Spirophosphoranes derived from 3H-2,1-benzoxaphospholes

Dahl, Britta Mynster; Dahl, Otto; Trippett, S.

doi:10.1039/p19810002239

Cited by 20 publications

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“…Cholesterol moieties were selected in the molecular design of our system for several reasons. One is the thermodynamic affinity of cholesterol for cell membranes and its ability to change their properties, for example enhance their mechanical durability and decrease passive permeability (5)(6)(7)(8). Also, cholesterol is an important component in the membranes of eukaryotic cells, and its homeostasis is critical to cell survival.…”

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confidence: 99%

Self-assembling biomaterials: Liquid crystal phases of cholesteryl oligo(l-lactic acid) and their interactions with cells

Hwang

Iyer²,

Li³

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

136

103

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We report here on the synthesis and characterization of a series of self-assembling biomaterials with molecular features designed to interact with cells and scaffolds for tissue regeneration. The molecules of these materials contain cholesteryl moieties, which have universal affinity for cell membranes, and short chains of lactic acid, a common component of biodegradable tissue engineering matrices. The materials were synthesized in good yields with low polydispersities in the range of 1.05-1.15, and their characterization was carried out by small-angle x-ray diffraction, transmission electron microscopy, electron diffraction, differential scanning calorimetry, and atomic force microscopy. These molecular materials form layered structures that can be described as smectic phases and can also order into singlecrystal stacks with an orthorhombic unit cell. Their layer spacings range from 58 to 99 Å, corresponding to bilayers of oligomers with an average of 10 and 37 lactic acid residues, respectively. The selforganized layered structures were found to promote improved fibroblast adhesion and spreading, although the specific mechanism for this observed response remains unknown. The ability of self-assembling materials to present ordered and periodic bulk structures to cells could be a useful strategy in tissue engineering.

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confidence: 99%

Self-assembling biomaterials: Liquid crystal phases of cholesteryl oligo(l-lactic acid) and their interactions with cells

Hwang

Iyer²,

Li³

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

136

103

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“…The response is synergistic, not additive (4). A significant result was that the membranes ofcells grown on lanosterol with low cholesterol show the same low microviscosity value as membranes isolated from cells cultured on lanosterol alone (4,6). In experiments designed to elucidate the basis of the synergistic sterol effect, we have obtained evidence that cholesterol specifically stimulates the uptake of unsaturated fatty acids by M. capricolum.…”

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confidence: 71%

“…Under these conditions, cholesterol, the minor membrane sterol, appears to be regulating specifically the uptake of unsaturated fatty acids into phospholipid (6). For further study of the synergistic effect, we have chosen to interrupt the growth of cells raised on 10 ug of lanosterol per ml at the midlogarithmic phase.…”

Section: Resultsmentioning

confidence: 99%

“…Cholesterol availability was suggested to be coupled to the synthesis of phospholipid in Mycoplasma capricolum, a sterol-and fatty acid-requiring prokaryote. In essence, a control mechanism distinct from that affecting the bulk physical state of the lipid bilayer was proposed (6), prompted by the following observations. A low level of cholesterol (0.5 ug/ml), insufficient to support significant growth, elicits a 2-fold stimulation of the Mycoplasma growth rate when combined with lanosterol (10 tkg/ml).…”

mentioning

confidence: 99%

“…In experiments designed to elucidate the basis of the synergistic sterol effect, we have obtained evidence that cholesterol specifically stimulates the uptake of unsaturated fatty acids by M. capricolum. The presence of a small quantity of cholesterol in lanosterol-rich cells lowers the Km value for the uptake ofunsaturated but not saturated fatty acids (6).…”

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confidence: 99%

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Coordinate regulation of unsaturated phospholipid, RNA, and protein synthesis in Mycoplasma capricolum by cholesterol.

Dahl¹,

Dahl²

1983

Proc. Natl. Acad. Sci. U.S.A.

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The effect of cholesterol, epicoprostanol, and phosphatidylcholine on phospholipid, RNA, and protein synthesis was investigated in the sterol auxotroph Mycoplasma capricolum. Cells growing poorly on lanosterol were stimulated to grow more rapidly by supplementing the medium with either 2 jig of cholesterol or 2.2 gg of egg phosphatidylcholine per ml, In such cells cholesterol caused a sequential stimulation of phospholipid, RNA, and protein synthesis. Enhanced oleate incorporation into phospholipid occurred early; the rates of RNA and protein synthesis increased later. In cells supplemented with phosphatidylcholine only RNA and protein syntheses were enhanced. The addition of 2 pzg of epicoprostanol per ml to cells growing on lanosterol promptly inhibited the rate ofunsaturated phospholipid synthesis and subsequently the rate of growth. Inhibition of both processes was relieved by supplying 2 pig of cholesterol or 2.2 pag of phosphatidylcholine per ml along with the inhibitory sterol. The results suggest that cholesterol, in small amounts exerts a positive regulatory effect and epicoprostanol exerts a negative one on unsaturated phospholipid synthesis and, in turn, that RNA and protein synthesis are coordinately controlled with phospholipid synthesis. Recent studies in this laboratory have furnished evidence in support ofthe view that the structure ofcholesterol is optimally designed for modulating the properties of both artificial and natural membranes (1-3). In order of importance, cholesterol appears to owe its unique properties to the following structural features: planarity of the a face in the region of C-14, absence of methyl substituents at C-4, and insertion of a 5,6 double bond.Further work, notably the discovery of sterol synergism, has led to the postulate that cholesterol may serve in more than one role as a constituent of biological membranes (4). It was suggested that, apart from its well-established ability to modify the bulk physical state of the lipid bilayer (5), cholesterol may function more specifically in localized membrane domains influencing certain metabolic processes. Cholesterol availability was suggested to be coupled to the synthesis of phospholipid in Mycoplasma capricolum, a sterol-and fatty acid-requiring prokaryote. In essence, a control mechanism distinct from that affecting the bulk physical state of the lipid bilayer was proposed (6), prompted by the following observations. A low level of cholesterol (0.5 ug/ml), insufficient to support significant growth, elicits a 2-fold stimulation of the Mycoplasma growth rate when combined with lanosterol (10 tkg/ml). Alone the latter sterol supports growth only poorly. The response is synergistic, not additive (4). A significant result was that the membranes ofcells grown on lanosterol with low cholesterol show the same low microviscosity value as membranes isolated from cells cultured on lanosterol alone (4, 6). In experiments designed to elucidate the basis of the synergistic sterol effect, we have obtained evidence that chole...

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Phenyl Dichlorophosphite

Ewin¹

2001

Encyclopedia of Reagents for Organic Synthesis

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Spirophosphoranes derived from 3H-2,1-benzoxaphospholes

Cited by 20 publications

References 0 publications

Self-assembling biomaterials: Liquid crystal phases of cholesteryl oligo(l-lactic acid) and their interactions with cells

Self-assembling biomaterials: Liquid crystal phases of cholesteryl oligo(l-lactic acid) and their interactions with cells

Coordinate regulation of unsaturated phospholipid, RNA, and protein synthesis in Mycoplasma capricolum by cholesterol.

Phenyl Dichlorophosphite

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