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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of dietary thyroxine (T4) supplementation for specific periods on the early development of the primary lymphoid organs and spontaneous autoimmune thyroiditis (SAT) was examined in the Obese (OS) strain of chicken. Effects of the treatments on concentrations of serum growth hormone (GH) and testosterone were also determined. All treatment groups were examined at 6 weeks. T4 supplementation did not affect serum testosterone or GH concentrations. However T4 given for the first three weeks resulted in significantly increased bursa weights, no change in thymic weights, significantly decreased lymphoid infiltration of the thyroid and reduced thyroglobulin autoantibody levels (TgAAb). T4 supplementation for the full six weeks resulted in no change in bursal weight, significantly increased thymic weight, significantly decreased lymphoid infiltration of the thyroid, and reduced TgAAb. These results suggest that the effects of T4 supplementation on SAT and immune development are dependent on the interval during which it is administered and that testosterone and GH probably do not mediate these effects.
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PMID:Differential effects of thyroxine on immune development and autoimmune thyroiditis in the obese strain chicken. 404 83

In this study we investigated the genetic background of primary abnormalities found in the thyroid gland of Obese strain (OS) chickens with spontaneous autoimmune thyroiditis (SAT), i.e., susceptibility to passively transferred antibodies to thyroglobulin (TgAb) and incomplete suppression of iodine uptake by thyroxine (T4). Several crosses between the B15/B15 subline of OS chickens and the inbred CB line (B12/B12) were done and the progeny was analyzed for thyroiditis after injection of OS serum containing high titers of TgAb. It was found that passive transfer of TgAb increased the lymphoid infiltration in the thyroids of OS chickens, but had no effect on CB birds. A genetic analysis of backcrosses revealed that this trait is, in the case of simple Mendelian inheritance, encoded by at least three recessive genes. The thyroidal 131I uptake of these crosses under T4 was also determined and we found that this trait is most probably encoded by only one recessive gene.
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PMID:Spontaneous autoimmune thyroiditis in obese strain chickens: a genetic analysis of target organ abnormalities. 405 27

A thymocyte-specific alloantigen, designated AT (avian thymus)-1.1, has been detected in Cornell C strain (CS) and Obese strain (OS) chickens, the latter being a strain derived from CS which develops a spontaneous form of autoimmune thyroiditis (SAT). Antisera specific for this antigen were developed first in a turkey immunized with thymocytes from an OS chicken and, later, in AT-1.1-negative CS chickens immunized with AT-1.1-positive thymocytes. AT-1.1 was detected in 50-70% of cells in a thymus cell suspension, but was not seen on peripheral blood lymphocytes, erythrocytes, or cells from bursa, spleen, kidney, liver, or brain. It was present on thymocytes of chickens at all ages tested, from 1 day to 6 months of age. AT-1.1 was not detected in six chicken lymphoid tumor cell lines tested, and birds expressing it were found to be negative for the presence of Marek's disease viral antigens. Pedigree studies on 287 (OS X CS)F2 chickens demonstrated that AT-1.1 is expressed in a dominant or codominant manner, and the gene coding for this antigen was not linked to the beta (major histocompatibility) complex. The genetics and tissue distributions of AT-1.1 indicate that it differs from thymus cell surface antigens, avian or mammalian, previously described.
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PMID:AT-1.1: a thymus-specific alloantigen of chickens. 614 92

Rous-associated virus 7 (RAV-7) is a subgroup C avian leukosis virus which does not transform cells in vitro or carry an oncogene. When injected into 1-day-old hatched chicks, RAV-7 causes a low incidence of lymphoid leukosis after a latent period of several months. In contrast, infection of 10-day-old chicken embryos with RAV-7 leads to a disease syndrome characterized by stunting, obesity, atrophy of the bursa and the thymus, high triglyceride and cholesterol levels, reduced thyroxine levels, and increased insulin levels (Carter et al., Infect. Immun. 39:410-422, 1983; J.K. Carter and R.E. Smith, Infect. Immun. 40:795-805, 1983). Histopathological examination of tissues from affected chicks revealed an accumulation of lipid in the liver and an extensive infiltration of the thyroid and pancreas by lymphoblastoid cells. In the present investigation, the subgroup specificity of this syndrome was investigated. Other subgroup C avian leukosis viruses (transformation-defective B77, transformation-defective Prague C strain of Rous sarcoma virus, and RAV-49) caused stunting, infiltration of the thyroid and pancreas, increased liver weights, decreased thyroxine levels, and increased insulin levels, but they did not cause a uniform, profound increase in triglyceride and cholesterol levels. Avian leukosis viruses of subgroup A [myeloblastosis-associated virus 1 causing osteopetrosis [MAV-1(O)] and RAV-1], subgroup B [MAV-2(O), MAV-2 causing nephroblastoma [MAV-2(N)], and RAV-2], subgroup D (RAV-50), and subgroup F (ring-necked pheasant virus and RAV-61) did not cause a syndrome identical to that induced by RAV-7. All of the viruses examined induced some stunting and a reduction in thyroxine levels which correlated with the stunting. The two subgroup F viruses caused an infiltration of the thyroid which may have been secondary to severe lung involvement. We conclude that the RAV-7 syndrome is unique, particularly in the induction of a hyperlipidemia.
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PMID:Specificity of avian leukosis virus-induced hyperlipidemia. 632 32

The B-L region of the chicken major histocompatibility complex (MHC), the so-called B-locus, corresponds to the murine H-2 I-region. Using alloantibodies and monoclonal antibodies to B-L we analyzed: (a) the tissue distribution of B-L+ cells, (b) the function of B-L+ cells, and (c) the possible role of B-L+ cells in the development of spontaneous autoimmune thyroiditis (SAT) in Obese strain (OS) chickens. The tissue distribution of B-L+ cells in peripheral blood and various lymphoid and nonlymphoid organs corresponds to what is known for mammals. In the bursa of Fabricius most lymphoid cells and the dendritic cells carry the B-L antigen; B-L+ thymic nurse cells (TNC) first appear on day 17 of embryonic life; chickens possess dendritic B-L+ cells in the skin resembling mammalian Langerhans cells; in addition we found that the microglia is unequivocally B-L+. B-L+ peripheral blood lymphocytes (PBL) were separated with a fluorescence-activated cell sorter. Ten percent of unstimulated PBL and 60% of phytohemagglutinin (PHA) stimulated T-cell blasts are B-L+. In graft-vs-host (GvH) assays B-L- cells were identified as the effector cells. These cells respond to PHA and concanavalin A (Con A), but not to pokeweed mitogen (PWM). B-L+ cells cannot be stimulated by Con A and PHA, but respond to PWM. They possess only a very low activity in GvH assays which can be inhibited by anti-T-cell sera. In OS chickens B-L+/non-B/, non-T and B-L+ T (blasts?) cells are found in the "first line" of mononuclear cell infiltration in the thyroid glands. Most interesting, thyroid epithelial cells--which are normally B-L- -become B-L+ in the neighbourhood of B-L+ infiltrating mononuclear cells. This observation may be of significance for autoantigen presentation and perpetuation in autoimmune thyroiditis. Finally, OS thymuses contain significantly less TNC than normal controls.
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PMID:Distribution and functional analysis of B-L/Ia-positive cells in the chicken: expression of B-L/Ia antigens on thyroid epithelial cells in spontaneous autoimmune thyroiditis. 644 Nov 16

This paper summarizes data obtained in our laboratory on the demonstration of receptors for IgG-Fc (FcR) and complement (CR) on mononuclear cells of the fowl. A clearcut distinction of these two structures on spleen cells was achieved in rosette assays using SRBC coated with rabbit IgG as indicator cells which bind avian complement, but are not bound by the FcR. The tissue distribution and localization of FcR and CR positive cells was studied in mixed hemadsorption assays on sections of both central (bursa, thymus) and peripheral (spleen) lymphoid organs from normal chickens, as well as lymphocytic infiltrated thyroid glands from animals of the Obese strain (OS) afflicted with spontaneous autoimmune thyroiditis. The possible significance of both receptors in the pathogenesis of this autoimmune process is discussed.
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PMID:IgG-Fc and C3 receptors in the chicken: distribution, tissue localization and functional significance. 689 42

The early, predictable, onset of spontaneous autoimmune thyroiditis (SAT) in Obese strain (OS) chickens provides a unique opportunity to analyse the mechanisms initiating autoimmunity which is virtually impossible to obtain in humans. In this study we focused on the respective roles of viruses and macrophages in the initiation of SAT. To analyse viruses, leukosis virus-free OS chickens were bred over three generations and reared under gnotobiotic conditions. By 2 weeks of age there were no differences in the levels of thyroid mononuclear cell infiltration between these and control animals. The role of mononuclear phagocytes in SAT was determined by their depletion via injecting newborn OS chicks with silica or carrageenan and dichloro-methylene diphosphonate encapsulated into liposomes. Although this treatment did not substantially change the amount of macrophages in primary lymphoid organs or blood, there was destruction of splenic architecture and, most importantly, mononuclear cell infiltration of the thyroids was significantly lower compared to controls. The role of activated macrophages in SAT is discussed.
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PMID:Analysis of the initiation period of spontaneous autoimmune thyroiditis (SAT) in obese strain (OS) of chickens. 873 56

Melanocortins, melanocyte-stimulating hormones (MSH) and adrenocorticotropic hormone (ACTH) are homologous natural peptides derived from pro-opiomelanocortin (POMC). Recent breakthroughs in melanocortin receptor (MCR) biology are relevant to neuroimmunomodulation because melanocortins are known to modulate fever, inflammation and immunity, by acting both on peripheral targets and within the brain. During fever, endogenous melanocortins exert antipyretic effects by acting on MCR located within the brain, suggesting a protective counterregulatory role of the central melanocortin system. MCR are also found in melanocytic cells and adrenal cortical cells, the classical targets for alpha-MSH and ACTH, respectively, in myelogenous and lymphoid tissues, and in various endocrine and exocrine glands, adipocytes, and in autonomic ganglia. In the CNS, MCR are prominently distributed in close proximity to the terminal fields of melanocortinergic neurons that innervate neuroendocrine and autonomic motor nuclei as well as other subcortical brain regions important in neuroendocrine and autonomic regulation, sensory processing and various aspects of behavior. Furthermore, the presence of MCR in circumventricular organs of the brain provides direct access of systemic melanocortin hormones to central MCR. Together, these attributes provide an anatomical basis for bidirectional MCR-mediated communication between brain and periphery. A group of five G-protein-associated MCR subtypes, each of which is positively coupled to adenylate cyclase, has been identified. Among these, the adrenal ACTH receptor (MC2-R) is selectively activated by ACTH. In contrast, the other MCR subtypes (MC1-R, MC3-R, MC4-R, MC5-R) recognize a common group of ligands that includes various forms of MSH as well as ACTH; nevertheless they do exhibit important differences in ligand selectivity. MCR concentrations and MCR mRNA levels are influenced by availability of cognate ligands, by drugs, and by pathological stimuli. Two types of endogenous MCR antagonist proteins have been discovered: agouti protein and the corticostatins. Agouti protein dramatically alters coat color in mammals by antagonizing melanocytic MC1-R. Moreover, spontaneous dominant mutations of the agouti gene in several strains of mice lead to its ubiquitous overexpression and produces not only yellow coat color, but also obesity and insulin resistance, perhaps as a result of its antagonism of other MCR subtypes. The recent emergence of synthetic MCR antagonists, and the feasibility of molecular approaches for targeted inactivation of individual MCR subtypes, should facilitate elucidation of the roles and mechanisms of neuroimmunomodulation by endogenous melanocortins, and the determination of whether selective pharmacological targeting of MCR may ultimately have therapeutic utility.
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PMID:Receptor biology of the melanocortins, a family of neuroimmunomodulatory peptides. 921 48

We have identified human 17beta-hydroxysteroid dehydrogenase type 7 (17beta-HSD 7). The novel human cDNA encodes a 37 kDa protein that shows 78 and 74% amino acid identity with rat and mouse 17beta-HSD 7, respectively. These enzymes are responsible for estradiol production in the corpus luteum during pregnancy, but are also present in placenta and several steroid target tissues (breast, testis and prostate) as revealed by RT-PCR. The human 17beta-HSD 7 gene (HSD17B7) consists of nine exons and eight introns, spanning 21. 8 kb and maps to chromosome 10p11.2 close to susceptibility loci for tumor progression, obesity and diabetes. The HSD17B7 promoter (1.2 kb) reveals binding sites for brain-specific and lymphoid transcription factors corresponding to additional expression domains in hematopoietic tissues and the developing brain as identified by in silico Northern blot.
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PMID:Determination of cDNA, gene structure and chromosomal localization of the novel human 17beta-hydroxysteroid dehydrogenase type 7(1). 1054 67

Adipose tissue develops in and/or around most lymphoid tissues in mammals and birds. Early reports of this widespread association and hypotheses for its functional basis were long ignored in the planning of in vitro studies and the interpretation of in vivo results. Biochemical studies on rodent tissues reveal many site-specific properties of adipocytes anatomically associated with lymph nodes and omental milky spots that equip them to interact locally with lymphoid cells. The paracrine interactions are strongest for the most readily activated lymph nodes and are modulated by dietary lipids. Perinodal adipocytes contribute less than those in the large nodeless depots to whole-body lipid supplies during fasting. Observations on wild animals show that perinodal adipose tissue is selectively conserved even in starvation but does not enlarge greatly in natural obesity. Such paracrine provisioning of peripheral immune responses improves their efficiency and emancipates activated lymphocytes from competition with other tissues for blood-borne nutrients. The relationship is found in extant protherians and metatherians, so it almost certainly arose early in the evolution of mammals, possibly as part of the metabolic reorganisation associated with homeothermy, viviparity, and lactation. Prolonged disruption to paracrine interactions between lymphoid and adipose tissue may contribute to the HIV-associated adipose redistribution syndrome, causing selective hypertrophy of the mesentery, omentum, and other adipose depots that contain much activated lymphoid tissue. Skeletal and cardiac muscle may also have paracrine relationships with anatomically associated adipose tissue, but interactions between contiguous tissues have not been demonstrated directly.
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PMID:Paracrine interactions of mammalian adipose tissue. 1250 8


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