36 research outputs found
Iron-induced relaxation mechanisms in the human substantia nigra: Towards quantifying iron load in dopaminergic neurons
Pathological iron accumulation in the human brain is a biomarker for neurodegeneration. Several diagnostically promising MR- based methods for in vivo iron quantification were proposed, based on the empirical relationship between R 2 * and iron concentration. However, these do not account for different chemical forms and cellular distribution of iron. We combined post mortem MRI, advanced quantitative histology and biophysical modeling to develop a generative theory linking obtained iron concentrations to quantitative MR parameters. The impact of nanoscale molecular interaction of water with iron and of iron-rich dopaminergic neurons was quantified in substantia nigra
Cell specific quantitative iron mapping on brain slices by immuno-ΞΌPIXE in healthy elderly and Parkinsonβs disease
Iron is essential for neurons and glial cells, playing key roles in neurotransmitter synthesis, energy production and myelination. In contrast, high concentrations of free iron can be detrimental and contribute to neurodegeneration, through promotion of oxidative stress. Particularly in Parkinsonβs disease (PD) changes in iron concentrations in the substantia nigra (SN) was suggested to play a key role in degeneration of dopaminergic neurons in nigrosome 1. However, the cellular iron pathways and the mechanisms of the pathogenic role of iron in PD are not well understood, mainly due to the lack of quantitative analytical techniques for iron quantification with subcellular resolution. Here, we quantified cellular iron concentrations and subcellular iron distribution in dopaminergic neurons and different types of glial cells in the SN both in brains of PD patients and in non-neurodegenerative control brains (Co). To this end, we combined spatially resolved quantitative element mapping using micro particle induced X-ray emission (ΞΌPIXE) with nickel-enhanced immunocytochemical detection of cell type-specific antigens allowing to allocate element-related signals to specific cell types. Distinct patterns of iron accumulation were observed across different cell populations. In the control (Co) SNc, oligodendroglial and astroglial cells hold the highest cellular iron concentration whereas in PD, the iron concentration was increased in most cell types in the substantia nigra except for astroglial cells and ferritin-positive oligodendroglial cells. While iron levels in astroglial cells remain unchanged, ferritin in oligodendroglial cells seems to be depleted by almost half in PD. The highest cellular iron levels in neurons were located in the cytoplasm, which might increase the source of non-chelated Fe3+, implicating a critical increase in the labile iron pool. Indeed, neuromelanin is characterised by a significantly higher loading of iron including most probable the occupancy of low-affinity iron binding sites. Quantitative trace element analysis is essential to characterise iron in oxidative processes in PD. The quantification of iron provides deeper insights into changes of cellular iron levels in PD and may contribute to the research in iron-chelating disease-modifying drugs
Cell specific quantitative iron mapping on brain slices by immuno-Β΅PIXE in healthy elderly and Parkinsonβs disease
Iron is essential for neurons and glial cells, playing key roles in neurotransmitter synthesis, energy production and myelination. In contrast, high concentrations of free iron can be detrimental and contribute to neurodegeneration, through promotion of oxidative stress. Particularly in Parkinson's disease (PD) changes in iron concentrations in the substantia nigra (SN) was suggested to play a key role in degeneration of dopaminergic neurons in nigrosome 1. However, the cellular iron pathways and the mechanisms of the pathogenic role of iron in PD are not well understood, mainly due to the lack of quantitative analytical techniques for iron quantification with subcellular resolution. Here, we quantified cellular iron concentrations and subcellular iron distributions in dopaminergic neurons and different types of glial cells in the SN both in brains of PD patients and in non-neurodegenerative control brains (Co). To this end, we combined spatially resolved quantitative element mapping using micro particle induced X-ray emission (mu PIXE) with nickel-enhanced immunocytochemical detection of cell type-specific antigens allowing to allocate element-related signals to specific cell types. Distinct patterns of iron accumulation were observed across different cell populations. In the control (Co) SNc, oligodendroglial and astroglial cells hold the highest cellular iron concentration whereas in PD, the iron concentration was increased in most cell types in the substantia nigra except for astroglial cells and ferritin-positive oligodendroglial cells. While iron levels in astroglial cells remain unchanged, ferritin in oligodendroglial cells seems to be depleted by almost half in PD. The highest cellular iron levels in neurons were located in the cytoplasm, which might increase the source of non-chelated Fe3+, implicating a critical increase in the labile iron pool. Indeed, neuromelanin is characterised by a significantly higher loading of iron including most probable the occupancy of low-affinity iron binding sites. Quantitative trace element analysis is essential to characterise iron in oxidative processes in PD. The quantification of iron provides deeper insights into changes of cellular iron levels in PD and may contribute to the research in iron-chelating disease-modifying drugs
ΠΠΎΠ²Π΅Π΄Π΅Π½ΠΈΠ΅ ΠΌΠΎΡΡΠΎΠ»ΠΈΠ½Π° ΠΈ Π΅Π³ΠΎ ΡΡΠΈΠΌΠ΅ΡΠΈΠ»ΡΠΈΠ»ΠΈΠ»ΠΏΡΠΎΠΈΠ·Π²ΠΎΠ΄Π½ΠΎΠ³ΠΎ Π² ΡΠ΅Π°ΠΊΡΠΈΡΡ Ρ ΡΡΠΈΠΌΠ΅ΡΠΈΠ»ΡΠΈΠ»ΠΈΠ»ΠΈΠ·ΠΎΡΠΈΠ°Π½Π°ΡΠΎΠΌ
Objectives. To study the patterns of behavior of morpholine and its trimethylsilyl derivative in reactions with trimethylsilyl isocyanate.Methods. The study employed infrared and nuclear magnetic resonance spectroscopy, as well as elemental analysis.Results. The formation of mixtures of tautomeric forms of silicon-containing ureaβN-(trimethylsilyl) morpholine-4-carboxamide and trimethylsilylmorpholine-4-carboximidoateβwas established.Conclusions. It is shown that the composition and structure of the resulting products are determined both by the presence of a morpholine substituent at the nitrogen atom and by the type of isocyanate used. Unlike the trimethylsilyl derivative of morpholine, morpholine itself reacts with trimethylsilyl isocyanate to form a mixture of tautomeric forms.Π¦Π΅Π»ΠΈ. ΠΠ·ΡΡΠΈΡΡ Π·Π°ΠΊΠΎΠ½ΠΎΠΌΠ΅ΡΠ½ΠΎΡΡΠΈ ΠΏΠΎΠ²Π΅Π΄Π΅Π½ΠΈΡ ΠΌΠΎΡΡΠΎΠ»ΠΈΠ½Π° ΠΈ Π΅Π³ΠΎ ΡΡΠΈΠΌΠ΅ΡΠΈΠ»ΡΠΈΠ»ΠΈΠ»ΠΏΡΠΎΠΈΠ·Π²ΠΎΠ΄Π½ΠΎΠ³ΠΎ Π² ΡΠ΅Π°ΠΊΡΠΈΡΡ
Ρ ΡΡΠΈΠΌΠ΅ΡΠΈΠ»ΡΠΈΠ»ΠΈΠ»ΠΈΠ·ΠΎΡΠΈΠ°Π½Π°ΡΠΎΠΌ.ΠΠ΅ΡΠΎΠ΄Ρ. Π ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΈ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π»ΠΈΡΡ ΠΌΠ΅ΡΠΎΠ΄Ρ ΠΈΠ½ΡΡΠ°ΠΊΡΠ°ΡΠ½ΠΎΠΉ ΡΠΏΠ΅ΠΊΡΡΠΎΡΠΊΠΎΠΏΠΈΠΈ, ΡΠΏΠ΅ΠΊΡΡΠΎΡΠΊΠΎΠΏΠΈΠΈ ΡΠ΄Π΅ΡΠ½ΠΎΠ³ΠΎ ΠΌΠ°Π³Π½ΠΈΡΠ½ΠΎΠ³ΠΎ ΡΠ΅Π·ΠΎΠ½Π°Π½ΡΠ° ΠΈ ΡΠ»Π΅ΠΌΠ΅Π½ΡΠ½ΠΎΠ³ΠΎ Π°Π½Π°Π»ΠΈΠ·Π°.Π Π΅Π·ΡΠ»ΡΡΠ°ΡΡ. Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΎ ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΠ΅ ΡΠΌΠ΅ΡΠΈ ΡΠ°ΡΡΠΎΠΌΠ΅ΡΠ½ΡΡ
ΡΠΎΡΠΌ ΠΊΡΠ΅ΠΌΠ½ΠΈΠΉΡΠΎΠ΄Π΅ΡΠΆΠ°ΡΠ΅ΠΉ ΠΌΠΎΡΠ΅Π²ΠΈΠ½Ρ: N-(ΡΡΠΈΠΌΠ΅ΡΠΈΠ»ΡΠΈΠ»ΠΈΠ»)ΠΌΠΎΡΡΠΎΠ»ΠΈΠ½-4-ΠΊΠ°ΡΠ±ΠΎΠΊΡΠ°ΠΌΠΈΠ΄Π° ΠΈ ΡΡΠΈΠΌΠ΅ΡΠΈΠ»ΡΠΈΠ»ΠΈΠ»ΠΌΠΎΡΡΠΎΠ»ΠΈΠ½ -4-ΠΊΠ°ΡΠ±ΠΎΠΊΡΠΈΠΌΠΈΠ΄ΠΎΠ°ΡΠ°.ΠΡΠ²ΠΎΠ΄Ρ. Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΎ, ΡΡΠΎ ΡΠΎΡΡΠ°Π² ΠΈ ΡΡΡΠΎΠ΅Π½ΠΈΠ΅ ΠΎΠ±ΡΠ°Π·ΡΡΡΠΈΡ
ΡΡ ΠΏΡΠΎΠ΄ΡΠΊΡΠΎΠ² ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΠ΅ΡΡΡ ΠΊΠ°ΠΊ Π½Π°Π»ΠΈΡΠΈΠ΅ΠΌ Π·Π°ΠΌΠ΅ΡΡΠΈΡΠ΅Π»Ρ ΠΏΡΠΈ Π°ΡΠΎΠΌΠ΅ Π°Π·ΠΎΡΠ° ΠΌΠΎΡΡΠΎΠ»ΠΈΠ½Π°, ΡΠ°ΠΊ ΠΈ ΡΠΈΠΏΠΎΠΌ ΠΈΡΠΏΠΎΠ»ΡΠ·ΡΠ΅ΠΌΠΎΠ³ΠΎ ΠΈΠ·ΠΎΡΠΈΠ°Π½Π°ΡΠ°. ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ, Π² ΠΎΡΠ»ΠΈΡΠΈΠ΅ ΠΎΡ ΡΡΠΈΠΌΠ΅ΡΠΈΠ»ΡΠΈΠ»ΠΈΠ»ΡΠ½ΠΎΠ³ΠΎ ΠΏΡΠΎΠΈΠ·Π²ΠΎΠ΄Π½ΠΎΠ³ΠΎ ΠΌΠΎΡΡΠΎΠ»ΠΈΠ½Π°, ΡΠ°ΠΌ ΠΌΠΎΡΡΠΎΠ»ΠΈΠ½ Π²Π·Π°ΠΈΠΌΠΎΠ΄Π΅ΠΉΡΡΠ²ΡΠ΅Ρ Ρ ΡΡΠΈΠΌΠ΅ΡΠΈΠ»ΡΠΈΠ»ΠΈΠ»ΠΈΠ·ΠΎΡΠΈΠ°Π½Π°ΡΠΎΠΌ Ρ ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΡΠΌΠ΅ΡΠΈ ΡΠ°ΡΡΠΎΠΌΠ΅ΡΠ½ΡΡ
ΡΠΎΡΠΌ
ΠΠ‘ΠΠΠΠΠΠΠ‘Π’Π ΠΠΠΠΠΠΠΠΠΠ‘Π’ΠΠΠ― ΠΠΠΠ¦ΠΠΠΠΠ’ΠΠ Π‘ ΠΠ ΠΠΠΠΠΠΠΠ«ΠΠ ΠΠΠΠ ΠΠΠΠΠ
The results of studies on chemical transformations of organic and organosilicon isocyanates in their interaction with hydrazine derivatives have been summarized in this review. It is shown that hydrazine and its derivatives including organosilicon compounds reacting with organic isocyanates form corresponding semicarbazides readily enough. The reaction conditions that effect the composition, structure and yield of the resulting target products are presented. A significant difference in the interaction of trimethylsilyl isocyanate with organic and organosilicon derivatives of hydrazine is demonstrated. It is demonstrated that the reason for the impossibility to isolate trimethylsilyl derivatives of semicarbazide is their low hydrolytic stability, as well as high silylating ability. Peculiarities of the reaction of trimethylsilyl isocyanate and dimethylchloromethyl isocyanate silane with 1,1-dimethylhydrazine, its trimethylsilyl analog and isoniazid are given. Possible schemes for the formation of a previously unknown O-trimethylsilyl-1,1-dimethylhydrazinecarboximidoate are presented. The results of using carbofunctional organosilicon isocyanates in these processes are discussed. Basic trends in practical use of the prepared compounds as physiologically active preparations in polymer chemistry and agriculture are shown.Π ΠΎΠ±Π·ΠΎΡΠ΅ ΠΎΠ±ΠΎΠ±ΡΠ΅Π½Ρ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΡ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΉ ΠΏΠΎ ΠΈΠ·ΡΡΠ΅Π½ΠΈΡ Ρ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΏΡΠ΅Π²ΡΠ°ΡΠ΅Π½ΠΈΠΉ ΠΎΡΠ³Π°Π½ΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΈ ΠΊΡΠ΅ΠΌΠ½ΠΈΠΉΠΎΡΠ³Π°Π½ΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΈΠ·ΠΎΡΠΈΠ°Π½Π°ΡΠΎΠ² ΠΏΡΠΈ ΠΈΡ
Π²Π·Π°ΠΈΠΌΠΎΠ΄Π΅ΠΉΡΡΠ²ΠΈΠΈ Ρ ΠΏΡΠΎΠΈΠ·Π²ΠΎΠ΄Π½ΡΠΌΠΈ Π³ΠΈΠ΄ΡΠ°Π·ΠΈΠ½Π°. ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ Ρ ΠΎΡΠ³Π°Π½ΠΈΡΠ΅ΡΠΊΠΈΠΌΠΈ ΠΈΠ·ΠΎΡΠΈΠ°Π½Π°ΡΠ°ΠΌΠΈ Π³ΠΈΠ΄ΡΠ°Π·ΠΈΠ½ ΠΈ Π΅Π³ΠΎ ΠΏΡΠΎΠΈΠ·Π²ΠΎΠ΄Π½ΡΠ΅, Π² ΡΠΎΠΌ ΡΠΈΡΠ»Π΅ ΠΈ ΠΊΡΠ΅ΠΌΠ½ΠΈΠΉΠΎΡΠ³Π°Π½ΠΈΡΠ΅ΡΠΊΠΈΠ΅, Π΄ΠΎΡΡΠ°ΡΠΎΡΠ½ΠΎ Π»Π΅Π³ΠΊΠΎ ΠΎΠ±ΡΠ°Π·ΡΡΡ ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²ΡΡΡΠΈΠ΅ ΡΠ΅ΠΌΠΈΠΊΠ°ΡΠ±Π°Π·ΠΈΠ΄Ρ. ΠΡΠΈΠ²Π΅Π΄Π΅Π½Ρ ΡΡΠ»ΠΎΠ²ΠΈΡ ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½ΠΈΡ ΡΠ΅Π°ΠΊΡΠΈΠΉ, ΠΎΠΊΠ°Π·ΡΠ²Π°ΡΡΠΈΠ΅ Π²Π»ΠΈΡΠ½ΠΈΠ΅ Π½Π° ΡΠΎΡΡΠ°Π², ΡΡΡΠΎΠ΅Π½ΠΈΠ΅ ΠΈ Π²ΡΡ
ΠΎΠ΄ ΠΎΠ±ΡΠ°Π·ΡΡΡΠΈΡ
ΡΡ ΡΠ΅Π»Π΅Π²ΡΡ
ΠΏΡΠΎΠ΄ΡΠΊΡΠΎΠ². ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ ΡΡΡΠ΅ΡΡΠ²Π΅Π½Π½ΠΎΠ΅ ΠΎΡΠ»ΠΈΡΠΈΠ΅ Π²Π·Π°ΠΈΠΌΠΎΠ΄Π΅ΠΉΡΡΠ²ΠΈΡ ΡΡΠΈΠΌΠ΅ΡΠΈΠ»ΡΠΈΠ»ΠΈΠ»ΠΈΠ·ΠΎΡΠΈΠ°Π½Π°ΡΠ° Ρ ΠΎΡΠ³Π°Π½ΠΈΡΠ΅ΡΠΊΠΈΠΌΠΈ ΠΈ ΠΊΡΠ΅ΠΌΠ½ΠΈΠΉΠΎΡΠ³Π°Π½ΠΈΡΠ΅ΡΠΊΠΈΠΌΠΈ ΠΏΡΠΎΠΈΠ·Π²ΠΎΠ΄Π½ΡΠΌΠΈ Π³ΠΈΠ΄ΡΠ°Π·ΠΈΠ½Π°. ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ ΠΏΡΠΈΡΠΈΠ½ΠΎΠΉ Π½Π΅Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΠΎΡΡΠΈ Π²ΡΠ΄Π΅Π»Π΅Π½ΠΈΡ ΡΡΠΈΠΌΠ΅ΡΠΈΠ»ΡΠΈΠ»ΠΈΠ»ΡΠ½ΡΡ
ΠΏΡΠΎΠΈΠ·Π²ΠΎΠ΄Π½ΡΡ
ΡΠ΅ΠΌΠΈΠΊΠ°ΡΠ±Π°Π·ΠΈΠ΄Π° ΡΠ²Π»ΡΠ΅ΡΡΡ ΠΈΡ
Π½ΠΈΠ·ΠΊΠ°Ρ Π³ΠΈΠ΄ΡΠΎΠ»ΠΈΡΠΈΡΠ΅ΡΠΊΠ°Ρ ΡΡΠ°Π±ΠΈΠ»ΡΠ½ΠΎΡΡΡ, Π° ΡΠ°ΠΊΠΆΠ΅ Π²ΡΡΠΎΠΊΠ°Ρ ΡΠΈΠ»ΠΈΠ»ΠΈΡΡΡΡΠ°Ρ ΡΠΏΠΎΡΠΎΠ±Π½ΠΎΡΡΡ. ΠΠ±ΡΡΠΆΠ΄Π΅Π½Ρ ΠΎΡΠΎΠ±Π΅Π½Π½ΠΎΡΡΠΈ ΡΠ΅Π°ΠΊΡΠΈΠΉ Π²Π·Π°ΠΈΠΌΠΎΠ΄Π΅ΠΉΡΡΠ²ΠΈΡ ΡΡΠΈΠΌΠ΅ΡΠΈΠ»ΡΠΈΠ»ΠΈΠ»ΠΈΠ·ΠΎΡΠΈΠ°Π½Π°ΡΠ° ΠΈ Π΄ΠΈΠΌΠ΅ΡΠΈΠ»Ρ
Π»ΠΎΡΠΌΠ΅ΡΠΈΠ»ΠΈΠ·ΠΎΡΠΈΠ°Π½Π°ΡΠΎΡΠΈΠ»Π°Π½Π° Ρ 1,1-Π΄ΠΈΠΌΠ΅ΡΠΈΠ»Π³ΠΈΠ΄ΡΠ°Π·ΠΈΠ½ΠΎΠΌ, Π΅Π³ΠΎ ΡΡΠΈΠΌΠ΅ΡΠΈΠ»ΡΠΈΠ»ΠΈΠ»Π½ΡΠΌ Π°Π½Π°Π»ΠΎΠ³ΠΎΠΌ ΠΈ ΠΈΠ·ΠΎΠ½ΠΈΠ°Π·ΠΈΠ΄ΠΎΠΌ. ΠΡΠΈΠ²Π΅Π΄Π΅Π½Ρ Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΡΠ΅ Π²Π°ΡΠΈΠ°Π½ΡΡ ΡΡ
Π΅ΠΌ ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΡ ΡΠ°Π½Π΅Π΅ Π½Π΅ΠΈΠ·Π²Π΅ΡΡΠ½ΠΎΠ³ΠΎ Π-ΡΡΠΈΠΌΠ΅ΡΠΈΠ»ΡΠΈΠ»ΠΈΠ»-1,1-Π΄ΠΈΠΌΠ΅ΡΠΈΠ»Π³ΠΈΠ΄ΡΠ°Π·ΠΈΠ½ΠΊΠ°ΡΠ±ΠΎΠΊΡΠΈΠΌΠΈΠ΄ΠΎΠ°ΡΠ°. ΠΠΎΠΊΠ°Π·Π°Π½Ρ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΡ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΡ Π² Π΄Π°Π½Π½ΡΡ
ΠΏΡΠΎΡΠ΅ΡΡΠ°Ρ
ΠΊΠ°ΡΠ±ΠΎΡΡΠ½ΠΊΡΠΈΠΎΠ½Π°Π»ΡΠ½ΡΡ
ΠΊΡΠ΅ΠΌΠ½ΠΈΠΉΠΎΡΠ³Π°Π½ΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΈΠ·ΠΎΡΠΈΠ°Π½Π°ΡΠΎΠ². ΠΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½Ρ ΠΎΡΠ½ΠΎΠ²Π½ΡΠ΅ Π½Π°ΠΏΡΠ°Π²Π»Π΅Π½ΠΈΡ ΠΏΡΠ°ΠΊΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΡ ΠΏΠΎΠ»ΡΡΠ°Π΅ΠΌΡΡ
ΡΠΎΠ΅Π΄ΠΈΠ½Π΅Π½ΠΈΠΉ - Π² ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ ΡΠΈΠ·ΠΈΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈ Π°ΠΊΡΠΈΠ²Π½ΡΡ
ΠΏΡΠ΅ΠΏΠ°ΡΠ°ΡΠΎΠ², Π² ΠΏΠΎΠ»ΠΈΠΌΠ΅ΡΠ½ΠΎΠΉ Ρ
ΠΈΠΌΠΈΠΈ ΠΈ Π² ΡΠ΅Π»ΡΡΠΊΠΎΠΌ Ρ
ΠΎΠ·ΡΠΉΡΡΠ²Π΅
PECULIARITIES OF ISOCYANATES INTERACTION WITH HYDRAZINE DERIVATIVES
The results of studies on chemical transformations of organic and organosilicon isocyanates in their interaction with hydrazine derivatives have been summarized in this review. It is shown that hydrazine and its derivatives including organosilicon compounds reacting with organic isocyanates form corresponding semicarbazides readily enough. The reaction conditions that effect the composition, structure and yield of the resulting target products are presented. A significant difference in the interaction of trimethylsilyl isocyanate with organic and organosilicon derivatives of hydrazine is demonstrated. It is demonstrated that the reason for the impossibility to isolate trimethylsilyl derivatives of semicarbazide is their low hydrolytic stability, as well as high silylating ability. Peculiarities of the reaction of trimethylsilyl isocyanate and dimethylchloromethyl isocyanate silane with 1,1-dimethylhydrazine, its trimethylsilyl analog and isoniazid are given. Possible schemes for the formation of a previously unknown O-trimethylsilyl-1,1-dimethylhydrazinecarboximidoate are presented. The results of using carbofunctional organosilicon isocyanates in these processes are discussed. Basic trends in practical use of the prepared compounds as physiologically active preparations in polymer chemistry and agriculture are shown
Correction of magnetization transfer saturation maps optimized for 7T postmortem MRI of the brain
PurposeMagnetization transfer saturation (MTsat) is a useful marker to probe tissue macromolecular content and myelination in the brain. The increased B1+ inhomogeneity at 7T and significantly larger saturation pulse flip angles which are often used for postmortem studies exceed the limits where previous B1+correction methods are applicable. Here, we develop a calibration-based correction model and procedure, and validate and evaluate it in postmortem 7T data of whole chimpanzee brains.TheoryThe B1+ dependence of was investigated by varying the off-resonance saturation pulse flip angle. For the range of saturation pulse flip angles applied in typical experiments on postmortem tissue, the dependence was close to linear. A linear model with a single calibration constant C is proposed to correct bias in MTsat by mapping it to the reference value of the saturation pulse flip angle.MethodsMTsat was estimated voxel-wise in five postmortem chimpanzee brains. βIndividual-based global parametersβ were obtained by calculating the meanC within individual specimen brains and βgroup-based global parametersβ by calculating the means of the individual-based global parameters across the five brains.ResultsThe linear calibration model described the data well, though C was not entirely independent of the underlying tissue and B1+. Individual-based correction parameters and a group-based global correction parameter (C=1.2) led to visible, quantifiable reductions of B1+-biases in high-resolution MTsat maps.ConclusionThe presented model and calibration approach effectively corrects for B1+inhomogeneities in postmortem 7T data