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Klaus Ring - One of the best experts on this subject based on the ideXlab platform.
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Thermotropic properties of dispersions of cholesterol with tetraether lipids from Thermoplasma acidophilum.
Archives of biochemistry and biophysics, 1991Co-Authors: Detlef Blöcher, Hans-joachim Freisleben, Klaus RingAbstract:The main glycophospholipid from Thermoplasma acidophilum is composed of a diisopranol-2,3-glycerotetraether. The fraction of pentane cyclizations of its Hydrocarbon chains increases with the growth temperature of the source organism (39-59’C). Hydrated mixtures of these lipids together with cholesterol have been studied by calorimetry. With the reduction of the phase transition temperatures and enthalpy changes of the transitions, cholesterol is readily incorporated into lipid monolayers in the liquid-crystalline and the (metastable) solid-analogue phase. Lipid samples with a high number of Acyclic Hydrocarbon chains form a stable and a metastable solidanalogue phase. With the increasing concentration of cholesterol the metastable solid-analogue phase is stabilized and the time constant for the formation of the stable solid-analogue phase is prolonged.
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Mixtures of tetraetherlipids from Thermoplasma acidophilum with varying degree of cyclization show a kinetic effect for a metastable phase
Chemistry and Physics of Lipids, 1991Co-Authors: Detlef Blöcher, Klaus RingAbstract:Abstract The main glycophospholipid of Thermoplasma acidophilum is composed of a di-isopranol-2,3-glycero-tetraether. Depending on the growth temperature of the source organism it shows an increasing fraction of pentane cyclizations of its Hydrocarbon chains. The thermotropic properties of hydrated samples of its main glycophospholipid, isolated from organisms grow at 39°C. 49°C and 59°C (designated as MPL39, MPL49 and MPL59) and mixtures of these lipids have been characterized by calorimetry. Whereas MPL59 merely shows a broad transitions at sub-zero temperatures. MPL49 and MPL39 exhibit complex thermotropic properties which include competing transition between a metastable and a stable gel phase as well as a liquid-crystalline phase. The formation of the stable gel phase was found to be dependent on the fraction of Acyclic Hydrocarbon chains and the pretreatment conditions of the sample. Its kinetics were studied in mixed samples and revealed that cyclic Hydrocarbon chains act as “impurities”; they quench the formation of the stable gel phase and drastically increase its time constant.
Detlef Blöcher - One of the best experts on this subject based on the ideXlab platform.
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Thermotropic properties of dispersions of cholesterol with tetraether lipids from Thermoplasma acidophilum.
Archives of biochemistry and biophysics, 1991Co-Authors: Detlef Blöcher, Hans-joachim Freisleben, Klaus RingAbstract:The main glycophospholipid from Thermoplasma acidophilum is composed of a diisopranol-2,3-glycerotetraether. The fraction of pentane cyclizations of its Hydrocarbon chains increases with the growth temperature of the source organism (39-59’C). Hydrated mixtures of these lipids together with cholesterol have been studied by calorimetry. With the reduction of the phase transition temperatures and enthalpy changes of the transitions, cholesterol is readily incorporated into lipid monolayers in the liquid-crystalline and the (metastable) solid-analogue phase. Lipid samples with a high number of Acyclic Hydrocarbon chains form a stable and a metastable solidanalogue phase. With the increasing concentration of cholesterol the metastable solid-analogue phase is stabilized and the time constant for the formation of the stable solid-analogue phase is prolonged.
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Mixtures of tetraetherlipids from Thermoplasma acidophilum with varying degree of cyclization show a kinetic effect for a metastable phase
Chemistry and Physics of Lipids, 1991Co-Authors: Detlef Blöcher, Klaus RingAbstract:Abstract The main glycophospholipid of Thermoplasma acidophilum is composed of a di-isopranol-2,3-glycero-tetraether. Depending on the growth temperature of the source organism it shows an increasing fraction of pentane cyclizations of its Hydrocarbon chains. The thermotropic properties of hydrated samples of its main glycophospholipid, isolated from organisms grow at 39°C. 49°C and 59°C (designated as MPL39, MPL49 and MPL59) and mixtures of these lipids have been characterized by calorimetry. Whereas MPL59 merely shows a broad transitions at sub-zero temperatures. MPL49 and MPL39 exhibit complex thermotropic properties which include competing transition between a metastable and a stable gel phase as well as a liquid-crystalline phase. The formation of the stable gel phase was found to be dependent on the fraction of Acyclic Hydrocarbon chains and the pretreatment conditions of the sample. Its kinetics were studied in mixed samples and revealed that cyclic Hydrocarbon chains act as “impurities”; they quench the formation of the stable gel phase and drastically increase its time constant.
Huachen Wei - One of the best experts on this subject based on the ideXlab platform.
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Dietary Lycopene Protects SKH-1 Mice Against Ultraviolet B-Induced Photocarcinogenesis
Journal of drugs in dermatology : JDD, 2019Co-Authors: Xueyan Zhou, Karen E. Burke, Yongyin Wang, Huachen WeiAbstract:Lycopene, an Acyclic Hydrocarbon, non-provitamin A carotenoid, is a potent antioxidant with well-documented anticancer properties. In this study, we investigated the effects of dietary lycopene on sub-acute and chronic ultraviolet B (UVB)-induced skin carcinogenesis in SKH-1 mice. Groups of three mice were fed with a nonsupplemented or 1% lycopene diet for two weeks before and throughout two weeks of UVB irradiation (30 mJ/cm2 UVB, thrice weekly). The lycopene diet significantly reduced the formation of pyrimidine dimers (PDs) and the expression of proliferative cellular nuclear antigen (PCNA) in UVB-irradiated skin. Then groups of eighteen mice were each fed with control diet or with a 0.25% or 1% (w/w) lycopene-supplemented diet for 40 weeks, beginning one week before UVB irradiation (30 mJ/cm2 UVB, thrice weekly for 23 weeks) and continuing after termination of UVB. Lycopene significantly inhibited the onset and decreased the incidence, multiplicity, and tumor weights of UVB-induced skin tumors. UVB-induced epidermal hyperplasia and PCNA expression were still remarkably inhibited by dietary lycopene, even up to 40 weeks. No significant difference in protection was detected between the low and high concentrations of lycopene. These results demonstrate that dietary lycopene does protect against UVB-induced epidermal hyperplasia and carcinogenesis. J Drugs Dermatol. 2019;18(12):1244-1254.
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Protective effects of lycopene against ultraviolet B-induced photodamage.
Nutrition and cancer, 2003Co-Authors: Zsuzsanna Fazekas, Dayuan Gao, Rao N. Saladi, Mark Lebwohl, Huachen WeiAbstract:Lycopene, an Acyclic Hydrocarbon carotenoid found in tomatoes and their products, is a well-established potent antioxidant, and its anticancer properties have been shown in cultured cells and animal models. We investigated the protective effects of two concentrations of topical lycopene against acute ultraviolet B (UVB)-induced photodamage. Application of lycopene dose dependently inhibited UVB-induced ornithine decarboxylase (P < 0.05) and myeloperoxidase (P < 0.05) and significantly reduced bifold skin thickness (P < 0.05). Immunohistochemical staining revealed increased active caspase-3 of apoptotic pathway in the UVB-exposed group compared with the unexposed control. Application of topical lycopene prevented the cleavage of caspase-3. UVB irradiation completely diminished proliferating cell nuclear antigen (PCNA), and the untreated skin maintained positively stained cells throughout the basal epidermis. Topical application of lycopene significantly reversed UVB-induced PCNA inhibition, and normal PCNA staining was restored in the lycopene-treated skin. Our results suggest that topical lycopene is able to exert its protective effects against acute UVB-induced photodamage. Furthermore, it may act as a preventative agent via inhibition of epidermal ornithine decarboxylase activity, reducing inflammatory responses, maintaining normal cell proliferation, and possibly preventing DNA damage as indicated by blocking the necessitating step of apoptosis following UVB injury.
Hans-joachim Freisleben - One of the best experts on this subject based on the ideXlab platform.
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Calorimetry of archaeal tetraether lipid—indication of a novel metastable thermotropic phase in the main phospholipid from Thermoplasma acidophilum cultured at 59°C
Chemistry and Physics of Lipids, 1998Co-Authors: Marc Ernst, Hans-joachim Freisleben, Emmanouil Antonopoulos, Lutz Henkel, Walter Mlekusch, Gilbert ReibneggerAbstract:The main glycophospholipid (MPL) from the archaeon Thermoplasma acidophilum is composed of a di-isopranol-2,3-glycerotetraether. The fraction of pentacyclizations of its Hydrocarbon chains increases with the growth temperature of the source organism (39 and 59°C), the respective lipids being named MPL39 and MPL59. MPL has a main phase transition between −15 and −30°C. Non-hydrated and hydrated samples of MPL59 have been studied by differential thermal analysis (DTA). Non-hydrated MPL59 does not exert any phase transition. Computer simulation of an unhydrated MPL molecule with four pentacycles and another without pentacyclations demonstrates similar behavior, i.e. the MPL molecules form coils with both polar ends getting closely together. The molecule without pentacyclation coils faster than that with pentacycles. With hydrated samples, DTA scanning conditions were varied. Under certain conditions, the shape of the calorimetric scans, i.e. occurrence of an additional (endotherm) phase transition peak at +17°C and enthalpy changes of the phase transitions indicate a (metastable) solid-analogue phase in MPL59 in addition to the well-known liquid–crystalline phase. Only lipid samples from T. acidophilum with a high degree of Acyclic Hydrocarbon chains (MPL39) had thus far been reported to form a metastable solid-analogue phase (Blocher, D., Gutermann, R., Henkel, B., Ring, K., 1990. Biochim. Biophys. Acta 1024, 54–60). A phase transition model is presented for MPL59 which includes the existence of a metastable solid-analogue phase.
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Thermotropic properties of dispersions of cholesterol with tetraether lipids from Thermoplasma acidophilum.
Archives of biochemistry and biophysics, 1991Co-Authors: Detlef Blöcher, Hans-joachim Freisleben, Klaus RingAbstract:The main glycophospholipid from Thermoplasma acidophilum is composed of a diisopranol-2,3-glycerotetraether. The fraction of pentane cyclizations of its Hydrocarbon chains increases with the growth temperature of the source organism (39-59’C). Hydrated mixtures of these lipids together with cholesterol have been studied by calorimetry. With the reduction of the phase transition temperatures and enthalpy changes of the transitions, cholesterol is readily incorporated into lipid monolayers in the liquid-crystalline and the (metastable) solid-analogue phase. Lipid samples with a high number of Acyclic Hydrocarbon chains form a stable and a metastable solidanalogue phase. With the increasing concentration of cholesterol the metastable solid-analogue phase is stabilized and the time constant for the formation of the stable solid-analogue phase is prolonged.
Gilbert Reibnegger - One of the best experts on this subject based on the ideXlab platform.
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Calorimetry of archaeal tetraether lipid—indication of a novel metastable thermotropic phase in the main phospholipid from Thermoplasma acidophilum cultured at 59°C
Chemistry and Physics of Lipids, 1998Co-Authors: Marc Ernst, Hans-joachim Freisleben, Emmanouil Antonopoulos, Lutz Henkel, Walter Mlekusch, Gilbert ReibneggerAbstract:The main glycophospholipid (MPL) from the archaeon Thermoplasma acidophilum is composed of a di-isopranol-2,3-glycerotetraether. The fraction of pentacyclizations of its Hydrocarbon chains increases with the growth temperature of the source organism (39 and 59°C), the respective lipids being named MPL39 and MPL59. MPL has a main phase transition between −15 and −30°C. Non-hydrated and hydrated samples of MPL59 have been studied by differential thermal analysis (DTA). Non-hydrated MPL59 does not exert any phase transition. Computer simulation of an unhydrated MPL molecule with four pentacycles and another without pentacyclations demonstrates similar behavior, i.e. the MPL molecules form coils with both polar ends getting closely together. The molecule without pentacyclation coils faster than that with pentacycles. With hydrated samples, DTA scanning conditions were varied. Under certain conditions, the shape of the calorimetric scans, i.e. occurrence of an additional (endotherm) phase transition peak at +17°C and enthalpy changes of the phase transitions indicate a (metastable) solid-analogue phase in MPL59 in addition to the well-known liquid–crystalline phase. Only lipid samples from T. acidophilum with a high degree of Acyclic Hydrocarbon chains (MPL39) had thus far been reported to form a metastable solid-analogue phase (Blocher, D., Gutermann, R., Henkel, B., Ring, K., 1990. Biochim. Biophys. Acta 1024, 54–60). A phase transition model is presented for MPL59 which includes the existence of a metastable solid-analogue phase.
