Lipofuscin-like Pigments Research Articles

Lipid-involved browning mechanism during the drying process of squid

The present study evaluated lipid-involved browning mechanism during the drying process of squid. Initially, different lipid-Maillard reaction (MR) models were conducted based on the composition of squid (lipids, reducing sugars and amino acids). The degree of MR as well as α-dicarbonyl compounds (α-DCs) and lipid oxidation-mediated browning products (pyrroles and lipofuscin-like pigments) were detected. The results indicated that arginine and ribose were blamed for the browning of dried squid. Moreover, lipid oxidation provided glyoxal and methylglyoxal to participate in MR, and long-time heating and salting produced more α-DCs and accelerated browning. Meanwhile, dried squid contained hydrophilic pyrrole (17.45 μg/g lipid) and hydrophobic pyrrole (113.00 μg/g lipid), and the content of lipofuscin-like pigments increased by 1.5-fold after drying. Finally, defatting treatment demonstrated that the browning of dried squid was moderately alleviated by fat removal (L* ↑, a* ↓ and b* ↓). These findings offer a novel perspective on moderately preventing the browning of dried aquatic products.

Influence of selected phenolic acids on advanced lipid oxidation end products generation in model systems

The objective of this study was to assess the inhibitory impacts of chlorogenic acid (CGA), ferulic acid (FA), and vanillic acid (VA) on advanced lipid oxidation end products (ALEs) generation in bovine serum albumin-linoleic acid models. The addition of 160 μg/mL CGA and VA significantly blocked the formation of lipofuscin-like pigments (LFLP), reducing them by 22.141% ± 1.823% and 12.156% ± 1.296% respectively. It is worth noting that the best inhibition of LFLP by FA was observed at 40 μg/mL (13.105% ± 0.731%). Compared to the control (25.280 ± 1.580 mg/kg protein), thiobarbituric acid reactive substances values were the lowest in the samples containing 160 μg/mL CGA (2.107 ± 0.912 mg/kg protein), 40 μg/mL FA (6.847 ± 1.824 mg/kg protein), and 160 μg/mL VA (10.007 ± 0.912 mg/kg protein) (P < 0.05). These results suggest that CGA has a more potent inhibitory effect on ALEs formation compared to FA and VA. Therefore, CGA, FA, and VA can be considered as safe dietary phenolic acids for reducing ALEs formation.

Molecular mechanism of color deepening of ready-to-eat shrimp during storage

Color deepening occurs during storage of ready-to-eat (RTE) shrimps, which seriously affects their marketing cycle. This study investigated the molecular mechanisms of color deterioration in RTE shrimps during accelerated storage, shedding light on the pattern of change in colored products and content. The findings revealed significant occurrences of phenolic oxidation, lipid oxidation, and Maillard browning reactions during accelerated storage. Qualitative and quantitative analyses were conducted on the colored products resulting from these chemical reactions. Multivariate mathematical models were employed to analyze the phenolic oxidation products (2-methylanthraquinone and p-benzoquinone), lipid oxidation products (lipofuscin-like pigments and hydrophobic pyrroles), and Maillard browning products (pyrazines and melanoidins). These products were identified as the main contributors to the deepening of the color of RTE shrimps during storage. The outcomes of this research could enhance our understanding of the color change mechanism in thermally processed marine foods, providing valuable insights for quality maintenance and industrial advancement.

Infrared radiation blanching-inhibited browning and extended shelf life of pecan kernels.

To evaluate infrared radiation (IR) blanching in comparison to conventional hot water (HW) blanching in inhibiting the browning and extending the shelf life of pecan kernels, the technology of IR blanching at 500-700W for 90-45s or HW blanching at 90°C for 60s, and subsequently drying with hot air at 60, 70, and 80°C, respectively, was used, and then the activities of lipoxidase (LOX) and polyphenol oxidase (PPO), antioxidant capacities, color change, microscopic structure, and the shelf life of kernels were analyzed. Results showed that IR blanching not only significantly decreased the subsequent drying time but also effectively inactivated the activities of LOX and PPO, showing a lower residual activity of 15.74%-40.41% and 16.75%-56.25%, respectively. A higher retention of total phenolics was observed in kernels subjected to IR blanching, from 25.03±0.04 to 29.50±0.96mgGAE/g compared with HW blanching (14.43±0.07mgGAE/g). Meanwhile, IR-blanched samples showed lower peroxide values, p-anisidine values, total color difference values, browning index, quinones contents, and lipofuscin-like pigments levels but had higher 2,2-diphenyl-1-picrylhydrazyl inhibition rate and better storage stabilities than HW-blanched samples. The technology of IR blanching at 600 W for 60s followed by drying with hot air at 70°C for 40min is suitable for producing pecan kernels with better qualities and a longer shelf life, through inactivating the endogenous enzymatic reactions and inhibiting the formation of lipofuscin-like pigments. PRACTICAL APPLICATION: Blanching is an essential pretreatment of food processing. Conventional blanching is achieved by hot water, which has some disadvantages of low-intensity enzyme inactivation, loss of water-soluble substances, etc. In this study, the potential of using infrared blanching, prior to drying, was studied to find solutions to improve the nutritional value, and the shelf life of pecan kernels. The results showed that infrared blanching at 600 W for 60 s followed by drying with hot air at 70°C for 40 min could inhibit the color degradation, improve the oxidation resistance, and prolong the shelf life of kernels.

Effect of (E,E)‐2,4‐decadienal on Side‐Chain Modification, Conformation Change, and Aggregation of Bovine Serum Albumin

AbstractProtein modification by active aldehydes is associated with ageing and some chronic diseases, and it is closely related to food quality and safety. In this study, the modification of bovine serum albumin (BSA) using trans,trans‐2,4‐decadienal at various concentrations (0–10 mm) is investigated. The results show that the changes in the number of free amino groups and arginine residues, carbonyl formation, aggregation characteristics, and fluorescent lipofuscin‐like pigments (LFLP) fluorescence are more severe at (E,E)‐2,4‐decadienal concentrations of 4–10 mm, whereas the conformational changes are more significant at low concentrations (0.1–2 mm). In the BSA modified by 1–10 mm (E,E)‐2,4‐decadienal, the microenvironment of tryptophan residues to become more hydrophobic, the structure became compact, hydrophobic binding sites decreases, molecular weight and particle size increases, and covalently cross‐linked heterogeneous aggregates increases. At the same time, the relationship between the oxidation parameters and samples is explained using principal component analysis and hierarchical cluster analysis.Practical Applications: (E,E)‐2,4‐decadienal is highly electrophilically active with biomacromolecules. However, compared to the widely studied malonaldehyde (MDA), acrolein (ACR), 4‐hydroxynonenal (HNE), and 4‐oxo‐trans‐2‐nonenal (ONE)‐protein adducts, research on the modification of a protein by (E,E)‐2,4‐decadienal is insufficient, and the chemical nature of (E,E)‐2,4‐decadienal‐protein adducts is not clear. This study may be useful for extending our understanding of the specific role of (E,E)‐2,4‐decadienal in the formation of modified proteins during the occurrence of chronic diseases and provides a theoretical reference for food quality and safety problems caused by protein carbonylation during processing and storage.

The neuronal ceroid lipofuscinosis-related protein CLN8 regulates endo-lysosomal dynamics and dendritic morphology.

The endo-lysosomal system (ELS) comprises a set of membranous organelles responsible for transporting intracellular and extracellular components within cells. Defects in lysosomal proteins usually affect a large variety of processes and underlie many diseases, most of them with a strong neuronal impact. Mutations in the endoplasmic reticulum-resident CLN8 protein cause CLN8 disease. This condition is one of the 14 known neuronal ceroid lipofuscinoses (NCLs), a group of inherited diseases characterised by accumulation of lipofuscin-like pigments within lysosomes. Besides mediating the transport of soluble lysosomal proteins, recent research suggested a role for CLN8 in the transport of vesicles and lipids, and autophagy. However, the consequences of CLN8 deficiency on ELS structure and activity, as well as the potential impact on neuronal development, remain poorly characterised. Therefore, we performed CLN8 knockdown in neuronal and non-neuronal cell models to analyse structural, dynamic and functional changes in the ELS and to assess the impact of CLN8 deficiency on axodendritic development. CLN8 knockdown increased the size of the Golgi apparatus, the number of mobile vesicles and the speed of endo-lysosomes. Using the fluorescent fusion protein mApple-LAMP1-pHluorin, we detected significant lysosomal alkalisation in CLN8-deficient cells. In turn, experiments in primary rat hippocampal neurons showed that CLN8 deficiency decreased the complexity and size of the somatodendritic compartment. Our results suggest the participation of CLN8 in vesicular distribution, lysosomal pH and normal development of the dendritic tree. We speculate that the defects triggered by CLN8 deficiency on ELS structure and dynamics underlie morphological alterations in neurons, which ultimately lead to the characteristic neurodegeneration observed in this NCL. This is, to our knowledge, the first characterisation of the effects of CLN8 dysfunction on the structure and dynamics of the ELS. Moreover, our findings suggest a novel role for CLN8 in somatodendritic development, which may account at least in part for the neuropathological manifestations associated with CLN8 disease.

Key factors behind autofluorescence changes caused by ablation of cardiac tissue

Radiofrequency ablation is a commonly used clinical procedure that destroys arrhythmogenic sources in patients suffering from atrial fibrillation and other types of cardiac arrhythmias. To improve the success of this procedure, new approaches for real-time visualization of ablation sites are being developed. One of these promising methods is hyperspectral imaging, an approach that detects lesions based on changes in the endogenous tissue autofluorescence profile. To facilitate the clinical implementation of this approach, we examined the key variables that can influence ablation-induced spectral changes, including the drop in myocardial NADH levels, the release of lipofuscin-like pigments, and the increase in diffuse reflectance of the cardiac muscle beneath the endocardial layer. Insights from these experiments suggested simpler algorithms that can be used to acquire and post-process the spectral information required to reveal the lesion sites. Our study is relevant to a growing number of multilayered clinical targets to which spectral approaches are being applied.

Histopathological assessment of the health status of Mytilus chilensis (Hupé 1854) in southern Chile

Mussel (Mytilus chilensis) farming is an important economic and social activity in the south of Chile. With a landing of 302,642 tons in year 2016, Chile is the second mytilid producer after China, and the first exporter worldwide. To be better prepared to protect this industry, the health status of a total number of 478 mussels (M. chilensis) from the Los Lagos Region, in the south of Chile, was assessed. Baseline information on symbionts, parasites and pathological conditions of both cultivated and natural mussels was collected using histology. Organisms detected included: intracellular microcolonies of bacteria (IMC), located in the epithelium of the gill and of digestive gland tubules; a microsporidian resembling Steinhausia mytilovum hosted by oocytes; two gill ciliates; a copepod; and a digenean trematode. Pathological conditions included neoplasia, hemocyte aggregates within digestive epithelia, lipofuscin-like pigments in various tissues, and gill epithelium desquamation. The prevalence of each finding was assessed and compared statistically between sites and between cultured and natural populations. The infection intensity of them was low, and no OIE listed parasite was detected. Of all the findings of this study, those that could be of concern are the IMC, neoplasia, and the Steinhausia mytilovum-like microsporidian. This study provided baseline data necessary for the design of a larger, seasonal sampling, which will allow to assess the feasibility of a permanent monitoring program to protect the huge mussel cultivating industry of the Los Lagos Region in Chile.

Changes in the composition of fatty acids and lipofuscin-like pigments during development of rat heart.

Postnatal heart development is characterized by critical periods of heart remodeling. In order to characterize the changes in the lipophilic fraction induced by free radicals, fatty acids and their oxidized products, lipofuscin-like pigments (LFP), were investigated. Fatty acids were analyzed by gas chromatography and LFP were studied by fluorescence techniques. A fluorophore characterized by spectral methods was further resolved by HPLC. Major changes in the composition of fatty acids occurred immediately after birth and then during maturation. Fluorescence of LFP changed markedly on postnatal days 1, 4, 8, and 14, and differed from the adult animals. LFP comprise several fluorophores that were present since fetal state till adulthood. No new major fluorophores were formed during development, just the abundances of individual fluorophores have been modulated which produced changes in the shape of the spectral arrays. HPLC resolved the fluorophore with excitation maximum at 360 nm and emission maximum at 410 nm. New chromatographically distinct species appeared immediately on postnatal day 1, and then on days 30 and 60. Consumption of polyunsaturated fatty acids immediately after birth and subsequent formation of LFP suggests that oxidative stress is involved in normal heart development.

Accumulation of lipofuscin‐like pigments of walnuts (Carya cathayensis) during storage: potential roles of lipid oxidation and non‐enzymatic glycosylation

Lipofuscin-like pigments (LFLP) are considered a hallmark of aging. The intracellular LFLP formation rate is negatively correlated with the life expectancy of cell. In food quality, increase of LFLP not only affects the appearance but also causes loss of nutritional value. The accumulation of LFLP increased during storage of all walnuts. LFLP fluorescent intensities of walnuts with 4%, 6%, 12% and 16% moisture at the end of storage were 8.1, 4.8, 4.3 and 2.8 times those at the beginning, respectively. The LFLP accumulation of walnuts with high moisture was found to be negatively correlated with soluble sugars and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical quenching rate, but positively correlated with the content of hydroxymethylfuraldehyde (HMF). While the LFLP accumulation of walnuts with low moisture had a strong positive correlation with anisidine value, it exhibited high negative correlations with acid phosphatase activity, DPPH(•) quenching rate and tocopherol content. In walnuts with low initial moisture, lipoxidation products increased markedly during storage and these products might provide the source for LFLP accumulation. On the other hand, in walnuts with high initial moisture, reducing sugars derived from the hydrolysis of soluble sugars might play an important role in initiating the Maillard-like reaction, leading to LFLP accumulation.

Ameliorative Action of Mn-Salen Derivatives on CCl&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt;-Induced Destructive Effects and Lipofuscin-Like Pigment Formation in Rats’ Liver and Brain: Post-Treatment of Young Rats with EUKs

Lipofuscin-like pigments (LFPs) are highly oxidized cross-linked aggregates of oxidized protein and lipids which are formed under oxidative state conditions by free radicals produced. The present study aimed to evaluate the probable ameliorative effects of some of the Mn-salens namely EUKs 8, 134, 15, 115, 122 and 132 (compounds 1-6) and vitamin C against carbon tetrachloride (CCl4)-induced acute damage on rats’ livers and brains. Exposure to CCl4 is believed to induce oxidative stress and cause tissue damage due to the formation of trichloromethyl (·CCl3) and peroxy trichloromethyl (·OOCCl3) radicals. In this study, 54 rats were randomly divided into 9 groups of six each: normal group received only vehicle (olive oil; 2 ml/kg b.w.) for 6 consecutive days; CCl4- intoxicated group received the vehicle and CCl4 (50% solution of CCl4 in olive oil, 2 ml/kg b.w.) on the first and second days and the vehicle on the third to sixth days; test rats received Mn-salens or vitamin C (20 mg/kg b.w.) and CCl4 (2 ml/kg b.w.) on the first and second days and Mn-salens or vitamin C (20 mg/kg b.w.) on the third to sixth days. Mn-salens administration ameliorated the effects of CCl4 by decreasing the levels of ROS, lipid and protein oxidations and LFPs formation on liver and brain as well as cholesterol and triglycerides, aminotransferases and alkaline phosphatase contents in sera of rats whereas increased the activities of catalase, superoxide dismutase,glutathione reductase, glutathione peroxidase and reduced glutathione in liver and brain tissues. Histopathological studies confirmed the toxic effects of CCl4 and ameliorative action of Mn-salens on tissues. These results suggest that the evaluated EUKs were able to attenuate LFPs accumulation and morphological changes caused by CCl4 in rats and thus, confirming the ameliorative role of Mn-salens against CCl4-induced oxidative damage and age-related diseases.

Interaction between oxidized lipids and amyloid-β in amplifying neuronal damage in Alzheimer's disease

Oxidative stress, which is present in Alzheimer's disease (AD), results in the formation of various end-products of free radical reactions with proteins and lipids. At present there are no reliable diagnostic biomarkers of AD in the blood. Therefore, specific products of lipid peroxidation in the blood of AD patients were investigated. Lipophilic extracts of erythrocytes in the group of patients with AD (n = 44) and age-matched controls (n = 16) were studied. The end-products of lipid peroxidation, so called lipofuscin-like pigments (LFP), were analysed by fluorescence spectroscopy. It was found that the level of these products is significantly increased in erythrocytes of AD patients compared to controls. LFP were further separated by means of HPLC into individual fractions to study their composition in AD and controls. The specific fraction of LFP in AD patients, which was isolated, might represent a disease-specific product in the blood.

Characterization and Quenching of Autofluorescence in Piglet Testis Tissue and Cells

Significant intrinsic fluorescence in tissues and in disassociated cells can interfere with fluorescence identification of target cells. The objectives of the present study were (1) to examine an intrinsic fluorescence we observed in both the piglet testis tissue and cells and (2) to test an effective method to block the autofluorescence. We observed that a number of granules within the testis interstitial cells were inherently fluorescent, detectable using epifluorescence microscopy, confocal laser scanning microscopy, and flow cytometry. The emission wavelength of the autofluorescent substance ranged from 425 to 700 nm, a range sufficiently broad that could potentially interfere with fluorescence techniques. When we treated the samples with Sudan Black B for different incubation times, the intrinsic fluorescence was completely masked after treatment for 10–15 min of the testis tissue sections or for 8 min of the testis cells, without compromising specific fluorescence labeling of gonocytes with lectin Dolichos biflorus agglutinin (DBA). We speculate that the lipofuscin or lipofuscin-like pigments within Leydig cell granules were mainly responsible for the observed intrinsic fluorescence in piglet testes. The method described in the present study can facilitate the identification and characterization of piglet gonocytes using fluorescence microscopy.

Ontogenetic Changes of Lipofuscin-Like Pigments in the Rat Heart

Increased generation of reactive oxygen species results in the formation of fluorescent end-products of lipid peroxidation - lipofuscin-like pigments (LFP). LFP increased up to six-fold from the fetal value in the rat heart immediately after birth. In the experimental design of this study the fetuses were sampled 1 day before birth, and then the samples were collected on postnatal days 1, 4, 7, 10, 15, 30, and 60. Males and females were compared on day 30 and 60 when the difference between right and left ventricle was studied as well. Four LFP fluorophores were analyzed: F355/440, F310/470, F350/450, F315/450 (excitation/emission, nm). All fluorophores decreased on day 4 relative to day 1, subsequent transient increases ended in a significant decrease on day 60. However, the LFP levels on day 60 are still about threefold higher than those in fetuses. Differences between male and female hearts were observed on day 30. The corresponding male ventricles contained by one third higher concentration of LFP than the female counterparts. The increase in LFP concentration in male ventricles on day 30 was only transient, no difference between corresponding male and female ventricles was found on day 60. The most distinguished feature in the male heart was a sharp LFP decrease in the right ventricle on day 60.

End products of lipid peroxidation in erythrocyte membranes in Alzheimer's disease

Alzheimer's disease (AD) is accompanied by oxidative stress in the brain. Because the brain tissue is rich in polyunsaturated fatty acids, it is prone to the free radical attack resulting in lipid peroxidation. Intermediates of lipid peroxidation may diffuse from the primary site, cross the blood-brain barrier and modify erythrocyte membranes in the bloodstream. We exposed isolated erythrocyte membranes from patients with AD and the control group to in vitro free radical damage and monitored the accumulation of the end products of lipid peroxidation, lipofuscin-like pigments (LFPs), by fluorescence spectroscopy. LFPs were analyzed by means of tridimensional and synchronous fluorescence spectroscopy. The levels of LFP formed during in vitro peroxidation were significantly higher in erythrocyte membranes from patients with AD compared with the control group. Furthermore, the chemical composition of LFP in AD was different from the control group. The analysis of the specific modifications of erythrocyte membranes in AD is of great medical importance regarding the need of a diagnostic blood biomarker.

Lipofuscin-Like Pigment in Gonads of Sea Urchin Strongylocentrotus intermedius as a Potential Biomarker of Marine Pollution: A Field Study

Accumulation of lipofuscin-like pigments (LLPs) has been shown to be an appropriate index of both age and stress in some aquatic invertebrates. In the present study, LLP was quantified by measuring its autofluorescence intensity (ex 450nm/em 512nm) in nutritive phagocytes (NPs) of sea urchins Strongylocentrotus intermedius inhabiting polluted and relatively clean areas of Japan Sea. To avoid variations in LLP content related to sea urchin reproductive condition, only developing gonads with acini occupied mostly by NPs were used for LLP quantification as well as semiquantitative histopathological analysis. LLP concentrations ranged from 0.0 to 4.57±0.53% area fraction in female gonads and from 0.0 to 4.61±0.35% in male gonads. The presence of specimens with extremely high LLP concentrations (>1.5%) in all examined samples, including specimens from the reference station, as well as the absence of strong correlations between LLP concentrations and several parameters related to pollution (heavy-metal concentrations in sea urchin gonads and concentrations of heavy metals, DDT, hexachlorocyclohexane, and total petroleum hydrocarbons in sediments), allow us to conclude that LLP content in sea urchin NPs can not be used as a biomarker in marine pollution monitoring.

Uptake of Foreign Ferritin in Heart of Firemouth Cichlid (Cichlidae: Teleostei)

The ultrastructure of the endothelium in the heart of the firemouth cichlid (Thorichthys meeki) and its capability and capacity to take up foreign ferritin are described. The entire wall in atrium and ventricle was spongy and composed of muscle trabeculae, covered by endothelial cells which were about 4-6-μm thick in atrium and flat in ventricle. These cells contained a number of moderately electron-dense bodies (MDBs, diameter 2 μm and less), clathrin-coated vesicles, and tubules of agranular endoplasmatic reticulum. Numerous yellow-brown granules, width 2 μm and less, occurred in the endocardial endothelium covering the cardiac muscle trabeculae in ferritin-injected firemouth cichlid 8 hr postinjection; much Prussian blue precipitated within these granules when treated with acid ferrocyanide. When the time between the injection and sacrifice was extended to 24 hr, the granules and Prussian blue precipitations in the corresponding endocardial endothelium displayed a width of 3 μm and more. The endocardial endothelium facing the cardiac main lumen or covering the valves and walls of the atrio-ventriclar or ventriculo-bulbar apertures nearly lacks such granules and precipitations as well as MDB, clathrin-coated vesicles and tubules of agranular endoplasmic reticulum, suggesting that the endothelium at these sites is not endocytic. Lipofuscinlike pigments were demonstrated by the Schmorl's technique in the endocardial endothelium covering the heart muscle trabeculae in firemouth cichlid. Together these findings suggest that the endocardial endothelium cover on the muscle trabeculae in heart wall in firemouth cichlid is highly specialized to play important roles in the uptake of scavenger molecules and foreign particles. Such an uptake may be very efficient as this cell layer comes in contact with nearly the entire blood volume throughout the spongy heart wall in this type of teleosts.

HPLC Separation of Fluorescent Products of Lipid Peroxidation in Erythrocytes and Mitochondria

Polyunsaturated fatty acids found in membrane phospholipids are readily oxidized by free radicals producing highly reactive aldehydes such as malondialdehyde. These aldehydes react with biological material to form fluorescent lipid peroxidation end products known as lipofuscin-like pigments. We studied fluorescent pigments from beef heart mitochondria incubated with malondialdehyde in vitro and from erythrocytes of patients with Alzheimer’s disease to evaluate their potential as markers of oxidative stress and to develop HPLC methods for their qualitative analysis. We used tridimensional fluorescence spectral arrays and synchronous fluorescence spectra in connection with HPLC separation with fluorescence detection. Stable fluorophores were found in both models and were successfully resolved into several distinctive fractions. This creates the basis for further characterization of this relatively less studied group of products of oxidative damage.

Early postnatal development of rat brain is accompanied by generation of lipofuscin-like pigments

The increased generation of free radicals results in the formation of fluorescent end-products of lipid peroxidation, lipofuscin-like pigments (LFPs). The authors observed that LFPs are generated in rat brain after a normal birth during 5 postnatal days. The experimental design of the study comprised 10 groups of animals. The authors measured prenatal values 1 day and 7 days before birth, and then the animals were sampled on postnatal day 1, 2, 5, 10, 15, 25, 35, and 90. Maximum LFP concentration is achieved on the postnatal day 2. Starting from postnatal day 10, LFP concentration returns to prenatal values. A new rise in LFP concentration is observed at 3 months of age. This is associated with the beginning of the aging process. LFPs were characterized by fluorescence spectroscopy using tridimensional excitation spectra, synchronous spectra and their derivatives, and HPLC with fluorescence detection. It was possible to discern several tens of fluorescent compounds of unknown structure that are generated and metabolized during early development. The authors suggest that LFPs are formed after respiratory burst of microglia phagocytosing apoptotic cells.

The lipid peroxidation products as possible markers of Alzheimer's disease in blood

Oxidative stress, which is present in Alzheimer's disease (AD), results in the formation of various end-products of free radical reactions with proteins and lipids. At present there are no reliable diagnostic biomarkers of AD in the blood. Therefore, specific products of lipid peroxidation in the blood of AD patients were investigated. Lipophilic extracts of erythrocytes in the group of patients with AD (n = 44) and age-matched controls (n = 16) were studied. The end-products of lipid peroxidation, so called lipofuscin-like pigments (LFP), were analysed by fluorescence spectroscopy. It was found that the level of these products is significantly increased in erythrocytes of AD patients compared to controls. LFP were further separated by means of HPLC into individual fractions to study their composition in AD and controls. The specific fraction of LFP in AD patients, which was isolated, might represent a disease-specific product in the blood.