N., and Bakry, N. M. (2006)

Publisher: Elsevier Science Ireland Ltd., Elsevier House, Brookvale Plaza East Park Shannon, Co. Clare Ireland, [mailto:[e-mail]], [URL:http://www.elsevier.nl/]
DOI: 10.1016/j.toxlet.2005.02.010
Language: English
English
Publication Type: Journal Article
Classification: X 24135 Biochemistry
Subfile: Toxicology Abstracts

Lima de Souza, Debora, Frisch, Benoit, Duportail, Guy, and Schuber, Francis (2002). Membrane-active properties of [alpha]-MSH analogs: aggregation and fusion of liposomes triggered by surface-conjugated peptides. Biochimica et Biophysica Acta (BBA) - Biomembranes 1558: 222-237.

Chem Codes: Chemical of Concern: DZ Rejection Code: METHODS.

Reaction of the melanotropin hormone analogs [Nle4,-Phe7]-[alpha]-MSH and [Nle4,-Phe7]-[alpha]-MSH(4-10), which were extended at their N-terminus by a thiol-functionalized spacer arm, with preformed liposomes containing thiol-reactive (phospho)lipid derivatives resulted in the aggregation of the vesicles and in a partial leakage of their inner contents. This aggregation/leakage effect, which was only observed when the peptides were covalently conjugated to the surface of the liposomes, was correlated with the fusion of the vesicles as demonstrated by the observed decrease in resonance energy transfer between probes in a membrane lipid mixing assay. A limited fusion was confirmed by monitoring the mixing of the liposome inner contents (formation of 1-aminonaphthalene-3,6,8-trisulfonic acid/p-xylene bis(pyridinium bromide) complex). The membrane-active properties of the peptides could be correlated with changes in the fluorescence emission spectra of their tryptophan residue, which suggested that after their covalent binding to the outer surface of the liposomes they can partition within the core of the bilayers. A blue shift of 10 nm was observed for [Nle4,-Phe7]-[alpha]-MSH which was correlated with an increase in fluorescence anisotropy and with changes in the accessibility of the coupled peptide as assessed by the quenching of fluorescence of its tryptophan residue by iodide (Stern-Volmer plots). These results should be related to the previously described capacity of [alpha]-MSH, and analogs, to interact with membranes and with the favored conformation of these peptides which, via a [beta]-turn, segregate their central hydrophobic residues into a domain that could insert into membranes and, as shown here, trigger their destabilization. [alpha]-Melanocyte-stimulating hormone/ Membrane-active peptide/ Membrane fusion/ Liposome

Lisi, Paolo, Caraffini, Stefano, and Assalve, Danilo (1987). Irritation and sensitization potential of pesticides. Contact Dermatitis 17: 212-18.
Chem Codes: Chemical of Concern: DZM Rejection Code: HUMAN HEALTH.

A pesticide series of 36 substances was patch tested in 652 subjects to establish the optimal test concn., and the frequency of irritant and allergic reactions. Allergic reactions to fungicides were found in 46 patients: thiophthalimides (captan (I), folpet, and difolatan) were the most common. Irritant and allergic reactions to other pesticides (insecticides, herbicides, etc) were rare. Sensitivity to pesticides was significant in patients who work, or have worked on the land. Cross sensitivity to bisdithiocarbamates or thiophthalimides is possible. [on SciFinder (R)] Copyright: Copyright 2005 ACS on SciFinder (R))

Database: CAPLUS
Accession Number: AN 1988:17485
Chemical Abstracts Number: CAN 108:17485
Section Code: 4-4
Section Title: Toxicology
Document Type: Journal
Language: written in English.
Index Terms: Fungicides and Fungistats; Herbicides; Insecticides; Pesticides (allergy to and skin irritation from, in humans); Hydrocarbon oils; Pyrethrins and Pyrethroids Role: BIOL (Biological study) (allergy to and skin irritation from, in humans); Skin (pesticides irritation of, in humans); Allergy (to pesticides, in humans); Health hazard (occupational, from pesticides)
CAS Registry Numbers: 56-38-2 (Parathion ethyl); 58-89-9 (Lindane); 60-51-5 (Dimethoate); 63-25-2; 76-87-9 (Fentin hydroxide); 81-81-2 (Warfarin); 86-50-0 (Azinphos methyl); 121-75-5 (Malathion); 133-06-2 (Captan); 133-07-3 (Folpet); 137-26-8 (Thiuram); 137-30-4 (Ziram); 298-00-0 (Parathion methyl); 298-02-2 (Phorate); 333-41-5 (Diazinon); 533-74-4 (Dazomet); 534-52-1 (Dinitro-o-cresol); 709-98-8 (Propanil); 959-98-8 (Endosulfan A); 1698-60-8 (Chloridazon); 1912-24-9 (Atrazine); 2212-67-1 (Molinate); 2425-06-1 (Difolatan); 2764-72-9 (Diquat); 4685-14-7 (Paraquat); 7758-98-7; 8018-01-7 (Mancozeb); 12122-67-7 (Zineb); 12427-38-2 (Maneb); 15972-60-8 (Alachlor); 17804-35-2 (Benomyl); 33213-65-9 (Endosulfan B); 37273-91-9 (Metaldehyde); 39300-45-3 (Dinocap) Role: BIOL (Biological study) (allergy to and skin irritation from, in humans) pesticide/ skin/ irritation/ allergy

Lisi, Paolo, Caraffini, Stefano, and Assalve, Danilo (1986). A test series for pesticide dermatitis. Contact Dermatitis 15: 266-9.

Chem Codes: Chemical of Concern: DZM Rejection Code: HUMAN HEALTH.

A pesticide patch test series was tested in 200 subjects, 50 of whom were agricultural workers. Pos. reactions to fungicides were found in 24, almost all to thiophthalimides, esp. captan (I) [133-06-2], difolatan [2425-06-1], and folpet [133-07-3]. Reactions to bis-dithiocarbamates and benomyl [17804-35-2] were rare, and to other pesticides not significant. [on SciFinder (R)] Copyright: Copyright 2005 ACS on SciFinder (R))

Database: CAPLUS
Accession Number: AN 1987:114892
Chemical Abstracts Number: CAN 106:114892
Section Code: 4-4
Section Title: Toxicology
Document Type: Journal
Language: written in English.
Index Terms: Dermatitis (from pesticides, in humans, skin patch test for detection of); Toxicity (of pesticides, in humans, skin patch test for detection of); Fungicides and Fungistats; Herbicides; Insecticides; Pesticides (toxicity of, to human skin, dermatitis patch test in relation to); Pyrethrins and Pyrethroids Role: ADV (Adverse effect, including toxicity), BIOL (Biological study) (toxicity of, to human skin, dermatitis patch test in relation to)
CAS Registry Numbers: 56-38-2 (Parathion ethyl); 58-89-9 (Lindane); 60-51-5 (Dimethoate); 62-73-7 (Dichlorvos); 63-25-2 (Carbaryl); 76-87-9 (Fentin hydroxide); 81-81-2 (Warfarin); 86-50-0 (Azinphos methyl); 108-62-3 (Metaldehyde); 115-29-7 (Endosulfan); 121-75-5 (Malathion); 133-06-2 (Captan); 133-07-3 (Folpet); 137-26-8 (Thiram); 137-30-4 (Ziram); 137-42-8 (Metam sodium); 298-00-0 (Parathion methyl); 298-02-2 (Phorate); 333-41-5 (Diazinon); 533-74-4 (Dazomet); 534-52-1 (Dinitro-o-cresol); 709-98-8 (Propanil); 1698-60-8 (Chloridazon); 1912-24-9 (Atrazine); 2212-67-1 (Molinate); 2425-06-1 (Difolatan); 2764-72-9 (Diquat); 4685-14-7 (Paraquat); 7758-98-7; 8018-01-7 (Mancozeb); 12122-67-7 (Zineb); 12427-38-2 (Maneb); 15972-60-8 (Alachlor); 17804-35-2 (Benomyl); 39300-45-3 (Dinocap) Role: ADV (Adverse effect, including toxicity), BIOL (Biological study) (toxicity of, to human skin, dermatitis patch test in relation to) pesticide/ dermatitis/ patch/ test

Littrell, E. E. (1986). Mortality of American Wigeon on a Golf Course Treated with the Organophosphate, Diazinon. Calif.Fish Game 72: 122-124.

Chem Codes: Chemical of Concern: DZ Rejection Code: SURVEY.

Litzinger, David C. and Huang, Leaf (1992). Phosphatodylethanolamine liposomes: drug delivery, gene transfer and immunodiagnostic applications. Biochimica et Biophysica Acta (BBA) - Reviews on Biomembranes 1113: 201-227.

Chem Codes: Chemical of Concern: DZ Rejection Code: METHODS.

Liu, B., McConnell, L. L., and Torrents, A. (2002). Herbicide and Insecticide Loadings from the Susquehanna River to the Northern Chesapeake Bay. Journal of Agricultural and Food Chemistry [J. Agric. Food Chem.]. Vol. 50, no. 15, pp. 4385-4392. 17 Jul 2002.

Chem Codes: Chemical of Concern: DZ Rejection Code: NO TOX DATA.

ISSN: 0021-8561

Descriptors: Nonpoint Pollution Sources
Descriptors: Herbicides
Descriptors: Insecticides
Descriptors: Agricultural Chemicals
Descriptors: Agricultural Runoff
Descriptors: Watershed Management
Descriptors: Water Pollution Control
Descriptors: Chesapeake Bay
Descriptors: USA, Susquehanna R.
Abstract: The Susquehanna River watershed has a large drainage area (71200 km super(2)) containing heavy agricultural land usage. The river provides approximately half the total freshwater input to the Chesapeake Bay. Water samples were collected at Conowingo Dam near the mouth of the river every 9 days from February 1997 through March 1998. Atrazine, its transformation product 6-amino-2-chloro-4-(isopropylamino)-s-triazine (CIAT), and metolachlor were found in the highest concentrations with maximums of 500, 150, and 330 ng/L, respectively. The annual mass loads for atrazine, CIAT, metolachlor, simazine, and 6-amino-2-chloro-4-(ethylamino)-s-triazine (CEAT) from the Susquehanna River to the Chesapeake Bay were 1600, 1600, 1100, 820, and 720 kg/year, respectively. Annual loadings of insecticides and organochlorine compounds ranged from 2.8 kg/year for alpha -HCH to 34 kg/year for diazinon. Strong correlations between loading data from this and previous studies and total annual water discharge through the dam were used to estimate total metolachlor and atrazine loads (12400 and 9950 kg, respectively) to the northern Chesapeake Bay from 1992 to 1997.
DOI: 10.1021/jf010133jS0021-8561(01)00133-9
Language: English
English
Publication Type: Journal Article
Classification: SW 3030 Effects of pollution
Classification: X 24136 Environmental impact
Classification: EE 40 Water Pollution: Monitoring, Control & Remediation
Subfile: Environmental Engineering Abstracts; Toxicology Abstracts; ASFA 3: Aquatic Pollution & Environmental Quality; Water Resources Abstracts

Liu, Bo, McConnell, Laura L, and Torrents, Alba (2002). Herbicide and insecticide loadings from the Susquehanna River to the northern Chesapeake Bay. Journal Of Agricultural And Food Chemistry 50: 4385-4392.

Chem Codes: SZ,MTL Rejection Code: NO SPECIES.

The Susquehanna River watershed has a large drainage area (71200 km(2)) containing heavy agricultural land usage. The river provides approximately half the total freshwater input to the Chesapeake Bay. Water samples were collected at Conowingo Dam near the mouth of the river every 9 days from February 1997 through March 1998. Atrazine, its transformation product 6-amino-2-chloro-4-(isopropylamino)-s-triazine (CIAT), and metolachlor were found in the highest concentrations with maximums of 500, 150, and 330 ng/L, respectively. The annual mass loads for atrazine, CIAT, metolachlor, simazine, and 6-amino-2-chloro-4-(ethylamino)-s-triazine (CEAT) from the Susquehanna River to the Chesapeake Bay were 1600, 1600, 1100, 820, and 720 kg/year, respectively. Annual loadings of insecticides and organochlorine compounds ranged from 2.8 kg/year for alpha-HCH to 34 kg/year for diazinon. Strong correlations between loading data from this and previous studies and total annual water discharge through the dam were used to estimate total metolachlor and atrazine loads (12400 and 9950 kg, respectively) to the northern Chesapeake Bay from 1992 to 1997. [Journal Article; In English; United States] http://www.sciencedirect.com/science/article/B6WVB-46DFV5F-8B/2/3d14cdd61e7c61a39eada3b395f8a3ab

Liu, Z. W., Han, Z. J., and Zhang, L. C. (2002). Cross Resistance of Methamidophos Resistant Strain of Brown Planthopper and the Biochemical Mechanism Responsible. Acta Entomol.Sin. 45: 447-452 (CHI) (ENG ABS) .
Chem Codes: EcoReference No.: 71636
Chemical of Concern: DZ Rejection Code: NON-ENGLISH.

Lloyd, J. E. and Matthysse, J. G. (1971). Residues of Dichlorvos, Diazinon, and Dimetilan in Milk of Cows fed Pvc-Insecticide Feed Additives. J.Econ.Entomol. 64 (4): 821-822.

EcoReference No.: 37737

Chemical of Concern: DZ,DDVP; Habitat: T; Effect Codes: ACC; Rejection Code: NO ENDPOINT(ALL CHEMS).

LLOYD JE, KUMAR, R., and WAGGONER JW (1993). EVALUATION OF MAX-CON AND OPTIMIZER EAR TAGS APPLIED AT 2 TAGS PER ANIMAL FOR CONTROL OF CATTLE LICE WYOMING 1992. BURDITT, A. K. JR. (ED.). INSECTICIDE & ACARICIDE TESTS, VOL. 18. II+405P. ENTOMOLOGICAL SOCIETY OF AMERICA: LANHAM, MARYLAND, USA.; 0 (0). 1993. 357-358.

Chem Codes: Chemical of Concern: DZ Rejection Code: ABSTRACT.

BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT INSECTICIDE Congresses/ Biology/ Biochemistry/ Poisoning/ Animals, Laboratory/ Herbicides/ Pest Control/ Pesticides/ Animals/ Arachnida/ Entomology/Economics/ Pest Control/ Arachnida/ Entomology/Economics/ Insecticides/ Pest Control/ Pesticides/ Animal/ Animals, Domestic/ Animals, Zoo/ Parasitic Diseases/Veterinary/ Animal/ Disease/ Insects/Parasitology/ Arthropods/ Artiodactyla

Lo, P. L. (2004). Toxicity of Pesticides to Halmus chalybeus (Coleoptera: Coccinellidae) and the Effect of Three Fungicides on Their Densities in a Citrus Orchard. N.Z.J.Crop Hortic.Sci. 32: 69-76.

EcoReference No.: 78126

Chemical of Concern: ALSV,BPZ,DZ,CPY,PMR,CuOH,CuS; Habitat: T; Effect Codes: MOR; Rejection Code: OK(ALL CHEMS),OK TARGET(ALSV,DZ).

Loague, K., Miyahira, R. N., Green, R. E., Oki, D. S., Giambelluca, T. W., and Schneider, R. C. (1995). Chemical leaching near the Waiawa Shaft, Oahu, Hawaii: 2. Modeling results. Ground Water [GROUND WATER]. Vol. 33, no. 1, pp. 124-138. 1995.

Chem Codes: Chemical of Concern: DZ Rejection Code: FATE.

ISSN: 0017-467X

Descriptors: organic compounds
Descriptors: leaching
Descriptors: groundwater
Descriptors: urbanization
Descriptors: environmental effects
Descriptors: water table
Descriptors: groundwater pollution
Descriptors: fate of pollutants
Descriptors: mathematical models
Descriptors: land use
Descriptors: stormwater runoff
Descriptors: fate
Descriptors: ecosystem management
Descriptors: USA, Hawaii, Oahu I.
Abstract: This paper is the second part of a two-part series concerned with assessing the potential for organic chemical leaching to a ground-water skimming tunnel in the Pearl Harbor Basin, Oahu, Hawaii, as a direct result of proposed urban development. The Pesticide Root Zone Model (PRZM) was used, after testing with field and laboratory data described in the companion paper, to make long-term predictions of the movement of chlorpyrifos, diazinon, metribuzin, and nitrate under various recharge scenarios. The PRZM simulations revealed that, with the exception of chlorpyrifos, detectable levels of all the chemicals considered in this study may leach through the unsaturated zone to the water table from where they may eventually migrate to the skimming tunnel. The simulated concentrations in leachate reaching the water table were sufficiently low, considering subsequent mixing in the ground water, to suggest no adverse health effects. The reliability of the simulated results are laced with enough uncertainty, however, to suggest the need for monitoring for diazinon, metribuzin, and nitrate, if development does proceed. The methodology presented in this series is a first attempt at establishing a protocol for using numerical modeling, supported by field and laboratory measurements to aid in land-use change consideration in Hawaii when nonpoint ground-water contamination from organic chemicals is of concern.
Contact: Ground Water Publishing Co., 6375 Riverside Dr., Dublin, OH 43017, USA. PH: [phone]. FAX: [phone].
Language: English
English
Publication Type: Journal Article
Environmental Regime: Freshwater
Classification: SW 3020 Sources and fate of pollution
Classification: P 2000 FRESHWATER POLLUTION
Classification: Q5 01502 Methods and instruments
Subfile: ASFA 3: Aquatic Pollution & Environmental Quality; Pollution Abstracts; Water Resources Abstracts

LOCKE JC and LUMSDEN RD (1989). COMPATIBILITY OF SOME COMMONLY USED SOIL DRENCH FUNGICIDES AND INSECTICIDES WITH THE BIOCONTROL AGENT GLIOCLADIUM-VIRENS. ANNUAL MEETING OF THE AMERICAN PHYTOPATHOLOGICAL SOCIETY, RICHMOND, VIRGINIA, USA, AUGUST 20-24, 1989. PHYTOPATHOLOGY; 79 1152.

Chem Codes: Chemical of Concern: DZ Rejection Code: ABSTRACT.

BIOSIS COPYRIGHT: BIOL ABS. RRM ABSTRACT PYTHIUM-ULTIMUM RHIZOCTONIA-SOLANI ZINNIA PLANT FUNGUS MICROORGANISM ALIETTE 80W DIAZINON AG4E VYDATE L BENLATE BANROT 40WP SUBDUE 2E TERRACLOR 75W TRUBAN 25EC CROP INDUSTRY AGRICULTURE Congresses/ Biology/ Biochemistry/ Plants/Growth & Development/ Fungi/ Plant Diseases/ Plant Diseases/ Preventive Medicine/ Herbicides/ Pest Control/ Pesticides/ Mitosporic Fungi/ Phycomycetes/ Plants

Lockridge, Oksana, Duysen, Ellen G., Voelker, Troy, Thompson, Charles M., and Schopfer, Lawrence M. (2005). Life without acetylcholinesterase: the implications of cholinesterase inhibitor toxicity in AChE-knockout mice: The Ninth Meeting of the International Neurotoxicology Association (INA). Environmental Toxicology and Pharmacology 19: 463-469.
Chem Codes: Chemical of Concern: DZ Rejection Code: NO TOX DATA.

Organophosphorus agent/ Acetylcholinesterase/ Knockout mouse/ Butyrylcholinesterase/ FP-biotin/ Chlorpyrifos oxon The acetylcholinesterase (AChE)-knockout mouse is a new tool for identifying physiologically relevant targets of organophosphorus toxicants (OP). If AChE were the only important target for OP toxicity, then mice with zero AChE would have been expected to be resistant to OP. The opposite was found. AChE-/- mice were more sensitive to the lethality of DFP, chlorpyrifos oxon, iso-OMPA, and the nerve agent VX. A lethal dose of OP caused the same cholinergic signs of toxicity in mice with zero AChE as in mice with normal amounts of AChE. This implied that the mechanism of toxicity of a lethal dose of OP in AChE-/- mice was the same as in mice that had AChE, namely accumulation of excess acetylcholine followed by overstimulation of receptors. OP lethality in AChE-/- mice could be due to inhibition of BChE, or to inhibition of a set of proteins. A search for additional targets used biotinylated-OP as a marker. In vitro experiments found that biotinylated-OP appeared to label as many as 55 proteins in the 100,000 x g supernatant of mouse brain. Chlorpyrifos oxon bound a set of proteins (bands 12, 41, 45) that did not completely overlap with the set of proteins bound by diazoxon (bands 9, 12, 41, 47) or dichlorvos (bands 12, 23, 24, 32, 44, 45, 51) or malaoxon (band 9). These results support the idea that a variety of proteins could be interacting with a given OP to give the neurotoxic symptoms characteristic of a particular OP.

Loeb, H. A. and Kelly, W. H. (1963). Acute Oral Toxicity of 1,496 Chemicals Force-fed to Carp. U.S.Fish.Wildl.Serv., Sp.Sci.Rep.-Fish.No.471, Washington, D.C. 124 p.

EcoReference No.: 15898

Chemical of Concern: AZ,Captan,CBL,CMPH,HCCH,MLN,Naled,SZ,PNB,ACL,WFN,FUR,DPC,RTN,NaN3,PCP,NaPCP,AsAC,ACL,ATZ,Se,Zn,DZ; Habitat: A; Effect Codes: MOR,BEH; Rejection Code: NO CONTROL(ALL CHEMS).

London, Erwin (1992). Diphtheria toxin: membrane interaction and membrane translocation. Biochimica et Biophysica Acta (BBA) - Reviews on Biomembranes 1113: 25-51.

Chem Codes: Chemical of Concern: DZ Rejection Code: METHODS.

LONG, J. LA, HOUSE WA, PARKER, A., and RAE JE (1998). Micro-organic compounds associated with sediments in the Humber rivers. SCIENCE OF THE TOTAL ENVIRONMENT; 210-211 229-253.

Chem Codes: Chemical of Concern: DZ Rejection Code: SURVEY.

BIOSIS COPYRIGHT: BIOL ABS. The study investigates pollution by micro-organic contaminants in riverine systems in NE England with the following four key objectives: (1) to establish the range and concentrations of micro-organic compounds in relation to land use; (2) investigate how the type and concentrations of micro-organics can vary seasonally; (3) compare bed-sediment and suspended-sediment concentrations, and to (4) assess the use of 'whole-water' samples as indicators of environmental water quality in particular with respect to the ecotoxicological impact of contaminant-laden sediments within fluvial systems. Waters, bed- and suspended sediments were collected from six freshwater tributaries of the Humber river at quarterly intervals during the period July 1995-1996. A wide range of micro-organic contaminants were analyzed by GC and GC/NPD, chosen on the basis of information provided through the UK Land Ocean Interaction Study (LOIS) core monitoring and additional data regarding water qualit Climate/ Ecology/ Meteorological Factors/ Ecology/ Fresh Water/ Biochemistry/ Biophysics/ Macromolecular Systems/ Molecular Biology/ Air Pollution/ Soil Pollutants/ Water Pollution/ Soil

LOPEZ-AVILA, V., YOUNG, R., and BECKERT WF (1997). On-line determination of organophosphorus pesticides in water by solid-phase microextraction and gas chromatography with thermionic-selective detection. HRC JOURNAL OF HIGH RESOLUTION CHROMATOGRAPHY; 20 487-492.
Chem Codes: Chemical of Concern: DZ Rejection Code: METHODS.

BIOSIS COPYRIGHT: BIOL ABS. This paper describes the extraction of 49 organophosphorus pesticides (OPPs) from water samples using solid-phase microextraction (SPME). Three fibers, including a 15-mum XAD-coated fiber, a 85-mum polyacrylate-coated fiber, and a 30-mum polydimethylsiloxane-coated fiber (PDMS), were evaluated here. The effects of stirring and the addition of NaCl to the sample were examined for the polyacrylate-coated fiber. The precision of the technique was examined for all three fibers and the extraction kinetics were investigated using the XAD- and polyacrylate-coated fibers. With some exceptions, the XAD- and polyacrylate-coated fibers performed better than the PDMS-coated fiber. The superiority of the XAD- and polyacrylate-coated fibers over the PDMS-coated fiber can be attributed to the aromatic functionalities of the XAD and the polar functionalities in the polyacrylate. The relatively high percent RSDs indicate that the SPME technique needs to be further refined before it can Minerals/Analysis/ Biophysics/Methods/ Herbicides/ Pest Control/ Pesticides

Lord, K. A., Briggs, G. G., Neale, M. C., and Manlove, R. (1980). Uptake of Pesticides from Water and Soil by Earthworms. Pestic.Sci. 11: 401-408.

EcoReference No.: 40522

Chemical of Concern: DLD,DZ,PCB,PRT,CBD; Habitat: T; Effect Codes: ACC; Rejection Code: NO CONTROL,ENDPOINT(ALL CHEMS).

Loura, Luis M. S., Fedorov, Aleksandre, and Prieto, Manuel (2001). Exclusion of a cholesterol analog from the cholesterol-rich phase in model membranes. Biochimica et Biophysica Acta (BBA) - Biomembranes 1511: 236-243.

Chem Codes: Chemical of Concern: DZ Rejection Code: METHODS.

Vesicles of phosphatidylcholine/cholesterol mixtures show a wide composition range with coexistence of two fluid phases, the ‘liquid disordered’ (cholesterol-poor) and ‘liquid ordered’ (cholesterol-rich) phases. These systems have been widely used as models of membranes exhibiting lateral heterogeneity (membrane domains). The distributions of two fluorescent probes (a fluorescent cholesterol analog, NBD-cholesterol, and a lipophilic rhodamine probe, octadecylrhodamine B) in dimyristoylphosphatidylcholine/cholesterol vesicles were studied, at 30[deg]C and 40[deg]C. The steady-state fluorescence intensity of both probes decreases markedly with increasing cholesterol concentration, unlike the fluorescence lifetimes. The liquid ordered to liquid disordered phase partition coefficients Kp were measured, and values much less than unity were obtained for both probes, pointing to preference for the cholesterol-poor phase. Globally analyzed time-resolved energy transfer results confirmed these findings. It is concluded that, in particular, NBD-cholesterol is not a suitable cholesterol analog and its distribution behavior in phosphatidylcholine/cholesterol bilayers is in fact opposite to that of cholesterol. Model membrane/ Cholesterol/ Phase separation/ Fluorescence/ Energy transfer/ Fluorescence resonance energy transfer/ Partition/ Fluorescent probe