Demonstration of amelogenin in the enamel-free cusps of rat molar tooth germs: immunofluorescent and immunoelectron microscopic studies.

The enamel-free cusps of 1-4 day-old rat mandibular first molars were investigated using the monoclonal antibody En3 against rat amelogenin at light and electron microscopic levels in order to clarify whether the enamel-free cusp is virtually devoid of enamel. At 1 day after birth, there were presecretory ameloblast-like cells (PALCs), which were short and were not polarized, at the cusp tips. They were close to the outer enamel epithelium. Hematoxylin positive enamel matrix was not distinctly observed in the enamel-free cusp by light microscopy, but almost continuous immunofluorescence for amelogenin was detected at the interface between PALCs and dentin. The penetration of immunopositive material toward the dental pulp was also observed in the enamel-free cusp. At 4 day after birth, both in the frontal section and in the horizontal section, almost continuous immunofluorescence was recognized at the interface between PALCs and dentin in the enamel-free cusp. The penetration of amelogenin toward the dental pulp was not seen in the enamel-free cusp. By immunoelectron microscopy, immunolabelling was recognized in the Golgi apparatus of PALCs, in a layer of amorphous material at the interface between PALCs and dentin, and in stippled material-like substance in the intercellular space between PALCs. Although no basement membrane was observed beneath PALCs, they did not have Tomes' processes. These investigations suggest that PALCs in the enamel-free cusp differentiate into the secretory cells and that they can synthesize and secrete the amorphous material containing amelogenin at the interface between PALCs and dentin. The penetration of amelogenin toward the dental pulp might play a role in the interaction between PALCs and odontoblasts in the enamel-free cusp and/or the initiation of mineralization of predentin.     

Safety and efficacy of Tolvaptan in real-world patients with autosomal dominant polycystic kidney disease- interim results of SLOW-PKD surveillance

Clinical and Experimental Nephrology - Tolvaptan is a vasopressin type 2 receptor antagonist and has been used to treat autosomal dominant polycystic kidney disease (ADPKD) since 2014. There has...     

Strain difference in transgene-induced tumorigenesis and suppressive effect of ionizing radiation

Transgenic expression in medaka of the Xiphophorus oncogene xmrk, under a pigment cell specific mitf promoter, induces hyperpigmentation and pigment cell tumors. In this study, we crossed the Hd-rR and HNI inbred strains because complete genome information is readily available for molecular and genetic analysis. We prepared an Hd-rR (p53^+/−, p53^−/−) and Hd-rR HNI hybrid (p53^+/−) fish-based xmrk model system to study the progression of pigment cells from hyperpigmentation to malignant tumors on different genetic backgrounds. In all strains examined, most of the initial hyperpigmentation occurred in the posterior region. On the Hd-rR background, mitf:xmrk-induced tumorigenesis was less frequent in p53^+/− fish than in p53^−/− fish. The incidence of hyperpigmentation was more frequent in Hd-rR/HNI hybrids than in Hd-rR homozygotes; however, the frequency of malignant tumors was low, which suggested the presence of a tumor suppressor in HNI genetic background fish. The effects on tumorigenesis in xmrk-transgenic immature medaka of a single 1.3 Gy irradiation was assessed by quantifying tumor progression over 4 consecutive months. The results demonstrate that irradiation has a different level of suppressive effect on the frequency of hyperpigmentation in purebred Hd-rR compared with hybrids.     

Recombinant Sendai viruses with L1618V mutation in their L polymerase protein establish persistent infection, but not temperature sensitivity

The Sendai virus pi strain (SeVpi) isolated from cells persistently infected with SeV shows mainly two phenotypes: (1) temperature sensitivity and (2) an ability of establishing persistent infection (steady state). Three amino acid substitutions are found in the Lpi protein and are located at aa 1088, 1618, and 1664. Recombinant SeV(Lpi) (rSeV(Lpi)) having all these substitutions is temperature sensitive and is capable of establishing persistent infection (steady state). rSeVs carrying the fragment containing L1618V show both phenotypes. rSeV(L1618V), in which leucine at aa 1618 is replaced with valine, has the ability of establishing persistent infection, but is not a temperature-sensitive mutant, indicating that the ability of a virus to establish persistent infection can be separated from temperature sensitivity. The amino acid change at 1618(L-->V) coexisting with aa 1169 threonine is required for acquirement of a temperature-sensitive phenotype. Three amino acid substitutions are also found in the Ppi protein, but rSeV(Ppi) does not show these phenotypes.     

Effects of GM1-ganglioside and α-sialyl cholesterol on amino acid uptake,protein synthesis,and Na+, K+-ATPase activity in superior cervical and nodose ganglia excised from adult rats

We examined the effect of GM₁-ganglioside in combination with cholera toxin B, and synthetic α-sialyl cholesterol (α-SC) on neutral amino acid (tritiated α-aminoisobutyric acid, [³H]AIB) uptake, protein synthesis ([³H]leucine incorporation), and Na⁺, K⁺-ATPase activity in isolated superior cervical ganglia (SCG) and nodose ganglia (NG) from adult rats after aerobic incubation, usually for 2 h at 37°C in vitro. Cholera toxin B, that specifically masks the oligosaccharide chain of GM₁-ganglioside, antagonized the GM₁-induced changes in [³H]AIB uptake, [³H]leucine incorporation, and Na⁺, K⁺-ATPase activity almost completely in SCG, but partially in NG. Although cholesterol itself had little effect on either [³H]AIB uptake and Na⁺, K⁺-ATPase activity both in SCG and NG, α-SC caused considerable reduction of both amino acid uptake and the transport enzyme activity in each ganglia. However, cholesterol was more effective than α-SC in decreasing [³H]leucine incorporation in either ganglia. Whereas addition of EGTA markedly reduced either GM₁-induced or α-SC-induced change in [³H]leucine incorporation into acid-insoluble fraction in both SCG and NG, application of Ca²⁺ ionophore produced considerable recovery of the protein synthesis from the inhibited level by Ca²⁺-deprivation. ATP and creatine phosphate contents in SCG were elevated by the presence of GM₁ or α-SC, whereas [³H]AIB uptake and Na⁺, K⁺-ATPase activity were inhibited, suggesting that utilization for membrane transport was diminished as a result of GM₁- or α-SC-induced decrease of ATPase activity.     

Activity of cytotoxic agents against clear cell carcinoma of the ovary which is intrinsically platinum-refractory

The aim of the present study was to evaluate cytotoxic agents active for clear cell carcinoma of the ovary (OCCA) which is intrinsically platinum-resistant. We first conducted in vitro chemosensitivity tests assessing antitumor activities of Various agents against OCCA using two cell lines (HAC-2 and KK) established from ascites of patients with pure OCCA. The most potent single agent was SN-38 (active substance of CPT-11 in vivo) in both cell lines. The second most potent agent was mitomycin-C (MMC) followed by doxorubicin (DOX) in HAC-2 and DOX followed by MMC in KK, respectively. In vivo chemosensitivity test of agents on HAC-2 transplanted into BALB/C nude mice demonstrated that MMC was most potent, followed by DOX and CPT-11. Moreover, a combination of CPT-11 and MMC exhibited the highest anti-tumor activity in this animal model. Cisplatin, etoposide, and paclitaxel were found to be ineffective in either the in vitro or in vivo experimental system. Clinical trial with a combination of MMC and CPT-11 are warranted in patients with OCCA.