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PubMed1989

Bilateral thymus found in association with unilateral cleft lip and palate.

Ectopic localizations of the thymus have been reported in a variety of unusual sites, but not on the surface of the skin of the neck. As one can see in our case, the left neck mass (1.5 x 2 x 0.5 cm) and the right neck mass (4 x 4 x 0.5 cm), when added together in weight, also equal the total weight of the thymus at birth. Also, not being able to encounter the "sail sign" of the thymus gland on the chest x-ray proved to us that no other thymus gland was present. Because of these unusual findings, prior to excision of any congenital lesion in the neck, a biopsy should be done, and only after that should one proceed with the necessary surgical intervention. We are presenting this case because it is unique in this category.

Choristoma↗
PubMed1988

Computed tomography and pathologic correlations of thymic lesions.

Computed tomographic and pathologic correlations of the thymus gland were assessed in 69 patients. The sensitivity of computed tomography (CT) for undifferentiated thymic pathology is 87.1%; the specificity is 85.7%. The sensitivity of CT for neoplasm or mass is 97.1%, the specificity is 97.1%. The sensitivity of CT for lymphoid follicular hyperplasia (LFH) is 71.4%, the specificity is 97.6%. Therefore, a normal-sized thymus gland on CT does not exclude LFH. Completely preserved fat planes between thymic mass and adjacent structures on CT usually indicate a benign (noninvasive) neoplasm; completely absent fat planes usually indicate a malignant (invasive) neoplasm; partially preserved fat planes are indeterminate in assessing invasiveness. CT is also useful in showing recurrence or remnants of thymic tissue in patients who have had a previous thymectomy.

Adolescent↗
PubMed2006

[Observation of sanxian xinli capsule on pathologic morphology in superheat mice].

OBJECTIVE: To investigate the change of pathologic morphology in superheat mice. METHOD: The superheat was used in the experinent. The pathologic morphology of thymus gland, spleen, liver and lung was observed by light microscope. RESULT: The histiocytes of thymus gland, spleen, liver and lung presented no changes in lesion, congestion and morphology. CONCLUSION: The Sanxian Xinli capsule have function of protecting the superheat mouse viscera.

Agrimonia↗
PubMed1949

The effect of podophyllotoxin on tissue metabolism and enzyme systems.

Podophyllotoxin, 10(-3) (M), inhibits the respiration in vitro of rat lymph nodes, thymus, kidney, tumor, spleen, liver, brain, testis, and chicken embryo. Lymph node and spleen respiration are most sensitive, and the degree of inhibition increases with time. The injection of podophyllotoxin into tumor-bearing mice (20 mg. per kg.) causes a dramatic reduction in the respiration of tumor slices. Within 6 hours, the respiration approaches zero. Inhibition is evident 2 hours after injection of the drug. Spleen respiration is reduced 50 per cent within 6 hours. Kidney and liver respirations remain within normal limits. Marked reductions in the respiration of spleen, lymph nodes, and thymus glands of normal rats are produced by the injection of 15 mg. per kg. Thymus gland is the most sensitive of these three tissues, and its respiration is reduced 66 per cent 24 hours after injection of the drug. The injection of 0.8 microgram podophyllotoxin into the yolk sac of chicken eggs bearing 5 day embryos has no effect on the respiration of the embryo within 8 hours, although this is a sufficiently toxic dose to kill 80 per cent of the embryos (within 24 hours). Kidney respiration in the presence of acetate, glucose, alanine, and glutamate is inhibited to approximately the same degree as in the absence of added substrate. Succinate and pyruvate oxidation by rat kidney slices appear to be less sensitive. Oxidation of acetate and butyrate by rabbit kidney homogenate is more sensitive to podophyllotoxin than oxidation by rabbit kidney homogenate without added substrate. Glucose oxidation by this preparation is not inhibited by 10(-3)M podophyllotoxin. The anaerobic glycolysis of chicken embryo, rat brain, and rat testis is stimulated by 10(-5) and 10(-6)M podophyllotoxin, and is inhibited by 10(-3)M. The following enzymes are not inhibited by 10(-3)M podophyllotoxin: succinoxidase from pigeon breast muscle, choline, xanthine and tyrosine oxidase from rat liver homogenate, and leucine oxidase from Proteus vulgaris; alkaline and acid phosphatase from dog serum; adenosine triphosphatase from rat liver; choline esterase from rat brain homogenate; ribonucleodepolymerase from spleen mince and thymonucleodepolymerase from dog serum. High concentrations of podophyllotoxin do not influence the viscosity and degree of polymerization of thymonucleic acid.

Animals↗
PubMed1989

Luteinizing hormone-releasing hormone (LHRH) agonist restoration of age-associated decline of thymus weight, thymic LHRH receptors, and thymocyte proliferative capacity.

The presence of specific LHRH-binding sites within the rat thymus gland and the ability of LHRH and its agonistic and antagonistic analogs to directly modulate thymus function prompted us to study the possible changes in the number of thymic LHRH-binding sites during aging-induced physiological immunosenescence. Moreover, the effects of chronic treatment of aging rats with a potent LHRH agonist (LHRH-A) on thymic LHRH receptors, thymus weight and histology, as well as thymocyte proliferative capacity were assessed. For comparison, the effects of castration on the same parameters was also investigated. The process of aging is accompanied by a sharp reduction in LHRH-A-binding sites within the thymus gland of both female and male rats. Starting at 7 months of age, a 50% decrease in thymic LHRH-A binding was followed, at 11-13 months of age, by a nearly 65% inhibition of receptor numbers. In 16- to 19-month-old rats, LHRH-A binding was almost completely lost. Thymus weight was 30% reduced in 7-month-old animals, while a 50% reduction in thymic size was reached at 11 months of age in males and 13 months in female rats. A further decrease in thymic mass was observed at 16 and 19 months. Chronic (45-day) treatment of aging (15-16 months old) female and male rates with the potent LHRH-A, [D-Trp6,Des-Gly10]LHRH-N-ethylamide, reversed the age-related decreases in both thymus weight and thymic LHRH-binding sites. Similarly, surgical removal of testicular hormones by castration restored thymus weight and increased LHRH-A binding in the thymus of aged rats. While thymus histology in 3-month-old rats was characterized by a clear demarcation of cortical and medullary regions, only thymic remnants were present in 16- to 17-month-old animals. Castration of old rats resulted in a partial restoration of thymic structure, while chronic treatment of aging rats with the LHRH-A produced a homogeneous organization of both cortical and medullary compartments accompanied by a marked increase in the width of the cortical layer, densely packed with lymphocytes. While the process of aging was accompanied by an almost complete loss of the proliferative response of thymocytes to optimal concentrations of the mitogen Concanavalin-A, thymocyte cultures from old rats treated with LHRH-A or from castrated animals, displayed significantly greater proliferative responses. Furthermore, the combination of both manipulations resulted in a further significant increase in thymocyte proliferative capacity.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗
PubMed1982

Development and properties of malignant lymphoma induced by magnesium deficiency in rats.

Female wistar rats were fed on an Mg-deficient diet. After 8 to 10 weeks, the thymus glands were strongly degenerated and the number of lymphocytes was reduced, especially in the cortex. Thymus degeneration was associated with a decreased rate of DNA, RNA, and protein biosynthesis and necrosis and phagocytosis of lymphocytes. The degeneration was normalized after feeding on an Mg-rich diet. After 10 or 11 weeks of Mg deficiency, local cell proliferations of immature lymphocytes with a great number of free ribosomes were found in some thymus glands. The local cell proliferations developed into infiltrating tumors without metastases. In lymphoma cells the Na+ and Ca2+ content, the turnover of cellular Na+ and K+, and the aerobic production of CO2 and lactate were increased.

Animals↗
PubMed1975

The immune system of the nine-banded armadillo (Dasypus novemcinctus, Linn).

The armadillo is rapidly emerging as an animal for biomedical research. A morphological study of the immune system of the armadillo was undertaken to try to demonstrate a possible defect in the morphogenesis of the lymphoid organs that could account for their susceptibility to leprosy. Blood from 20 domesticated adult armadillos revealed lymphocytes predominated among circulating leukocytes in the majority of animals, whereas in wild animals neutrophils predominated. Necropsies revealed well-developed thymus glands and the thymus-dependent areas in lymph nodes and spleens contained abundant lymphoid cells. Hence, we conclude that the susceptibility of the armadillo to leprosy cannot be explained on a morphological basis.

Age Factors↗
PubMed1975

Thymus dependence of tapeworm (Hymenolepis diminuta) elimination from mice.

Although normal mice eliminated the lumen-dwelling intestinal cestode Hymenolepis diminuta by day 21 post-cysticercoid inoculation, congenitally thymus-deficient (nude) mice maintained their work burdens. Nude mice grafted with thymus glands or injected with thymus cells eliminated their worms.

Animals↗
PubMed1980

The mitogenic action of prolactin on some endocrine organs of chicks.

The aim of the present investigation was to explore the mitogenic action of ovine and bovine prolactin hormones in the thyroid, the parathyroid and the thymus glands of chicks. Both the hormones in lowest dosage (1.5 i.u.) increased the mitotic rate in majority of these organs, but it failed to accelerate the mitotic incidence further or were almost ineffective with the higher dosages (5 i.u. and 10 i.u.). Ovine prolactin showed a higher mitogenic response than that seen with the bovine hormone. It is suggested that prolactin in optimal dosage promotes mitosis in these organs of chicks.

Animals↗
PubMedDate not supplied

Thymus: primary site of lymphopoiesis.

The thymus of the leopard frog is the primary, if not the sole, source of progenitor lymphocytic cells that normally colonize the spleen. Following embryonal parabiosis, a high level of cell chimerism exists in the thymus glands of each member of the parabiotic pair. Evidently, there can be an appreciable amount of cross-circulation of thymic cells between thymus glands.

Animals↗
PubMed2004

Full spectrum of malformations in velo-cardio-facial syndrome/DiGeorge syndrome mouse models by altering Tbx1 dosage.

Velo-cardio-facial syndrome/DiGeorge syndrome (VCFS/DGS) is associated with de novo hemizygous 22q11.2 deletions and is characterized by malformations attributed to abnormal development of the pharyngeal arches and pouches. The main physical findings include aortic arch and outflow tract heart defects, thymus gland hypoplasia or aplasia and craniofacial anomalies. The disorder varies greatly in expressivity; while some patients are mildly affected with learning disabilities and subtle craniofacial malformations, others die soon after birth with major cardiovascular defects and thymus gland aplasia. In addition to the main clinical features, many other findings are associated with the disorder such as chronic otitis media and hypocalcemia. Tbx1, a gene encoding a T-box transcription factor, which is hemizygously deleted on chromosome 22q11.2, was found to be a strong candidate for the equivalent of human VCFS/DGS in mice. Mice hemizygous for a null allele of Tbx1 had mild malformations, while homozygotes had severe malformations in the affected structures; neither precisely modeling the syndrome. Interestingly, bacterial artificial chromosome (BAC) transgenic mice overexpressing human TBX1 and three other transgenes, had similar malformations as VCFS/DGS patients. By employing genetic complementation studies, we demonstrate that altered TBX1 dosage and not overexpression of the other transgenes is responsible for most of the defects in the BAC transgenic mice. Furthermore, the full spectrum of VCFS/DGS malformations was elicited in a Tbx1 dose dependent manner, thus providing a molecular basis for the pathogenesis and varied expressivity of the syndrome.

Animals↗
PubMed1994

Involution and cystic transformation of the thymus in the bottlenose dolphin, Tursiops truncatus.

The thymus glands of 10 bottlenose dolphins, Tursiops truncatus, collected along the Texas Gulf coast were examined using standard histologic and immunocytochemical methods. The thymus gland of Tursiops persists into adult life, represented by medulla and progressively thinning cortex. A network of epithelial cells, including Hassal bodies, is demonstrable using polyclonal anti-cytokeratin antibody. The network condenses, with loss of lymphoid cells as involution progresses. Cysts arise within the condensed network. These cysts, found in eight of 10 animals, increase in number and size with increasing body size. Body size tends to reflect age. Thymic cysts typically have an irregular shape when small but tend to become spherical as they enlarge. They may be lined by squamous epithelium of variable thickness. Eventually, the cysts become macroscopic and filled with a colloidlike material and may largely replace the thymus, which may be identified by noncystic remnants adjacent to the cysts.

Aging↗
PubMed1976

Calcitonin cells and unusual follicles of the thyroid of the indian grey mongoose, Herpestes edwardsi (Geoffroy).

Histological preparations of thyroid, parathyroid and thymus glands of Herpestes edwardsi were examined for calcitonin cells. They reveal that (1) the thyroid calcitonin cells are oval, rounded and rarely elongated in shape; these cells and their nuclei are distinctly larger than those of the follicular cells and their nuclei; (2) calcitonin cells are unevenly distributed in the thyroid, with the result that certain portions of the thyroid are completely devoid of these cells; (3) on an average, calcitonin cells are in a ratio of 10-15 cells/100 follicular cells; (4) the parathyroid and thymus glands do not display calcitonin cells, and (5) the thyroid gland displays unusual follicles of two categories, (a) follicles with ciliated epithelial cells and (b) follicles with squamous epithelium.

Animals↗
PubMed2005

Lithium increases body weight of rats: relation to thymolysis.

Lithium treatment of patients and laboratory animals causes increased body weight. Lithium also elevates the plasma corticosterone levels of rats. Our purpose was to correlate the gain of body weight with the effects of lithium on the thymus gland, the organ most susceptible to stress and to elevated corticosterone levels. Toward this end, it was also necessary to establish a reliable and reproducible model by use of an inbred strain of rats. Female rats of the inbred Lewis strain were injected subcutaneously with lithium chloride or saline for an 18-day period. Necropsies were performed one day after the last treatment or at intervals during the treatment period. Lithium increased body weight gain compared to controls in all the experiments on Lewis rats. Contrary to the body as a whole, lithium caused loss of weight of the thymus gland. The spleen lost less weight than the thymus. Both lithium and nonspecific stress elevate plasma corticosterone and cause thymolysis. Mild nonspecific stress is known to cause increased weight gain in rats as well as in humans. Our data suggest that lithium acts like nonspecific stress to increase weight gain as a consequence of elevated glucocorticoids, manifested in our experiments by thymolysis. This mechanism has not been proposed previously.

Animals↗
PubMedDate not supplied

Nuclear matrix bound terminal deoxynucleotidyl transferase in rat thymus nuclei. I. A possible site for TdT mediated function.

Approximately 80% of the terminal deoxynucleotidyl transferase (TdT) in thymus glands from 3-4 week old rats was found to be localized in the nucleus and the remaining 20% in the cytosol. Following endogenous nuclease digestion of the thymus nuclei, 70-85% of the nuclear TdT could be removed by low salt and high salt extractions, whereas 15-30% of the enzyme remained tightly bound to the residual nuclear matrix. Low salt and high salt extracts of the nuclei contained a mixture of 58, 56, 45 and 44 kDa species of TdT whereas only 58 kDa species of the enzyme was found to be associated with the matrix. In addition to TdT, 20-25% of the nuclear DNA polymerase alpha was also tightly bound to the isolated nuclear matrix. These observations lead us to propose that besides being the site of DNA replication via-matrix bound replicational complexes [Van der Velden H.M.W. & Wanka F., Molecular Biology Reports 12 (1987): 69], nuclear matrix may also be the site of TdT mediated function and that matrix bound TdT and free TdT could be the functional and nonfunctional forms of the enzyme, respectively, in the thymus gland.

Affinity Labels↗
PubMed1996

Normal thymic uptake of FDG on PET imaging.

Assessment and characterization of the thymus by various imaging methods have been extensively described. The authors report increased uptake of 2-(18)Fluoro-2-deoxy-D-glucose (FDG) in the normal thymus gland of patients between the ages of 2 and 13 years. Most of these patients had PET scans for various oncologic conditions and had no clinical problems referable to the thymus gland. This uptake assumes an important role when evaluating mediastinal uptake in whole-body PET scans in pediatric oncology patients to avoid false-positive interpretation.

Adolescent↗
PubMed1979

Lymphocyte subpopulations in thymus and blood from patients with myasthenia gravis.

Cell suspensions were prepared from hyperplastic thymic tissue and lymphoepithelioma from patients with myasthenia gravis and from presumed normal thymic tissue obtained at cardiac surgery. The mononuclear cells were examined for surface markers. The mean percentages of both T lymphocytes and Fc receptor-carrying lymphocytes were similar in the three groups, whereas there was an increase in C receptor-carrying lymphocytes in the samples from myasthenic patients. Sections from the thymus gland were examined for T and B markers. In the hyperplastic thymus and in lymphoepithelioma, the T lymphocytes were distributed diffusely throughout the cortex and the medulla; in the normal thymus they were predominant in the cortex. The mean percentage of T and B lymphocytes in peripheral blood from patients with myasthenia gravis was normal. Thymectomy involved a transitory decrease in T lymphocytes with a corresponding increase in B lymphocytes.

B-Lymphocytes↗
PubMed1996

The combined cervical and partial sternotomy approach for thymectomy.

Removal of a normal appearing thymus gland may be necessary, particularly in patients with myasthenia gravis. Complete removal is a basic tenet of this type of operation. A combined cervical and upper sternotomy incision is described. This is appropriate for thymectomy in such patients because of the minimal morbidity and excellent exposure for the thoracic portion of the thymus gland.

Cervical Vertebrae↗