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At least 73 records · Page 4Linked to original sources
PubMed1994

Nodular sclerosing Hodgkin's disease of the thymus gland.

An asymptomatic anterior mediastinal mass in a 22-year-old man proved to be nodular sclerosing Hodgkin's disease of the thymus gland. Complete excision was possible via a left posterolateral thoracotomy. Postoperative chemotherapy was given. Follow-up after 1 year showed no residual disease. Nodular sclerosing Hodgkin's disease is an uncommon tumor of the thymus gland and should be incorporated in the differential diagnosis of anterior mediastinal tumors. Multimodality treatment is advocated.

Adult↗
PubMed2002

The thymus gland is a target in malnutrition.

Malnutrition, secondary to deficiency in uptake of proteins, metal elements or vitamins, consistently results in changes in the thymus gland. The organ undergoes a severe atrophy due to apoptosis-induced thymocyte depletion, particularly affecting the immature CD4(+) CD8(+) cells, as well as a decrease in cell proliferation. Such a feature is apparently linked to a hormonal imbalance, involving decrease of leptin and consequent raise of glucocorticoid hormone levels in the serum. Interestingly, this picture can be reversed after appropriate diet rehabilitation. The thymic microenvironment is also affected in malnutrition: morphological changes in thymic epithelial cells were found, together with a decrease of thymic hormone production by these cells. Additionally, intrathymic contents of extracellular proteins, such as fibronectin, laminin and collagens, are increased in the thymuses from malnourished children. Conjointly, the bulk of data discussed herein clearly points to the notion that the thymus gland is a target in malnutrition. Nevertheless, further relevant information regarding the physiology of the thymus, including the cytokine/chemokine secretion as well as the positive and negative selection events driven by TCR/MHC-peptide interactions in malnutrition, remains to be defined. These are questions that need to be answered in order to have a better understanding of the immunodeficiency seen in malnourished individuals.

Animals↗
PubMed1991

Sodium and potassium channels in epithelial cells from thymus glands and thymomas of myasthenia gravis patients.

In both normal and neoplastic epithelial cells from human thymus glands and thymomas, respectively, we found voltage-gated sodium and potassium channels that resemble the adult-type Na channel and the delayed outward rectifier K channel, respectively, of human skeletal muscle and mammalian nervous system. These voltage-gated ion channels might be part of a communication system between epithelial cells and other components of the microenvironment of the thymus.

Electric Conductivity↗
PubMed1986

Vitamin D, parathyroid, and thymus gland influences on seasonal variations in renal electrolyte excretion.

Effects of the thymus gland and vitamin D and other calcium-regulating hormones on electrolyte balance were investigated. In studies conducted over 3 successive years male hooded rats excreted more chloride (Cl) and less inorganic phosphate (P) in April-August (summer) than in November-March (winter) when subjected to sham operation (SHAM) or to the surgical procedures described herein and exposed to natural sunlight in temperature- and humidity-controlled rooms. Parathyroidectomy, combined with sham thymectomy (PX), thymectomy (PX-TMX), thyroidectomy-sham thymectomy (TPX), or thyroidectomy-thymectomy (TPX-TMX), significantly increased Cl excretion during both seasons. The same surgical procedures also reduced P excretion in the winter. However, PX and PX-TMX lowered the P values only slightly in summer, and the effects were reversed by thyroid ablation. Thymectomy (TMX), alone or in combination with PX or TPX, increased Cl excretion during the summer, but it did not affect the outputs of winter animals with intact thyroid or parathyroid glands. Vitamin D3 (400 IU) injected three times weekly for 3 weeks increased the Cl excretion of all surgical groups during the winter. In the summer, it increased the Cl excretion of SHAM only, and it diminished the Cl excretion of thyroidectomized rats. Significant increases in P excretion were found only in PX-winter and TMX-summer groups. A vitamin D-deficient diet during the summer resulted in a more than four-fold increase in P excretion in TMX and SHAM rats, and it significantly reduced Cl excretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Acetylcholine receptors of skeletal muscle cells in cultures of rat thymus glands.

Skeletal muscle fibres develop in cultures established from dissociated rat thymus glands. The properties of their acetylcholine receptors were compared with those on fibres in skeletal muscle cultures. Acetylcholine depolarized the thymus-derived muscle cells in a concentration-dependent manner. Under voltage clamp the reversal potential was determined to be -0.4 mV, which was not significantly different from the reversal potential of cells in the muscle cultures. In both types of cultures, sensitivity to ionophoretically applied acetylcholine decreased during the period when fibres were growing rapidly and then increased. The mean channel lifetime of acetylcholine-activated channels was similar in both types of muscle fibre (3-4 ms at -40 mV), but the single channel conductance was significantly higher in the thymus-derived cells (70-75 pS compared to 55-60 pS). The cholinoceptors on both types of muscle fibre had nicotinic properties as judged by their preferential activation by acetylcholine rather than by acetyl-beta-methylcholine and oxotremorine and by the selective blockade by tubocurarine and erabutoxin b rather than by atropine.

Acetylcholine↗
PubMed1987

Re-investigation of the innervation of the thymus gland in mice and rats.

Central to the postulated relationship between the brain and the immune system has been evidence for the direct neural innervation of primary organs of the immune system. It has been reported previously that the thymus gland in rats and mice receives a substantial innervation from the "retrofacial" nucleus of the brain stem and ventral horn cells of the upper cervical spinal cord. Based on the proximity of the thymus to thoracic viscera and neck musculature known to receive motor fibers from these same areas of the brain stem and spinal cord, we examined the possibility that retrogradely labeled cells in the brain stem and spinal cord following injections of tracers into the thymus are due to spread of tracer into the esophagus and neck musculature. Small injections (0.5-2.0 microliter) of wheatgerm agglutinin-horseradish peroxidase (WGA-HRP) were made into the thymus, the esophagus, and the longus colli muscle of rats or mice. Also, the effects of a unilateral cervical vagotomy on cholinesterase activity in the thymus were examined. Finally, the source of the sympathetic supply to the thymus and the presence of catecholamine and cholinesterasic fibers in the thymus was reassessed. Injections of WGA-HRP into the thymus produced little or no labeling in the brain stem and spinal cord. In contrast, control injections into the esophageal wall resulted in numerous intensely labeled cells in the compact formation of the nucleus ambiguus, irrespective of the rostral-caudal level of the esophageal injection. Similarly, tracer injections into the longus colli muscle resulted in numerous intensely labeled cells in the ventral horn of the upper cervical spinal cord. Unilateral vagotomy did not alter cholinesterase activity in the thymus even though it was largely depleted in the ipsilateral nucleus ambiguus. The histochemical studies verified a major sympathetic innervation of the thymus gland. In keeping with this result, in animals in which no labeled cells were observed in the brain stem or spinal cord following thymus injection, labeled cells were, however, observed in the sympathetic chains from the superior cervical ganglia caudal to the T3 ganglia. In summary, all labeled cells in the brain stem and cervical spinal cord observed following tracer injections into the thymus can be accounted for by spread of the tracer into surrounding structures, leading to spurious labeling.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Absence of acetylcholine-induced current in epithelial cells from thymus glands and thymomas of myasthenia gravis patients.

We investigated the activity of ion channels in epithelial cells from human thymus glands and thymomas kept in short-term cell culture by clamping the membrane potential of the cells at -85 mV and determining the membrane current flowing on application of acetylcholine, glycine, or gamma-aminobutyric acid. In concentrations of up to 10(-3) M, none of the neurotransmitters induced any detectable current. This suggests (1) that there are no acetylcholine receptors (AChRs) or other products of the AChR gene family having ion-channel properties in the membranes of these epithelial cells, and (2) that the alpha-bungarotoxin-binding protein of thymus and thymoma has no AChR-like ion-channel property. These results support the hypothesis that the cross-reacting structures that elicit the anti-AChR autoimmune response in thymoma-associated myasthenia gravis are antigens having only limited homology with the AChR. Myasthenia gravis not associated with thymoma might have a different pathogenesis.

Acetylcholine↗
PubMed1988

Hormonal characterization of female SL/Ni mice: a small thymus gland strain exhibiting ovarian dysgenesis.

Female SL/Ni mice have a small thymus gland and show accelerated aging of the reproductive system characterized by an early loss of the follicular apparatus and early onset of ovarian tumors. At 9 months of age, circulating levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were higher in the SL/Ni animals than in controls while prolactin (PRL) was lower in the SL/Ni mice. The trends of these hormones are consistent with the loss of the follicular apparatus which is responsible for estradiol production. The high levels of gonadotropins which precede the onset of the tumors confirm the hypothesis that prolonged stimulation by gonadotropins can be a cause of ovarian tumorigenesis. Further, these data suggest that aging of the reproductive system may be a thymus-dependent phenomenon.

Aging↗
PubMed1984

[Mucoepidermoid tumor of the thymus gland].

The description of mucoepidermoid tumour of the thymus in a 14-year-old girl is given. The observation is of interest due to unusual localization and the rarity of thymic tumours in children.

Adolescent↗
PubMed1975

Sizes and numbers of nuclei in the cortex of thymus glands of red-billed weavers Quelea quelea.

The cortex of the thymus glands of embryos, chicks, juveniles, fledglings and adults from several colonies of Quelea quelea were studied using an image analyser (Quantimet 720) to determine cell populations and nuclear sizes. Just prior to hatching the lobes showed a high level of mitosis and consisted of predominantly small lymphocytes. The larger glands of chicks and juveniles had higher cell populations; pyknotic cells and erythrocytes occurred free in the cortex. The lobes of adults were more variable but in general mitosis occurred in enlarging glands of adults from colonies with eggs; most lobes contained pyknotic cells but not in such high numbers as in lobes from chicks and fledglings. Erythrocytes were common, occurring in large numbers in the cortex in some birds. The factors affecting the interpretation of these data are discussed in detail.

Age Factors↗
PubMed1983

Ultrastructural studies on the thymus gland after the administration of phenylhydrazine to bank voles (Clethrionomys glareolus).

The thymus glands of wild and laboratory reared bank voles (Clethrionomys glareolus) were examined for ultrastructural changes before and after the administration of low (20 mg/kg) and high (60 mg/kg) doses of phenylhydrazine (PhZ) given intraperitoneally on days 0, 1 and 3 of a dosing regime. Erythrocytes developed in focal aggregations in the subcapsular and outer cortical zones. There was a marked depletion of the subcapsular cortex following drug treatment that was reversed with time. A large number of granulocytes were visible in the cortex after PhZ, and mast cells developed in situ.

Animals↗
PubMed1980

The weight of the human thymus gland at necropsy.

The wet, lipid and lean dry weights of 574 thymus glands from Coroner's necropsies were examined for age-related changes. Despite enormous variation in wet and lipid weights at all ages there was a gradual decrease in wet weight with age and a significant increase in lipid weight until 40--50 years of age, with little change thereafter. There was a small decrease in lean dry weight with age, but it is not known if this reflects a change in cellularity. Multiple regression analysis showed that lower wet and lipid thymic weights were associated with long-term stressful conditions, and higher weights with deaths from asphyxia (largely in younger persons) and five groups of cardiovascular conditions. The percentage of lipid in these groups was not increased.

Adolescent↗
PubMed1979

Ultrastructural and histochemical features of the thymus glands of the adult lungless salamander, Plethodon glutinosus (Caudata: Plethodontidae).

The thymus glands of adult slimy salamanders (Plethodon glutinosus) were examined by light and electron microscopy with the objective of describing the populations of epithelial cells believed to be secretory. The results of various histochemical procedures designed to demonstrate nucleic acids, proteins, lipids, and mucosubstances were evaluated by light microscopy. Each thymus is incompletely subdivided into a variable number of interconnected lobules by trabeculae extending inward from a thin capsule composed of connective tissues. The thymic parenchyma lacks distinct cortical and medullary regions, although developing lymphocytes and plasma cells tend to accumulate in larger numbers in the outermost portions of the glands. Basophils are found regularly in the capsule and trabeculae, but only very rarely within the thymic parenchyma. The epithelial cells of the thymus can be classified into five categories: epithelial reticular cells; three varieties of granulated cells (types I, II, and III), and myoid cells. Epithelial reticular cells form a three-dimensional network which extends throughout all portions of the thymus. Type I and type II granulated cells can be distinguished from one another by various morphological criteria at the ultrastructural level, but only small differences in the composition of their inclusions can be demonstrated histochemically. Both types of granules are composed principally of a proteinaceous material containing an abundance of primary amino and guanidyl groups. In addition, most type I inclusions possess a lipid component that cannot be demonstrated in type II granules. Type III granulated cells possess very small cytoplasmic inclusions resembling those of gastroenteric endocrine cells. Myoid cells contain concentrically arranged myofibrils composed of sarcomeres. In favorably oriented material, small cysts can be identified whose walls are composed of mixtures of type I cells, type II cells, and epithelial reticular cells. Groups of degenerating epithelial cells form lamellated structures corresponding to Hassall's (thymic) corpuscles.

Animals↗
PubMed1984

Purification of a DNA polymerase-DNA primase complex from calf thymus glands.

An immunoabsorbent column, prepared by covalently linking mouse monoclonal anti-calf thymus DNA polymerase-alpha to Protein A-Sepharose, was used as the primary purification step for rapid isolation of DNA polymerase-alpha from calf thymus-gland extracts. In a 4-step procedure consisting of the removal of nucleic acids by protamine sulfate precipitation, chromatography on the immunoabsorbent column, desalting on Sephadex G-50, and removal of bovine immunoglobulins on Protein A-Sepharose, DNA polymerase-alpha activity was purified about 5000-fold from the crude extract with greater than 40% recovery of total enzyme activity. The antibody column-purified DNA polymerase-alpha fraction contains a DNA primase activity that is efficient in replication of single-stranded DNA and poly(dT) when rNTPs are included in the replication reactions. Synthesis by calf thymus DNA polymerase-primase is totally dependent on added template. Complete replication of circular single-stranded phage DNA is achieved with polymerase-primase producing a nicked circular DNA containing oligoribonucleotide primer in the final product. Primers synthesized with single-stranded phage DNA as template were up to 10 nucleotides long when dNTPs were omitted from the reaction and 8 or less nucleotides long when dNTPs were present. Primers synthesized using poly(dT) consisted of three populations when dATP was absent from the reaction, averaging 20 nucleotides, 10 nucleotides, and 3-4 nucleotides. The 20-nucleotide population was not found when dATP was included in the reaction.

Animals↗