Immunohistochemical Study of Dendritic Cells and Kupffer Cells in Griseofulvin-Induced Protoporphyric Mice

To determine whether protoporphyric liver injury affects hepatic dendritic cells (DC) and Kupffer cells, we examined liver tissues of griseofulvin-induced protoporphyric mice using histological and immunohistochemical methods. After 1 week of griseofulvin feeding, the protoporphyric liver showed prominent hepatomegaly and a gradual increase in histopathological changes such as hepatocellular hypertrophy, focal necrosis and brown pigment deposits. After 4 weeks of treatment, marked ductular reaction was observed in the liver tissue. Immunohistochemical analyses indicated that the density of NLDC-145-positive hepatic DC gradually decreased during griseofulvin feeding. However, the index of the number of DC in the whole liver appeared to fall sharply after 6 weeks. In contrast, the density of F4/80-positive Kupffer cells gradually increased during griseofulvin feeding. In the spleen and lung, no significant differences were noted in the distribution of NLDC-145-positive DC between experimental and control mice. These results suggested that griseofulvin-induced protoporphyria leads to a specific decrease in the density of hepatic DC due to hepatomegaly until 4 weeks of treatment and is substantial after 6 weeks. This substantial decrease of hepatic DC might have been induced by some alterations in protoporphyric liver injury including ductular reaction at a later stage in this experiment. Since hepatic DC were reduced in number, they seemed to have no significant relation to the progression of griseofulvin-induced protoporphyric liver injury. However, the decrease of hepatic DC might affect the cellular immune response in protoporphyria

Crystalline Inclusions in Hepatocyte Mitochondria of a Patient with Porphyria Cutanea Tarda

Intramitochondrial crystalline inclusions were found in hepatocytes of a patient with porphyria cutanea tarda (PCT). They were composed of parallel filamentous structures which measured approximately 12 nm in diameter. Each filament was separated from an adjacent filament by a space measuring approximately 5 nm. The mitochondria containing such inclusions were usually elongated and enlarged. It seemed likely that these changes are not particular in PCT, but indicate one reversible pathological finding in the liver

MexEF-OprN multidrug efflux pump transporter negatively controls N-acyl-homoserine lactone accumulation in pseudomonas syringae pv. Tabaci 6605

Our previous studies revealed that flagellar-motility-defective mutants such as ∆fliC of Pseudomonas syringae pv. tabaci 6605 (Pta6605) have remarkably reduced production of N-acyl-homoserine lactones (AHL), quorum-sensing molecules. To investigate the reason of loss of AHL production in ∆fliC mutant, we carried out transposon mutagenesis. Among approximately 14,000 transconjugants, we found 11 AHL production-recovered (APR) strains. In these APR strains, a transposon was inserted into either mexE or mexF, genes encoding for the multidrug efflux pump transporter MexEF-OprN, and mexT, a gene encoding a putative transcriptional activator for mexEF-oprN. These results suggest that MexEF-OprN is a negative regulator of AHL production. To confirm the negative effect of MexEF-OprN on AHL production, loss- and gain-of-function experiments for mexEF-oprN were carried out. The ∆fliC∆mexF and ∆fliC∆mexT double mutant strains recovered AHL production, whereas the mexT overexpressing strain abolished AHL production, although the psyI, a gene encoding AHL synthase, is transcribed as wild type. Introduction of a mexF or mexT mutation into another flagellar-motility- and AHL production-defective mutant strain, ∆motCD, also recovered the ability to produce AHL. Furthermore, introduction of the mexF mutation into other AHL production-defective mutant strains such as ∆gacA and ∆aefR also recovered AHL production but not to the ∆psyI mutant. These results indicate that MexEF-OprN is a decisive negative determinant of AHL production and accumulation

Clozapine and Antipsychotic Monotherapy

Background: Although clozapine is effective for treatment-resistant schizophrenia (TRS), the rate of clozapine prescription is still low. Whereas antipsychotic monotherapy is recommended in clinical practice guidelines, the rate of antipsychotic polypharmacy is still high. There is little evidence on whether a clozapine prescription influences changes in the rate of monotherapy and polypharmacy, including antipsychotics and other psychotropics. We therefore hypothesized that the rate of antipsychotic monotherapy in patients with TRS who were prescribed clozapine would be higher than that in patients with schizophrenia who were not prescribed clozapine. Methods: We assessed 8306 patients with schizophrenia nationwide from 178 institutions in Japan from 2016 to 2019. We analyzed the psychotropic prescription data at discharge in patients diagnosed with TRS and with no description of TRS (ND-TRS) based on the diagnosis listed in the discharge summary. Results: The rate of antipsychotic monotherapy in the TRS with clozapine group (91.3%) was significantly higher than that in the TRS without clozapine group (45.9%; P < 2.0 × 10−16) and the ND-TRS without clozapine group (54.7%; P < 2.0 × 10−16). The rate of antipsychotic monotherapy without any other concomitant psychotropics in the TRS with clozapine group (26.5%) was significantly higher than that in the TRS without clozapine group (12.6%; P = 1.1 × 10−6) and the ND-TRS without clozapine group (17.0%; P = 5.9 × 10−6). Conclusions: Clozapine prescription could be associated with a high rate of antipsychotic monotherapy. Patients will benefit from the correct diagnosis of TRS and thus from proper clozapine prescription

Casein kinase II is responsible for phosphorylation of NF-L at Ser-473

AbstractSer-473 is solely phosphorylated in vivo in the tail region of neurofilament L (NF-L). With peptides including the native phosphorylation site, it was not possible to locate responsible kinases. We therefore adopted full-length dephosphorylated NF-L as the substrate, and employed MALDI/TOF (matrix-assisted laser desorption and ionization/time of flight) mass spectrometry and a site-specific phosphorylation-dependent antibody recognizing Ser-473 phosphorylation. The antibody showed that casein kinase I (CK I) as well as casein kinase II (CK II) phosphorylated Ser-473 in vitro, while neither GSK-3β nor calcium/calmodulin-dependent protein kinase II did so. However, the mass spectra of the tail fragments of the phosphorylated NF-L indicated that CK II was the kinase mediating Ser-473 phosphorylation in vitro as opposed to CK I, because CK I phosphorylated another site as well as Ser-473 in vitro. The antibody also demonstrated that NF-L phosphorylated at Ser-473 was abundant in the neuronal perikarya of the rat cortex, indicating that phosphorylation of Ser-473 may take place there. This result may support the suggestion that CK II is the kinase responsible for Ser-473 phosphorylation. Despite many reports showing that CK I mediates phosphorylation of neurofilaments, CK II may phosphorylate NF-L in vivo