Vitamin C depletion increases superoxide generation in brains of SMP30/GNL knockout mice

Vitamin C (VC) has a strong antioxidant function evident as its ability to scavenge superoxide radicals in vitro. We verified that this property actually exists in vivo by using a real-time imaging system in which Lucigenin is the chemiluminescent probe for detecting superoxide in senescence marker protein-30 (SMP30)/gluconolactonase (GNL) knockout (KO) mice, which cannot synthesize VC in vivo. SMP30/GNL KO mice were given 1.5 g/L VC [VC(+)] for 2, 4, or 8 weeks or denied VC [VC(−)]. At 4 and 8 weeks, VC levels in brains from VC(−) KO mice were <6% of that in VC(+) KO mice. Accordingly, superoxide-dependent chemiluminescence levels determined by ischemia-reperfusion at the 4- and 8 weeks test intervals were 3.0-fold and 2.1-fold higher, respectively, in VC(−) KO mice than in VC(+) KO mice. However, total superoxide dismutase activity and protein levels were not altered. Thus, VC depletion specifically increased superoxide generation in a model of the living brain.     

Developmental and androgenic regulation of the immunocytochemical distribution of mK1, a true tissue kallikrein, in the granular convoluted tubule of the mouse submandibular gland.

The action of androgens on the immunocytochemical distribution of mK1, a true tissue kallikrein, was examined in the submandibular gland (SMG) of developing and adult mice by indirect enzyme-labeled and immunogold-labeled antibody methods for light and electron microscopy, respectively. In both sexes at 3 weeks of age, essentially all of the immature granular convoluted tubule (GCT) cells were uniformly immunostained. At 4 weeks of age (the onset of puberty), morphological differences between the two sexes appeared in the GCTs, in which some cells became immunonegative. Thereafter, the immunonegative GCT cells became more abundant in the SMG of males than of females and considerable intercellular variation in staining intensity for mK1 was seen, especially in males. A few slender GCT cells with strong immunoreactivity appeared in GCT segments only in males. Castration of males resulted in an increase in the number of immunopositive GCT cells, whereas administration of dihydrotestosterone (DHT) decreased the number of immunopositive GCT cells in the SMGs of both sexes. Slender GCT cells immunoreactive for mK1 were seen in females treated with DHT for 6 days. However, there were no immunostained slender GCT cells in female SMGs after injection of DHT for 2 weeks. Immunoelectron microscopy disclosed this type of cell in male SMGs, which closely resembles immature GCT cells of prepubertal mice, with a few small secretory granules uniformly labeled with gold particles, a sparse Golgi apparatus and RER, and basal infoldings. In mature male SMGs and in SMGs of DHT-treated females and castrated males, typical GCT cells had a well-developed Golgi apparatus and a net-like RER but few to no basal infoldings, whereas in the female gland equivalent cells had moderately developed RER and some basal infoldings. These results suggest that mK1 is one of the enzymes characteristically present in immature GCT cells and that its synthesis is inhibited in part by androgens, resulting in decreased numbers of immunopositive cells.     

p73 is expressed in human thymic epithelial cells.

The thymus is a heterogeneous immune organ in which immature T-cells develop and eventually specialize to make certain immune responses of their own. Among various types of stromal cells in the thymus, thymic epithelial cells (TECs) have a crucially important function for presenting self-antigens and secreting cytokines to thymocytes for their maturation into T-cells. In this study we show that the p73 gene, a homologue of the tumor suppressor gene p53, was expressed in the nucleus of the human TEC in vivo and in TEC lines in vitro. Because p73 has the capacity to be a transactivator like p53, it may contribute to T-cell development in the context of TEC biology as regulated in the cell cycle and apoptosis.     

Control of differentiation and apoptosis of human myeloid leukemia cells by cytokinins and cytokinin nucleosides, plant redifferentiation-inducing hormones.

We examined the effects of various adenine analogues on the growth and differentiation of human myeloid leukemia HL-60 cells. Some of these analogues inhibit growth and induce nitroblue tetrazolium reducing activity in HL-60 cells. Cytokinins such as kinetin, isopentenyladenine, and benzyladenine were very effective in inducing nitroblue tetrazolium reduction and morphological changes in the cells into mature granulocytes. On the other hand, cytokinin ribosides such as kinetin riboside, isopentenyladenosine, and benzylaminopurine riboside were the most potent for growth inhibition and apoptosis. Cytokinin ribosides greatly reduced the intracellular ATP content and disturbed the mitochondrial membrane potential and the accumulation of reactive oxygen species, whereas cytokinins did not. When the cells were incubated with cytokinin ribosides in the presence of O(2)(-) scavenger, antioxidant or caspase inhibitor, apoptosis was significantly reduced and differentiation was greatly enhanced. These results suggest that both cytokinins and cytokinin ribosides can induce granulocytic differentiation of HL-60 cells, but cytokinin ribosides also induce apoptosis prior to the differentiation process.     

Light-Controlled Cytoplasmic Streaming in Vallisneria Mesophyll Cells

The effect of light irradiation on cytoplasmic streaming inVallisneria mesophyll cells was investigated. Red light (     

Vancomycin-Resistant Gram-Positive Cocci Isolated from the Saliva of Wild Songbirds

We analyzed highly vancomycin-resistant Gram-positive bacteria isolated from the saliva of migratory songbirds captured, sampled, and released from a bird-banding station in western Kansas. Individual bacterial isolates were identified by partial 16S rRNA sequencing. Most of the bacteria in this study were shown to be Staphylococcus succinus with the majority being isolated from the American Robin. Some of these bacteria were shown to carry vanA, vanB, and vanC vancomycin-resistance genes and have the ability to form biofilms. One of the van gene-carrying isolates is also coagulase positive, which is normally considered a virulence factor. Other organisms isolated included Staphylococcus saprophyticus as well as Enterococcus gallinarum. Given the wide range of the American Robin and ease of horizontal gene transfer between Gram-positive cocci, we postulate that these organisms could serve as a reservoir of vancomycin-resistance genes capable of transferring to human pathogens.     

Effect of Alteration of Sterol Composition on the Salt Sensitivity of a Tobacco Cell Suspension Culture

A Nicotiana tabacum cell line, KS-1, which is tolerant to morethan 1% NaCl, was treated with buthiobate. The cells accumulated14a-methylsterols such as obtusifoliol, instead of campesteroland sitosterol. The buthiobate-treated cells lost their salttolerance. These results suggest that the buthiobate-inducedsalt sensitivity is closely associated with changes in the molecularspecies of sterols in the cell membranes. (Received October 16, 1986; Accepted April 13, 1987)