Myositis with sarcoplasmic inclusions in Nakajo-Nishimura syndrome: a genetic inflammatory myopathy.

AIMS: Nakajo-Nishimura syndrome (NNS) is an autosomal recessive disease caused by biallelic mutations in the PSMB8 gene that encodes the immunoproteasome subunit ß5i. There have been only a limited number of reports on the clinicopathological features of the disease in genetically confirmed cases. METHODS: We studied clinical and pathological features of three NNS patients who all carry the homozygous p.G201V mutations in PSMB8. Patients' muscle specimens were analysed with histology and immunohistochemistry. RESULTS: All patients had episodes of typical periodic fever and skin rash, and later developed progressive muscle weakness and atrophy, similar to previous reports. Oral corticosteroid was used for treatment but showed no obvious efficacy. On muscle pathology, lymphocytes were present in the endomysium surrounding non-necrotic fibres, as well as in the perimysium perivascular area. Nearly all fibres strongly expressed MHC-I in the sarcolemma. In the eldest patient, there were abnormal protein aggregates in the sarcoplasm, immunoreactive to p62, TDP-43 and ubiquitin antibodies. CONCLUSIONS: These results suggest that inflammation, inclusion pathology and aggregation of abnormal proteins underlie the progressive clinical course of the NNS pathomechanism.

Utility of osteopontin in cerebrospinal fluid as a diagnostic marker for neuropsychiatric systemic lupus erythematosus.

The whole protein of osteopontin (OPN full) and its cleaved form (OPN N-half) are involved in the immune response and the migration of immune cells to an inflammatory lesion. We have reported that serum OPN full and urine OPN N-half are elevated in lupus nephritis (LN). Neuropsychiatric systemic lupus erythematosus (NPSLE) is a refractory complication of SLE. To investigate whether OPN full and OPN N-half could serve as diagnostic markers for NPSLE, and to elucidate their role in NPSLE pathogenesis, the concentrations of OPN full and OPN N-half in cerebrospinal fluid (CSF) were measured in NPSLE and non-NPSLE patients. We found that the concentration of OPN full in the CSF was significantly higher in NPSLE than in non-NPSLE, and it decreased after treatment. When the cutoff value of OPN full in CSF was set to 963.4 ng/ml, the sensitivity and specificity for the diagnosis of NPSLE were 70% and 100%, respectively. The correlation analysis of OPN full, OPN N-half and various cytokines/chemokines suggested that the cytokines/chemokines could be divided into two clusters: cluster A, which contains OPN full and cluster B, which contains interleukin-6. OPN full in CSF could be a novel diagnostic marker for NPSLE.

Mutations induced in Drosophila during space flight.

To examine the possible effects of space radiation on living organisms, fruit flies Drosophila melanogaster were loaded on the US Space Shuttle Endeavour, and after the flight we have analyzed two types of mutations, sex-linked recessive lethal mutations induced in male reproductive cells and somatic mutations which give rise to morphological changes in hairs growing on the surface of wing epidermal cells. Wild type strains and a radiation-sensitive strain mei-41 were used. The frequencies of sex-linked recessive lethal mutations in flight groups were 2 and 3 times higher for wild type Canton-S and mei-41 strains, respectively, than those in ground control groups. By contrast, the frequencies of wing-hair somatic mutations differed little between flight and control groups. The possibility that the space environment causes mutations in certain types of cells such as male reproductive cells, is discussed.

Induced rates of mitotic crossing over and possible mitotic gene conversion per wing anlage cell in Drosophila melanogaster by X rays and fission neutrons.

As a model for chromosome aberrations, radiation-induced mitotic recombination of mwh and flr genes in Drosophila melanogaster strain (mwh +/+ flr) was quantitatively studied. Fission neutrons were five to six times more effective than X rays per unit dose in producing either crossover-mwh/flr twins and mwh singles-or flr singles, indicating that common processes are involved in the production of crossover and flr singles. The X-ray-induced rate/wing anlage cell/Gy for flr singles was 1 X 10(-5), whereas that of crossover was 2 x 10(-4); the former and the latter rate are of the same order of magnitude as those of gene conversion and crossover in yeast, respectively. Thus, we conclude that proximal-marker "flr" singles induced in the transheterozygote are gene convertants. Using the model based on yeast that recombination events result from repair of double-strand breaks or gaps, we propose that mitotic recombination in the fly is a secondary result of recombinational DNA repair. Evidence for recombinational misrepair in the fly is given. The relative ratio of radiation-induced mitotic crossover to spontaneous meiotic crossover is one order of magnitude higher in the fly than in yeast and humans.

Proliferation of both somatic and germ cells is affected in the Drosophila mutants of raf proto-oncogene.

The genomic and cDNA fragments of Drosophila melanogaster, homologous to human c-raf-1, were cloned. The nucleotide sequence predicted the primary structure of a polypeptide of 666 amino acid residues with a highly conserved Ser-Thr kinase domain on its carboxy terminal half. Draf-1 was mapped to the 2F region of the X chromosome. Two newly induced recessive lethals belonging to a complementation group in this region were identified to be defective in Draf-1 by P element-mediated rescue experiments. The mutants die at larval/pupal stages. The mutant larvae are apparently normal, but they harbor serious defects in the organs containing proliferating cells of both somatic and germ line origins. Maternal effects on embryogenesis indicated that Draf-1 is also required in early larval development.

Linear relationship between lethal mutation yield and intake of ethyl methanesulfonate in Drosophila melanogaster.

Males of Drosophila melanogaster were fed sucrose solutions containing various concentrations of EMS (from 0.25 to 10 mM) for 24 hr. To measure the intake of an EMS solution, 3H-labeled sucrose was added to the feeding solution, and the 3H activity inside the flies was used as a measure for the intake volume of EMS solution. Each absorbed dose of EMS was estimated from the intake volume of an EMS solution multiplied by its EMS concentration in the feeding solution in a way similar to that described in a previous report [Ayaki et al, 1984]. The relationship between the estimated absorbed dose and the exposure concentration was almost linear in a low concentration range but became concave with a downward curvature in a high concentration range. The dose-response relationship between the frequency of sex-linked recessive lethals and the estimated absorbed dose showed no deviation from linearity at all the five absorbed doses tested. It may be concluded that the absorbed doses thus estimated were very close to true absorbed doses, indicating the usefulness of the present method for dosimetry of chemicals to be given to flies.

The relationship between lethal mutation yield and intake of ethylnitrosourea (ENU) in Drosophila melanogaster.

To estimate the absorbed dose of N-ethyl-N-nitrosourea (ENU) ingested in Drosophila melanogaster, males were fed with sucrose solutions containing various concentrations of ENU plus 3H-labeled sucrose for 24 hr. Flies showed decreasing intakes with increase in ENU concentration when monitored by intake 3H radioactivity. Absorbed dose, D, per male can be estimated by the following formula: D = v . C, where v is intake volume per male of sucrose solution at concentration C. Estimating the v value for each ENU solution from 3H radioactivities in male flies, and using the above formula, we reached the conclusion that average absorbed doses of ENU were 0.064, 0.221, and 0.302 nmol, respectively, for the ENU concentrations of 0.03, 0.3, and 1.0 mM. Sex-linked recessive lethals were measured for males exposed to these sucrose solutions at three different ENU concentrations. Their frequencies increased nonlinearly with increasing exposure doses--ie, ENU concentration C--but linearly with increasing absorbed doses estimated in the above-mentioned way.

Comparative studies of dose-response curves for recessive lethal mutations induced by ethylnitrosourea in spermatogonia and in spermatozoa of Drosophila melanogaster.

Induction of recessive lethal mutations by N-ethyl-N-nitrosourea (ENU) was studied for the second chromosome of spermatogonia and spermatozoa in Drosophila melanogaster. ENU (0.03, 0.3, and 1.0 mM) was given to flies by dissolving it in feeding sucrose solution. Since flies are known to show increased avoidance of the feeding solution with increase in ENU concentration, the absorbed doses of ENU by flies were estimated from the previously determined empirical data for relation of ENU concentration in the feeding solution and the intake volumes of the solution by flies as measured indirectly via intake radioactivities of 3H-labeled sucrose added to the solution. When plotted against absorbed doses of ENU, the observed frequencies of recessive lethals showed a linear relationship for induction in spermatozoa but a sigmoidal relationship for induction in spermatogonia. These results suggest that in spermatogonia ENU-induced mutational damage is more repairable in a lower dose range of ENU. Mosaic lethal mutations were induced by ENU but not in spermatogonia.