a b s t r a c tWe report here the functional analysis of human Regulator of Ribosome Synthesis 1 (RRS1) protein during mitosis. We demonstrate that RRS1 localizes in the nucleolus during interphase and is distributed at the chromosome periphery during mitosis. RNA interference experiments revealed that RRS1-depleted cells show abnormalities in chromosome alignment and spindle organization, which result in mitotic delay. RRS1 knockdown also perturbs the centromeric localization of Shugoshin 1 and results in premature separation of sister chromatids. Our results suggest that a nucleolar protein RRS1 contributes to chromosome congression.

To investigate the modulatory effects of sigma ligands on the N-methyl- D-aspartate (NMDA) receptor-ion channel complex in vivo, we examined the intact cell binding of 3H-N-[1-(2-thienyl)cyclohexyl]piperidine (3H- TCP) to cultured neuronal cells prepared from fetal rat telencephalon. The 3H-TCP binding was saturable, reversible, and inhibited by a selective NMDA receptor antagonist, D-amino-5-phosphonovaleric acid. MII-limolar Mg2+ inhibited 3H-TCP binding both in the absence and presence of L-glutamate. 5-Methyl-10,11-dihydro-5H-dibenzo [a,d]cyclohepten-5,10-imine maleate (MK801) inhibited 3H-TCP intact cell binding in a competitive manner, while haloperidol inhibited it in a noncompetitive manner. The effect of the test drugs to inhibit 3H-TCP intact cell binding was in the order of dextromethorphan, haloperidol > (+/-)MK 801 > (+)pentazocine > (-)pentazocine > DTG > PCP > (+)-N- allylnormetazocine [(+)SKF 10047] > (+)3-(3-hydroxyphenyl)-N- (1- propyl)piperidine [(+)3-PPP] > (-)SKF 10047 > (-)3-PPP. The IC50 values of the six sigma ligands for 3H-TCP binding were closely correlated with the Ki values of the corresponding drugs for DTG site 1 in the guinea pig brain reported by Rothman et al. (1991). These findings suggest that the sigma ligand indirectly modulates the NMDA receptor ion channel complex, presumably through sigma 1 sites in vivo as well as in vitro.

An autopsy case of myotonic dystrophy (MD) is reported. The patient was a 58-year-old male.He presented with muscular weakness and muscular atrophy at the age of 33 and was diagnosed as having MD from myotonic symptoms (i.e. percussion and grip myotonia) at 49 years old. Mental disorders including a delusional hallucinatory state, mental slowness, indifference, and lack of spontaneity as well as visual cognitive impairments were noted at the age of 55. He showed Parkinsonism and died of septic shock. T2-weighted magnetic resonance imaging demonstrated diffuse cortical atrophy with a marked frontal atrophy and high-intensity signals in the white matter. Single photon emission computed tomography demonstrated hypoperfusion in the frontal cortex. Neuropathologic observation revealed neuronal loss in the superficial layer of the frontal and parietal cortices and extensive neuronal loss in the occipital cortex, intracytoplasmic inclusion body in the nerve cell of the medial thalamic nuclei, neuronal loss and presence of Lewy bodies in the substantia nigra and locus ceruleus corresponding to the pathologic features of Parkinson's disease, as well as abnormalities of myelin in the white matter. The present case suggests that in MD brain, various neuropathologic changes may occur and they contribute to the mental disorders.

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