Clinical characteristics and prognosis of myasthenia gravis with other autoimmune diseases

Of 277 patients with myasthenia gravis (MG) who underwent thymectomy, including 78 with thymomatous MG, 33 patients had other autoimmune diseases. The clinical characteristics of MG with other autoimmune disease were investigated. Graves's disease and rheumatoid arthritis were the most common autoimmune diseases seen. The association rate of autoimmune disease in patients with thymomatous MG (3.8%) was significantly lower than that in patients with nonthymomatous MG (15.1%). The positive rate for a germinal center in the thymus was significantly higher in patients with other autoimmune disease than in those without such disease. Thymectomy was effective for MG in patients with an associated disease as well as in those without such a complication. The clinical course of the associated autoimmune disease did not seem to be adversely affected by thymectomy. Therefore, thymectomy should be performed in MG patients with other autoimmune disease.

Myasthenia gravis in elderly patients

The clinical features and the effect of thymectomy were compared between 27 elderly patients (Group 2) and 119 young adult patients (Group 1) with myasthenia gravis (MG). In the elderly group, MG was type I in 3 patients, type IIA in 6, type IIB in 17, and type III in 1; and in the young group, type I in 6, type IIA in 36, type IIB in 73, and type III in 4. The association rate with autoimmune disease in patients without thymoma was 12.5% (1/8) in Group 2 and 21.3% (20/94) in Group 1. Autoimmune diseases were not seen in any patients with thymoma. The clinical stage of thymoma was not significantly different between the two groups. The rates of remission and of palliation at 3 years after thymectomy were 18.2% and 72.7%, respectively, in Group 2 patients with thymoma, 21.4% and 78.6% in Group 1 patients with thymoma, 50% and 100% in Group 2 patients without thymoma, and 50% and 98.1% in Group 1 patients without thymoma.

Acetylcholine receptor antibody production by bone marrow cells in a patient with myasthenia gravis

We briefly report antiacetylcholine receptor antibody production by cultured bone marrow cells (4.9 +/- 0.9 fmol/10(6) cells/wk, mean +/- SD) in a 65-year-old man with myasthenia gravis without thymoma. Lymphocytes from peripheral blood, thymus, and lymph nodes produced less antibody (1.8 +/- 0.1, 0.9 +/- 0.3, and 1.0 +/- 0.4, respectively). The thymus was involuted, and the effect of thymectomy was doubtful 6 months postoperatively.

Recurrence of thymoma: clinicopathological features, therapy, and prognosis

Factors influencing the recurrence or persistence of thymoma after therapy were investigated in 127 patients with thymoma, including 75 with thymoma and myasthenia gravis. The rate of recurrence or persistence was 19% (24 of 127 patients) overall, 11% (8 of 75 patients) in myasthenic thymoma, and 31% (16 of 52 patients) in nonmyasthenic thymoma. The more advanced the clinical stage, the higher the rate of recurrence or persistence. The recurrence/persistence rate for patients with the same clinical stage was higher in those with nonmyasthenic thymoma (8% in Stage I, 11% in Stage II, 36% in Stage III, and 75% in Stage IV) than in those with myasthenic thymoma (0 in Stage I, 13% in Stage II, 18% in Stage III, and 20% in Stage IV). The prognosis for patients having subtotal resection of tumor was good in myasthenic thymoma (recurrence/persistence rate, 17%) in contrast with nonmyasthenic thymoma (recurrence/persistence rate, 78%). These results suggest that nonmyasthenic thymoma is more malignant than myasthenic thymoma. Postoperative radiotherapy was effective in preventing the recurrence or persistence of thymoma after therapy.

[Distribution of cefotiam dihydrochloride to the bloodless lung]

The concentration of cefotiam (CTM) in the serum and the bloodless lung with time is discussed. Five patients who were undergone pneumonectomy or lobectomy, were given 1 g of CTM intravenously during the operation. Blood samples and lung samples were collected 15, 30, 60, 90, 120, and 300 minutes after the administration. The CTM levels in the blood and the lung samples were measured by the agar well bioassay. The CTM levels in the lung samples were modified as the CTM levels in the bloodless lung by calculating the contained blood volume, as lung samples were proven to have a mean value of 34.2% of blood in weight. The serum CTM level was 73.3 micrograms/ml at 15 minutes after injection and then decreased gradually. The CTM level in bloodless lung was elevated during the first 60 minutes, became equal to that of the blood during next 30 minutes and then exceeded the serum levels thereafter. These results indicate that the distribution of CTM to the bloodless lung was excellent and a satisfactory preventative effect against postsurgical infection could be expected.

Acetylcholine receptor antibody-producing cells in thymus and lymph nodes in myasthenia gravis

Eleven patients with myasthenia gravis (5 with thymoma) were studied and spontaneous production of antibody to acetylcholine receptor (AChR) in vitro was found by thymus cells in 10 (and in all 5 with thymoma) and by lymph node cells in 8 (and in 3 with thymoma). The rate of AChR antibody production by thymus cells was greater than that by lymph node cells (10.7 +/- 11.6 and 1.4 +/- 1.5 fmol/10(6) cells/week, respectively, mean +/- SD, P less than 0.05 by paired t test), although the B-cell population was always smaller in the thymus than in the lymph nodes (9.5 +/- 9.4 and 31 +/- 12.7%, P less than 0.001), suggesting the principal role of the thymus in AChR antibody production. It is suggested that lymph nodes can be one of the main sites of AChR antibody production in myasthenia gravis but the antibody-producing cells may originate in the thymus.

Antibody to acetylcholine receptor in myasthenia gravis: production by lymphocytes from thymus or thymoma

In 13 of 17 myasthenic patients without thymoma and all 7 patients with thymoma, thymic lymphocytes produced antibody to acetylcholine receptor (AChR). Lymphocytes from the thymoma itself did not produce AChR antibody except in one patient. The rate of antibody production was higher in patients without thymoma than in patients with thymoma (32.5 and 3.9 fmol/10(6) cells/week, respectively). The rate of antibody production was related to the serum titer of AChR antibody (r = 0.7, p less than 0.001). Enrichment of B cells using a nylon wool column increased the rate of antibody production by thymic lymphocytes 1.3- to 8.0-fold.

Importance of 5'-terminal blocking structure to stabilize mRNA in eukaryotic protein synthesis

The 7-methylguanylic acid residue confronting the 5'-terminal nucleotide of mRNA through two pyrophosphate linkages was completely removed by tobacco pyrophosphatase from mRNAs of cytoplasmic polyhedrosis virus, tobacco mosaic virus (viral RNA), and globin without any scission in the inner part of the RNA chain. Protein synthesis ability in a wheat germ cell-free system was lost after this treatment of all three kinds of mRNA. The initiation complexes for protein synthesis of these three RNAs were not obtained after using tobacco phosphodiesterase-treated mRNA. On incubation of mRNA in a wheat germ extract, the mRNA lacking m7G was quickly degraded from the 5' terminus in an exonucleolytic way, whereas the intact mRNA remained stable. These results show that one of the confronting nucleotide structure's functions is to stabilize the mRNA, to prevent its degradation.

Chemical modifications of ribonuclease U1

In order to obtain information on the nature of the amino acid residues involved in the activity of ribonuclease U1 [EC 3.1.4.8], various chemical modifications of the enzyme were carried out. RNase U1 was inactivated by reaction with iodoacetate at pH 5.5 with concomitant incorporation of 1 carboxymethyl group per molecule of the enzyme. The residue specifically modified by iodoacetate was identified as one of the glutamic acid residues, as in the case of RNase T1. The enzyme was also inactivated extensively by reaction with iodoacetamide at pH 8.0 with the loss of about one residue each of histidine and lysine. When RNase U1 was treated with a large excess of phenylglyoxal, the enzymatic activity and binding ability toward 3'-GMP were lost, with simultaneous modification of about 1 residue of arginine. The reaction of citraconic anhydride with RNase U1 led to the loss of enzymatic activity and modification of about 1 residue of lysine. The inactivated enzyme, however, retained binding ability toward 3'-GMP. These results indicate that there are marked similarities in the active sites of RNases T1 and U1.