Yoshinobu Nakao

Gm ALLOTYPES IN MYASTHENIA GRAVIS

Gm typing and acetylcholine receptor antibody assay were performed on serum samples from 74 patients with myasthenia gravis (31 male, 43 female) and from 236 unrelated normal blood-donors. The haplotype Gm1,2,21 was significantly more common in patients with myasthenia gravis (relative risk = 3.24), especially those with thymoma (relative risk = 6.99). The frequency of haplotype Gm1,2,21 was further increased in patients with severe generalised myasthenia gravis (relative risk = 10.52). The frequency of Gm1,2,21 was also increased in patients with high acetylcholine receptor antibody titres (greater than 5 pmol/ml). The results indicate the presence of a pathogenic gene close to the IgG heavy-chain gene complex in the 6th chromosome in the patients with myasthenia gravis, especially those with thymoma.

Effects of Corticosteroid and 1,24R-Dihydroxy-Vitamin D3 Administration on Lymphoproliferation and Autoimmune Disease in MRL/MP-lpr/lpr Mice

The pharmacological effects of prolonged administration of a corticosteroid, betamethasone, and active vitamin D3 [1,24R-(OH)2D3] on lymphoproliferation and autoimmune disease of MRL/MP-lpr/lpr (MRL/1) mice were examined. Relatively high doses of betamethasone (0.25 mg/kg/day) prevented lymphoproliferation, reduced serum levels of anti-dsDNA, anti-ssDNA, and anti-poly (ADP-ribose) antibodies, and brought about clinical improvement, such as reduced proteinuria and diminution of skin lesions. It is noteworthy that not only did prevention of lymphoproliferation occur, but also recovery of the Lyt-2+ T cell subset in the thymus and the spleen was observed. The administration of 1,24R-(OH)2D3 (0.1 microgram/kg/day) similarly prevented proteinuria, and produced recovery of a Lyt-2+ subset in the thymus.

IgG Heavy-Chain (GM) Allotypes and Immune Response to Insulin in Insulin-Requiring Diabetes Mellitus

IN guinea pigs1 , 2 and mice, 3 4 5 the ability to develop humoral and cell-mediated immune responses to heterologous insulins is in part controlled by immune-response genes linked to the major his...

Multiple Point Mutation of N-ras and K-ras Oncogenes in Myelodysplastic Syndrome and Acute Myelogenous Leukemia

We analyzed activating mutations of N-ras and K-ras by the polymerase chain reaction and oligonucleotide hybridization in hematological disorders. Activating mutations of these codons were detected in 4 of 20 cases of myelodysplastic syndrome (MDS) and 15 of 77 cases of acute myelogenous leukemia (AML). Our of 19 cases of MDS and AML who carried active mutations, 7 cases were found to have two or more distinct mutations in activating codons of N-ras and K-ras. Ras mutation was found preferentially in progressive disease such as refractory anemia with excess of blasts (RAEB) of RAEB in transformation (RAEB-t). A relatively high incidence of ras mutation was found in M5 AML (40%). No ras mutations were found in other hematological disorders, such as acute lymphoblastic leukemia and chronic myelogenous-leukemia. The most frequent amino acid substitution was that of an aspartate for glycine at codon 12 of N-ras resulting from G to A mutation (11/35). The survival of AML patients who carried ras mutations showed no significant differences from those without ras mutations calculated by Kaplan-Meier. Seven cases of MDS and 7 cases of AML patients could be investigated at various points during their clinical course. Among these 14 cases, we found 2 interesting cases of MDS. The first case lost multiple clones carrying ras mutations during disease progression, the second case acquired mutation of the ras gene during disease progression. These results suggested that multiple point mutations of ras genes may not be initiating events but may contribute to a clonal evolution of MDS and AML.

Identification of HTLV p19 specific natural human antibodies by competition with monoclonal antibody.

Abstract A competitive binding assay using a monoclonal antibody to the human T-cell lymphoma/leukemia virus (HTLV) p19 was developed for use in detecting natural antibodies to the protein in human sera. The specificity of the assay for HTLV p19 was demonstrated using a variety of antisera. While sera known to contain antibodies to HTLV p19 competed in the assay, antisera prepared against purified HTLV p24, the major core protein of the virus, or against other disrupted type-C retroviruses did not. Sera of Japanese patients with adult T-cell leukemia and similar T-cell malignant lymphomas were examined by this technique for the presence of antibodies to HTLV p19. The results were compared with those obtained by a solid-phase radioimmunoassay (RIA) against disrupted HTLV. The majority of Japanese ATL patients possess natural antibodies to HTLV as shown by solid-phase RIA (88%) and also specifically to HTLV p19 (77%). Similarly, 50% of Japanese patients with similar T-cell malignant lymphomas possess HTLV antibodies by solid-phase RIA and nearly as many (42%) possess anti-p19 reactivity. Twelve and eight percent, respectively, of normal Japanese donors from the ATL endemic region possessed HTLV-specific antibody by the solid-phase RIA or competitive binding assay. Normal donors from nonendemic areas lacked antibodies to HTLV. These results extend our previous findings of natural antibodies to HTLV in Japanese patients with ATL. The finding of p19-specific antibodies in these Japanese sera, together with previous reports of natural antibodies to HTLV p24 in sera from this same geographic cluster, strengthens the association of HTLV with Japanese ATL.

Werner's syndrome: In vivo and in vitro characteristics as a model of aging☆

Abstract Three patients who suffered from Werners syndrome were studied to help to elucidate differences from and/or analogies to both clinical symptoms and biochemical changes in normal aging. Our patients commonly manifested graying of hair, atrophy and hyperkeratosis of the skin, cataracts and hypogonadism. Such alterations would appear to be analogous to normal aging phenomena. However, the types of cataracts, degree of skin changes and growth retardation in Werners syndrome differed from the normal aging phenomena. Studies of endocrine functions in our patients did not show definite evidence of generalized hypopituitarism and impaired function of hormone secretion. Resistance to hormones human cholionic gonadotropin (hCG), luteinizing hormone-releasing hormone (LH-RH) and insulin was observed, suggesting a possible alteration of a diversity of proteins which may affect hormone receptors. Immunologic aspects were also studied, since the genetically programmed failure of thymic function could play a major role in the pathogenesis of aging and age-related diseases. Our results in three patients did not indicate any definite immunologic abnormalities. Culture studies showed that skin fibroblasts in Werners syndrome exhibited more decreased potentials of in vitro clonal growth and elongation of newly synthesizing DMA as phenotypic expressions than did normal skin cells. Yet, in Werners syndrome, cells repaired DNA damage normally. The relationship of these findings to the basic genetic defect of Werners syndrome remains unknown.

Cytokines and Osteoporosis

Bone remodeling is controlled by systemic factors such as parathyroid hormone (PTH), calcitonin (CT), and 1,25(OH)2 vitamin D and by local factors including cytokines and growth factors such as IL-1, IL-2, TNF alpha, TGF beta, IFN alpha, and IFN gamma. Derangement of such control mechanisms leading to an imbalance between osteoclastic bone resorption and osteoblastic bone formation could cause osteoporosis. Conditions associated with immune dysfunction such as aging, corticosteroid therapy, and rheumatoid arthritis are associated with osteoporosis, which is also more common in females than in males, like most of the autoimmune-collagen diseases. Peripheral lymphocyte subsets CD4/CD8 were higher in patients with senile osteoporosis than in the age-matched controls, and returned to normal after 1 month of 1 alpha(OH)vitamin D3 treatment. On multiple regression analysis of histomorphometric data and lymphocyte subsets, a negative correlation was found between CD4 lymphocytes and bone resorption. High CD4 is thus associated with a low level of osteoclastic bone resorption or low turnover osteoporosis. Plasma interferon reflecting macrophage function decreased with advance in age and increased in response to 1 alpha(OH)D3 treatment. As one of the immunoregulators, vitamin D tends to stimulate the macrophage-natural killer system and suppress the lymphocyte system, stimulating TGF beta and TNF alpha activity. Senile osteoporosis of low turnover thus appears to be associated with vitamin D deficiency, low macrophage function, high CD4 lymphocyte proportion, low IL-1 and high IL-2 activity, low IFN alpha and high IFN gamma activity, and low TGF beta and TNF alpha activity. Treatment with vitamin D derivatives tends to reverse these changes.

IgG heavy chain allotypes (Gm) in atrophic and goitrous thyroiditis.

We typed coded sera from 135 healthy controls, seventy‐six patients with autoimmne goitrous and seventy‐three with atrophic thyroiditis for IgG heavy chain markers (Gm). All subjects were Caucasian from Newfoundland. An increase in the Gm phenotype ag was found in the 149 patients with thyroiditis compared to controls (X12= 5.82, P <0.01); significance was, however, not maintained after correction for the number of variables tested. The difference in ag phenotype was more pronounced among the seventy‐three patients with atrophic thyroiditis (X12= 8.80 corrected P < 0.05). Because the haplotype ag was not significantly increased in this group, we conclude that homozygotes for Gm ag are at an increased risk of developing atrophic thyroiditis.

Clinical, Endocrine and Metabolic Aspects of the Werner Syndrome Compared with Those of Normal Aging

Data on the clinical features of the Werner syndrome in 102 patients in Japan were collected by sending questionnaires to major hospitals and analyzed. The male-to-female ratio was 3 to 2 and the incidences of consanguinity and familial occurrence were 51% and 39.4%, respectively. These patients were divided into 3 subgroups; group 1, 2, and 3 lacked short stature, cataract, and hypogonadism, respectively. Each group had somewhat different clinical features. Endocrine and metabolic abnormalities in the Werner syndrome patients were compared with those in normal aged subjects. Impaired plasma growth-hormone responses to insulin and arginine were more common and impaired plasma thyrotropin responses to TRH were less common in the Werner syndrome patients than in aged subjects. Plasma LH and FSH levels were higher in most patients than those in age- and sex-matched controls; also, their serum testosterone concentrations were lower than those in age-matched controls and testicular biopsy revealed more marked atrophy than in aged subjects. Serum triiodothyronine levels tended to be lower than in age-matched controls. Oral glucose tolerance test revealed diabetic glucose tolerance in 55% and impaired glucose tolerance in 22%, although fasting blood glucose levels were elevated only in 20%. Plasma insulin response to glucose was more exaggerated in those with the Werner syndrome than in normal aged subjects. The euglycemic glucose clamp method revealed lower glucose disposal rates and insulin sensitivity indices in the Werner syndrome than in normal subjects of similar age. The number of erythrocyte insulin-binding sites was normal in the Werner syndrome patients. These results suggest a postreceptor defect in insulin resistance in the Werner syndrome.

1,25-dihydroxyvitamin D3 regulates proliferation of activated T-lymphocyte subsets

The biologically active vitamin D metabolite, 1,25-(OH) 2D3 suppressed phytohaemagglutinin (PHA)-induced lymphocyte proliferation dose-dependently (0.1 nM-100 nM), and decreased the OKT4+/OKT8+ ratio and transferrin-receptor-positive (OKT9+) cells. A possible parallelism between expression of 1,25-(OH) 2D3 receptors and interleukin 2 (IL2)-receptors recognized by anti-Tac antibody was not confirmed in this study. However, the addition of exogenous IL2 abolished the inhibitory effects of 1,25-(OH) 2D3 on PHA-stimulated T-cell proliferation, and the decrease of OKT4+ and OKT9+ T-cell in this population. Among various vitamin D3 analogues examined, 1,25-(OH) 2D3 was the most potent anti-proliferative effect, followed in order by 1,24S-(OH) 2D3, 1 alpha OH D3, 25 OH D3 and 24,25-(OH) 2D3.