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1.
IEEE Open J Eng Med Biol ; 3: 178-188, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36712319

RESUMO

Goal: Implementation of an artificial intelli gence-based medical diagnosis tool for brain tumor classification, which is called the BTFSC-Net. Methods: Medical images are preprocessed using a hybrid probabilistic wiener filter (HPWF) The deep learning convolutional neural network (DLCNN) was utilized to fuse MRI and CT images with robust edge analysis (REA) properties, which are used to identify the slopes and edges of source images. Then, hybrid fuzzy c-means integrated k-means (HFCMIK) clustering is used to segment the disease affected region from the fused image. Further, hybrid features such as texture, colour, and low-level features are extracted from the fused image by using gray-level cooccurrence matrix (GLCM), redundant discrete wavelet transform (RDWT) descriptors. Finally, a deep learning based probabilistic neural network (DLPNN) is used to classify malignant and benign tumors. The BTFSC-Net attained 99.21% of segmentation accuracy and 99.46% of classification accuracy. Conclusions: The simulations showed that BTFSC-Net outperformed as compared to existing methods.

2.
Neuroimage ; 245: 118706, 2021 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-34780916

RESUMO

The development of scanners with ultra-high gradient strength, spearheaded by the Human Connectome Project, has led to dramatic improvements in the spatial, angular, and diffusion resolution that is feasible for in vivo diffusion MRI acquisitions. The improved quality of the data can be exploited to achieve higher accuracy in the inference of both microstructural and macrostructural anatomy. However, such high-quality data can only be acquired on a handful of Connectom MRI scanners worldwide, while remaining prohibitive in clinical settings because of the constraints imposed by hardware and scanning time. In this study, we first update the classical protocols for tractography-based, manual annotation of major white-matter pathways, to adapt them to the much greater volume and variability of the streamlines that can be produced from today's state-of-the-art diffusion MRI data. We then use these protocols to annotate 42 major pathways manually in data from a Connectom scanner. Finally, we show that, when we use these manually annotated pathways as training data for global probabilistic tractography with anatomical neighborhood priors, we can perform highly accurate, automated reconstruction of the same pathways in much lower-quality, more widely available diffusion MRI data. The outcomes of this work include both a new, comprehensive atlas of WM pathways from Connectom data, and an updated version of our tractography toolbox, TRActs Constrained by UnderLying Anatomy (TRACULA), which is trained on data from this atlas. Both the atlas and TRACULA are distributed publicly as part of FreeSurfer. We present the first comprehensive comparison of TRACULA to the more conventional, multi-region-of-interest approach to automated tractography, and the first demonstration of training TRACULA on high-quality, Connectom data to benefit studies that use more modest acquisition protocols.


Assuntos
Conectoma , Imagem de Tensor de Difusão/métodos , Substância Branca/diagnóstico por imagem , Humanos , Aumento da Imagem , Processamento de Imagem Assistida por Computador
3.
J Int Soc Prev Community Dent ; 6(Suppl 3): S219-S225, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28217540

RESUMO

AIMS AND OBJECTIVES: This study was conducted to compare the clinical assessment of impacted third molars of mandible with panaromic radiograph (OPG) and intraoral periapical radiograph (IOPA) and to assess the efficacy of IOPA and. Moreover, we corroborated the OPG and IOPA findings of impacted mandiblar third molar root apex to inferior alveolar canal. MATERIALS AND METHODS: A total of 200 patients with pericoronitis were examined who were indicated for surgical extraction, among which 50 patients were selected for the study. All the patients underwent a radiographic survey with a digital OPG and IOPA of impacted mandibular third molars, along with clinical survey for anatomic relationship, type of impaction, space available, position in relation to second molar, number of roots, root curvature, and proximity of nerve canal. The data was subjected to statistical analysis. The Statistical Package for Social Sciences version 4.0.1 software was used for analyzing the collected data. RESULTS: The study revealed that IOPA was more accurate in determining a majority of the factors affecting the third molar surgery, including relationship of the external oblique ridge (IOPA vs OPG = 96%:90%), anteroposterior relation with ramus (IOPA vs OPG = 70%:66%), vertical depth of impaction (IOPA vs OPG = 72%:68%), number of roots (P = 0.013), morphology of roots (IOPA vs OPG = 96%:90%); however, OPG was found to be accurate in evaluating the type of impaction (IOPA vs OPG = 88%:94%), canal relation, along with root of impacted molar (IOPA vs OPG = 74%:86%). CONCLUSION: To conclude, although IOPA has a marginal angle over OPG in assessing various parameters, only the number of roots have a greater accuracy (P < 0.0013) in IOPA than with OPG. However, the OPG is the better choice to be considered when the patient is associated with trismus.

4.
J Bodyw Mov Ther ; 15(4): 485-95, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21943622

RESUMO

The purpose of this study was to examine the relation between fear of movement and perturbation induced electromyographic global trunk muscle voluntary responses with pre-programmed reactions among persons with chronic low back pain (CLBP). CLBP subjects (n = 25) were challenged to unexpected and expected perturbations on stable and unstable surfaces. 'Tampa scale for kinesiophobia - Adjusted version-13' was used to measure kinesiophobia. Regression analysis revealed significant negative correlation between kinesiophobia scores and voluntary responses of rectus abdominis (RA) for unexpected perturbations on stable (r = -0.69, 95% of CI: -0.85 to -0.40, p < 0.000, r(2) = 0.41) and unstable surfaces (r = -0.47, 95% of CI: -0.72 to -0.09, p < 0.018, r(2) = 0.29). The activity of erector spinae was not influenced by most of testing conditions in the study except task on unstable surface for expected perturbation (r = -0.593, 95% of CI: -0.8 to -0.25, p = 0.002, r(2) = 0.15). RA activity and kinesiophobia score of the CLBP population was significantly inversely associated during anteriorly directed unexpected perturbations. In our study, the significant association between fear of movement and the trunk muscle responses was differentially influenced by expected and unexpected postural demands.


Assuntos
Dor Lombar/fisiopatologia , Dor Lombar/psicologia , Músculo Esquelético/fisiopatologia , Transtornos Fóbicos/fisiopatologia , Transtornos Fóbicos/psicologia , Tronco/fisiopatologia , Doença Crônica , Eletromiografia , Feminino , Humanos , Masculino , Movimento
5.
J Back Musculoskelet Rehabil ; 23(2): 77-86, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20555120

RESUMO

BACKGROUND: Preprogrammed reactions (PPR) appear at a latency of higher than 40 ms, but before the voluntary muscle responds (approximately 120 ms) to postural perturbations. OBJECTIVE: To examine the difference in magnitude of preprogrammed reactions in patients with chronic low back pain (CLBP) and without low back pain. METHODS: we analyzed electromyographic Root Mean Square (RMS) amplitudes of asymptomatic (n=25) and CLBP patients (n=25) on stable and unstable surfaces during expected and unexpected perturbations for rectus abdominus and erector spinae muscles. The mean PPR and PPR-combined voluntary response RMS amplitudes (VRPPR) were compared between the two groups. To find the presence of PPR in LBP patients, a criteria was set that the obtained PPR RMS amplitude value should exceed 60% mean reflex RMS amplitude that occur within 50 ms after perturbation. RESULTS: Fleiss' kappa revealed a good agreement (kappa = 0.7 to 0.9) among raters for absence of PPR in patients with CLBP and presence of PPR in asymptomatic population. The two way ANOVA revealed significantly different mean PPR and VRPPR RMS amplitudes between asymptomatic and LBP population for rectus abdominus and erector spinae muscles (p<0.05). CONCLUSION: PPR responses were found absent (<60% of Mean Reflex RMS) in patients with CLBP. Further, patients with CLBP demonstrated lower PPR amplitudes with higher peak voluntary responses compared to asymptomatic population, indicating difficulties in presetting of voluntary responses for regaining postural stability after perturbation.


Assuntos
Dor Lombar/fisiopatologia , Músculo Esquelético/fisiopatologia , Adulto , Análise de Variância , Doença Crônica , Eletromiografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Estudos Prospectivos , Processamento de Sinais Assistido por Computador
6.
Indian Pediatr ; 47(7): 575-80, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20019396

RESUMO

BACKGROUND: Carrying heavy backpacks could cause a wide spectrum of pain related musculoskeletal disorders and postural dysfunctions. OBJECTIVE: To determine the changes in various postural angles with different backpack weights in preadolescent children. DESIGN: Cross-sectional. PARTICIPANTS: Healthy male school-children (n=200), mean (SD) age: 12.5 (0.5) years, from high schools in Mangalore, India. MEASUREMENTS: Bodyweight and height were measured using a forceplate and stadiometer, respectively. From the weight recorded, 5%, 10%, 15%, 20%, and 25% of the bodyweight were calculated and implemented as their respective backpack loads. The Image Tool version 3.0, digitizing software was used for analyzing photographs to determine craniovertebral (CV), head on neck (HON), head and neck on trunk (HNOT), trunk and lower limb angles. Postural angles were compared with no backpack and with backpacks weighing 5% to 25% of the subject's bodyweight. RESULTS: The CV angle changed significantly after 15% of backpack load (P <0.05). The HON and HNOT angles changed significantly after 10% of backpack load (P <0.05). The trunk and lower limb angle also changed significantly after 5% of backpack load (P <0.05). CONCLUSIONS: Carrying a backpack weighing 15% of body weight change all the postural angles in preadolescent children.


Assuntos
Postura/fisiologia , Suporte de Carga/fisiologia , Adolescente , Análise de Variância , Antropometria , Dor nas Costas , Estatura , Peso Corporal , Vértebras Cervicais , Criança , Humanos , Masculino , Cervicalgia , Estudantes
7.
Proc Natl Acad Sci U S A ; 97(13): 7488-93, 2000 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-10852956

RESUMO

We have cloned a human macrophage receptor that binds to apolipoprotein (apo)B48 of dietary triglyceride (TG)-rich lipoproteins. TG-rich lipoprotein uptake by the apoB48R rapidly converts macrophages and apoB48R-transfected Chinese hamster ovary cells in vitro into lipid-filled foam cells, as seen in atherosclerotic lesions. The apoB48R cDNA (3,744 bp) encodes a protein with no known homologs. Its approximately 3.8-kb mRNA is expressed primarily by reticuloendothelial cells: monocytes, macrophages, and endothelial cells. Immunohistochemistry shows the apoB48R is in human atherosclerotic lesion foam cells. Normally, the apoB48R may provide essential lipids to reticuloendothelial cells. If overwhelmed, foam cell formation, endothelial dysfunction, and atherothrombogenesis may ensue, a mechanism for cardiovascular disease risk of elevated TG.


Assuntos
Apolipoproteínas B/fisiologia , Arteriosclerose , Macrófagos/fisiologia , Receptores de Lipoproteínas/genética , Sequência de Aminoácidos , Animais , Apolipoproteína B-48 , Células CHO , Clonagem Molecular , Cricetinae , DNA Complementar/genética , DNA Complementar/isolamento & purificação , Humanos , Dados de Sequência Molecular , Receptores de Lipoproteínas/metabolismo , Triglicerídeos/metabolismo
8.
J Leukoc Biol ; 67(1): 104-8, 2000 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-10648004

RESUMO

Macrosialin, the mouse homolog of human CD68, is a heavily glycosylated transmembrane protein found almost exclusively in macrophages. Its function remains uncertain. It has a high affinity for oxidized low-density lipoprotein (LDL) in ligand blots and antibodies against the human homolog, CD68, inhibit the binding of oxidized LDL to a human monocyte-derived cell line (THP-1). However, there is still controversy as to whether macrosialin, found predominantly in late endosomes, is expressed at all on the plasma membrane. The present studies, done in thioglycollate-elicited peritoneal macrophages, confirm that macrosialin is predominantly intracellular but show clearly that 10-15% of it is expressed on the cell surface. Exchange with intracellular pools occurs at an extremely high rate. The results are compatible with a surface function, including internalization of bound ligands or adhesion to surfaces.


Assuntos
Antígenos CD/metabolismo , Antígenos de Diferenciação Mielomonocítica/metabolismo , Macrófagos Peritoneais/metabolismo , Animais , Células Cultivadas , Humanos , Lipoproteínas LDL/metabolismo , Camundongos
9.
J Lipid Res ; 40(4): 744-52, 1999 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-10191299

RESUMO

Two human monocyte-macrophage (HMM) membrane binding proteins, (MBP) 200 and 235, are receptor candidates that bind to the apolipoprotein (apo)B-48 domain in triglyceride-rich lipoproteins for uptake independent of apoE. Microsequence analysis of the purified reduced MBP 200R characterized tryptic peptides of MBP 200R. A synthetic peptide mimicking a unique, unambiguous 10-residue sequence (AEGLMVTGGR) induced antipeptide antibodies that specifically recognized MBP 200, 235 and 200R, in 1- and 2-dimensional analyses, indicating 1) the ligand binding protein was sequenced and 2) MBP 200 and 235 yielded MBP 200R upon reduction. These antibodies identified the MBPs in human blood-borne, THP-1, U937 MMs, and endothelial cells (EC) but not in human fibroblasts or Chinese hamster ovary (CHO) cells. Fluorescence activated cell sorting (FACS) analysis located the MBPs on the MM surface as necessary for receptor function. The 10-residue, unambiguous MBP 200-derived sequence is unique, with no matches in extant protein databases. Antipeptide antibodies bind to the MBPs in reticuloendothelial cells that have this receptor activity, but not to proteins in cells that lack this receptor activity. These studies provide the first direct protein sequence and immunochemical data that a new, unique apoB receptor for triglyceride-rich lipoproteins exists in human monocytes, macrophages, and endothelial cells.


Assuntos
Lipoproteínas/metabolismo , Macrófagos/química , Monócitos/química , Receptores de Lipoproteínas/análise , Triglicerídeos/análise , Sequência de Aminoácidos , Animais , Anticorpos/imunologia , Especificidade de Anticorpos , Apolipoproteína B-48 , Apolipoproteínas B/metabolismo , Células CHO/química , Cricetinae , Epitopos/imunologia , Fibroblastos/química , Citometria de Fluxo , Humanos , Peptídeos/imunologia , Receptores de Lipoproteínas/química , Receptores de Lipoproteínas/metabolismo , Análise de Sequência
10.
Arterioscler Thromb Vasc Biol ; 18(6): 968-76, 1998 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-9633939

RESUMO

Studies in animals and humans have demonstrated uptake of plasma chylomicrons (triglyceride-rich lipoprotein [TGRLP] of Sf>400) by accessible macrophages in vivo. One potential mechanism is via a unique receptor pathway we previously identified in human blood and THP-1 monocytes and macrophages for the lipoprotein lipase (LpL)- and apolipoprotein (apo) E-independent, high-affinity, specific binding of plasma chylomicrons and hypertriglyceridemic VLDL (HTG-VLDL) to cell-surface membrane-binding proteins (MBP 200, 235; apparent Mr 200, 235 kD on SDS-PAGE) that leads to lipid accumulation in vitro. Competitive binding studies reported here demonstrate that anti-apoB antibodies specifically block the high-affinity binding of TGRLP to this receptor on THP-1 cells and on ligand blots. LpL, which binds to an N-terminal domain of apoB, also inhibits TGRLP binding both to this site on THP-1s and to MBP 200, 235 by binding to apoB. Chylomicrons of Sf>1100 that contain apoB-48, but not apoB-100, bind specifically to MBP 200, 235, and this binding is blocked by anti-apoB IgG. In contrast, lactoferrin and heparin do not inhibit TGRLP binding. We conclude that the receptor-binding domain is within apoB-48 (or an equivalent in apoB-100) near the LpL-binding domain, but not a heparin-binding domain. Uptake of TGRLP by this mechanism could provide essential nutrients or, in HTG, cause excess lipid accumulation and foam cell formation.


Assuntos
Apolipoproteínas B/metabolismo , Quilomícrons/metabolismo , Macrófagos/metabolismo , Monócitos/metabolismo , Receptores de Lipoproteínas/metabolismo , Anticorpos/metabolismo , Apolipoproteína B-100 , Apolipoproteína B-48 , Fibroblastos/metabolismo , Heparina/metabolismo , Heparina/farmacologia , Humanos , Lactoferrina/metabolismo , Lactoferrina/farmacologia , Lipase Lipoproteica/metabolismo , Lipoproteínas VLDL/metabolismo , Receptores de LDL/metabolismo , Triglicerídeos/metabolismo , Células Tumorais Cultivadas
11.
Proc Natl Acad Sci U S A ; 93(25): 14833-8, 1996 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-8962141

RESUMO

We have previously identified a 94- to 97-kDa oxidized low density lipoprotein (LDL)-binding protein in mouse macrophages as macrosialin (MS), a member of the lamp family. Earlier immunostaining studies have shown that MS and its human homolog, CD68, are predominantly intracellular proteins. However, using sensitive techniques such as flow cytometry (FACS) and cell-surface-specific biotinylation, we now show that there is significant surface expression of these proteins. FACS analysis of intact cells using mAb FA/11 showed small but definite surface expression of MS in resident mouse peritoneal macrophages but this was greatly enhanced with thioglycollate elicitation. Biotinylation of intact cells and detergent-solubilized cell preparations followed by immunoprecipitation revealed 10-15% of the total MS content of elicited macrophages on the plasma membrane. Similar results were obtained with untreated RAW 264.7 cells. FACS analysis of intact THP-1 monocytic cells showed minimal surface expression of CD68 on unactivated cells (4% of total cell content). Stimulation with phorbol 12-myristate 13-acetate increased both surface and total CD68 expression considerably. Furthermore, the specific binding at 4 degrees C and uptake at 37 degrees C of 125I-labeled oxidized LDL by activated THP-1 cells was inhibited by 30-50% by CD68 mAbs KP-1 and EBM-11. Thus, although the surface expression of MS/CD68 at steady-state represents only a small percentage of their total cellular content, these proteins can play a significant role in oxidized LDL uptake by activated macrophages in vitro and could contribute to foam cell formation in atherosclerotic lesions.


Assuntos
Antígenos CD/metabolismo , Antígenos de Diferenciação Mielomonocítica/metabolismo , Lipoproteínas LDL/metabolismo , Macrófagos/metabolismo , Glicoproteínas de Membrana/metabolismo , Receptores de Superfície Celular/metabolismo , Receptores de LDL/metabolismo , Animais , Células Cultivadas , Citometria de Fluxo , Humanos , Camundongos
12.
Proc Natl Acad Sci U S A ; 92(21): 9580-4, 1995 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-7568176

RESUMO

We have previously reported the partial purification of a 94- to 97-kDa plasma membrane protein from mouse peritoneal macrophages that binds oxidatively modified low density lipoprotein (OxLDL) and phosphatidylserine-rich liposomes. We have now identified that protein as macrosialin, a previously cloned macrophage-restricted membrane protein in the lysosomal-associated membrane protein family (mouse homologue of human CD68). Early in the course of purification of the 94- to 97-kDa protein, a new OxLDL-binding band at 190-200 kDa appeared and copurified with the 94- to 97-kDa protein. The HPLC pattern of tryptic peptides from this higher molecular mass ligand-binding band closely matched that derived from the 94- to 97-kDa band. Specifically, the same three macrosialin-derived tryptic peptides (9, 9, and 15 residues) were present in the purified 94- to 97-kDa band and in the 190- to 200-kDa band and antisera raised against peptide sequences in macrosialin recognized both bands. An antiserum against macrosialin precipitated most of the 94- to 97-kDa OxLDL-binding material. We conclude that the binding of OxLDL to mouse macrophage membranes is in part attributable to macrosialin. Our previous studies show that OxLDL competes with oxidized red blood cells and with apoptotic thymocytes for binding to mouse peritoneal macrophages. Whether macrosialin plays a role in recognition of OxLDL and oxidatively damaged cells by intact macrophages remains uncertain.


Assuntos
Antígenos CD/química , Antígenos de Diferenciação Mielomonocítica/química , Macrófagos Peritoneais/química , Glicoproteínas de Membrana/química , Sequência de Aminoácidos , Animais , Antígenos CD/metabolismo , Antígenos de Diferenciação Mielomonocítica/metabolismo , Western Blotting , Células Cultivadas , Ligantes , Lipoproteínas LDL/metabolismo , Lipossomos/metabolismo , Glicoproteínas de Membrana/metabolismo , Camundongos , Dados de Sequência Molecular , Oxirredução , Fosfatidilserinas/metabolismo , Testes de Precipitina , Ligação Proteica , Análise de Sequência , Frações Subcelulares
13.
Biochemistry ; 34(28): 9126-35, 1995 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-7619811

RESUMO

An apolipoprotein (apo) E- and lipoprotein lipase-independent, high affinity, saturable and specific binding site and pathway for uptake of certain triglyceride-rich lipoproteins (TGRLP) by human monocyte-macrophages that leads to lipid accumulation and foam cell formation in vitro has been reported; two membrane binding activities were identified as receptor candidates with apparent molecular masses of 200 and 235 kDa [Gianturco et al. (1994) J. Lipid Res. 35, 1674-1687]. Here we present new evidence that these activities are TGRLP receptors with unique biochemical properties which distinguish them from other lipoprotein receptors. Protease and heparinase susceptibility studies demonstrate that (1) these activities have essential protein, but not heparan sulfate proteoglycan (HSPG) components; (2) the membrane binding proteins (MBPs) are located on the cell surface; (3) HSPGs do not facilitate TGRLP binding to this specific cellular site. Upon reduction, MBP 200 and 235 are both converted into a single, new binding activity of intermediate mobility (MBP 200R); all MBP forms displayed high affinity, saturable TGRLP binding with similar Kds (1.4-2.2 micrograms/mL). Notably, MBP 200R retained the combined ligand binding capacity of MBP 200 and 235 prior to reduction, demonstrating that, unlike members of the LDL receptor or the scavenger receptor families, disulfide bonds are not critical for activity. At 65 degrees C, MBP 235 was converted into MBP 200 without loss of total binding activity, suggesting heat dissociates a small subunit not required for binding from a common large protein subunit that binds TGRLP. Since the MBPs are found on the cell surface, are themselves functionally and structurally related, have distinctly different biochemical properties from members of the LDL receptor and scavenger receptor families, and share all critical characteristics with the cellular binding site, we hypothesize that they represent a new and unique receptor family for apoE- and lipoprotein lipase-independent uptake of TGRLP by human monocyte-macrophages.


Assuntos
Receptores de Lipoproteínas/metabolismo , Triglicerídeos/metabolismo , Apolipoproteínas E/metabolismo , Sítios de Ligação , Transporte Biológico Ativo , Proteínas de Transporte/química , Proteínas de Transporte/metabolismo , Linhagem Celular , Heparina Liase , Humanos , Técnicas In Vitro , Cinética , Ligantes , Lipase Lipoproteica/metabolismo , Macrófagos/metabolismo , Proteínas de Membrana/química , Proteínas de Membrana/metabolismo , Modelos Biológicos , Monócitos/metabolismo , Oxirredução , Polissacarídeo-Liases , Pronase , Receptores de Lipoproteínas/química , Temperatura
14.
Biochem Biophys Res Commun ; 210(2): 491-7, 1995 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-7755626

RESUMO

Previously we reported that human blood-borne and THP-1 monocyte-macrophages have an apolipoprotein E- and lipoprotein lipase-independent, high affinity, specific binding site for the uptake and degradation of hypertriglyceridemic VLDL and plasma chylomicrons distinct from the LDL receptor gene family and the acetyl LDL receptor (Gianturco et al., J. Lipid Res. 35:1674-1687, 1994). Ligand blot analyses identified two cell-surface, structurally related membrane binding proteins as receptor candidates of M(r) approximately 200 kDa and M(r) approximately 235 kDa which are converted into a single ligand binding species of intermediate mobility upon reduction. We now report a approximately 1200-fold purification of the reduced candidate receptor protein from cultured THP-1 monocytes.


Assuntos
Células Espumosas/metabolismo , Receptores de Lipoproteínas/isolamento & purificação , Triglicerídeos/metabolismo , Cromatografia DEAE-Celulose , Eletroforese em Gel de Poliacrilamida , Humanos , Receptores de Lipoproteínas/metabolismo
15.
Proc Natl Acad Sci U S A ; 92(5): 1391-5, 1995 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-7533292

RESUMO

The binding and uptake of oxidatively modified low density lipoprotein (OxLDL) by mouse peritoneal macrophages occurs, in part, via the well characterized acetyl LDL receptor. However, several lines of evidence indicate that as much as 30-70% of the uptake can occur via a distinct receptor that recognizes OxLDL with a higher affinity than it recognizes acetyl LDL. We describe the partial purification and characterization of a 94- to 97-kDa plasma membrane protein from mouse peritoneal macrophages that specifically binds OxLDL. This receptor is shown to be distinct from the acetyl LDL receptor as well as from two other macrophage proteins that also bind OxLDL--the Fc gamma RII receptor and CD36. We suggest that this OxLDL-binding membrane protein participates in uptake of OxLDL by murine macrophages and also represents a receptor responsible for macrophage binding and phagocytosis of oxidatively damaged cells.


Assuntos
Moléculas de Adesão Celular , Lipoproteínas LDL/metabolismo , Macrófagos/metabolismo , Receptores de Superfície Celular/isolamento & purificação , Receptores de LDL/metabolismo , Animais , Antígenos CD/química , Antígenos CD36 , Feminino , Humanos , Técnicas In Vitro , Lipoproteínas LDL/química , Macrófagos/química , Proteínas de Membrana/isolamento & purificação , Proteínas de Membrana/metabolismo , Camundongos , Oxirredução , Coelhos , Receptores de Superfície Celular/química , Receptores Depuradores
16.
J Lipid Res ; 35(9): 1674-87, 1994 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-7806981

RESUMO

Triglyceride- and cholesterol-rich foam cells derived from monocyte-macrophages are commonly associated with some forms of hypertriglyceridemia. In this report, direct binding studies at 4 degrees C demonstrate that human monocyte-macrophages (HMM) 1-6 days after isolation from blood and human THP-1 monocytic cells, before and up to 7 days after differentiation with phorbol ester, exhibit a high affinity (Kd 3-6 nM), saturable, specific, and apolipoprotein (apo) E-independent binding site for the uptake and degradation of certain triglyceride-rich lipoproteins (TGRLP). Ligand blotting analysis identified two membrane binding proteins (MBP) of apparent molecular weights of 200 and 235 kDa (MBP 200 and MBP 235) in both cell types that share the same ligand specificity as the cellular site and bind hypertriglyceridemic (HTG) VLDL, trypsinized VLDL devoid of apoE (tryp-VLDL), and dietary plasma chylomicrons from normal subjects but not LDL, acetyl LDL, or normal VLDL with high affinity. Neither lipoprotein lipase nor apoE are required for TGRLP binding to the cells or the isolated MBPs. The cellular binding site and the MBPs are expressed at similar levels at all stages of differentiation, unlike the LDL or the acetyl LDL receptor. TGRLP that bind to the MBPs induce rapid, saturable, cellular triglyceride accumulation in monocytes as well as macrophages; normal VLDL does not. In addition, the cellular high affinity binding site and MBP 200 and 235 are not affected by the media sterol content, unlike the LDL receptor. Taken together, these data indicate that human monocyte-macrophages exhibit a high affinity, saturable, specific, apoE- and lipoprotein lipase-independent binding site and membrane binding proteins for TGRLP that differ in expression, specificity, and molecular size from receptors of the LDL receptor gene family or the acetyl LDL receptor. The shared characteristics of the cellular binding site with MBP 200 and MBP 235 suggest that they are candidates for the receptor-mediated, apoE-independent uptake of HTG-VLDL and chylomicrons by monocytes and macrophages and therefore may be involved in foam cell formation.


Assuntos
Lipoproteínas/metabolismo , Macrófagos/metabolismo , Monócitos/metabolismo , Triglicerídeos/metabolismo , Animais , Sítios de Ligação , Proteínas de Transporte/química , Proteínas de Transporte/metabolismo , Bovinos , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular , Humanos , Técnicas In Vitro , Cinética , Ligantes , Proteínas de Membrana/química , Proteínas de Membrana/metabolismo , Peso Molecular , Monócitos/citologia , Monócitos/efeitos dos fármacos , Ligação Proteica , Receptores de LDL/metabolismo , Esteróis/metabolismo , Acetato de Tetradecanoilforbol/farmacologia
17.
Biochem Biophys Res Commun ; 181(2): 787-96, 1991 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-1721810

RESUMO

Autoimmune diseases are characterized by the presence of autoantibodies often restricted to host proteins exhibiting charge rich domains. Charged polypeptides elicit strong immune responses, and cationized bovine serum albumin and other cationic proteins are significantly more immunogenic than their less charged counterparts. These phenomena may involve enhanced protein uptake by macrophages, resulting in greater processing and presentation of antigenic peptide-MHC complexes to T-cells. We compared macrophage cell-surface binding and uptake of native and cationized bovine serum albumin. Specific binding of [125I]cationized bovine serum albumin to THP-1 macrophages in vitro was 11-16 fold greater than for native albumin. Half-maximal inhibition of [125I]cationized albumin binding was observed at 10-7M ligand. The specificity of [125I]cationized bovine serum albumin binding and uptake was further studied in terms of competitive inhibition of proteolysis by proteins of varying charge content. Cationized bovine serum albumin, but not native albumin, inhibited proteolysis of [125I]cBSA. Calf thymus histones also inhibited cBSA degradation. High concentration of myelin basic protein was moderately effective at blocking cBSA degradation, while myoglobin and beta lactalbumin showed no inhibition. These results indicate that specific cell-surface binding sites which occur on macrophages may mediate selective uptake of certain proteins with highly charged domains including some autoantigens.


Assuntos
Macrófagos/metabolismo , Soroalbumina Bovina/metabolismo , Ligação Competitiva , Cátions , Membrana Celular/metabolismo , Eletroquímica , Endopeptidases/metabolismo , Ferritinas/química , Ferritinas/farmacologia , Histonas/química , Histonas/farmacologia , Humanos , Ponto Isoelétrico , Leucemia , Proteína Básica da Mielina/química , Proteína Básica da Mielina/farmacologia , Soroalbumina Bovina/química , Soroalbumina Bovina/farmacologia , Células Tumorais Cultivadas
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