Cortical Lipids Research Articles

Genetic markers associated with bone composition in Rhode Island Red laying hens

BackgroundBone damage has welfare and economic impacts on modern commercial poultry and is known as one of the major challenges in the poultry industry. Bone damage is particularly common in laying hens and is probably due to the physiological link between bone and the egg laying process. Previous studies identified and validated quantitative trait loci (QTL) for bone strength in White Leghorn laying hens based on several measurements, including bone composition measurements on the cortex and medulla of the tibia bone. In a previous pedigree-based analysis, bone composition measurements showed heritabilities ranging from 0.18 to 0.41 and moderate to strong genetic correlations with tibia strength and density. Bone composition was measured using infrared spectroscopy and thermogravimetry. The aim of this study was to combine these bone composition measurements with genotyping data via a genome-wide association study (GWAS) to investigate genetic markers that contribute to genetic variance in bone composition in Rhode Island Red laying hens. In addition, we investigated the genetic correlations between bone composition and bone strength.ResultsWe found novel genetic markers that are significantly associated with cortical lipid, cortical mineral scattering, medullary organic matter, and medullary mineralization. Composition of the bone organic matter showed more significant associations than bone mineral composition. We also found interesting overlaps between the GWAS results for tibia composition traits, particularly for cortical lipid and tibia strength. Bone composition measurements by infrared spectroscopy showed more significant associations than thermogravimetry measurements. Based on the results of infrared spectroscopy, cortical lipid showed the highest genetic correlations with tibia density, which was negative (− 0.20 ± 0.04), followed by cortical CO3/PO4 (0.18 ± 0.04). Based on the results of thermogravimetry, medullary organic matter% and mineral% showed the highest genetic correlations with tibia density (− 0.25 ± 0.04 and 0.25 ± 0.04, respectively).ConclusionsThis study detected novel genetic associations for bone composition traits, particularly those involving organic matter, that could be used as a basis for further molecular genetic investigations. Tibia cortical lipids displayed the strongest genetic associations of all the composition measurements, including a significantly high genetic correlation with tibia density and strength. Our results also highlighted that cortical lipid may be a key measurement for further avian bone studies.

Imaging mass spectrometry (IMS) of cortical lipids from preclinical to severe stages of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease affecting millions of patients worldwide. Previous studies have demonstrated alterations in the lipid composition of lipid extracts from plasma and brain samples of AD patients. However, there is no consensus regarding the qualitative and quantitative changes of lipids in brains from AD patients. In addition, the recent developments in imaging mass spectrometry methods are leading to a new stage in the in situ analysis of lipid species in brain tissue slices from human postmortem samples. The present study uses the matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS), permitting the direct anatomical analysis of lipids in postmortem brain sections from AD patients, which are compared with the intensity of the lipid signal in samples from matched subjects with no neurological diseases. The frontal cortex samples from AD patients were classified in three groups based on Braak's histochemical criteria, ranging from non-cognitively impaired patients to those severely affected. The main results indicate a depletion of different sulfatide lipid species from the earliest stages of the disease in both white and gray matter areas of the frontal cortex. Therefore, the decrease in sulfatides in cortical areas could be considered as a marker of the disease, but may also indicate neurochemical modifications related to the pathogenesis of the disease. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá.

Changes in the serum, liver, and renal cortical lipids and electrolytes in rabbits with cisplatin-induced nephrotoxicity.

Cisplatin is an anticancer drug that can induce nephrotoxicity. Its toxicity is associated with dyslipidemia and disturbed electrolyte balance. In the present study we investigated the changes in serum lipid profile and electrolyte levels and their contents in kidney and liver tissues of rabbits treated with cisplatin. Twenty-eight adult male New Zealand White rabbits were used in the experiment. Animals of groups C, P1, and P2 were injected with saline, cisplatin (4.0 mg/kg bw), and cisplatin (6.5 mg/kg bw), respectively, and killed 3 days after the injections. Animals of group R were given cisplatin (6.5 mg/kg bw) and killed after 7 days. All animals were killed after an overnight fast. The P2 animals showed reductions in their body weights, significant (P < 0.001) increases in serum creatinine and urea levels, and significant (P < 0.001) drops in cortical alkaline phosphatase activity and necrotic kidney histology. The treatments had no effect on liver function. Moreover, the P2 animals showed increased serum cholesterol, TAG, and elevated LDL-cholesterol, with significant accumulations of the kidney cholesterol and TAG, but no change in serum phospholipid and depleted hepatic cholesterol. Moreover, the P2 animals had depressed serum levels of potassium, calcium, and magnesium, and reduced renal cortical calcium and magnesium contents and depressed liver calcium but not magnesium. However, the P1 animals had no significant alterations in their lipid or electrolyte levels. Most of the perturbed parameters returned to normal levels in the recovery group. Cisplatin nephrotoxicity in rabbits is accompanied by reductions in body weight, secondary dyslipidemia, and reduced serum potassium, calcium, and magnesium with depleted renal cortical magnesium and calcium and accumulated cortical lipids.

Spin-label saturation-recovery EPR at W-band: Applications to eye lens lipid membranes

Saturation-recovery (SR) EPR at W-band (94 GHz) to obtain profiles of the membrane fluidity and profiles of the oxygen transport parameter is demonstrated for lens lipid membranes using phosphatidylcholine ( n-PC), stearic acid ( n-SASL), and cholesterol analog (ASL and CSL) spin labels, and compared with results obtained in parallel experiments at X-band (9.4 GHz). Membranes were derived from the total lipids extracted from 2-year-old porcine lens cortex and nucleus. Two findings are especially significant. First, measurements of the spin–lattice relaxation times T 1 for n-PCs allowed T 1 profiles across the membrane to be obtained. These profiles reflect local membrane properties differently than profiles of the order parameter. Profiles obtained at W-band are, however, shifted to longer T 1 values compared to those obtained at X-band. Second, using cholesterol analog spin labels and relaxation agents (hydrophobic oxygen and water-soluble NiEDDA), the cholesterol bilayer domain was discriminated in membranes made from lipids of the lens nucleus. However, membranes made from cortical lipids show a single homogeneous environment. Profiles of the oxygen transport parameter obtained from W-band measurements are practically identical to those obtained from X-band measurements, and are very similar to those obtained earlier at X-band for membranes made of 2-year-old bovine cortical and nuclear lens lipids (M. Raguz, J. Widomska, J. Dillon, E.R. Gaillard, W.K. Subczynski, Biochim. Biophys. Acta 1788 (2009) 2380–2388). Results demonstrate that SR EPR at W-band has the potential to be a powerful tool for studying samples of small volume, ∼30 nL, compared with the sample volume of ∼3 μL at X-band.

Discrimination and Characterization of Cholesterol Crystalline Domains using EPR Spin-Labeling: Application to Lens Lipid Membranes

Saturation-recovery EPR at X-band (9.4 GHz) and W-band (94 GHz) was used to discriminate cholesterol crystalline domains (CCDs) in model phospholipid membranes and membranes made of pigs lens lipids. We used dual-probe saturation-recovery EPR approach with cholesterol analogue spin labels, CSL or ASL, and oxygen (hydrophobic) or NiEDDA (polar) relaxation agents. The CCD was present in all of the phospholipid membranes when the cholesterol-to-phospholipid mixing ratio exceeded the cholesterol solubility threshold. Saturation-recovery curves show that spin labels detect a single homogenous environment in membranes made from cortical lipids. However, in membranes made from nuclear lipids, two domains were detected and were assigned to the bulk phospholipid-cholesterol domain and the CCD, respectively. Profiles of the oxygen transport parameter (oxygen diffusion-concentration product) across these domains contain significant structural information. These profiles also allow calculating the oxygen permeability coefficient across domain. The evaluated upper limit of the oxygen permeability coefficient across the CCD at 37°C (34.4 cm/s) is significantly lower than across the water layer of the same thickness (85.9 cm/s), indicating that the CCD can form a barrier for oxygen transport in the lens nucleus. The new capabilities in measurements of the oxygen transport parameter at W-band are demonstrated and compared with results obtained at X-band. The loop-gap resonators used for W-band measurements have a sample volume of 30 nL, while the sample volume of the loop-gap resonator used for X-band is 3µL. These specifications ensure feasibility of experiments planned for samples with a limited sample volume. For example, the oxygen transport parameter profiles measured at X-band for lens lipid membranes were obtained for samples prepared from 50 - 100 eyes. Reliable profiles at W-band can be obtained based on samples prepared from one eye.

Physical properties of the lipid bilayer membrane made of cortical and nuclear bovine lens lipids: EPR spin-labeling studies

The physical properties of membranes derived from the total lipids extracted from the lens cortex and nucleus of a 2-year-old cow were investigated using EPR spin-labeling methods. Conventional EPR spectra and saturation–recovery curves show that spin labels detect a single homogenous environment in membranes made from cortical lipids. Properties of these membranes are very similar to those reported by us for membranes made of the total lipid extract of 6-month-old calf lenses (J. Widomska, M. Raguz, J. Dillon, E. R. Gaillard, W. K. Subczynski, Biochim. Biophys. Acta 1768 (2007) 1454–1465). However, in membranes made from nuclear lipids, two domains were detected by the EPR discrimination by oxygen transport method using the cholesterol analogue spin label and were assigned to the bulk phospholipid–cholesterol domain (PCD) and the immiscible cholesterol crystalline domain (CCD), respectively. Profiles of the order parameter, hydrophobicity, and the oxygen transport parameter are practically identical in the bulk PCD when measured for either the cortical or nuclear lipid membranes. In both membranes, lipids in the bulk PCD are strongly immobilized at all depths. Hydrophobicity and oxygen transport parameter profiles have a rectangular shape with an abrupt change between the C9 and C10 positions, which is approximately where the steroid ring structure of cholesterol reaches into the membrane. The permeability coefficient for oxygen, estimated at 35 °C, across the bulk PCD in both membranes is slightly lower than across the water layer of the same thickness. However, the evaluated upper limit of the permeability coefficient for oxygen across the CCD (34.4 cm/s) is significantly lower than across the water layer of the same thickness (85.9 cm/s), indicating that the CCD can significantly reduce oxygen transport in the lens nucleus.

Calcium Permeability in Large Unilamellar Vesicles Prepared from Bovine Lens Cortical Lipids

The loss of calcium homeostasis in the lens is thought to play an important role in cataract formation. Although both lens Ca2+-ATPase and membrane lipid permeability are essential to calcium homeostasis, membrane permeability has been studied less extensively. In the present study, the calcium permeability of large unilamellar vesicles (LUVs) prepared from bovine lens cortical lipids has been characterized. When a calcium gradient had been established by the addition of CaCl2to the external medium, calcium influx through the membrane was monitored by calcium concentration sensitive changes in Fura-2 fluorescence as a function of time. The calcium permeability coefficient, P, was 4.46×10−13cm s−1at 37°C. This value was about 4 fold higher than that for LUVs prepared from egg phosphatidylcholine and many times higher than that for LUVs prepared from sphingomyelin. These results provide a basis for future studies of factors that influence the permeability of lens cell membranes to calcium.

Nitric oxide responsible for NMDA receptor-evoked inhibition of arachidonic acid incorporation into lipids of brain membrane.

The activation of the glutamatergic NMDA receptor has no effect on arachidonic acid release from cortical synaptoneurosomal lipids prelabeled with [1-14C]arachidonic acid ([14C]AA). However, activation of NMDA receptor leads to the reduction of AA incorporation into rat brain cortex synaptoneurosomal membrane phosphatidylinositol (PI). The competitive NMDA receptor antagonist, 2-amino-5-phosphovaleric acid (APV), completely eliminates the effect of NMDA on this process. More precise analysis of the sequence of events leading to NMDA-induced decrease of AA incorporation indicates that this process is significantly blocked by voltage-gated sodium and calcium channels inhibitors, such as tetrodotoxin (TTX) and omega-conotoxin (CTX), respectively. Then the antagonist of inositol trisphosphate receptor, TMB-8, totally abolishes the effect of NMDA on AA incorporation into PI. The lowering of AA incorporation evoked by NMDA is significantly diminished by nitric oxide (NO) synthase inhibitor, NG-nitro-L- arginine (NNLA). Further studies were carried out with NO donor(s) to explain the mechanism of NO action in the inhibition of AA incorporation into PI. Our results suggest the following sequence of events: opening of voltage-dependent sodium and calcium channels, subsequent activation of PI-4,5-bisphosphate-specific phospholipase C (PLC), elevation of inositol trisphosphate (IP3)-sensitive calcium ions, stimulation of NO production and NO-mediated S-nitrosylation, or free radical effect on enzymes involved in AA incorporation. Our data suggest that NO-mediated events may be responsible for NMDA-evoked inhibition of AA incorporation into PI of synaptoneurosomal membrane.

Role of Cholesterol in the Structural Order of Lens Membrane Lipids

Cholesterol may order or disorder phospholipids. The physiological contribution of cholesterol to the structural order of lens membrane lipids was determined. Cholesterol and phospholipid from bovine lens nuclear and cortical tissue were separated by thin layer chromatography. The effect of cholesterol upon the trans to gauche transition of the hydrocarbon chains was assessed by measuring CH 2infrared stretching band frequencies as cholesterol was added back to the phospholipids. Although the relative cholesterol level of nuclear lipid was much higher than that of the cortex (59 vs. 36mol%, respectively), the structural order of unfractionated nuclear and cortical lipids were similar at physiological temperature. Cholesterol added to lipids devoid of cholesterol produced a sharp biphasic effect on the structural order of nuclear lipids, increasing the trans conformation from 56% of 0mol% cholesterol to 74% at 18% cholesterol to 41% trans at 59mol% cholesterol. Cholesterol addition produced a shallow biphasic change in the percentage trans conformation of cortical lipids. Maximum order (about 40% trans conformation) was seen at a cholesterol level equal to that of intact cortical lipid (36mol%). The physiological role of cholesterol is to increase the structural order of cortical membrane lipid and decrease order in nuclear lipid. The net result is a similarity in the structural order of cortical and nuclear membrane. We suggest that the different response of cortical and nuclear lipids to added cholesterol is linked to differences in the phospholipid composition between these two lens regions. In the absence of cholesterol, nuclear phospholipids are much more highly ordered than those of the cortex.

Spectral characterization of lipid peroxidation in rabbit lens membranes induced by hydrogen peroxide in the presence of [formula omitted] cations: A site-specific catalyzed oxidation

The role of free-radical-induced lipid peroxidation (LPO) in relation to lens opacity is investigated using Fourier transform infrared spectroscopy. Phospholipids extracted from nuclear and cortical regions of the rabbit lens membranes are subjected to oxidative-damage induced by hydrogen peroxide and Fe 2+ Fe 3+ cations. Vibrational data suggest a homolytic decomposition of the unsaturated membrane hydrocarbon chains at cis-double bonds, as well as structural modifications at the carbonyl and phosphate-oxygen sites of the fiber cell membranes upon metal oxidation. This is also evident from a substantial induction of the carbonyl groups and a significant dephosphorylation of the phosphate groups in lens phospholipids. These covalent modifications and/or alterations of the carbonyl and phosphate groups, and specificity of certain vibrational modes only to iron oxidation, may serve as a diagnostic probe of the metal-catalyzed LPO in lens membranes. Despite covalent modifications of the hydrophilic part of the lens membranes, hydrocarbon chain region remains largely intact at physiological concentrations of hydrogen peroxide. However, at elevated concentrations of hydrogen peroxide, a substantial breakdown of the acyl chains occurs. Striking similarities observed between the spectral features of the oxidized rabbit lens phospholipids and those of the cataractous human lenses suggest that the mechanism and pathways of lipid oxidation in model animal membranes and in human lenses are similar. Differences in the nuclear or cortical regions are also evident upon metal oxidation. Nuclear lipids experience increased effects of the metal oxidation compared to cortical lipids. Both the nuclear or the cortical lipids indicate effective penetration of the bilayer water creating segregated membrane domains, possibly through breakdown of headgroup-specific lipid-water interactions. This could effectively alter the lens membrane permeability and fluidity, rendering it susceptible to a host of toxic oxidants present in the eye. These findings also demonstrate that LPO can lead to acyl chain degradation that may effectively derange the lens membrane function, which could be a contributing factor in cataractogenesis.

Structural Characterization of Lipid Membranes from Clear and Cataractous Human Lenses

Lipid composition related structural changes in human cataractous lenses was explored by characterizing the hydrophobic hydrocarbon chains in lipid membranes corresponding to twelve Indian cataractous lenses and eight American clear lenses of similar age. The nuclear-lipid phase transitions corresponding to the clear lenses exhibited significantly higher average transition temperatures (nucleus 33°C, cortex 26·3°C) and cooperativities, 38·1, as compared to the value of 24·1 for the cortical-lipid phase transitions. At 36°C, the phase transitions corresponding to cortical and nuclear lipids indicate a similar degree of disorder, 63%, in the hydrocarbon chains, i.e., similar relative amounts of gauche and trans rotomers. The twelve cataractous lenses investigated all had nuclear opacities, four were brunescent and four had cortical opacities. No significant differences were observed in the phase transition parameters (temperature, cooperativity, magnitude, enthalpy) evaluated for the nuclear-lipid membranes corresponding to the different types of cataracts. Furthermore, for the cataractous membranes, the phase transition parameters obtained for the nuclear lipids were comparable to those evaluated for the cortical lipid membranes. However, the cortical lipids exhibited the highest order in membranes from nuclear cataracts without cortical opacity. The cortical lipids from clear, non-cataractous lenses had the lowest level of order. At 36°C, the degree of order in the cortical lipid from clear lenses was comparable to that from nuclear cataractous lenses without cortical opacity. The transition temperature, and cooperativity were significantly higher for cortical lipids from cataractous lenses as compared to those from clear lenses. At 36°C, the degree of order in the cortical lipid membranes was lower for all cataract types vs. clear lens fractions. Our results suggest the possibility that lipid-lipid interactions could be different in cataractous lens membranes. Lipid compositional and chemical differences must account for these altered lipid interactions. These studies will provide a basis for studying lipid-protein interactions and structure-function relationships in the lens membrane.

Infrared Study of the Structure and Composition of Rabbit Lens Membranes: a Comparative Analysis of the Lipids of the Nucleus, Cortex and Epithelium

Infrared spectra of the phospholipids extracted from the nuclear, cortical and epithelial regions of the rabbit lens membrane bilayers are examined for the first time. Major structural, conformational and compositional differences in the lens membrane are correlated at physiological temperature. Vibrational data distinguish two classes of the phospholipids present in the rabbit lens membranes. Sphingo-lipids with a sphingosine backbone are largely concentrated in the nucleus whereas phospholipids with a glycerol backbone (glycero-lipids) such as phosphatidylcholine and phosphatidylethanolamine are abundant in the cortical region of the lens. Nuclear lipids are more saturated by a factor of four over the lipids of the cortical region. Nuclear lipids also exhibit increased headgroup and interface hydration and stronger hydrogen bonding over cortical lipids which provide them additional structural stability needed for the clarity of the lens. The lipid composition of the epithelial membranes is structurally similar to that of the cortical region but the hydrocarbon chains are more saturated. Epithelial membranes are largely shielded from bilayer water indicating hydrophilic lipid-water interactions are not important for the stability of these membranes. These membranes exhibit much stronger lipid-lipid interactions, vital for many physical properties like membrane fluidity and permeability. The fiber cell membranes are stabilized by hydrogen bonding of the carbonyls of the interface region and by headgroup-specific lipid-water interactions, while epithelial membranes are stabilized primarily through hydrophobic lipid-lipid interactions.Data also exhibit two phase transitions around 16 and 35°C corresponding to the melting of the hydrocarbon chains from two pools of the phospholipids i.e. glycero- and sphingo-phospholipids, respectively. The first transition is caused by disruption of the carbonyl hydrogen bonding and disordering of the acyl chains of the glycero-lipids, while second transition is driven mainly from the hydrogen bonding effects of the carbonyls of the sphingo-lipids followed by acyl/sphingosine chain disordering. Upon transition to the liquid-crystalline phase, a sizable amount of the fiber cell membranes are disordered (approximately 33%) due to increased conformational motion of the acyl chains resulting from a loss of extended CH2 trans segments. These chains of the fully hydrated lipids pack in an hexagonal or triclinic unit cell in rabbit lens membranes.

Raman structural characterization of clear human lens lipid membranes.

Raman spectroscopy was used for the first time to characterize the structure of lipid membranes prepared from the nuclear and cortical regions of 48 and 69 year old clear human lenses. The interface region carbonyl band appears as a doublet at 1742 and 1728 cm-1. The lower frequency band is characteristic of a hydrogen bonded carbonyl group, perhaps to bilayer water. From the intensity of the curve fit bands, we calculate that 43% of the carbonyl groups are hydrogen bonded. Our data show that the hydrocarbon chains of the nuclear lipids are 1.4 times more saturated than those of the cortical lipids. The molar ratio of phospholipid CH2/= C-H groups was calculated to be 13 and 18 for cortical and nuclear lipids, respectively. Hydrocarbon chain disorder was estimated to be 72 and 58% (+/- 8% disorder) for the cortical and the nuclear lipids, respectively. Raman spectroscopy is sensitive to structural differences in various regions of the lipid bilayer and could be an effective tool to explore lipid and protein interactions in terms of lens region, age and opacity.

Renal injury of diet-induced hypercholesterolemia in rats

Abnormalities in lipid metabolism frequently accompany renal disease and may be important in the pathogenesis of progressive renal injury. In the present study, the effects of a high cholesterol diet on renal histology, cortical lipids, and glomerular hemodynamic function were examined in normal rats with and without reduced renal mass. Cholesterol feeding for 19 weeks increased serum cholesterol from 66 +/- 10 mg/dl to 256 +/- 93 mg/dl in two-kidney rats, and from 73 +/- 15 mg/dl to 407 +/- 274 mg/dl in nephrectomy rats (P less than 0.01). Both sham-operated and unilateral nephrectomy rats fed a high cholesterol diet had a greater amount of glomerulosclerosis and tubulointerstitial damage than rats fed standard chow. Cortical cholesteryl esters were increased by the cholesterol diet, and correlated with the amount of glomerulosclerosis (r = 0.90, P less than 0.01) and tubulointerstitial injury (r = 0.64, P less than 0.05). Cholesterol feeding and nephrectomy both caused alterations in tissue essential fatty acids, and a panel of specific monoclonal antibodies indicated that renal injury and cortical lipid alterations were associated with an increase in glomerular macrophages. Finally, micropuncture experiments carried out in a separate group of rats fed high cholesterol for 8 to 10 weeks demonstrated increases in glomerular capillary pressure. These results suggest that additional investigations may ultimately determine how cholesterol deposition, altered fatty acid metabolism, macrophages, and increased glomerular pressure might combine to cause chronic progressive renal injury.

Glomerular disease in hypercholesterolemia guinea pigs: A pathogenetic study

Recent evidence suggests a role for lipid deposition in the pathogenesis of some forms of glomerular disease. To gain further insight into this phenomenon guinea pigs (GP) were fed a 2% cholesterol (HC) diet and compared to GP on a normal diet (C). Serial observations were made 5, 10, 30 and 70 days after the initiation of the experiment. HC gained less weight than C (P less than 0.001) and developed hemolytic anemia after 30 days. At all time periods serum total cholesterol (TC) was significantly elevated in HC (P less than 0.001). High density lipoprotein-cholesterol and total phospholipids (PL) were significantly higher in HC at days 30 and 70. Lipoprotein-X was detected in HC serum. The relative proportion (%) of cholesteryl ester (CE) at day 70 was significantly higher in HC than in C when renal cortical lipids were analyzed (P less than 0.017). Renal function was normal in both groups throughout the 70 days. The HC group developed proteinuria and hematuria (proteinuria, HC = 22.1 +/- 7.2 mg/24 hr; C, 6.4 +/- 2.3 mg/24 hr), which was detected at day 70 but not at day 30. HC developed significant progressive mesangial expansion which was first evident at day 30. In HC only oil red 0 material was first detected in glomeruli at day 5 and was very conspicuous at day 70. Increased intraglomerular monocyte numbers were detected at day 70 (P less than 0.017) but not at day 30 in HC. No glomerulosclerosis was observed in GP's with drug-induced hemolysis on a normal diet. To see the effect of high protein intake on HC GP's, a group of GP's was put on a HC diet for 30 days followed by a 2% cholesterol-high protein (HCHP) diet for 40 days. Compared to HC GP's, the HCHP group showed significantly higher serum TC and PL (P less than 0.017), mesangial expansion (P less than 0.01) and proteinuria (P less than 0.01). The results indicate that hypercholesterolemia plays an important role in the pathogenesis of glomerulosclerosis in this model and that the process appears to be mediated, at least in part in the later stages, by monocytes. The addition of protein to the HC diet augments these effects.

Physical properties of membranes and membrane lipids from the fiber cell of the U18666A-cataractous rat.

Steady state fluorescence anisotropy of parinaric acid probes was used to examine lipid motion in membranes and membrane lipids from U18666A-induced cataractous rat lenses. Cortical and nuclear fractions were examined separately. The drug treatment resulted in an increase in the sterol/phospholipid ratio in the nucleus and a decrease in this ratio in the cortex. Fluorescence anisotropy of trans parinaric acid (tPnA) suggested that membranes from the cortex of cataractous lenses were more ordered than the cortical membranes from control or treated-but-clear lenses. Membranes from the nucleus of control lenses were more ordered than membranes from the cortex of controls. Nuclear membranes from cataractous lenses were slightly less ordered than nuclear membrane from control or treated-but-clear lenses. Similar experiments using liposomes prepared with membrane lipid from lens cortex showed that membrane lipids from treated lenses, control lenses, and treated-but-clear lenses had similar fluorescence anisotropy profiles, suggesting that cortical lipids had similar order. Conversely, fluorescence anisotropy of parinaric acid probes in liposomes prepared from nuclear fractions showed a slight increase in lipid order from control to treated-but-clear to cataractous preparations. These results are interpreted to indicate the presence of an alteration in lipid-protein interactions in cortical membranes in the cataractous lenses; this results in more ordered membranes at the physiological temperature in these lenses. The increase in the order of cortical membranes from cataractous lenses is dependent on the presence of membrane proteins rather than lipids, since it is not seen in the liposome preparations (which are protein-free).(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrastructure of Dormant, Converted, and Germinating Oospores of Pythium ultimum

The ultrastructural aspects of the conversion of constitutively dormant oospores of Pythium ultimum to thin-walled germinable oospores and their subsequent germination were studied by electron microscopy. During conversion, the thick inner oospore wall dissolves leaving the outer oospore wall as a loose but intact layer surrounding the spore. A thin germination wall, which eventually extends as the germ tube wall, becomes apparent around the protoplast. The protoplasm of the dormant oospore is predominantly reserve cytoplasm and includes a cortical layer of lipid bodies and a dense central ooplast. Converted oospores contain a more functional protoplasm including nuclei, mitochondria, endoplasmic reticulum, dictyosomes, and unattached ribosomes. The cortical lipids disperse within the cytoplasm while the ooplast breaks into fragments which are enveloped in membranes to form the densebody or “fingerprint” vacuoles characteristic of the oomycetous fungi. After sucrose is added, germinable oospores produce single germ tubes which rupture the outer oospore and oogonial walls. Germ tube tips are laden with dictyosome-derived vesicles.

Histopathological effects of Naja haje snake venom and a venom gland extract of the scorpion Buthus quinquestriatus on the liver, suprarenal gland and pancreas of mice

Lethal doses of Naja haje snake venom produced central and midzonal hydropic degeneration in hepatic lobules. Buthus quinquestriatus scorpion venom gland extract caused peripheral zonal hydropic degeneration, sinusoidal dilatation and disruption. Fatty degenerative changes started earlier after use of the scorpion preparation. Both preparations depleted glycogen, inhibited succinic dehydrogenase and increased alkaline phosphatase activity in degenerated hepatocytes. Signs of regeneration followed sublethal doses of Naja haje venom. Lethal doses of both venom preparations caused rupture of the capsule of the suprarenal gland and detachment of its cortex. Blood extravasated in the medulla. Zona fasciculata cells were hypertrophied and vacuolated and cortical lipids increased. Depletion of ascorbic acid and medullary catecholamines occurred. After a single sublethal dose the zona reticularis region increased in thickness due to proliferation of its cells. These cells invaded the medullary clumps. Repeated sublethal doses increased the thickness of both the zona fasciculata and reticularis. In the pancreas, lethal doses of both venom preparations produced vacuolization of alpha and beta cells. Partial and complete degranulation were observed in hydropically degenerated beta cells. Alpha cells showed decreased alkaline phosphatase activity.

Cortical and medullary lipids of normal and nephrosclerotic human kidney

1. 1. Major lipid classes from cortical and medullary zones of normal and nephrosclerotic human kidneys have been isolated and the fatty acid composition of each determined. 2. 2. The nephrosclerotic tissue contained two times more total lipid than the normal kidney but, irrespective of kidney pathology, phospholipids were the major cortical lipids and neutral lipids were the predominant lipids in medullary zones. 3. 3. Human kidney contained large amounts of phosphatidylcholines, phosphatidylethanolamines and sphingomyelins and although these were slightly increased in the sclerotic kidney, anatomical differences in phospholipid content were not significant. 4. 4. Quantitative differences between the zones of normal kidney were found with triglycerides, diglycerides. free fatty acids and cholesterol; overall, the sclerotic tissue contained more triglycerides and small amounts of cholesterol esters with less significant regional differences. 5. 5. Palmitic, oleic and stearic acid were the major fatty acids of neutral lipids; these plus linoleic acid were prevalent in phospholipids.

Changes in cerebral cortical lipids in cobalt-induced epilepsy.

Abstract– In control rats and in rats rendered epileptic by insertion of cobalt slivers into the cerebral cortex, total free fatty acids, free cholesterol, esterified cholesterol, triglycerides and phospholipids were measured in normal and lesion areas of cerebral cortex. The cortical lipid profile of the adult rat resembled that of the whole brain of very young rats rather than that of adult whole brain, with the principal differences from whole adult brain being lower total lipid content, increased proportions of phosphatidyl choline in the phospholipid fraction, and higher levels of cholesterol esters. Cobalt‐induced epilepsy was associated with significant changes in cerebral cortical lipids in the area of the lesion and in the non‐necrotic tissue adjacent to the lesion. The total lipid in the area of the lesion decreased sharply as a result of reductions in free cholesterol and total phospholipids. The levels of cholesterol esters and triglycerides increased in the area of the lesion, and cholesterol esters were also increased in the adjacent tissue. In addition there were decreases in the proportion of phosphatidyl ethanolamine in the phospholipids from the lesion site and adjacent tissue and decreases in the proportions of oleic, arachidonic and nervonic acids (unsaturated acids), and an increase in the proportions of lignoceric acid in the phospholipids. In the site of the lesion only, we observed a decrease in phospholipid palmitic acid and an appreciable increase in the proportions of an unidentified long‐chained fatty acid.