Phospholipids in tissues of the eye

Broekhuyse, R.M.

doi:10.1016/0005-2760(69)90009-5

Cited by 82 publications

(8 citation statements)

References 20 publications

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“…Some reports provide evidence that the relative amount of cholesterol in cataractous lenses is not significantly different than the amount of cholesterol in normal lenses (6,24,40,44). However, some investigators have found increased cholesterol levels (5,45,46), while others have reported decreased cholesterol content in cataracts (4).…”

Section: Discussionmentioning

confidence: 97%

“…This hypothesis is supported by experiments conducted in our laboratory showing that oxidative stress independently induces the formation of well defined cholesterol domains in model membrane systems, an effect that is attenuated by treatment with vitamin E. 2 Lenticular enrichment of sphingomyelin and its lens-specific derivative, 4,5-dihydrosphingomyelin, may also contribute to maximization of cholesterol domain structures in lens plasma membranes. Sphingophospholipids account for greater than 50% of total lens phospholipids (22) and increase even more substantially with age and cataract development (4,5,61,64). Age-related accumulation of sphingomyelin is also correlated with membrane rigidity (60).…”

Section: Discussionmentioning

confidence: 99%

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Evidence for Distinct Cholesterol Domains in Fiber Cell Membranes from Cataractous Human Lenses

Jacob

Cenedella

Mason

2001

Journal of Biological Chemistry

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Previous studies in our laboratory have provided direct evidence for the existence of distinct cholesterol domains within the plasma membranes of human ocular lens fiber cells. The fiber cell plasma membrane is unique in that it contains unusually high concentrations of cholesterol, with cholesterol to phospholipid (C/P) mole ratios ranging from 1 to 4. Since membrane cholesterol content is disturbed in the development of cataracts, it was hypothesized that perturbation of cholesterol domain structure occurs in cataracts. In this study, fiber cell plasma membranes were isolated from both normal (control) and cataractous lenses and assayed for cholesterol and phospholipid. Control and cataractous whole lens membranes had C/P mole ratios of 3.1 and 1.7, respectively. Small angle x-ray diffraction approaches were used to directly examine the structural organization of the cataractous lens plasma membrane versus control. Both normal and cataractous oriented membranes yielded meridional diffraction peaks corresponding to a unit cell periodicity of 34.0 Å, consistent with the presence of immiscible cholesterol domains. However, comparison of diffraction patterns indicated that cataractous lens membranes contained more pronounced and better defined cholesterol domains than controls, over a broad range of temperature (5-40°C) and relative humidity (52-92%) levels. In addition, diffraction analyses of the sterol-poor regions of cataractous membranes indicated increased membrane rigidity as compared with control membranes. Modification of the membrane lipid environment, such as by oxidative insult, is believed to be one potential mechanism for the formation of highly resolved cholesterol domains despite significantly reduced cholesterol content. The results of this x-ray diffraction study provide evidence for fundamental changes in the lens fiber cell plasma membrane structure in cataracts, including the presence of more prominent and highly ordered, immiscible cholesterol domains.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Evidence for Distinct Cholesterol Domains in Fiber Cell Membranes from Cataractous Human Lenses

Jacob

Cenedella

Mason

2001

Journal of Biological Chemistry

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“…Eyes were obtained from freshly killed cattle at a local slughterhouse, and lenses were dissected within 2 to 4 hr. Total lipids were extracted according to the method of Broekhuyse (9), special care being taken to make sure that the tightly bound lipids were completely freed from the proteolipids (10). The total lipids were reextracted by the Folch procedure (11), and the methyl esters were prepared from the purified lipids using 6% H2SO 4 in methanol at 90 C for 4 hr in sealed tubes.…”

Section: Methodsmentioning

confidence: 99%

Mass spectrometric identification of C₂₀ fatty acids bovine lens using the pyrrolidide derivative

Valicenti

Chapman

Holman

et al. 1978

Lipids

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“…Total phospholipid phosphate [5] and total cholesterol [I] (using kit no. 351, Sigma, St. Louis) were determined by the indicated published methods.…”

Section: Chemical Analysismentioning

confidence: 99%

Rabbit distal colon epithelium: I. Isolation and characterization of basolateral plasma membrane vesicles from surface and crypt cells

Wiener

Turnheim

1989

J. Membrain Biol.

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A method has been developed for the simultaneous isolation of basolateral plasma membrane vesicles from surface and crypt cells of rabbit distal colon epithelium by sequential use of differential sedimentation, isopycnic centrifugation and Ficoll 400 barrier centrifugation. The protein yield was high (total 0.81 mg/g mucosa) and surface and crypt cell-derived basolateral membrane fractions have been purified 34- and 9-fold with respect to the homogenate. The pattern of marker enzyme enrichments revealed only minor contamination by subcellular organelles. Latency of ouabain-sensitive (Na+,K+)-ATPase activity prior and after trypsin treatment of membranes indicated a vesicle configuration of sealed right side-out: sealed inside-out: leaky of approximately 2:1:1. The presence of sealed vesicles was also evident from the osmotic sensitivity of the D-[1-14C] mannitol equilibrium space determined with either fraction. Although considerably different in protein profile, surface and crypt basolateral membranes were similar in cholesterol to phospholipid molar ratio and membrane fluidity as determined by steady-state fluorescence polarization. Stopped-flow light scattering experiments revealed a rather low water permeability of the membranes with a permeability coefficient of 6 microns/sec at 35 degrees C, which is one order of magnitude lower than reported for small intestinal plasma membranes. Both membrane fractions have been shown to effectively generate outward uphill potassium ion gradients, a process that is energized by ATP and inhibited by the membrane-permeant cardiac-glycoside digitoxin. These characteristics are consistent with the activity of a (Na+,K+) pump operating in inside-out vesicles.

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Phospholipids in tissues of the eye

Cited by 82 publications

References 20 publications

Evidence for Distinct Cholesterol Domains in Fiber Cell Membranes from Cataractous Human Lenses

Evidence for Distinct Cholesterol Domains in Fiber Cell Membranes from Cataractous Human Lenses

Mass spectrometric identification of C₂₀ fatty acids bovine lens using the pyrrolidide derivative

Rabbit distal colon epithelium: I. Isolation and characterization of basolateral plasma membrane vesicles from surface and crypt cells

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Phospholipids in tissues of the eye

Cited by 82 publications

References 20 publications

Evidence for Distinct Cholesterol Domains in Fiber Cell Membranes from Cataractous Human Lenses

Evidence for Distinct Cholesterol Domains in Fiber Cell Membranes from Cataractous Human Lenses

Mass spectrometric identification of C20 fatty acids bovine lens using the pyrrolidide derivative

Rabbit distal colon epithelium: I. Isolation and characterization of basolateral plasma membrane vesicles from surface and crypt cells

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Mass spectrometric identification of C₂₀ fatty acids bovine lens using the pyrrolidide derivative