Semaphorin3A signalling is mediated via sequential Cdk5 and GSK3beta phosphorylation of CRMP2: implication of common phosphorylating mechanism underlying axon guidance and Alzheimer's disease

Collapsin response mediating protein-2 (CRMP2) has been identified as an intracellular protein mediating Semaphorin3A (Sema3A), a repulsive guidance molecule. In this study, we demonstrate that cyclin-dependent kinase 5 (Cdk5) and glycogen synthase kinase 3beta (GSK3beta) plays a critical role in Sema3A signalling. In In vitro kinase assay, Cdk5 phosphorylated CRMP2 at Ser522, while GSK3beta did not induce any phosphorylation of CRMP2. Phosphorylation by GSK3beta was exclusively observed in Cdk5-phosphorylated CRMP2, but barely in CRMP2T509A. These results indicate that Cdk5 primarily phosphorylates CRMP2 at Ser522 and GSK3beta secondarily phosphorylates at Thr509. The dual-phosphorylated CRMP2, but not non-phosphorylated or single-phosphorylated CRMP2, is recognized with the antibody 3F4, which is highly reactive with the neurofibrillary tangles of Alzheimer's disease. 3F4 recognized the CRMP2 in the wild-type but not cdk5-/- mouse embryonic brain lysates. The phosphorylation of CRMP2 at Ser522 caused reduction of its affinity to tubulin. In dorsal root ganglion neurones, Sema3A stimulation enhanced the levels of the phosphorylated form of CRMP2 detected by 3F4. Over-expression of CRMP2 mutant substituting either Ser522 or Thr509 to Ala attenuates Sema3A-induced growth cone collapse response. These results suggest that the sequential phosphorylation of CRMP is an important process of Sema3A signalling and the same mechanism may have some relevance to the pathological aggregation of the microtubule-associated proteins.     

A novel mutation in the FcgammaRIIIA gene (CD16) results in active natural killer cells lacking CD16

We report a novel mutation in FcgammaRIIIA (the transmembrane-form CD16) on natural killer (NK) cells in a patient with polyneuropathy. She had no history of recurrent infections. Her NK cells expressed no detectable CD16; however, her NK cytotoxic activity was normal, suggesting that CD16 expression and cytotoxic activity are independent of one another. Molecular analysis revealed a deletion of a single adenine base in exon 4 of CD16 at nucleotide 550. This deletion generates a STOP codon in an extra-cellular domain of the FcgammaRIIIA gene, thereby truncating the CD16 molecule. The patient's NK cells were not recognized by the anti-CD16 monoclonal antibodies 3G8 and Leu11c. Whether the development of her polyneuropathy is associated with this novel mutation is unclear.     

Cytogenetic characterization of ten cases of Ph1-positive acute myelogenous leukemia

Chromosome banding analyses were made on 10 cases of Ph1-positive AML (7 M1 and 3 M2). The standard type Ph1 translocation, t(9q +;22q -), was identified in all of them. Karyotypically normal cells were observed in 6-65% of bone marrow metaphases at the initial cytogenetic examination of 7 patients, whereas the remaining 3 patients had only Ph1-positive cells at diagnosis. Follow-up studies performed in 5 cases indicated that the frequency of karyotypically normal cells increased up to 81-100% when the patients were in remission, whereas it was much reduced in relapse. In 5 cases, there was observed a clone of cells in which the Ph1 translocation was the sole karyotypic abnormality. Various types of other chromosome abnormalities, in addition to the Ph1, were observed in all cases, among which-7 was the most frequent, being found in three cases as a stem line. Other additional changes encountered were + Ph1, del(5), i(17q), - 10, + 18, + X, and various numerical and structural changes including certain secondary translocations that occurred in the Ph1 (22q -) or its partner (9q +). The types and frequencies of these additional changes appeared to be different from those found in the acute phase of CML or in Ph1-positive ALL.     

Development of enrofloxacin ELISA using a monoclonal antibody tolerating an organic solvent with broad cross-reactivity to other newquinolones

Antibacterial reagents, especially quinolones, are widely used in animals and humans, and have caused serious problems to human health because of their residual contaminants in food. In order to screen for different kinds of newquinolones at the same time, a sensitive and specific enzyme-linked immunoassay (ELISA) has been developed. The anti-enrofloxacin monoclonal antibody was selected because of its ability to react with structurally related newquinolones in organic solvent. The antibody has 100% cross-reactivity with norfloxacin, ciprofloxacin and other newquinolones at 50% inhibition of control values IC₅₀, but not with nitroflazone, sulphadimethoxine. The lowest detection limit of this ELISA was 0.7 ng/ml (ppb) when enrofloxacin was used as the calibrator. Eel extracts were spiked with enrofloxacin and the average recoveries at 10, 50, 100 ng/ml were 98, 102 and 91%, respectively. The proposed ELISA is a useful method for the practical microquantitation of various newquinolones in biological and environmental specimens.     

Electrophysiologic studies on the pallido- and cerebellothalamic projections in squirrel monkeys (Saimiri sciureus)

Summary Thalamic projections of the pallidum and the deep cerebellar nuclei were studied by unitary recordings as well as field potential analysis in the thalamus of squirrel monkeys (Saimiri sciureus) under sodium pentobarbital anesthesia.Stimulation of the pallidum produced a positive field potential preceded by incoming afferent fiber volleys in the thalamus. Spontaneous discharges of thalamic neurons were suppressed during this positive potential, and intracellular recordings from the thalamic neurons revealed that the time course of this field potential corresponded to that of the hyperpolarizing potential. The hyperpolarization was presumed to be a monosynaptic inhibitory postsynaptic potential by the short synaptic delay (about 0.5–0.7 ms) and responsiveness to high frequency stimulation (over 150 Hz). The positive field potential on stimulation of the external pallidal segment was distributed in L.po (VA) and the reticular thalamic nucleus around L.po, whereas that on stimulation of the internal segment was in V.o.a (the anterior basal part of VL) and in Z.o (upper part of VL). The projection of the external segment appeared to be less dense than that of the internal segment.The projection of deep cerebellar nuclei was situated in V.o.a, V.o.p (posterior part of basal part of VL), V.o.i (VLm), the intralaminar nucleus (CL), and some part of V. im (the rostral part of VPLo). Projections of the interpositus and dentate nuclei were distributed in a more anterior part than those of the fastigial nucleus. A certain topographical arrangement of the projections of these three nuclei was found in V.o.p, V.o.i and V.im. No significant overlap was detected between projections of the pallidum and the deep cerebellar nuclei within the thalamus.     

Loss of mammalian Sprouty2 leads to enteric neuronal hyperplasia and esophageal achalasia

We report here that loss of the Sprouty2 gene (also known as Spry2) in mice resulted in enteric nerve hyperplasia, which led to esophageal achalasia and intestinal pseudo-obstruction. Glial cell line-derived neurotrophic factor (GDNF) induced hyperactivation of ERK and Akt in enteric nerve cells. Anti-GDNF antibody administration corrected nerve hyperplasia in Sprouty2-deficient mice. We show Sprouty2 to be a negative regulator of GDNF for the neonatal development or survival of enteric nerve cells.     

Accumulation of prion protein in muscle fibers of experimental chloroquine myopathy: in vivo model for deposition of prion protein in non-neuronal tissues

Prion protein (PrP) is known to accumulate in some non-neuronal tissues under conditions unrelated to prion diseases. The biochemical and biological nature of such accumulated PrP molecules, however, has not been fully evaluated. In this study, we established experimental myopathy in hamsters by long-term administration of chloroquine, and we examined the nature of the PrP molecules that accumulated. PrP accumulation was immunohistochemically demonstrated in autophagic vacuoles in degenerated muscle fibers, and this was accompanied by the accumulation of other molecules related to the neuropathogenesis of prion diseases such as clathrin, cathepsin B, heparan sulfate, and apolipoprotein J. Accumulated PrP molecules were partially insoluble in detergent solution and were slightly less sensitive to proteinase K digestion than normal cellular PrP. Muscle homogenates containing these PrP molecules did not cause disease in inoculated hamsters. The findings indicate that the PrP molecules that accumulated in muscle fibers have distinct biochemical and biological properties. Therefore, experimental chloroquine myopathy is a novel and useful model to investigate the mechanism of deposition of PrP in non-neuronal tissues and might provide new insights in the pathogenesis of prion diseases.     

Evaluation of anti-parvovirus B19 activity in sera by assay using quantitative polymerase chain reaction

Human parvovirus B19 (B19) infects cells of erythroid lineage. Production of neutralizing antibodies (Abs) is indispensable for recovery from B19-related disease state. In this study, we used a convenient method to measure neutralizing activities in human sera by using a real-time quantitative PCR based assay. Erythroid cell line KU812Ep6 was incubated with test sera before infection with B19 virus. The copy number of B19-DNA in cultures was decreased in the presence of the sera from patients who recovered from acute B19 infection, whereas no decrease in B19-DNA was in cultures incubated with sera from healthy volunteers who had no B19 infection. The decrease in B19-DNA copy number was calculated and the inhibition percentage was expressed as neutralizing activity to B19. A clinical study showed that the levels of neutralizing ability were high in patients who recovered soon after acute B19 infection, but were low in some patients with a prolonged clinical course for recovery from B19 infection. This method is simple and convenient compared with methods described previously, showing its usefulness to evaluate the neutralizing activity to B19.     

Laboratory testing for rheumatic diseases]

The diagnosis of rheumatic diseases is primarily based on clinical symptoms and laboratory findings. However, diagnosis of rheumatic disease is often difficult because of the variations even in the same disease. Routine laboratory tests are valuable in detecting renal dysfunctions. In this review, the important auto-antibodies and inflammatory markers associated with rheumatic diseases are described. Further, their utility as diagnostic and prognostic tools, including their specificity, sensitivity and practical applications, is discussed.