Bortezomib induces thrombocytopenia by the inhibition of proplatelet formation of megakaryocytes

Bortezomib is a potent proteasome inhibitor that has been extensively used to treat multiple myeloma. One of the most common grade 3 adverse events is cyclic thrombocytopenia. In this study, we studied the mechanism by which bortezomib induces thrombocytopenia in a mouse model. After the intravenous administration of bortezomib (2.5 mg/kg) via tail vein, platelet counts significantly decreased on days 2–4 and recovered to the normal range on day 6. Bortezomib (2.5 mg/kg) injected into mice in vivo did not affect colony‐forming unit‐megakaryocytes (CFU‐Mk) or megakaryocytes in the bone marrow. However, proplatelet formation (PPF) significantly decreased on days 2 and 4, after bortezomib administration to mice. Meanwhile, CFU‐Mk formation and the ploidy distribution of cultured megakaryocytes in vitro were not affected by bortezomib used at concentrations of ≤1 ng/mL. The PPF of megakaryocytes in vitro significantly decreased with 0.1, 1, 10, and 100 ng/mL bortezomib. Considering the bortezomib concentration in clinical studies, these data strongly suggest that decreased PPF activity induces thrombocytopenia. To elucidate the mechanism behind decreased PPF, Western blot was performed. Activated Rho expression increased after the incubation of murine platelets with bortezomib. Decreased PPF activity was eliminated by the addition of Y27632, a Rho kinase inhibitor, in vitro. Given that the Rho/Rho kinase pathway is a negative regulator of PPF, bortezomib increases activated Rho, inducing decreased PPF, which results in decreased platelet count.     

Effect of endodontic irrigation on bonding of resin cement to radicular dentin

The influence of endodontic irrigation on shear bond strengths of resin cement to radicular dentin was investigated. Human radicular dentin blocks were divided into four groups and subjected to one of four endodontic irrigations: ethylenediaminetetraacetic acid (EDTA) group, 17% EDTA for 60 s; EDTA/sodium hypochlorite (NaOCl) group, 17% EDTA for 60 s followed by 10 ml of 5% NaOCl for 15 s; NaOCl group, 10 ml of 5% NaOCl for 15 s; and control group, no treatment. Morphological changes of dentin surface after endodontic irrigation were observed by scanning electron microscopy (SEM). A resin block was bonded to the radicular dentin after irrigation using resin cement with either wet-bonding (Uni-Etch/One-Step; Bisco) or self-etching (Tyrian SPE/One-Step Plus; Bisco) adhesives. Shear bond strengths were measured and the penetration of resin tags into dentinal tubules at resin-dentin interface was observed by SEM. With the wet-bonding system, the shear bond strengths for the EDTA/NaOCl group, in which dentinal tubules openings and uniform resin tag penetration into dentinal tubules were observed, were significantly higher than the EDTA and control groups. With the self-etching system, the shear bond strengths were significantly lower in the EDTA group compared with the NaOCl and control groups. The effects of endodontic irrigation on the bonding of resin cement to radicular dentin depended on the dentin bonding system used.     

Acute disseminated encephalomyelitis in an infant with incontinentia pigmenti

We report the case of a female Japanese infant who was diagnosed with incontinentia pigmenti (IP) on the basis of the clinical and pathological findings of characteristic skin lesions and the detection of deletion in the nuclear factor-kappa B essential modulator gene at Xq28. The patient developed repetitive seizures at the age of 7 months when she was diagnosed with acute disseminated encephalomyelitis (ADEM), an inflammatory demyelinating disease of the central nervous system that often occurs after vaccination or infection. The causative infectious agent in this patient seemed to be Mycoplasma pneumoniae because of the increased titer of its serum antibody and the detection of its DNA in the initial cerebrospinal fluid sample. This patient showed significant improvement on receiving immunosuppressive therapy with corticosteroids. This is the second case report presenting an IP patient susceptible to ADEM, and therefore, ADEM should be considered early in the differential diagnosis of acute neurological illness for IP patients.     

Relationship between colors of carious dentin and laser fluorescence evaluations in caries diagnosis

This in vitro study investigated the relationship between assessments of dentin caries using a laser fluorescence device (DIAGNOdent) and a caries detector dye during caries removal. The dentin of eight extracted carious molars was removed at 300-microm interval points from the dentin surface toward the pulp chamber. Before and after each removal, images of the carious surfaces were taken in association with color-matching stickers (for color correction) and the surfaces were evaluated by DIAGNOdent based on fluorescence emission from the tooth surface. For the L* values (CIE 1976 L*a*b* color system), there was a strong negative correlation between DIAGNOdent results and the corrected L* values of the carious surfaces (Pearson's correlation coefficient: -0.853); additionally, there was a significant correlation between them (p<0.05). However, there were no significant correlations between the DIAGNOdent results and the corrected a* and b* values of the carious surfaces (Pearson's correlation coefficients: 0.108 and 0.018 respectively). In conclusion, DIAGNOdent was shown to be applicable for caries diagnosis during caries removal.     

Role of Clast1 in development of cerebellar granule cells

We have identified the murine Clast1/LR8 gene by subtraction of cDNA derived from CD40 ligand-activated and naive B cells. The Clast1 gene is ubiquitously expressed in various organs of adult mice. However, its physiological function was largely unknown. To study a role of Clast1, we established Clast1-deficient (Clast1-KO) mice. Here, we reveal that approximately 65% of Clast1-KO mice showed severe ataxia. The Clast1-KO cerebellum with ataxia is small in size and revealed a severely aberrant lobulation, loss of the internal granule cell layer, and the disorganized Purkinje cells. Clast1 mRNA is expressed in the cerebellar granule cells of normal adult mice. Developmentally, Clast1 mRNA is also detected in the external germinal layer of the embryonic cerebellum, indicating its expression in granule cell precursors. Histopathological analysis of the developing Clast1-KO cerebellum demonstrated the reduced number of cells in the external germinal layer. Thus, Clast1 is required for development of cerebellar granule cells.     

Antitumor effects of minodronate,a third-generation nitrogen-containing bisphosphonate,in synergy with γδT cells in human glioblastoma in vitro and in vivo

Nitrogen-containing bisphosphonates (N-BPs), which prevent bone resorption, exert direct and γδT cell (GDT)-mediated antitumor effects against several tumor cell types, including glioblastoma (GBM). However, limited information is available regarding the antitumor effects of N-BPs in GBM. Specifically, the antitumor effects of minodronate (MDA), a third-generation N-BP, in GBM are yet unclear. This study aimed to investigate the antitumor effects of MDA in GBM in vitro and in vivo. We performed growth inhibition and apoptosis detection assays using the GBM cell lines U87MG and U138MG. Apoptosis inhibition assays were also conducted. In vivo xenograft assays were performed in highly immunodeficient NOD.Cg-Prkdc^scid Il2rg^tm1Sug/Jic mice subcutaneously implanted with U87MG and U138MG cells. Growth inhibition and apoptosis detection assays demonstrated that MDA inhibited GBM cell growth via apoptosis, which was markedly enhanced by ex vivo expanded GDT. A pan-caspase inhibitor, z-VAD-fmk, inhibited MDA-induced U138MG apoptosis and MDA/GDT-induced U87MG and U138MG apoptosis. But z-VAD-fmk increased MDA-induced U87MG apoptosis. MDA/GDT-mediated apoptosis was blocked by the anti-T cell receptor (TCR) Vγ9, mevalonate pathway inhibitor, granzyme B inhibitor, and antitumor necrosis factor (TNF)-α. In vivo xenograft assays showed that combined intraperitoneal administration of MDA/GDT induced antitumor effects on unestablished U87MG-derived subcutaneous tumors. MDA exerted direct and GDT-mediated anti-GBM apoptotic effects in a caspase-dependent manner. GDT recognized MDA-exposed GBM cells via TCRVγ9 and induced apoptosis via granzyme B and TNF-α release. Because MDA elicited anti-GBM effects in synergy with GDT in vivo, a combination of MDA and ex vivo-generated GDT could be an effective treatment in patients with GBM.     

Diagnostic problems in a patient with amicrofilaremic Loa loa

We report a Japanese patient with loiasis who became infected in Cameroon. Despite the clinical history and laboratory data providing adequate evidence for suspecting loiasis, microfilariae were not detected in the blood. It is important to note that most infected travelers whose home countries are in nonendemic regions are amicrofilaremic.