Characterization of the cells in the repair tissue of full-thickness articular cartilage defects

 It is well established that a full-thickness articular cartilage defect is repaired with a fibrocartilaginous tissue, cells of which are derived from undifferentiated mesenchymal stem cells in the bone marrow. To characterize the repair cells biochemically, full-thickness defects were created in rabbit knee joints and the repair tissues taken at 3, 6, and 12 weeks after surgery. The repair cells were cultured and examined biochemically to investigate the effects of four exogenous growth factors with regard to the metabolism of type II collagen and proteoglycans. A significant increase of carboxy-terminal type II procollagen peptide production was observed in the conditional medium of the repair cells, especially taken at 6 weeks after surgery, in the presence of each growth factor. Glycosaminoglycan content was also increased and proteoglycan synthesis stimulated. The repair cells taken at the early stage of the repair process could originally have more activity of type II collagen synthesis, and the growth factors used could enhance the differentiation of the repair cells in vitro. Accepted: 3 November 1997     

Association of mast cells with Warthin's tumor in fine needle aspirates of the salivary gland

OBJECTIVE: To determine the significance of the presence of mast cells in Warthin's tumor by evaluating the occurrence of these cells in cellular and immunohistochemical preparations. STUDY DESIGN: Specimens derived from five cases of FNAC were examined. A total of four slides from five cases were prepared from each: two air-dried smears were stained with May-Grünwald-Giemsa (MGG) stain and two with Hansel's stain. The other two were alcohol fixed and stained using the Papanicolaou method. The smears were evaluated for the presence of mast cells, especially associated with oxyphilic cells. In order to investigate the location of mast cells, we also counted those cells by means of immunohistochemistry using anti-mast cell monoclonal antibody AA1. RESULTS: The Hanselstained cellular sample from Warthin's tumor contained numerous mast cells, associated mainly with large, oxyphilic cell sheets. The number of AA1-positive cells (mast cells) stained with immunohistochemistry was greater in epithelial component than in lymphoid stroma. CONCLUSION: Mast cells in a salivary gland aspirate might be indicative of Warthin's tumor; therefore, MGG-stained slides offer the advantage of ease of preparation, particularly when the typical cytologic features are not present.     

Water-soluble ferulic acid derivatives improve amyloid-β-induced neuronal cell death and dysmnesia through inhibition of amyloid-β aggregation

Ferulic acid (FA) has been reported to exhibit protective effects against amyloid-β (Aβ)-induced neurodegeneration in vitro and in vivo. Recently, we developed two water-soluble FA derivatives: 1-feruloyl glycerol and 1-feruloyl diglycerol. In this study, we examined the neuroprotective effects of these water-soluble FA derivatives on Aβ-induced neurodegeneration both in vitro and in vivo. FA and water-soluble FA derivatives inhibited Aβ aggregation and destabilized pre-aggregated Aβ to a similar extent. Furthermore, water-soluble FA derivatives, as well as FA, inhibited Aβ-induced neuronal cell death in cultured neuronal cells. In in vivo experiments, oral administration of water-soluble FA derivatives to mice improved Aβ-induced dysmnesia assessed by contextual fear conditioning test and protected hippocampal neurons against Aβ-induced neurotoxicity. This study provides useful evidence suggesting that water-soluble FA derivatives are expected to be effective neuroprotective agents.     

Importance of the G protein gamma subunit in activating G protein-coupled inward rectifier K(+) channels

Arachidonic acid (AA) is generated via Rac-mediated phospholipase A2 (PLA2) activation in response to growth factors and cytokines and is implicated in cell growth and gene expression. In this study, we show that AA activates the stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) in a time- and dose-dependent manner. Indomethacin and nordihydroguaiaretic acid, potent inhibitors of cyclooxygenase and lipoxygenase, respectively, did not exert inhibitory effects on AA-induced SAPK/JNK activation, thereby indicating that AA itself could activate SAPK/JNK. As Rac mediates SAPK/JNK activation in response to a variety of stressful stimuli, we examined whether the activation of SAPK/JNK by AA is mediated by Rac1. We observed that AA-induced SAPK/JNK activation was significantly inhibited in Rat2-Rac1N17 dominant-negative mutant cells. Furthermore, treatment of AA induced membrane ruffling and production of hydrogen peroxide, which could be prevented by Rac1N17. These results suggest that AA acts as an upstream signal molecule of Rac, whose activation leads to SAPK/JNK activation, membrane ruffling and hydrogen peroxide production.     

Phospholipase D production using immobilized cells of Streptoverticillium cinnamoneum

Summary Production of phospholipase D (PLD) by Streptoverticillium cinnamoneum immobilized within porous particles was investigated in repeated batch fermentation. The enzyme productivity in repeated batch fermentation was 2.2-fold that obtained in batch fermentation without immobilization, since many of the immobilized cells could be utilized as seed cells for each subsequent batch cycle.     

Chromosome engineering in Saccharomyces cerevisiae by using a site-specific recombination system of a yeast plasmid.

We have developed an effective method to delete or invert a chromosomal segment and to create reciprocal recombination between two nonhomologous chromosomes in Saccharomyces cerevisiae, using the site-specific recombination system of pSR1, a circular cryptic DNA plasmid resembling 2 microns DNA of S. cerevisiae but originating from another yeast, Zygosaccharomyces rouxii. A 2.1-kilobase-pair DNA fragment bearing the specific recombination site on the inverted repeats of pSR1 was inserted at target sites on a single or two different chromosomes of S. cerevisiae by using integrative vectors. The cells were then transformed with a plasmid bearing the R gene of pSR1, which encodes the site-specific recombination enzyme and is placed downstream of the GAL1 promoter. When the transformants were cultivated in galactose medium, the recombination enzyme produced by expression of the R gene created the modified chromosome(s) by recombination between two specific recombination sites inserted on the chromosome(s).     

mTORC1 serves ER stress-triggered apoptosis via selective activation of the IRE1-JNK pathway

Mammalian target of rapamycin (mTOR) has a key role in the regulation of an array of cellular function. We found that rapamycin, an inhibitor of mTOR complex 1 (mTORC1), attenuated endoplasmic reticulum (ER) stress-induced apoptosis. Among three major branches of the unfolded protein response, rapamycin selectively suppressed the IRE1-JNK signaling without affecting PERK and ATF6 pathways. ER stress rapidly induced activation of mTORC1, which was responsible for induction of the IRE1-JNK pathway and apoptosis. Activation of mTORC1 reduced Akt phosphorylation, which was an event upstream of IRE-JNK signaling and consequent apoptosis. In vivo, administration with rapamycin significantly suppressed renal tubular injury and apoptosis in tunicamycin-treated mice. It was associated with enhanced phosphorylation of Akt and suppression of JNK activity in the kidney. These results disclosed that, under ER stress conditions, mTORC1 causes apoptosis through suppression of Akt and consequent induction of the IRE1-JNK pathway.