrosterone (DHEA), and DHEA sulfate in 19 RA patients.Results. Upon treatment with anti-TNF, we observed a fast decrease in the levels of serum IL-6, particularly in RA patients who did not receive parallel prednisolone treatment (P ‫؍‬ 0.043). In these RA patients who had not received prednisolone, the mean serum ACTH levels sharply increased after every injection of anti-TNF, which indicates a sensitization of the pituitary gland (not observed for the adrenal gland). During treatment, the ratio of serum cortisol to serum ACTH decreased, which also indicates a sensitization of the pituitary gland (P < 0.001), and which was paralleled by constant cortisol secretion. The adrenal androgen ASD significantly increased relative to its precursor 17(OH)progesterone (P ‫؍‬ 0.013) and relative to cortisol (P ‫؍‬ 0.009), which indicates a normalization of adrenal androgen production. The comparison of patients previously treated with prednisolone and those without previous prednisolone revealed marked differences in the central and adrenal level of this endocrine axis during long-term anti-TNF therapy.Conclusion. Long-term therapy with anti-TNF sensitizes the pituitary gland and improves adrenal androgen secretion in patients who have not previously received prednisolone treatment. These changes are indicative of normalization of the HPA axis and must therefore be considered as evidence of an additional antiinflammatory influence of anti-TNF treatment in patients with RA.

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Section: Resultsmentioning

confidence: 64%

Section: Resultsmentioning

confidence: 99%

Long‐term anti–tumor necrosis factor antibody therapy in rheumatoid arthritis patients sensitizes the pituitary gland and favors adrenal androgen secretion

Straub

Pongratz

Schölmerich

et al. 2003

Arthritis & Rheumatism

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“…Figure 3 shows the 13 C NMR spectra of the PMMA and PMMA‐AES blends. The triad tacticity of PMMA was determined on the basis of the peaks of the CO group and α‐methyl group in the 13 C NMR spectra 24, 25. The 13 C NMR resonance of the ester carbonyl group is recorded in the region of 176‐179 ppm and the α‐methyl group is recorded in the region of 16‐22 ppm 24, 26.…”

Section: Resultsmentioning

confidence: 99%

Natural Compounds against Alzheimer’s Disease: Molecular Recognition of Aβ1–42 Peptide by Salvia sclareoides Extract and its Major Component, Rosmarinic Acid, as Investigated by NMR

Airoldi

Sironi

Dias

et al. 2013

Chemistry An Asian Journal

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Amyloid peptides, Aβ1-40 and Aβ1-42, represent major molecular targets to develop potential drugs and diagnostic tools for Alzheimer's Disease (AD). In fact, oligomeric and fibrillar aggregates generated by these peptides are amongst the principal components of amyloid plaques found post mortem in patients suffering from AD. Rosmarinic acid has been demonstrated to be effective in preventing the aggregation of amyloid peptides in vitro and to delay the progression of the disease in animal models. Nevertheless, no information is available about its molecular mechanism of action. Herein, we report the NMR characterization of the interaction of Salvia sclareoides extract and that of its major component, rosmarinic acid, with Aβ1-42 peptide, whose oligomers have been described as the most toxic Aβ species in vivo. Our data shed light on the structural determinants of rosmarinic acid-Aβ1-42 oligomers interaction, thus allowing the elucidation of its mechanism of action. They also provide important information for the rational design of new compounds with higher affinity for Aβ peptides to generate new anti-amyloidogenic molecules and/or molecular tools for the specific targeting of amyloid aggregates in vivo. In addition, we identified methyl caffeate, another natural compound present in different plants and human diet, as a good ligand of Aβ1-42 oligomers, which also shows anti-amyloidogenic activity. Finally, we demonstrated the possibility to exploit STD-NMR and trNOESY experiments to screen extracts from natural sources for the presence of Aβ peptide ligands.

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“…The copolymer composition with MMA is interesting due to the fact that the 13 C NMR spectrum for polymethylmethacrylate (PMMA) is the most studied [9][10][11], despite the fact that the copolymer of MMA with VBE comprises slightly more than 50% of acrylate units, whereas compositions with BA are practically equimolar [5][6][7]. In order to obtain comparable data PVBE homopolymer was also synthesized.…”

Section: Resultsmentioning

confidence: 99%

Structure of the copolymers of alkyl methacrylate and vinyl alkyl ethers, novel viscosity modifiers of lubricating oils

et al. 2015

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Copolymers of vinyl butyl ethers and alkyl methacrylates may fi nd use as resource-saving viscosity modifi ers of oils that is due to a new approach to their synthesis, which allows reaching high compositional homogeneity of the polymer chain. The data of 13 C NMR spectroscopy were reported which show the structure of alternating copolymers obtained by compensation copolymerization in boiling monomer under the radical initiation.

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High resolution NMR analysis of the stereochemistry of poly(methyl methacrylate)

Cited by 71 publications

References 4 publications

Long‐term anti–tumor necrosis factor antibody therapy in rheumatoid arthritis patients sensitizes the pituitary gland and favors adrenal androgen secretion

Long‐term anti–tumor necrosis factor antibody therapy in rheumatoid arthritis patients sensitizes the pituitary gland and favors adrenal androgen secretion

Natural Compounds against Alzheimer’s Disease: Molecular Recognition of Aβ1–42 Peptide by Salvia sclareoides Extract and its Major Component, Rosmarinic Acid, as Investigated by NMR

Structure of the copolymers of alkyl methacrylate and vinyl alkyl ethers, novel viscosity modifiers of lubricating oils

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