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Objective To improve the fixation method of the transmission electron microscope for better morphological preservation of mitochondria and lipid droplets in mouse brown adipose tissue. Methods The fixation method for mouse brown adipose tissue was optimized, mainly including an increased concentration of paraformaldehyde from 2% to 4% in the pre-fixative, employment of transcardial perfusion followed by immersion fixation in pre-fixation, and using imidazole-buffered osmium tetroxide as the post-fixative. The ultrastructures of brown adipocytes prepared by the improved method were observed and compared with those of a known standard protocol (3 mice in each group). The improved method was further validated in the quantitative analysis of mitochondrial cristae density and lipid droplets. Results The mitochondrial cristae and membrane structure of other organelles of brown adipocytes were better preserved using the optimized method compared with those of the standard method. Lipid droplets were presented as round structures with high electron density instead of vacuolated appearances. Using this method, we observed that the density of mitochondrial cristae and the content of lipid droplets increased in brown adipocytes after cold adaptation. Conclusion The optimized method can better preserve the ultrastructure of organelles in brown adipocytes, especially mitochondria and lipid droplets, and ma)' be applicable for studying the ultrastructures remodeling of brown adipose tissue under different physiological or pathological conditions.
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AIM: With building a proliferation model of PA-induced VSMC, the effect of ATGL, a key fat metabolism enzyme, on the phenotype transformation of VSMC was preliminarily explored. METHODS: 40 μmol/L Atglistatin was added to the proliferation model of VSMC induced by PA (50 μmol/L, 100 μmol/L, and 200 μmol/L, respectively) at separately administered concentrations, and cell viability and cell proliferation were detected by CCK-8 and EDU; cell migration ability was detected by scratch assay; oil red staining was used to detect the accumulation of lipid droplets in VSMC was detected by oil red staining; the effects of PA on ATGL as well as the effects of smooth muscle contraction phenotype proteins were examined by Western blot. RESULTS: PA at a concentration of 100 μmol/L could significantly induce VSMC proliferation, promote lipophagy and increase lipid droplet accumulation in VSMC; meanwhile, Atglistatin could exacerbate these changes caused by PA and increase lipid droplet accumulation in VSMC. CONCLUSION: Atglistatin exacerbates PA-induced VSMC proliferation and increases VSMC lipid droplet accumulation, and exacerbates transformation of proliferative phenotype of VSMC.
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BACKGROUND The knowledge about eicosanoid metabolism and lipid droplet (LD) formation in the Leishmania is very limited and new approaches are needed to identify which bioactive molecules are produced of them. OBJECTIVES Herein, we compared LDs and eicosanoids biogenesis in distinct Leishmania species which are etiologic agents of different clinical forms of leishmaniasis. METHODS For this, promastigotes of Leishmania amazonensis, L. braziliensis and L. infantum were stimulated with polyunsaturated fatty acids (PUFA) and LD and eicosanoid production was evaluated. We also compared mutations in structural models of human-like cyclooxygenase-2 (GP63) and prostaglandin F synthase (PGFS) proteins, as well as the levels of these enzymes in parasite cell extracts. FINDINGS PUFAs modulate the LD formation in L. braziliensis and L. infantum. Leishmania spp with equivalent tissue tropism had same protein mutations in GP63 and PGFS. No differences in GP63 production were observed among Leishmania spp, however PGFS production increased during the parasite differentiation. Stimulation with arachidonic acid resulted in elevated production of hydroxyeicosatetraenoic acids compared to prostaglandins. MAIN CONCLUSIONS Our data suggest LD formation and eicosanoid production are distinctly modulated by PUFAS dependent of Leishmania species. In addition, eicosanoid-enzyme mutations are more similar between Leishmania species with same host tropism.
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Objective To establish the theoretical model for morphology of lipid droplets adhering to inner vascular wall, so as to provide the theoretical model for the study and analysis of the overall morphology of lipid droplets on inner vascular wall of patients with fat embolism. MethodsThe model of the droplet with variable radius on inner wall of the cylindrical tube was established to describe morphology of lipid droplets on inner vascular wall, and accuracy of the theoretical model was verified by Surface Evolver (SE) software simulation results. According to the theoretical model, the influencing patterns of lipid droplet volume and contact angle on dimensionless adhesion area Sb0 and blockage ratio κ of lipid droplets in blood vessels were analyzed. Results The theoretical model could predict contour parameters of adhesion morphology for lipid droplets on inner vascular wall, including the height and arc radius of lipid droplet at azimuth angle of 0 and π/2. The relative errors between contour parameters obtained from the theoretical model and corresponding parameters obtained from the SE simulation were smaller than 10%. For lipid droplets with the same dimensionless volume V0, Sb0 of inner vascular wall decreased with contact angle increasing, and blockage ratio κ increased with contact angle increasing. At the same contact angle, the smaller V0 , the smaller Sb0 and κ would be. Conclusions The established theoretical model with variable radius can well describe morphological characteristics of lipid droplets on inner vascular wall. The influening pattern of volume, contact angle and other parameters on height, adhesion area and cross-sectional area of lipid droplets can be accurately and quickly obtained through the theoretical model, indicating that the larger the contact angle of lipid droplets or the smaller the dimensionless volume, the lower the probability of embolism. The research findings provide theoretical support for the analysis on related diseases.
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Pancreatic adenocarcinoma (PAAD) is one of the most lethal malignancies. Although gemcitabine (GEM) is a standard treatment for PAAD, resistance limits its application and therapy. Secoemestrin C (Sec C) is a natural compound from the endophytic fungus Emericella, and its anticancer activity has not been investigated since it was isolated. Our research is the first to indicate that Sec C is a broad-spectrum anticancer agent and could exhibit potently similar anticancer activity both in GEM-resistant and GEM-sensitive PAAD cells. Interestingly, Sec C exerted a rapid growth-inhibiting effect (80% death at 6 h), which might be beneficial for patients who need rapid tumor shrinkage before surgery. Liquid chromatography/mass spectrometry and N-acetyl-l-cysteine (NAC) reverse assays show that Sec C sulfates cysteines to disrupt disulfide-bonds formation in endoplasmic reticulum (ER) proteins to cause protein misfolding, leading to ER stress and disorder of lipid biosynthesis. Microarray data and subsequent assays show that ER stress-mediated ER-associated degradation (ERAD) ubiquitinates and downregulates YAP to enhance ER stress via destruction complex (YAP-Axin-GSK-βTrCP), which also elucidates a unique degrading style for YAP. Potent anticancer activity in GEM-resistant cells and low toxicity make Sec C a promising anti-PAAD candidate.
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Objective:To investigate the possible role of long non-coding RNA (LncRNA) 00602 in promoting browning in adipocytes induced by adenovirus type 36 (Ad36).Methods:According to Ad36 infection, adipose tissue samples of obese patients were divided into Ad36-negative group and Ad36-infected group. Realtime fluorescent quantitative PCR (qRT-PCR) was used to detect the changes in the expression of LncRNA00602 mRNA in omental adipose tissue of the two groups, and analyze the differences between the two groups. The correlation between waist-to-hip ratio, systolic blood pressure, diastolic blood pressure, fasting blood glucose, triacylglyceride and other indicators of the patients in the group with LncRNA00602 mRNA expression were analyzed. HE staining was used to detect the size of adipocytes in the omental adipose tissue of the Ad36 negative group and the Ad36 infection group. qRT-PCR and Western blotting were used to detect the mRNA and protein expression levels of uncoupling protein 1 (UCP1) and PR domain containing 16 (PRDM16) in omental adipose tissue of two groups of patients. Human adipose-derived stem cells (hADSC) were isolated and cultured, using Ad36 to induce differentiation, and divided into control group and LncRNA00602 knockdown group. On 0, 2, and 4 days after LncRNA00602 knockdown, fluoroboron dipyrrole (BODIPY) and mitochondrial red fluorescence (Mito-Tracker Red) were used to stain intracellular lipid droplets and mitochondria. At the same time, qRT-PCR and Western blotting were used to detect changes in the expression of UCP1 and PRDM16.Results:The expression of LncRNA00602 gene in the Ad36 infection group was higher than that in the Ad36 negative group (all P<0.05). The expression of LncRNA00602 in the Ad36 negative group was not significantly different from the above clinical indicators, while the expression of LncRNA00602 was negatively correlated with serum fasting blood glucose and triacylglyceride ( r=-0.522, -0.486, P<0.05) in the Ad36 infection group; HE staining showed that the average adipocyte area of the Ad36 infection group was smaller than that of the Ad36 negative group. At the same time, UCP1 and PRDM16 gene expression were higher than the negative group (all P<0.05). At the cellular level, on the 2nd and 4th days after knockdown of LncRNA00602, the lipid droplet area of adipocytes in the LncRNA00602 knockdown group was larger than that of the control group, the number of mitochondria decreased compared with the control group, and difference was statistically significant ( P<0.05 or P<0.01); Compared with the control group, there was significantly lower expression of the browning marker genes UCP1, PRDM16, and protein in the adipocytes in the LncRNA00602 knockdown group (all P<0.05). Conclusion:In Ad36-induced adipocyte differentiation, LncRNA00602 may positively regulate the expression of UCP1, PRDM16 and lipid droplet metabolism, and promote the browning of adipocytes.
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Hepatic stellate cells (HSCs) are non-parenchymal pericytes resided in liver. In chronic liver injury, the cells are activated from quiescent state into myofibroblasts, and then drive liver fibrosis. The process, activated HSCs secreting extracellular matrix, is crucial to liver fibrosis, which needs enormous energy and triggers the metabolic reprogramming including Warburg effect, degradation of lipid droplets with increasing lipid metabolism and the change of amino acid metabolism. This paper mainly reviews the glucose, lipid and protein metabolic reprogramming of HSCs during the development of liver fibrosis and its potential applications, controbuting to design novel targeted therapies against liver fibrosis.
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Lipid droplets (LDs; lipid bodies) are intracellular sites of lipid storage and metabolism present in all cell types. Eukaryotic LDs are involved in eicosanoid production during several inflammatory conditions, including infection by protozoan parasites. In parasites, LDs play a role in the acquisition of cholesterol and other neutral lipids from the host. The number of LDs increases during parasite differentiation, and the biogenesis of these organelles use specific signaling pathways involving protein kinases. In addition, LDs are important in cellular protection against lipotoxicity. Recently, these organelles have been implicated in eicosanoid and specialised lipid metabolism. In this article, we revise the main functions of protozoan parasite LDs and discuss future directions in the comprehension of these organelles in the context of pathogen virulence.
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Camellia oil has become an important plant oil in China in recent years, but its effects on non-alcoholic fatty liver disease (NAFLD) have not been documented. In this study, the effects of camellia oil, soybean oil, and olive oil on NAFLD were evaluated by analyzing the fatty acid profiles of the plant oils, the serum lipids and lipoproteins of rats fed different oils, and by cytological and ultrastructural observation of the rats' hepatocytes. Analysis of fatty acid profiles showed that the polyunsaturated fatty acid (PUFA) n-6/n-3 ratio was 33.33 in camellia oil, 12.50 in olive oil, and 7.69 in soybean oil. Analyses of serum lipids and lipoproteins of rats showed that the levels of total cholesterol and low-density lipoprotein cholesterol in a camellia oil-fed group (COFG) were lower than those in an olive oil-fed group (OOFG) and higher than those in a soybean oil-fed group (SOFG). However, only the difference in total cholesterol between the COFG and SOFG was statistically significant. Cytological observation showed that the degree of lipid droplet (LD) accumulation in the hepatocytes in the COFG was lower than that in the OOFG, but higher than that in the SOFG. Ultrastructural analysis revealed that the size and number of the LDs in the hepatocytes of rats fed each of the three types of oil were related to the degree of damage to organelles, including the positions of nuclei and the integrity of mitochondria and endoplasmic reticulum. The results revealed that the effect of camellia oil on NAFLD in rats was greater than that of soybean oil, but less than that of olive oil. Although the overall trend was that among the three oil diets, those with a lower n-6/n-3 ratio were associated with a lower risk of NAFLD, and the effect of camellia oil on NAFLD was not entirely related to the n-6/n-3 ratio and may have involved other factors. This provides new insights into the effect of oil diets on NAFLD.
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Animals , Male , Rats , Camellia/chemistry , Fatty Acids/analysis , Hepatocytes/ultrastructure , Lipid Droplets/physiology , Lipids/blood , Non-alcoholic Fatty Liver Disease/pathology , Plant Oils/administration & dosage , Rats, Sprague-DawleyABSTRACT
Camellia oil has become an important plant oil in China in recent years, but its effects on non-alcoholic fatty liver disease (NAFLD) have not been documented. In this study, the effects of camellia oil, soybean oil, and olive oil on NAFLD were evaluated by analyzing the fatty acid profiles of the plant oils, the serum lipids and lipoproteins of rats fed different oils, and by cytological and ultrastructural observation of the rats’ hepatocytes. Analysis of fatty acid profiles showed that the polyunsaturated fatty acid (PUFA) n-6/n-3 ratio was 33.33 in camellia oil, 12.50 in olive oil, and 7.69 in soybean oil. Analyses of serum lipids and lipoproteins of rats showed that the levels of total cholesterol and low-density lipoprotein cholesterol in a camellia oil-fed group (COFG) were lower than those in an olive oil-fed group (OOFG) and higher than those in a soybean oil-fed group (SOFG). However, only the difference in total cholesterol between the COFG and SOFG was statistically significant. Cytological observation showed that the degree of lipid droplet (LD) accumulation in the hepatocytes in the COFG was lower than that in the OOFG, but higher than that in the SOFG. Ultrastructural analysis revealed that the size and number of the LDs in the hepatocytes of rats fed each of the three types of oil were related to the degree of damage to organelles, including the positions of nuclei and the integrity of mitochondria and endoplasmic reticulum. The results revealed that the effect of camellia oil on NAFLD in rats was greater than that of soybean oil, but less than that of olive oil. Although the overall trend was that among the three oil diets, those with a lower n-6/n-3 ratio were associated with a lower risk of NAFLD, and the effect of camellia oil on NAFLD was not entirely related to the n-6/n-3 ratio and may have involved other factors. This provides new insights into the effect of oil diets on NAFLD.
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Lipid droplets (LDs) are ubiquitous dynamic organelles that store and supply lipids in all eukaryotic and some prokaryotic cells for energy metabolism, membrane synthesis and production of essential lipid-derived molecules. There is increasing evidence that hepatitis C virus (HCV) has co-evolved due to its lack of lipid biosynthetic pathways to utilize host lipid metabolic pathways to establish a suitable environment for virus proliferation and obtain the necessary components, eventually promote the assembly and transportation of virus. In this review, we outline the relationship between HCV life cycle and lipid droplet biosynthesis and metabolism, with the aim to discover potential antiviral targets for development of new therapeutic interventions.
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Chromochloris zofingiensis represents an industrially relevant and unique green alga, given its capability of synthesizing triacylglycerol (TAG) and astaxanthin simultaneously for storage in lipid droplets (LDs). To further decipher lipid metabolism, the nitrogen deprivation (ND)-induced LDs from C. zofingiensis were isolated, purified, and subjected to proteomic analysis. Intriguingly, many C. zofingiensis LD proteins had no orthologs present in LD proteome of the model alga Chlamydomonas reinhardtii. Seven novel LD proteins (i.e., two functionally unknown proteins, two caleosins, two lipases, and one l-gulonolactone oxidase) and the major LD protein (MLDP), which were all transcriptionally up-regulated by ND, were selected for further investigation. Heterologous expression in yeast demonstrated that all tested LD proteins were localized to LDs and all except the two functionally unknown proteins enabled yeast to produce more TAG. MLDP could restore the phenotype of mldp mutant strain and enhance TAG synthesis in wild-type strain of C. reinhardtii. Although MLDP and caleosins had a comparable abundance in LDs, they responded distinctly to ND at the transcriptional level. The two lipases, instead of functioning as TAG lipases, likely recycled polar lipids to support TAG synthesis. For the first time, we reported that l-gulonolactone oxidase was abundant in LDs and facilitated TAG accumulation. Moreover, we also proposed a novel working model for C. zofingiensis LDs. Taken together, our work unravels the unique characteristics of C. zofingiensis LDs and provides insights into algal LD biogenesis and TAG synthesis, which would facilitate genetic engineering of this alga for TAG improvement.
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The lipid droplet (LD) is a unique multi-functional organelle that contains a neutral lipid core covered with a phospholipid monolayer membrane. The LDs have been found in almost all organisms from bacteria to humans with similar shape. Several conserved functions of LDs have been revealed by recent studies, including lipid metabolism and trafficking, as well as nucleic acid binding and protection. We summarized these findings and proposed a hypothesis that the LD is a conserved organelle.
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Animals , Humans , Bacteria , Metabolism , Biological Evolution , Cholesterol Esters , Metabolism , Lipid Droplets , Chemistry , Metabolism , Lipid Metabolism , Genetics , Nucleic Acids , Metabolism , Peptide Initiation Factors , Chemistry , Metabolism , Protein Binding , RNA-Binding Proteins , Chemistry , Metabolism , Ribosome Subunits , Chemistry , Metabolism , Triglycerides , MetabolismABSTRACT
With basal medium, we studied the growth status, lipid droplet distribution, total lipid content of Chlorella protothecoides CS-41 treated with different concentrations of sodium chloride (0, 150, 300 and 600 mmol/L) by optical microscopy, electron microscopy, confocal laser focusing and Nile red staining. Results show that the addition of NaCl affected the growth of Chlorella protothecoides CS-41. With the increase of NaCl concentration, the growth rate of Chlorella was inhibited. Chlorella cell wall became thicker, and lipid droplets increased. At the early stage, the amount of lipid droplets in the 600 mmol/L NaCl culture was the highest, but at the late-log stage, the amount of lipid droplets increased with the increase of the biomass of culture in 150 and 300 mmol/L NaCl culture. At the stable stage, biomass (dry weight) in 300 mmol/L NaCl culture was 73.55% of that in the control, but the total lipid content was 2.22 times higher than that in the control. A certain concentration of sodium chloride treatment can significantly increase the lipid content of Chlorella protothecoides CS-41.
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Human mast cells are potent effector cells in host defense mechanisms of innate and acquired immunity, including inflammatory diseases such as asthma and atherosclerosis. Mast cells originate from pluripotent hematopoietic progenitors in the bone marrow. Activation of mast cells by different stimuli triggers the release of a large range of mediators, including de novo synthesized eicosanoids which are highly biologically active lipid mediators. For the generation of lipid mediators, cytoplasmic lipid droplets have been shown to function as a major intracellular pool of arachidonic acid, the precursor for eicosanoids biosynthesis. The article summarizes current knowledge on mast cell biosynthesis of lipid mediator and the role in inflammation.
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Humans , Adaptive Immunity , Arachidonic Acid , Asthma , Atherosclerosis , Bone Marrow , Cytoplasm , Defense Mechanisms , Eicosanoids , Inflammation , Mast CellsABSTRACT
A teratoma is a neoplasm that contains tissues originating from three germ cell layers at ectopic sites. The embryology of teratomas remains unclear. Teratomas are usually composed of cystic and solid components, and they are usually associated with syringomyelia. Cystic lesions of teratomas may rupture in a spontaneous, iatrogenic, or traumatic manner. Lipid droplets in the ventricles and subarachnoid space are rare. We managed a case of a spinal teratoma in the lumbar region in a 67-year-old man. He complained of nocturia, frequent urination, and difficulty in walking for 2 months. Radiographic imaging revealed a lumbar spinal intradural mass. Intracranial lipid droplets dissemination was also existed. The patient underwent surgery, and a diagnosis of mature teratoma was confirmed histopathologically. During the operation, the cystic portion of the intradural mass ruptured. During the hospital stay, the patient's mental status declined. On radiological examination, slightly enlarged ventricle size was observed. Dissemination of lipid droplets within ventricles occurs because of spontaneous, iatrogenic, or traumatic rupture. Additional lipid droplet dissemination to the intracranial space associated with neurologic deterioration after a spinal teratoma surgery should be considered when iatrogenic rupture of the cyst portion occurs.
Subject(s)
Aged , Humans , Diagnosis , Embryology , Germ Cells , Length of Stay , Lumbosacral Region , Nocturia , Rupture , Spine , Subarachnoid Space , Syringomyelia , Teratoma , Urination , WalkingABSTRACT
Leprosy is an infectious disease caused by Mycobacterium leprae that affects the skin and nerves, presenting a singular clinical picture. Across the leprosy spectrum, lepromatous leprosy (LL) exhibits a classical hallmark: the presence of a collection of M. leprae-infected foamy macrophages/Schwann cells characterised by their high lipid content. The significance of this foamy aspect in mycobacterial infections has garnered renewed attention in leprosy due to the recent observation that the foamy aspect represents cells enriched in lipid droplets (LD) (also known as lipid bodies). Here, we discuss the contemporary view of LD as highly regulated organelles with key functions in M. leprae persistence in the LL end of the spectrum. The modern methods of studying this ancient disease have contributed to recent findings that describe M. leprae-triggered LD biogenesis and recruitment as effective mycobacterial intracellular strategies for acquiring lipids, sheltering and/or dampening the immune response and favouring bacterial survival, likely representing a fundamental aspect of M. leprae pathogenesis. The multifaceted functions attributed to the LD in leprosy may contribute to the development of new strategies for adjunctive anti-leprosy therapies.
Subject(s)
Humans , Leprosy, Lepromatous/pathology , Mycobacterium leprae/immunology , Schwann Cells/microbiology , Inclusion Bodies/immunology , Inclusion Bodies/metabolism , Inclusion Bodies/pathology , Leprosy, Lepromatous/immunology , Lipids/immunology , Organelles/immunology , Schwann Cells/immunologyABSTRACT
Aim To investigate the time-dependent effect of insulin on the expression of SREBP-1(sterol regulatory element binding protein-1),FAS(fat acid synthase)and lipid droplet formation in HKC cells(human renal proximal tubular epithelial cells line).MethodsHKC cells were respectively treated with 100 nmol·L~(-1) insulin for 0,2,4,6,12 h and 24 h.The analysis of SREBP-1 and FAS mRNA was performed by RT-PCR and the expression of SREBP-1 protein was detected by Western blot and immunocytochemistry.Furthermore,Oil Red O staining was used to determine cellular lipid droplet formation.ResultsCompared with HKC cells of 0 h group,there was no difference of SREBP-1 and FAS mRNA in HKC cells of 2 h group.However,the expression of SREBP-1 and FAS mRNA was significantly increased in HKC cells of 4,6 h and 12 h group.Further,the most expression of SREBP-1 and FAS mRNA was at 6 h group and was respectively increased by 3.578 and 4.272 times compared with 0 h group.The results of Western blot showed that the precursor and mature segments of SREBP-1 protein in 4,6 h and 12 h group HKC cells were increased and those of 6 h group HKC cells were the highest and about 4.106 and 5.167 times than those of 0 h group HKC cells.Immunocytochemistry presented the result that SREBP-1 protein was located in the plasma and the expression of 4,6 h and 12 h group HKC cells was significantly higher than that of 0,2 h and 24 h group HKC cells.The result of Oil Red O staining showed that lipid droplet markedly deposited in 6 h group HKC cells,contrarily,no lipid droplet was found in HKC cells of other groups.ConclusionAbove results suggested that insulin up-regulated SREBP-1 and FAS in time-dependent manner that led to cellular lipid droplet deposit,which may play an important role in the pathogenesis of renal lipid accumulation in metabolism syndrome.
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A clear cell islet cell tumor of the pancreas is extremely rare and characterized by extensive clear cell components. Electron microscopic and immunohistochemical findings are essential to prove that the mass with clear cells is an unusual manifestation of an islet cell tumor. Herein, we report a case of clear cell islet cell tumor of a 54-year-old woman with abdominal pain. The tumor was composed of polygonal clear cells arranged in nests, trabeculae, and ribbon pattern with the extensively fibrous stroma. These tumor cells showed strong reactivity for chromogranin and weak reactivity for somatostatin and glucagon. An electron microscope revealed that the important contributing factor of the clear cytoplasmic change was mainly due to an accumulation of lipid droplets, coupled with cytoplasmic swelling in some areas. Some tumor cells showed many endosecretory granules ranging from 111 to 297nm in diameter. In the clinical and immunohistochemical findings these granules were consistent with somatostatin granules in morphology and size.
Subject(s)
Female , Humans , Middle Aged , Abdominal Pain , Adenoma, Islet Cell , Cellular Structures , Cytoplasm , Glucagon , Islets of Langerhans , Pancreas , SomatostatinABSTRACT
A clear cell islet cell tumor of the pancreas is extremely rare and characterized by extensive clear cell components. Electron microscopic and immunohistochemical findings are essential to prove that the mass with clear cells is an unusual manifestation of an islet cell tumor. Herein, we report a case of clear cell islet cell tumor of a 54-year-old woman with abdominal pain. The tumor was composed of polygonal clear cells arranged in nests, trabeculae, and ribbon pattern with the extensively fibrous stroma. These tumor cells showed strong reactivity for chromogranin and weak reactivity for somatostatin and glucagon. An electron microscope revealed that the important contributing factor of the clear cytoplasmic change was mainly due to an accumulation of lipid droplets, coupled with cytoplasmic swelling in some areas. Some tumor cells showed many endosecretory granules ranging from 111 to 297nm in diameter. In the clinical and immunohistochemical findings these granules were consistent with somatostatin granules in morphology and size.