Mesenchymal progenitor cells in adult human dental pulp and their ability to form bone when transplanted into immunocompromised mice

The technique of tissue engineering is developing for the restoration of lost tissues. This new technique requires cells that fabricate tissue. Mesenchymal stem cells in bone marrow have been used as the cell source for this technique; however, dental pulp cells have recently been shown to possess stem-cell-like properties. We earlier demonstrated that dental pulp cells proliferate and produce an extracellular matrix that subsequently becomes mineralized in vitro. We now report that such dental pulp cells (first to eighth passage) produced bone instead of dentin when those cells were implanted into subcutaneous sites in immunocompromised mice with HA/TCP powder as their carrier. This evidence shows that dental pulp cells are the common progenitors of odontoblasts and osteoblasts, or dental pulp cells are mesenchymal stem cells themselves. It is expected that dental pulp cells can be a useful candidate cell source for tissue engineering, and contain the potential of new therapeutic approaches for the restoration of damaged or diseased tissue.     

Purification and characterization of a novel imidazole dipeptide synthase from the muscle of the Japanese eel Anguilla japonica

We have purified a novel enzyme from eel white muscle which catalyzes the syntheses of imidazole dipeptides, such as carnosine (β-alanyl-l-histidine), anserine (β-alanyl-π-methyl-l-histidine), and balenine (ophidine; β-alanyl-τ-methyl-l-histidine), directly from their precursors. The enzyme was purified 1130-fold from eel muscle by a series of column chromatographies. Although eel muscle contains a large amount of carnosine and only trace amounts of anserine and balenine, the anserine synthesizing activity was by far the highest. From gel permeation chromatography, the molecular mass of the enzyme was calculated to be 275 kDa. SDS-PAGE of the purified enzyme represented a band around 43 kDa, suggesting that the native enzyme is a hexamer or heptamer. The optimal pH and temperature were around 9.5 and 60 °C, respectively. K_m values for β-alanine and π-methyl-l-histidine were 44 and 89 mM, respectively. The enzyme was greatly activated by Zn²⁺ and inhibited by EDTA. The N-terminal amino acid sequence of 25 residues of the purified enzyme showed 52% amino acid identity to 38–62 residues of zebrafish haptoglobin precursor. The purified enzyme also exhibited hydrolytic activity against these imidazole dipeptides.     

Materials for the fungus flora of Japan (57)

Two microfungi are described as new to Japan:Amaurascopsis reticulatus (Amauroascaceae, Ascomycetes), isolated from forest soil in Kamakura, has not been recorded since it was originally found and is characterized by yellow to orange-red ascomata with undifferentiated peridial hyphae and globose ascospores with contorted ridges appearing irregularly punctate-reticulate; andHobsonia mirabilis (helicosporous hyphomycete), isolated from the cut stem of a thistle in Hachijo-jima, is characterized by gelatinous sporodochia and hyaline, tortuously coiled conidia. (56): Okuda, T. and Yamamoto, K., Mycoscience41: 411–414, 2000.     

Leptographium pini-densiflorae sp. nov. from Japanese red pine

ALeptographium species was isolated from deadPinus densiflora at six sites in Japan. The fungus is morphologically most similar toL. lundbergii but could be distinguished from that species by its short stipes, primary branches of conidiophores, and conidia with a rounded to sub-truncate base. In addition, the colony morphology, growth rate and tolerance to the antibiotic cycloheximide of theLeptographium species andL. lundbergii differed markedly. Here we describe the fungus as a new species,Leptographium pini-densiflorae. Contribution No. 144, Laboratory of Plant Pathology and Mycology, Institute of Agriculture and Forestry, University of Tsukuba.     

Enhancement of ascospore germination fromAleuria aurantia after cold storage

Ascospores ofAleuria aurantia did not germinate soon after collection. The treatment with alkali induced germination, but the rate was less than 0.01%. After storage of the ascospore at 4°C or at −20°C for three mo, germination was enhanced, and its rate was approximately 60%.     

Endogenous and exogenous hydrogen sulfide facilitates T-type calcium channel currents in Cav3.2-expressing HEK293 cells

Hydrogen sulfide (H₂S), a gasotransmitter, is formed from l-cysteine by multiple enzymes including cystathionine-γ-lyase (CSE). We have shown that an H₂S donor, NaHS, causes hyperalgesia in rodents, an effect inhibited by knockdown of Ca_v3.2 T-type Ca²⁺ channels (T-channels), and that NaHS facilitates T-channel-dependent currents (T-currents) in NG108-15 cells that naturally express Ca_v3.2. In the present study, we asked if endogenous and exogenous H₂S participates in regulation of the channel functions in Ca_v3.2-transfected HEK293 (Ca_v3.2-HEK293) cells. dl-Propargylglycine (PPG), a CSE inhibitor, significantly decreased T-currents in Ca_v3.2-HEK293 cells, but not in NG108-15 cells. NaHS at 1.5 mM did not affect T-currents in Ca_v3.2-HEK293 cells, but enhanced T-currents in NG108-15 cells. In the presence of PPG, NaHS at 1.5 mM, but not 0.1–0.3 mM, increased T-currents in Ca_v3.2-HEK293 cells. Similarly, Na₂S, another H₂S donor, at 0.1–0.3 mM significantly increased T-currents in the presence, but not absence, of PPG in Ca_v3.2-HEK293 cells. Expression of CSE was detected at protein and mRNA levels in HEK293 cells. Intraplantar administration of Na₂S, like NaHS, caused mechanical hyperalgesia, an effect blocked by NNC 55-0396, a T-channel inhibitor. The in vivo potency of Na₂S was higher than NaHS. These results suggest that the function of Ca_v3.2 T-channels is tonically enhanced by endogenous H₂S synthesized by CSE in Ca_v3.2-HEK293 cells, and that exogenous H₂S is capable of enhancing Ca_v3.2 function when endogenous H₂S production by CSE is inhibited. In addition, Na₂S is considered a more potent H₂S donor than NaHS in vitro as well as in vivo.     

Ablation of Elovl6 protects pancreatic islets from high-fat diet-induced impairment of insulin secretion

ELOVL family member 6, elongation of very long-chain fatty acids (Elovl6) is a microsomal enzyme that regulates the elongation of C12–16 saturated and monounsaturated fatty acids and is related to the development of obesity-induced insulin resistance via the modification of the fatty acid composition. In this study, we investigated the role of systemic Elovl6 in the pancreatic islet and β-cell function. Elovl6 is expressed in both islets and β-cell lines. In mice fed with chow, islets of the Elovl6^−/− mice displayed normal architecture and β-cell mass compared with those of the wild-type mice. However, when fed a high-fat, high-sucrose (HFHS) diet, the islet hypertrophy in response to insulin resistance observed in normal mice was attenuated and glucose-stimulated insulin secretion (GSIS) increased in the islets of Elovl6^−/− mice compared with those of the wild-type mice. Enhanced GSIS in the HFHS Elovl6^−/− islets was associated with an increased ATP/ADP ratio and the suppression of ATF-3 expression. Our findings suggest that Elovl6 could be involved in insulin secretory capacity per β-cell and diabetes.