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PubMed1991

Influence of castration, alone or combined with thymectomy, on the development of diabetes in the nonobese diabetic mouse.

The nonobese diabetic (NOD) mouse is a recognized model for studying immunologically-mediated insulin-dependent diabetes mellitus. The disease appears with a greater preponderance in females than in males. Castration at weaning led to a significant increase in the prevalence of diabetes in NOD males, whereas a tendency to a decreased prevalence was observed in NOD females. Castration combined with thymectomy was found to further increase the prevalence of diabetes in NOD males, whereas in females castration reversed the effect of thymectomy. These results on changes in diabetes prevalence were corroborated by the degree of lymphocytic infiltration directed toward the pancreatic islets of Langerhans. Taken together these results indicate a direct relationship between the endocrine and immune systems, whereby orchidectomy has a deleterious effect on the immunopathogenesis of diabetes. In addition, we examined whether the distribution of lymphocyte subpopulations, mitogen reactivity, lymphokine production, and in vivo response to a thymus-dependent antigen, such as sheer red blood cell, were dependent or independent of the sex steroid environment.

Animals↗
PubMed1980

Humoral immunity in myasthenia gravis: effect of steroids and thymectomy.

Antibody to the nicotinic acetylcholine receptor is detectable in most patients with myasthenia gravis and is responsible for the defect in neuromuscular transmission present in the disorder. We evaluated the effects of thymectomy and steroid therapies on antireceptor antibody titers. The thymectomy-treated group (consisting of juvenile and early adult-onset patients) experienced a variable change in postoperative antibody titers, ranging from a 28% increase to an 84% decrease, with the mean change of an 18.3% decrease. The steroid-treated group consisted of late adult-onset myasthenics. In these patients there was a decrease in antibody titer ranging from 29% to 83%. The average time required for a 50% reduction in titer was 4.85 months and was associated with a marked clinical improvement or complete remission.

Acetylcholine↗
PubMed1983

Acetylcholine receptor antibody and clinical response to thymectomy in myasthenia gravis.

We studied serum anti-acetylcholine receptor (AChR) antibody and clinical response to thymectomy in myasthenia gravis for 1 to 3 1/2 years postoperatively in 25 patients who did not receive immunosuppressive drugs. Clinical grade was assessed "blind." Mean final anti-AChR values were significantly reduced compared with thymectomy values (69.6 +/- 7.5% SEM; p less than 0.05). Anti-AChR fell steadily to 42-15% in the six patients who developed remission. Overall, there was a significant correlation between changes in anti-AChR and in clinical grade at 1 year (p less than 0.01) and at final assessment (p less than 0.001). An association between fall in anti-AChR and clinical improvement was absent in five individuals and not accounted for by change in antibody characteristics.

Acetylcholine↗
PubMed1990

Indications for thymectomy in myasthenia gravis.

Fifty-six board-certified neurologists with interest and expertise in myasthenia completed a survey of indications for thymectomy in myasthenia gravis. Thymectomy was advocated for virtually all patients with thymoma, for a variable subset of patients with generalized myasthenia without thymoma, and occasionally for selected patients with disabling ocular myasthenia.

Humans↗
PubMed1990

Neonatal thymectomy affects follicle populations before the onset of autoimmune oophoritis in B6A mice.

Using a variation on a standard follicle classification technique, 5 classes of follicles were quantified in serial sections of ovaries from intact mice and mice thymectomized on Day 3 at 5-day intervals from 5 to 40 days of age. Sera from these animals and from animals 60 days of age were analysed for the presence of anti-oocyte antibodies. Ovaries from intact animals 10 to 40 days of age were examined for the presence of antigen(s) using anti-oocyte antibody-positive sera from all ages of mice. There was a dramatic decrease in the primordial follicle population at 10 days of age in thymectomized mice and that population remained significantly lower until 40 days of age. The growing follicle population was also significantly lower at 20 days of age in thymectomized mice and remained lower through 40 days of age. Anti-oocyte antibodies were not detectable until 30 days of age and at that age reacted with oocytes from all follicle types including primordial. Ovarian antigens were present in similar patterns in ovaries from mice at all ages tested. We conclude that thymectomy has an earlier influence on the ovary than previously thought and this influence does not appear to involve the immune activity associated with autoimmune ovarian dysgenesis. This suggests that the effect of thymectomy on the ovary may be biphasic: (1) an early effect, possibly involving a disruption in the hypothalamic-pituitary-ovarian-thymic axis, that influences the primordial and growing follicle populations before 20 days of age; and (2) a later effect involving an immune imbalance first evident by 25-30 days of age that ultimately results in the destruction of the ovary.

Animals↗
PubMed1978

[Thymectomy in myasthenia gravis. Evaluation of the results in 73 patients].

An evaluation of results obtained after 73 thymectomies is reported. A transthoracic approach was used on all of the patients. Thymomas were found in 9 out of the 73 patients with myasthenia. All of the 64 patients without thymomas suffered from generalized myasthenia gravis with predominance of severe forms. The results of the early, intermediate and late post-operative course were analysed. A comparative study of results as related to age, sex, duration of disease and presence or absence of thymomas was made. Statistical analysis failed to show any significant difference in the results of thymectomy between selected and randomly chosen patients without thymomas.

Adolescent↗
PubMed1987

[Conservative treatment and thymectomy in myasthenia gravis: short- and long-term evaluated results].

A retrospective survey of the records of 33 patients with generalized acquired myasthenia gravis treated at Hospital das Clínicas, Medical School of The University of São Paulo, Brazil and in private practice, with and without thymectomy, is reported. Nineteen were thymectomized and 14 non operated. Both groups were demographically homogeneous and were followed from 8 to 24 years. Parameters for evaluating the natural history of disease and other ones for a comparative analysis of the improvement or remissions were established. The influence of the individualized therapy was evaluated by McNemar test (chi 2); the U-Mann-Whitney was used for evaluation of the populational behavior groups; variable parameter with possible influence in the useful life were studied by multivariate analysis. The difference of distance between both groups was not significant: (D2 = 0.08894); T2 = 7.17 (Hottelling test). There were differences of the isolate clinic parameter response in both groups, but the global analysis of the parameters did not permit to discriminate them, possibly because of interaction of the parameters influencing the analytic result. Inspite of the fact that superposition of the parameter occurred when analysed for a long period, we believe the early thymectomy to be beneficial. Our patients who had their operation at a younger age and specially those with recent disease had a maximum improvement.

Adolescent↗
PubMed2000

Effects of infantile thymectomy on ovarian functions and gonadotrophin-induced ovulation in prepubertal mice: role of thymulin.

The effects of thymectomy performed on 10-day-old (Tx-10) mice on spontaneous puberty and the ovulatory response induced by gonadotrophin treatment were analysed, together with the effects of thymulin replacement from 10 days of age. Infantile thymectomy induced a delay of puberty, a decrease in serum 17beta-oestradiol concentration and a reduced total number of follicles. Injection of thymulin (12 ng/g body weight) to Tx-10 mice resulted in an earlier onset of puberty, a decrease in the weights of ovaries and uterus, and an increase in serum 17beta-oestradiol concentrations. In control and Tx-10 mice, treatment with pregnant mare serum gonadotrophin (PMSG) (5 IU) at 25 days of age resulted in ovulation and the numbers of ova shed by ovulating animals were similar. When the animals were injected with 1 IU PMSG ovulation did not occur. In Tx-10 mice, both 1 and 5 IU PMSG increased the number of follicles to values similar to those observed in the controls. In Tx-10 mice the sequential injection of PMSG (1 IU) and human chorionic gonadotrophin (hCG) (3 IU) resulted in ovulation, but the number of ova shed was lower than in controls. When these animals were injected daily with thymulin, an increase in the number of ova shed and serum 17beta-oestradiol concentrations was observed. The uterine weight of Tx-10 mice was always significantly reduced in response to gonadotrophin treatment. Thymulin injection in PMSG-hCG-treated Tx-10 mice provoked a significant increase in uterine weight. The results suggest that the presence of the thymus after the neonatal period is necessary to normal ovarian development and function. The increase in gonadotrophin-induced ovarian response produced by thymulin replacement indicates that this peptide has a role in this process as one of the connecting signals between thymus and ovaries.

Animals↗
PubMed2000

Myasthenia gravis with membranous nephropathy, successfully treated with extended total thymectomy.

A 46-year-old woman showed proteinuria and hematuria after left blepharoptosis, and revealed a histopathology of membranous nephropathy (MN) at renal biopsy. She was diagnosed as having myasthenia gravis (MG) because of a positive edrophonium test and anti-acetylcholine receptor (AchR) antibodies in serum. We found a decrease in anti-AchR antibodies after extended total thymectomy, in parallel with an improvement in both urinary findings and myasthenic symptoms. In this case, MG preceded MN and the thymectomy was effective for both diseases, suggesting that the thymus might play an important role in the pathogenesis of MN.

Female↗
PubMed1994

Loss of RT6 message and most circulating T cells after thymectomy of diabetes prone BB rats.

T cells expressing the RT6 surface alloantigen perform important immunoregulatory functions in the rat. Diabetes prone (DP) BB rats are deficient in circulating RT6+ T cells and develop spontaneous autoimmune diabetes mellitus. Transfusions leading to engraftment of RT6+ T cells prevent the disease. Coisogenic diabetes resistant (DR) BB rats do circulate RT6+ T cells and are free of disease. We investigated the basis for the deficiency of RT6+ T cells in the DP-BB rat and made the following observations. 1. Thymectomy causes the rapid loss of most peripheral T cells in the DP-BB rat. 2. Concomitant with the loss of T cells is the total loss of mRNA encoding RT6. 3. In contrast to the effects observed in peripheral lymphoid tissues, thymectomy does not lead to a detectable loss in RT6+ protein found in the small intestine. We conclude that the deficiency of RT6+ peripheral T cells in the DP-BB rat is due either to their short life span or to their reduced proliferative capacity following release from the thymus.

ADP Ribose Transferases↗
PubMed2003

Multiple Langerhans cell nodules in an incidental thymectomy.

The isolated appearance of Langerhans cell histiocytosis in the thymus is quite rare. We report the finding of multiple small Langerhans cell nodules in the thymus of an 11-month-old infant who had undergone thymectomy in the course of surgical correction of tetralogy of Fallot. The subtle appearance of some of these nodules and aggregates was unlike the pattern of massive thymic infiltration seen in 7 previously reported cases of thymic Langerhans cell histiocytosis in childhood. This difference led us to consider whether these aggregates might be common in the thymus but overlooked in thymus glands removed incidental to cardiac surgery. We examined histologic material from 22 sequential thymectomy specimens removed during cardiac surgery from infants and children. None (0/22) had cohesive aggregates of Langerhans cells, as were seen in the index patient's thymus. Our patient's small thymic nodules resemble more closely a pattern found in adult patients with myasthenia gravis who have been incidentally shown to have Langerhans cell histiocytosis.

Adolescent↗
PubMed1999

[A case of pure red cell aplasia with hypogammaglobulinemia appearing after thymo-thymectomy].

We present a case of 83-year-old woman with pure red cell aplasia appearing eight months after thymo-thymectomy for an invasive thymoma. She underwent thymo-thymectomy for an invasive thymoma in July 1996. Preoperative examination revealed neither anemia nor hypogammaglobulinemia. About eight months after the operation, she was readmitted because of anemia and hypogammaglobulinemia. Bone marrow aspiration revealed absence of erythroblasts and chest CT revealed norecurrence of thymoma. Her anemia had responded to ciclosporin.

Agammaglobulinemia↗
PubMed1999

[Results and problems of thymectomy in myasthenia gravis over 65 years old].

From June 1975 to March 1999, 300 cases of myasthenia gravis (MG) have undergone thymectomy. Twenty-eight patients over 65 years old were examined, focusing on the relationship between clinical appearances and microscopic findings of the thymuses. Among these cases, six were classified as ocular type (one case with thymoma) and 22 generalized type (eight cases with thymoma). According to the thymoma registering stages defined by Masaoka and colleagues, those nine cases with thymoma associated with stages I (n = 7), II (n = 1) and III (n = 1), respectively. The case of stage III (74 year old female) died four years and eight months after surgery. The case of stage II died of old age two years after the surgery. Complete remission was achieved in two cases of stage I. The follicular hyperplasia were seen in eight cases, and all resulted in improvement. Nine cases with no particular findings of thymuses classified into four ocular type and five generalized type including one fulminating type. Post-operative course of all these cases were uneventful. Although one recurrent of the thymoma and one death of the tumor were observed, post-operative outcomes of these elderly patients were generally satisfactory. We concluded that there is an operative indication of thymectomy for MG of even elderly patients, if no particular findings were recognized in the thymus.

Aged↗
PubMed2000

Myasthenia gravis: a retrospective study comparing thymectomy to conservative treatment.

OBJECTIVES: To study the effectiveness of thymectomy (TY) in a group of patients with myasthenia gravis compared to a group of patients submitted to conservative treatment (CT) at a similar clinical stage. METHODS: Among 153 patients with myasthenia gravis, we paired 28 patients who underwent TY, with 28 cases under CT. The following data were analyzed: gender, age, and age at the beginning of symptoms, illness duration, follow-up time and type of medical treatment. There was no statistical difference between these 2 groups. The mean time for TY was 2.5 (0.2-13) years after the onset of the disease. The cases were evaluated through a functional scale at the beginning and at the end of the study. RESULTS: We found complete remission in 15 cases (TY 6, CT 9), improved (normal life with or without minimal symptoms and with or without medication) 9 cases (TY 8, CT 1), improved with partial control and minimal limitation 32 cases (TY 14, CT 18), and poor control 2 cases (TY 2). No death was found in this group. CONCLUSION: There was no statistical difference between the conservative treatment and thymectomy groups, regarding remission or improvement. Furthermore TY done in the first year of the disease or latter, did not change the final outcome.

Adolescent↗
PubMed2000

[A case of myasthenia gravis, who developed minimal change nephrotic syndrome during immunosuppressive therapy after thymectomy].

Myasthenia gravis is caused by antibodies against acetylcholine receptors and is treated with inhibition or elimination of antibody production. We report a 58-year-old woman who had been suffering from myasthenia gravis and underwent thymectomy in July 1995. Her myasthenic symptoms improved with immunosuppressive treatment using corticosteroid(100 mg/day) and azathioprine(100 mg/day). However she presented edema with massive proteinuria(7.54 g/day) and was admitted to our hospital on July 1997. She was diagnosed as having nephrotic syndrome and a renal biopsy was performed. The histological findings showed minimal change nephrotic syndrome. After pulse therapy with methylprednisolone(1 g/day x 3 days) following oral administration of prednisolone(60 mg/day), proteinuria disappeared after one month. Nephrotic syndrome is a rare complication in patients with myasthenia gravis. The increase in lymphokine production caused by thymectomy may be closely associated with the occurrence of nephrotic syndrome in spite of intensive immunosuppressive treatment in the present case. In this report, we also summarized reported cases of minimal change nephrotic syndrome with thymoma and myasthenia gravis.

Azathioprine↗
PubMedDate not supplied

[The effect of thymectomy on several types of metabolism in tissues and on the concentration of corticosteroids in the blood of adult rats].

The concentration of 11-OCS in the blood plasma increased 2 weeks after thymectomy of adult rats; 3 to 4 weeks later this index fell to subnormal values. The following changes were observed in the spleen 2 to 4 weeks after the operation: a reduction of P-32 incorporation into the RNA and particularly into the DNA and also a fall of the ATP phosphate and lactic acid concentration with a simultaneous increase of P-32 incorporation into the whole tissue and of the K/Na ratio. With some reduction of ATP phosphate and in the absence of any increase in P-32 incorporation into the whole tissue there was an increase in P-32 incorporation into the RNA. The absence of such metabolic changes in case of false thymectomy and following splenectomy pointed to their specific dependence on the exclusion of the thymus function. Dynamics of these shifts failed to correlate with the changes in the 11-OCS content in the majority of the tissues.

11-Hydroxycorticosteroids↗
PubMed1999

[Long-term outcome and relevant factors of thymectomy for myasthenia gravis].

OBJECTIVE: To evaluate the long-term outcome and relevant factors of thymectomy for myasthenia gravis (MG) by analyzing patients data. METHODS: 114 patients with MG operated between May 1990 and 1997 were reviewed. The results of operation were classified in to 4 grades: remission, improvement (efficiency includes remission and improvement), no change, and deterioration. The relativity between the long-term outcome and the factors of age, sex, the serum titer of AchR antibodies, duration of disease, pathological classification of thymus, modified osserman classification, and follow-up period was analyzed by logistic and chi(2) test. RESULTS: There were 47 man and 67 women aged from 4 to 72 years. Follow-up ranged from 10 to 82 months (mean 42, 8 months). The remission rate was 27.2% and the effective rate 67.5%. No patient died in the hospital, and the late-death rate was 7.0% (8 cases). CONCLUSION: Long follow-up (over 5 years) is necessary for evaluating the results of the treatment. There is no correlation between the outcome sex, and the serum titer of AchR antibodies. Associated diseases show no influence on the outcome of thymectomy.

Adolescent↗
PubMed1975

[Thymectomy in myasthenia gravis (author's transl)].

Experiences with 13 thymectomies for myasthenia gravis between 1966-1973 are reported. Incomplete median sternotomy was preferred. Myasthenic or cholinergic respiratory failure was a major complication after surgery. Daily measurements of VC were useful indicators to dedect beginning failures. Results depend on duration of the disease and histological type of lesion. Recommendation of thymectomy at an early stage of the disease is justified.

Humans↗