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PubMed1982

A comparative study of age involution of the bursa of Fabricius an thymus in birds.

The differential growth patterns of the bursa of Fabricius and thymus of Comet strain chicks were examined up to 60 days of age. It was found that the bursa increased in size, in relation to body weight, during the first 3 wk of life but thereafter underwent involution. The thymic tissue increased in weight throughout the period of investigation, from 3 to 58 days of age; when this total weight was related to the number of thymus glands, it was found that during the first days of life, thymus tissue was increased by the growth of pre-existing thymic glands but that this was followed by a phase when new thymus glands appeared with no increase in the size of the largest glands. Although the growth and involution patterns of the thymus and bursa differed it was found that, for each age group, a linear relationship existed between the bursa and thymus, suggesting that there may be a common control of development in the two organs.

Aging↗
PubMed1991

DNA synthesis is reduced in selected fetal tissues during prolonged hypoxemia.

The effects of 24 h of reduced maternal uterine blood flow (RUBF) on relative DNA synthesis rates in different tissues and on blood glucose and lactate concentrations were studied in fetal sheep. In six sheep, RUBF was induced for 24 h, whereas in another six sheep (controls), uterine blood flow was not reduced. To estimate DNA synthesis rate, [3H]thymidine (1 mCi/kg) was injected intravenously into each fetus 8 h before the end of the 24-h experimental period. Fetal arterial oxygen saturation decreased from 59.1 +/- 3.3 to 25.7 +/- 5.6% after 1 h of RUBF and remained significantly reduced for the duration of the experiment. Fetal blood lactate concentrations were significantly increased by RUBF from 14.3 +/- 6.5 to 57.8 +/- 12.4 mg/dl at 1 h and remained elevated, whereas fetal blood glucose concentrations were not affected. A 24-h period of RUBF did not significantly alter fetal body weights, tissue weights, tissue-to-body weight ratios, or tissue DNA content. Over the last 8 h of the 24-h experimental period, RUBF was found to significantly reduce the relative rate of DNA synthesis (as assessed by [3H]thymidine incorporation into DNA) in the lung (104.7 +/- 26.6 vs. 17.1 +/- 3.1 dpm/micrograms DNA), quadriceps muscle (92.8 +/- 20.7 vs. 14.4 +/- 5.3 dpm/micrograms DNA), and thymus gland (87.5 +/- 7.1 vs. 32.9 +/- 12.2 dpm/micrograms DNA). Relative DNA synthesis rates in the fetal liver, kidney, small intestine, cerebral cortex, cerebellum, placenta, thyroid gland, and adrenal gland were not significantly affected by RUBF. In this study, we have shown that DNA synthesis was greatly reduced in selected fetal tissues (lung, quadriceps muscle, and thymus gland) by a 24-h period of RUBF, although it is not known why a reduction was only observed in these tissues.

Adrenal Glands↗
PubMed2006

[Expression of human annexin V in different fetal tissues].

OBJECTIVE: To investigate the expression of human annexin-V (HA-V) in relation to HBV infection in different fetal tissues. METHODS: Immunohistochemistry was employed to detect the expression and distribution of HA-V in the liver, kidney, ovary, heart, fallopian tube, spleen, and thymus gland of human fetus. RESULTS: HA-V expression was detected in different tissues including the ovary, liver, intrahepatic bile duct, heart, kidney, lymphocytic cells in the thymus gland, epithelial cells of the fallopian, and cortical and medullary cells of the spleen. HA-V was distributed mainly in the cytoplasm of the cells. The liver tissues exhibited greater gray scale for HA-V expression than in the other tissues (P<0.05) and no significant difference was observed in the other tissues than the liver (P>0.05) in image analysis with Photoshop 7.0. CONCLUSION: HA-V is an inherent protein in fetal tissues with possible relation to HBV infection of different tissues as a HBV receptor. Greater amount of HA-V in the liver may account for the vulnerability of the liver to HBV infection.

Annexin A5↗
PubMed1993

Visualization of the thymus with therapeutic doses of radioiodine in patients with thyroid cancer.

Two cases of papillary carcinoma of the thyroid are presented in which whole-body scans following therapeutic doses of iodine-131 revealed intense anterior mediastinal uptake. In both cases, the mediastinal uptake was absent from scans obtained after removal of the entire thymus. Histologically, the resected thymus glands showed hyperplasia and contained neither thyroid tissue nor metastatic foci of thyroid carcinoma. We therefore concluded that anterior mediastinal uptake of radioiodine may be caused by hyperplasia of the thymus.

Adult↗
PubMed1998

[Hypophyseal-adreno-gonadal system function in myasthenia patients with tumorous and nontumorous pathology of the thymus].

Overall twenty-five patients (all women) who ranged from 16 to 56 years old were examined. They were divided into two groups: group I was formed of subjects with hyperplasia of the thymus gland, group II--thymoma. Blood serum levels of prolactin, progesterone, estriol, estradiol, testosterone hydrocortisone. All patients showed a significant increase in average blood plasma levels of estrogens, testosterone and prolactin. Average levels of progesterone and hydrocortisone in patients with thymus hypertrophy were lower than in controls, while in thymoma patients these were much higher. The data submitted are indicative of substantial differences in the endocrine status of myasthenia patients depending on tumor or nontumor lesion of the thymus gland, which fact may suggest different pathogenetic mechanisms of development of the condition.

Adolescent↗
PubMed2002

[Effect of the stem and leaf of Tripterygium wilfordii on immune function].

OBJECTIVE: To study the effect of water extracts from the stem and leaf of Tripterygium wilfordii Hook. f. on Hook. f. immune function. METHODS: The effect of the stem and leaf of Trpterygium wilfordii on the clearance of charcoal particles, the index of thymus gland and spleen, the level of serum hemolysin and the delayed hypersensitivity were observed in mice by ig. RESULTS: The stem and leaf of Tripterygium wilfordi could decrease the clearance of charcoal particles, the index of thymus gland and spleen, the level of serum hemolysin and inhibit the delayed hypersensitivity in mice. CONCLUSION: The stem and leaf of Tripterygium wilfordii could inhibit nonspecific, humeral and cellular immunity.

Animals↗
PubMedDate not supplied

[Carcinoid tumor of the thymus: report of a case (author's transl)].

Carcinoid tumor primarily developing in the thymus gland is very rare. A new case is reported to add to the 35 previously reported. In most cases, patients have no endocrinological syndrome; the tumor is rarely associated with a multiple endocrine adenomatosis. This neoplasm probably derived from Kultschizky cells which are present in the normal thymus gland. Histologically they are very similar to the carcinoid tumor of other organs. Complete surgical excision is the best treatment when possible.

Apudoma↗
PubMed1978

Translation of mRNA from calf thymus in the wheat germ system: evidence for a precursor of thymosin alpha1.

When translated in the wheat germ system, mRNA from fresh calf thymus stimulates incorporation of radioactive amino acids into an acid-insoluble product, and 10--20% of the total radioactivity incorporated is precipitated with antisera to active thymosin fractions. In sodium dodecyl sulfate disc gel electrophoresis, radioactivity was recovered mainly in two peptides, corresponding to 16,000 and 11,000 daltons; the latter probably represents incomplete chains. Tryptic digests of each of these peptides yielded fragments corresponding to the sequence of residues 15--19 of thymosin alpha1; these peptides were characterized by cochromatography with digests of synthetic thymosin alpha1 and by Edman degradation. Thus, the 16,000-dalton peptide synthesized in the cell-free system appears to be q precursor of thymosin alpha1 and possibly of other peptides in the fractions isolated from calf thymus. The results support the conclusion that this peptide is synthesized in the thymus gland.

Cell-Free System↗
PubMed1993

Myasthenia gravis and primary squamous cell carcinoma of the thymus.

Occurrence of primary squamous cell carcinoma of the thymus gland in a 65-year-old man with myasthenia gravis is reported. Histologic and immunohistochemical studies confirmed the diagnosis of a differentiated squamous cell carcinoma. Extensive clinical investigations ruled out another primary site for the tumor. The patient made a full recovery postoperatively. Only three cases of primary squamous cell carcinoma of the thymus gland in association with myasthenia gravis have been reported in the literature.

Aged↗
PubMed1989

Pulmonary embolization-induced thymus hyperplasia in rabbits.

The effects of pulmonary embolization on the thymus glands of rabbits were studied morphologically, morphometrically and immunohistochemically. Pulmonary embolization was induced by an intravenous injection of 0.4 ml of Sephadex bead suspension (particle size; 150 to 300 microns, about 2,000 per ml). Both mean weight and volume of the thymus of rabbits killed at 2 weeks after embolization, were about 1.5 times more than those in control animals treated with physiologic saline. Histological examinations showed enlargement of the cortex and medulla of the thymus, and the embolized Sephadex beads in the branches of pulmonary arteries of the lung. The area ratios of medulla/cortex, in the embolization group and in control, were not significantly different. The cells with immunohistochemically positive staining of anti-nuclear antigen of monoclonal antibody of Ki-67, were found in both portions of the medulla and cortex. These data suggest that pulmonary embolization in the rabbit induces true thymic hyperplasia. An intravenous injection of India ink into the right highest intercostal artery revealed the distribution of bronchial arteries, which send the branches to the right lobe of the thymus. In 2 out of 4 animals killed 2 weeks after pulmonary embolization, the left lobe of the thymus as well as the right were stained with the injected ink. As it is known that pulmonary vascular obstruction caused a marked increase in the bronchial blood flow, these data suggest that the thymus blood supply from the bronchial arteries increases in the conditions of pulmonary embolization, which might contribute to thymus hyperplasia.

Animals↗
PubMed1996

Myasthenia gravis.

The annual incidence rate of myasthenia gravis (MG) was estimated as 4.6 per million population, and the rate was found to be constant in calendar-time. Age- & sex-specific incidence rates disclosed a bimodal appearance for both sexes. According to the epidemiological data, the age limit between early onset and late onset of MG should be set at 50 years. The point prevalence rate has increased in time from 41 per million population in 1950 to 77 in 1988, and model calculation predicts an increased rate of 83 in year 2000. This reflects an improvement in the prognosis of MG. Standardized mortality rate for MG was estimated as 1.87. The total patient population was weighted 6 to 4 with predominance of females. A decrement of the muscle action potential (AP) and of the muscle twitch (TW) was found in 72% and 49% of the cases respectively, the diagnostic yield being proportional to the severity of MG. Post-tetanic facilitation of AP and TW was found in 25% and 20% of the cases respectively. The analogue estimates for post-tetanic exhaustion were 44% and 25% respectively. An abnormal staircase phenomenon was present in 37% of MG patients. Neurophysiological evidence of myopathy, which was not correlated to the degree of neuromuscular transmission failure, was found in 19% of the patients, more often in cases with late onset than in those with early onset (31% compared with 11%). The occurrence of myopathy was associated with pathological muscular biopsy (78%), and with anti-striated muscle antibodies (53%) suggesting that a myopathy of possibly autoimmune origin may coexist with MG. The overall diagnostic sensitivity of anti-AChR antibodies RIA was found to be 88%, the positivity being proportionate to the clinical severity of MG (ocular MG: early onset 71%, late onset 88%; severe generalized MG: early onset 89%, late onset 98%). The finding of anti-AChR antibodies is highly specific for MG (>99.9%). The distribution of antibodies titres was approximately lognormal. The concentration of the antibodies correlated with the clinical severity of the disease, female or male gender, and the pathology of the thymus gland. The improved outlook for MG during the last 4 decades may be ascribed to the combined results of all the new modalities of treatment. Experimental results towards selective plasma exchange are expounded. As opposed to MG patients with hyperplasia or involution of the thymus gland, thymoma cases exhibited exacerbation of the clinical course and also of the anti-AChR antibody titres after thymectomy. Possible steps to circumvent the therapeutical impasse in thymoma cases are discussed, such as combined immunosuppressive therapy along with surgery or conservative treatment for as long as possible.

Adult↗
PubMed1984

Have we underestimated the importance of the thymus in man?

Recent immunological research has concentrated on the complex and subtle interactions between T cells, B cells and accessory cells. In these studies, little attention has been given to the adult thymus gland. Modern textbooks of disease and anatomy all stress that the gland undergoes fatty involution with age in man but omit reference to the statements here and there in the literature that the gland is active and produces lymphocytes throughout life. To suggest that the bone marrow, which also builds up fat throughout life, is atrophic and not important to adult man would deny all modern hematological concepts. Yet few people today take a parallel view of the thymus except perhaps those investigating aging and thymic hormones. In both of these areas of research it is obvious that the thymus must be active throughout life for continued good health. This brief review urges that a thorough understanding of the vital importance of the thymus in adult life is now needed. From it could emerge a new philosophy on the treatment of immune diseases in both the young (SCID and AIDS patients) and in the aged (autoimmune conditions and cancers) and it would aid our treatment of patients recovering from illness and from many drug treatments.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Thymectomy in myasthenia with pure ocular symptoms.

Eighteen patients with exclusively ocular symptoms of myasthenia were thymectomised. Suspected thymoma, resistance to pyridostigmine therapy or relapse following immunosuppressive therapy were taken as indications for surgery. The mean preoperative observation period before operation was 40 months, and after operation was 26 months. There was no operative or postoperative morbidity or mortality. Histological thymic abnormalities were found in all patients (in one case, thymoma; in four, persistent thymus; in 13, thymic hyperplasia). The histological abnormalities were identical to those found in generalised myasthenia. This included the distribution of T-cell subtypes as identified by use of monoclonal antibodies. The severity of ocular symptoms was rated using a score developed for this purpose. The score progressively declined after surgery to an average of 70% of its initial amount in 80% of patients. Full remission occurred in three cases. No patient developed generalized myasthenia. Antibody titres against acetylcholine receptors if elevated preoperatively also dropped following surgery, with one exception. Clear criteria for the expected therapeutic success of thymectomy could not be identified. Based on our results, and on the assumed significance of the thymus gland for pathogenesis, thymectomy should be considered in patients with pure ocular symptoms.

Adult↗
PubMed2003

[Effect of xue hanjing oral fluid on mice immunological function].

OBJECTIVE: To observe effect of Xue Hanjing oral fluid on mice immunological function. METHOD: The weight of thymus gland and spleen and the function of abdominal cavity macrophage were measured. Production of the hemolysin antibody, the immunoglobulin of blood serum and complement and the proliferation of T lymphocytes were observed respectively by means of microblood, immune-turbidimetry and MTT staining. RESULT: Xue Hanjing oral fluid could enhance index of the thymus gland and spleen and the phago-percent of abdominal cavity macrophage, increase the immunoglobulin of blood serum(IgG and IgM), and accelerate production of the hemolysin antibody and the proliferation of T lymphocytes. CONCLUSIONS: Xue Hanjing oral can reinforce immunological function in mice.

Adjuvants, Immunologic↗
PubMedDate not supplied

Critical reexamination of the thymus immunization model of myasthenia gravis.

Previous studies have described an experimental model of myasthenia gravis (MG) produced by immunizing animals with thymus extracts. In view of the hypothesis that the autoimmune process in MG may be initiated within the thymus itself, we have reexamined this model using presently available methods to evaluate its resemblance to MG. We immunized Lewis rats with extracts of rat thymus in Freund's adjuvant, as originally described by G. Goldstein. Five procedures were used to test for myasthenic characteristics: (1) repetitive nerve stimulation; (2) recording of miniature endplate potentials; (3) assays of anti-ACh receptor antibodies in serum; (4) determination of ACh receptors at neuromuscular junctions by [125I] alpha-bungarotoxin binding; and (5) evaluation of the histology of the thymus gland. Our results showed that the thymus-immunized animals did not demonstrate abnormalities in any of these parameters. We conclude that immunization of rats with thymus extracts, as described, failed to produce a myasthenia-like condition.

Animals↗
PubMed1988

Effects of neonatal treatment with estrogens on the development of the thymus in rats.

In order to study the effects of sex hormones administered during the neonatal period on the thymic development we have injected 5 days old female rats with a single dose (0.1mg) of estradiol benzoate. The evolution of the thymus gland after treatment was morphometrically analyzed. The thymus of the estrogen-injected animals diminished in size between the 7th and the 15th day, increasing afterwards. The cortex was the most sensitive compartment in the thymus to estrogenic treatment. Both thymic involution and enlargement were associated to changes in the frequency of large lymphoid cells in the subcapsular region and variations in the thymic cortex weights. The observed effects are tentatively attributed to alterations in the thymocyte differentiation probably due to modifications in the secretion of thymic hormones.

Animals↗