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PubMed1987

Effects of growth hormone on the adult canine thymus.

The ability of bovine growth hormone therapy to stimulate regeneration of age involuted thymus glands in adult dogs was evaluated. The thymuses of growth hormone treated dogs regenerated, resembling thymic tissue of young dogs. Some of the thymuses of bovine serum albumin treated control dogs also regenerated, but only 2 of 5 control dogs had marked regeneration. White blood cell counts in peripheral blood were not different between groups. Serum thymosin alpha 1 concentrations were not different between groups, but decreased in each group during the treatment period.

Age Factors↗
PubMed2001

Inhibitory activities of (-)-epigallocatechin-3-O-gallate against topoisomerases I and II.

The substitution of gallic acid at the 3 position of (-)-epigallocatechin-3-O-gallate (EGCG) increased the inhibition against topoisomerase I from calf thymus gland and topoisomerase II from human placenta, and the substitution of a hydroxyl group at the 3' position increased the inhibition against the topoisomerase I. These results suggested that the 3 and 3' positions of the EGCG molecule play important roles in the process of inhibition of topoisomerases I and II. EGCG showed strong inhibition against topoisomerases I from wheat germ, calf thymus gland and Vero cells, and showed weak or no inhibition against topoisomerases I from carcinoma cells such as A549, HeLa and COLO 201 cells. EGCG differentially inhibited the topoisomerases I from different sources.

Animals↗
PubMed1982

Thymosin beta 4: a ubiquitous peptide in rat and mouse tissues.

Thymosin beta 4, recently isolated from calf thymus, is present in a number of rat and mouse tissues, including spleen, thymus, brain, lung, liver, and heart muscle. High concentrations are found in peritoneal macrophages, suggesting that its occurrence in other tissues may be related to the presence of macrophages or macrophage-like cells in these tissues. The conclusion that "thymosin" beta 4 does not originate solely in the thymus gland is supported by the high concentrations found in tissues of athymic (nu/nu) mice.

Animals↗
PubMed1982

Age-related changes in localization of thymosin in the human thymus.

Using an indirect fluorescent antibody technique, localization of thymosin alpha 1, thymosin beta 3 and thymosin fraction 6 was studied in human thymus glands ranging in age from newborn to 62 yr old. Thymosin alpha 1 was detected specifically in thymic epithelial cells of the medulla and in cells covering the cortical surface. Thymosin beta 3 was detected almost exclusively in cells covering the cortical surface. Epithelial cells in the medulla, which were positive for thymosin alpha 1, decreased in number progressively with age, beginning at around 13 yr of age. Epithelial cells positive for thymosin alpha 1 and covering the cortical surface were observed in thymus tissue from all ages, although the absolute number decreased. Several of the peptide components of thymosin fraction 6 were found in thymic epithelial cells as well as in macrophages in the thymus and spleen.

Adolescent↗
PubMed2000

DiGeorge anomaly: a comparative study of the clinical and immunologic characteristics of patients positive and negative by fluorescence in situ hybridization.

BACKGROUND: DiGeorge anomaly (DGA) is defined as a field defect characterized by dysmorphic facies, hypoparathyroidism, congenital heart defects, and a deficiency in cell-mediated immunity, usually associated with a microdeletion in chromosome 22q11.2. Data correlating clinical and genetic information, especially in terms of the extent of the immunodeficiency and infectious complications, are scant. OBJECTIVE: The goal of this study was to define the severity of the immunodeficiency and infectious illnesses in DGA patients with characteristic clinical and genetic findings and compare them with a similar group of patients without a microdeletion in chromosome 22q11.2. METHODS: A retrospective chart review of patients referred for evaluation of DGA to our immunology service from 1989 to 1995 was conducted. Clinical and immunologic data were collected from their initial evaluation. Patients meeting at least 3 of 4 of these criteria were considered to meet strict clinical diagnostic criteria for DGA, and the results of analysis for a microdeletion in chromosome 22q11.2 for each patient was noted. RESULTS: Sixteen of the 22 patients meeting strict clinical criteria for DGA were available for analysis for the microdeletion at chromosome 22q.11.2. Of these, 13 (81%) were positive by fluorescence in situ hybridization (FISH); 9 of 13 (69%) had low CD3 numbers, 6 of 10 assayed (60%) had low thymulin levels; 10 of 13 (77%) had low CD4 numbers, and 10 of 12 (83%) had absent or small thymus glands. B cells were increased in 9 of 13 (69%) patients. Mitogen and antigen responses were normal in 6 of 7 (86%) patients tested. Eight of 13 (62%) had a history of increased frequency of infectious illnesses. All had recurrent respiratory infections, including sinusitis, otitis media, and pneumonia. Three of the 16 patients tested (19%) were FISH negative. Two of 3 (67%) had low CD3 and CD4 numbers. B cells were elevated in all patients. All had recurrent respiratory infections, low thymulin levels, and absent thymus glands. CONCLUSIONS: Contrary to traditional descriptions, this group of clinically and genetically defined patients with DGA had a predominantly mild cell-mediated immunodeficiency syndrome usually associated with infections characteristic of humoral immunodeficiencies. The patients who were FISH positive did not differ significantly from those that were FISH negative in terms of clinical and immunologic findings or infectious complications.

Child↗
PubMed2000

Cytologic diagnosis of true thymic hyperplasia by combined radiologic imaging and aspiration cytology: a case report including flow cytometric analysis.

True thymic hyperplasia (TH) is an age-dependent increase in size and weight of the thymus gland, which by definition maintains a normal histologic architecture. TH can mimic other important diseases, including lymphofollicular hyperplasia, thymoma, lymphoma, and germ-cell tumors. Traditionally, separating these entities has required a formal surgical biopsy. Given that many of these conditions occur in children, this can be a traumatic experience for both the patient and family members. Fine-needle aspiration biopsy has the distinct advantage of being able to obtain diagnostic material without requiring general anesthesia. We are aware of only one previously reported case of an enlarged thymus being subjected to aspiration cytology. We therefore present a case of thymic hyperplasia in a 5-mo-old child diagnosed by combined radiologic and cytologic parameters, including flow cytometric analysis.

Biopsy, Needle↗
PubMed1977

Immunofluorescence localization of thyroglobulin autoantibody producing cells in various organs of obese strain (OS) chickens.

All major lymphoid organs from animals of the Obese strain (OS) of chickens which develop a spontaneous autoimmune thyroiditis with circulating thyroglobulin autoantibodies (Tg-AAb) were investigated for Tg-AAb producing cells using the immunofluorescence method (IF). No Tg-binding cells could be detected in spleen, bursa. Harderian glands, thymus, coecal tonsils or bone marrow. The infiltrated thyroid gland was shown to be the only site of Tg-AAb production detectable by IF.

Animals↗
PubMed1991

Vitamin A deficiency and the induction of cutaneous toxicity in murine skin by TCDD.

The mechanisms involved in the induction of toxicity by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a prototype for a group of toxic polyhalogenated aromatic hydrocarbons, are largely unknown. To test the hypothesis that TCDD-induced toxicity involves the reduction of vitamin A levels, we investigated the role of vitamin A deficiency in modulating the cutaneous response of congenic haired (+/+) and hairless (hr/hr) mice to TCDD. Hairless mice are recognized as sensitive models for expression of TCDD-induced cutaneous toxicity. Haired mice normally do not develop a cutaneous response to TCDD. Mice raised on a vitamin A-deficient diet, and age- and sex-matched controls raised on standard chow, were treated topically with TCDD and their cutaneous responses monitored histologically. Body weights and thymus gland weights were monitored as additional parameters of toxicity. Liver and skin vitamin A levels were determined by HPLC. Vitamin A depletion by itself had no effect on the normal cutaneous histology of the haired phenotype, nor were any changes in cutaneous morphology attributable to TCDD toxicity observed in haired, TCDD-treated animals even when they were severely vitamin A depleted. On the other hand, in hairless mice, vitamin A deficiency caused a distinct increase in keratinization of dermal epithelial cysts, and an increase in the sensitivity of these cysts to TCDD-induced hyperkeratinization. TCDD-induced body weight loss and atrophy of the thymus gland were not affected by the vitamin A status of either the haired or hairless animals. Analysis of vitamin A levels in skin and liver, following topical treatment of mice with TCDD, indicated that TCDD exposure did not affect cutaneous levels, but did significantly lower liver levels of vitamin A. These experiments suggest that although systemic vitamin A deficiency may potentiate the expression of TCDD-induced toxicity in skin of hairless mice, expression of TCDD-induced toxicity probably involves more complex mechanisms than a reduction in vitamin A levels.

Administration, Topical↗
PubMed1987

Ultrasonographic findings in thymic lymphoma in children.

The sonographic manifestations of thymic involvement by T lymphoblastic non-Hodgkin's lymphoma/leukaemia in 6 children are presented. The criteria which may help in its differentiation from a normal thymus gland are reviewed. Hypoechoic and non-homogeneous large masses are the most typical presentation of thymic infiltration. Fixity of tumour and compression of surrounding structures are the most important associated signs with pleural and pericardial effusions. In children, ultrasonography of the mediastinum can play a role by establishing the nature of anterior masses.

Child, Preschool↗
PubMed1989

Evidence of enhanced recombinant interleukin-2 sensitivity in thymic lymphocytes from patients with myasthenia gravis: possible role in autoimmune pathogenesis.

We evaluated the activation state of thymic lymphocytes in patients with myasthenia gravis (MG) by cytofluorographic analysis of CD25 expression and by testing their sensitivity to recombinant interleukin-2 (rIL-2) in the absence of any known previous stimulation. We detected no phenotypic signs of activation in fresh MG thymic lymphocyte suspensions, while functional signs of activation were reflected in a significantly higher sensitivity to rIL-2 in MG patients than in controls. The responses to rIL-2 were time- and dose-dependent, were inhibited by a blocking anti-IL-2 receptor antibody, and were associated with an increase in CD25+ T cells in both patients and controls. The T cells with functional signs of previous activation may represent autoreactive cells involved in the autoimmune process and confirm thymus gland hyperactivity in MG. These cells could result from primary autosensitization against the thymic acetylcholine receptor (AChR)-like molecule or from altered migration of peripheral activated cells into an abnormal thymic environment. Our results also provide a clue for understanding the effect of thymectomy in myasthenia gravis.

Antibodies, Monoclonal↗
PubMed1994

Response to thymectomy in Chinese patients with myasthenia gravis.

Myasthenia gravis was diagnosed in 48 patients between 1985 and 1991 in this Chinese community. Thymectomy was performed on 36 patients and the mean postoperative follow-up period was 49 months. Significant improvement was seen in 72% of the thymectomised patients, with 33% achieving complete remission. Patients with mild generalised myasthenia at presentation or those found to have thymic hyperplasia had the best prognosis. Patients with more severe symptoms or those with an underlying thymoma also responded favourably. Only patients with ocular myasthenia or those with a normal or atrophic thymus gland had no more than an even chance of gaining significant improvement. Although previous reports suggested a high prevalence of ocular myasthenia and of thymoma among Chinese myasthenic patients, the present study has found no evidence that they respond differently to thymectomy than their Western counterparts.

Adolescent↗
PubMed1982

Thymectomy in late-onset myasthenia gravis.

Between 1977 and 1979, 12 consecutive patients with myasthenia gravis who were over the age of 55 years were treated by thymectomy. In all, their conditions improved clinically; 11 of the 12 became free of the generalized features of myasthenia gravis. Nine patients required no further medication. Acetylcholine-receptor antibody titers did not change significantly. Although five patients had atrophic thymus glands, their conditions also improved. We conclude that (1) thymectomy is a safe and effective therapy for patients with myasthenia gravis who are over the age of 55 years; (2) steroids and anticholinesterase agents are not essential in the management of late-onset myasthenia gravis; and (3) reduction in acetylcholine-receptor antibody titer is not essential for beneficial clinical response.

Aged↗
PubMed1985

Cystic degeneration of thymic Hodgkin's disease following radiation therapy.

A case of thymic Hodgkin's disease presenting with an anterior mediastinal mass is reported. The mass progressively expanded in size on plain chest radiography during and following a mantle radiation therapy. A repeat computed tomographic (CT) scan of the chest in this patient revealed a cystic component to the mass, and thin-needle aspiration of the cyst led to a shrinkage of the mass. An experience in this case and review of literature suggest Hodgkin's disease involving the thymus gland frequently predisposes to cystic degeneration especially following radiotherapy, leaving a stable or progressively enlarging residual mass. A precise diagnosis of such a progressively expanding mass despite the adequate radiation therapy is crucial. CT scan of the chest in such cases and a thin-needle aspiration of the cystic mass offer precise diagnosis and may obviate the need for an open thoracotomy procedure.

Adult↗
PubMed2003

Presentation of primary mediastinal masses in Ibadan.

OBJECTIVES: To determine clinical features, anatomic location and histological types of primary mediastinal masses diagnosed and treated in a black African population. DESIGN: A retrospective study of clinical data collected from patients case notes, the cardiothoracic unit's and pathology records between June 1975 and May 1999. SETTING: University College Hospital, Ibadan, Nigeria which hosts a major cancer center in the West African sub-region, and serves community clinics. PATIENTS: All patients with primary mediastinal masses referred for evaluation and treatment. MAIN OUTCOME MEASURES: Excluded metastatic, oesophageal and vascular-lesions. All patients had radiological evalulation and tissue biopsies. The anatomic subdivision of the mediastinum into anterosuperior, middle and posterior section was used. RESULTS: One hundred and five consecutive patients were evaluated and treated. The mean age was 34.0 +/- 20.4 years. There were 75 males and 30 females. Eighty one (77.1%) were symptomatic, 24 (22.9%) were asymptomatic. Thirty seven (45.7%) of the symptomatic patients had malignant disease while 44 (54.3%) had benign disease. Forty five patients (43%) and 60 patients (57%) had malignant and benign diseases respectively. Incidence of symptoms, was 82.2% for malignant and 73.3% for benign diseases. This difference in incidences is statistically insignificant (p=0.283). Majority of asymptomatic patients (70.8%) had benign disease while 29.2% of patients with malignancy were asymptomatic. This difference in incidence was statistically significant (p=0.0039). The frequency of mediastinal masses were anterosuperior, in 67 patients (63.8%), posterior mediastinal, 24 patients (22.9%) and middle mediastinal in 14 patients (13.3%). Lymphoma 23 (21.9%), thymus glands tumours 19 (18.1%) and endocrine tumours (goiters) 18 (17.1%) were the commonest types of primary mediastinal masses treated. CONCLUSION: Majority of our patients with mediastinal masses (whether benign or malignant) are symptomatic and the absence of symptoms is more associated with benign disease. Majority of lesions are situated in the anterosuperior mediastinum. Lymphoma is the most frequent primary mediastinal mass.

Adolescent↗
PubMedDate not supplied

[Myasthenia gravis and non-Hodgkin's lymphoma].

We describe 2 patients with myasthenia gravis and non-Hodgkin's lymphoma outside the thymus gland, in whom the two diseases progressed at different rates. Diagnosis of myasthenia gravis was based on clinical signs and compatible neurophysiologic studies, specifically by high acetylcholine antireceptor titers in the first patient and a positive Tensilon test in the second. In the first patient the clinical and serological signs of the two diseases progressed similarly. The association of these two diseases may have been the result of an underlying immunological disorder favoring their appearance, or of an immune response, caused by the lymphoma involving postsynaptic nicotinic acetylcholine receptors.

Autoimmune Diseases↗
PubMed1995

Efficacy of thymectomy in myasthenia gravis.

We sought to determine the efficacy of thymectomy in patients with myasthenia gravis (MG). The roles of age, gender, age of onset of MG, acetylcholine receptor antibodies (AchR's) titers, and pathology of the thymus gland were evaluated. Twenty-one patients were analyzed retrospectively. Twenty patients belonged to Osserman Class IIA or higher; 71.42% belonged to IIB. All patients were on either anticholinesterase and/or immunosuppressive agents. The mean follow up was three years. Seventy-six percent of the patients showed improvement by Osserman and by "results of treatment" classification, 14.28% were in complete remission, on no medications. The age, gender, age of onset, thymic pathology and AchR titers had no correlation with post-operative improvement. With longer follow up the beneficial effect is more apparent.

Adolescent↗
PubMedDate not supplied

[Advances in the research on immunopathogenesis of myasthenia gravis].

Microscopic structure and immunologic function of the thymus gland are outlined, with an emphasis on its role in the process of T and B lymphocytes maturation. Other types of thymic cells are also described, including epithelial and myoid cells that presumably have a central role in initiation of an autoimmunologic process leading to myasthenic symptoms development. A detailed account is presented of issues concerning pathophysiology of myasthenia, the structure of nicotinic acetylcholine receptor (AchR) at neuromuscular junctions, and mechanisms underlying its destruction by autoantibodies. The role of T and B lymphocytes, of various cytokine types, of autoantibodies to various striated muscle antigens, as well as a possible role of genetic and bacterial factors in the development of myasthenia gravis are discussed. In conclusion it is stressed that since recent research findings go beyond the classic theory of myasthenia, a new consistent theory of the disease immunopathogenesis must be created in the future to place all the newly discovered phenomena in a logical conceptual structure.

Autoantibodies↗
PubMed1992

Thymic regulation of the hypothalamic-pituitary-gonadal axis.

The thymus gland and the cells that it regulates produce a number of soluble factors that are capable of indirectly modulating the immune system via reproductive neuroendocrine circuits. Studies dating to the turn of the century were designed to evaluate the effects of partially purified thymic extracts in treating various reproductive disorders as well as changes in gonadal tissue weights. More recent studies have focused on the chemical nature of the factors responsible for regulating reproductive function. A number of factors have been described. These include thymosin beta 4 which has been found to stimulate the release of luteinizing hormone releasing hormone and luteinizing hormone (LH). Other factors such as interleukin-1 (IL-1) have been found to inhibit the release of these two peptides. IL-1 has also been found to alter the expression of LH receptors in rat granulosa cells. Certain interferons have been found capable of suppressing estrogen and progesterone release. While many of the studies have been carried out using adult animal models, there is increasing evidence that exposure to cytokines during early development can have long lasting if not permanent effects upon the reproductive axis. These and related topics are the subject of this review.

Animals↗