Hyperglycemia induces abnormal gene expression in hematopoietic stem cells and their progeny in diabetic neuropathy

Diabetic peripheral neuropathy is a major chronic diabetic complication. We have previously shown that in type 1 diabetic streptozotocin-treated mice, insulin- and TNF-α co-expressing bone marrow-derived cells (BMDCs) induced by hyperglycemia travel to nerve tissues where they fuse with nerve cells, causing premature apoptosis and nerve dysfunction. Here we show that similar BMDCs also occur in type 2 diabetic high-fat diet (HFD) mice. Furthermore, we found that hyperglycemia induces the co-expression of insulin and TNF-α in c-kit⁺Sca-1⁺lineage⁻ (KSL) progenitor cells, which maintain the same expression pattern in the progeny, which in turn participates in the fusion with neurons when transferred to normoglycemic animals.     

Polyphenolic constituent structures of Zanthoxylum piperitum fruit and the antibacterial effects of its polymeric procyanidin on methicillin-resistant Staphylococcus aureus

Zanthoxylum piperitum (Rutaceae) is used as a spice and a natural medicine in Japan. Our study found that ZP-CT-A, a polymeric proanthocyanidin purified from the fruit of this species, noticeably decreased the minimum inhibitory concentrations of beta-lactam antibiotics for methicillin-resistant Staphylococcus aureus (MRSA). The structure of ZP-CT-A was characterized on the basis of (13)C NMR and size exclusion chromatographic data and the results of thiolytic degradation. A mechanistic study of the effects of ZP-CT-A indicated that it suppressed the activity of beta-lactamase and largely decreased the stability of the bacterial cell membrane of MRSA, as shown by a reduction in the tolerance of MRSA to low osmotic pressure and high ionic strength solutions.     

Identification of a male-specific RNA binding protein that regulates sex-specific splicing of Bmdsx by increasing RNA binding activity of BmPSI

Bmdsx is a sex-determining gene in the silkworm and is alternatively spliced in males and females. CE1 is a splicing silencer element responsible for the sex-specific splicing of Bmdsx. To identify sex-specific factors implicated in the sex-specific splicing of Bmdsx, we performed RNA affinity chromatography using CE1 RNA as a ligand. We have identified BmIMP, a Bombyx homolog of IGF-II mRNA binding protein (IMP), as a male-specific factor that specifically binds to CE1. The gene encoding BmIMP is localized on the Z chromosome and is male-specifically expressed in various tissues. Antisense inhibition of BmIMP expression increased female-specific splicing of Bmdsx pre-mRNA. Coimmunoprecipitation and glutathione S-transferase (GST) pulldown analyses demonstrated that BmIMP physically interacts with BmPSI, which has been identified as a factor implicated in the sex-specific splicing of Bmdsx, through the KH domains of BmIMP. The functional consequence of this interaction was examined using RNA mobility shift analysis. BmIMP increased BmPSI-CE1 RNA binding activity by decreasing the rate of BmPSI dissociation from CE1 RNA. Truncation analysis of BmIMP suggested that the KH domains are responsible for enhancing BmPSI-CE1 RNA binding activity. These results suggest that BmIMP may enhance the male-specific splicing of Bmdsx pre-mRNA by increasing RNA binding activity of BmPSI.     

Inhibition of the in vitro formation of dense cells and of irreversibly sickled cells by charybdotoxin, a specific inhibitor of calcium-activated potassium efflux

Charybdotoxin, a specific inhibitor of the calcium-activated potassium channel, was found to inhibit the in vitro formation of irreversibly dehydrated cells and of irreversibly sickled cells, which occur as a result of repeated cycles of sickling and unsickling of sickle red blood cells. The degree of formation of dense cells was measured by Percoll-renografin density gradient centrifugation. 50% inhibition of the formation was achieved at a concentration of 30 nM of charybdotoxin. The approximate half-life of this compound in the circulation of the guinea pig was determined to be 4 h. Charybdotoxin did not inhibit the sickling of sickle cells under deoxygenation. The effects of charybdotoxin in preventing the irreversible changes of sickle cell membranes may be related to the inhibition of calcium-activated potassium efflux in sickle red blood cells.     

Localization of sialidase-positive cells expressing Mac-1 and immunoglobulin in the mouse thymus

We have sought an endogenous membrane bound sialidase acting at neutral pH in immune system, because the removal of sialic acid from cell surfaces will affect the cell-cell interaction directly or indirectly. The levels of activity of unique membrane-bound sialidase at neutral pH and also soluble sialidase are high in the thymus but low in the spleen and lymph nodes. These are thought to be plasma membrane and cytosolic types based on the behavior of inhibition by Cu²⁺ and 2-deoxy-2, 3-dehydro-N-acetylneuraminic acid. Newly synthesized 5-bromo-4-chloro-3-indolyl-N-acetylnueraminic acid was used for histochemical staining of sialidase-positive thymic cells, and the results showed positive cells sparsely distributed in the corticomedullar region or medullary region of the thymus. They expressed immunoglobulin and Mac-1 antigen on their surfaces. These cells must therefore be of a B cell lineage, not a T cell lineage. We also found that some vessels in the thymus were sialidase-positive. Published in 2004. This revised version was published online in July 2006 with corrections to the Cover Date.     

Local and systemic expression of inducible nitric oxide synthase in comparison with that of cyclooxygenase-2 in rat carrageenin-induced pleurisy.

Expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) is up-regulated in response to inflammatory stimuli. To evaluate the extent to which local pleural inflammation involves additional site in the pleural cavity and elsewhere, we investigated the time course of the levels of iNOS and its product in the inflammatory and other sites, and compared those with a level of COX-2 in rat carrageenin-induced pleurisy. The exudate and plasma NOx levels rose, reaching peaks at 9 and 14 h, respectively. Both COX-2 and iNOS became detectable in exudate leukocytes, their levels reaching peaks at 3 and 9 h after irritation, respectively. COX-2 was detectable mainly in neutrophils, but iNOS was detectable in both neutrophils and mononuclear leukocytes. Furthermore, iNOS became detectable in neutrophils and mononuclear leukocytes in enlarged parathymic lymph nodes from 3h in addition to those in peripheral blood and Kupffer cells from 3 to 14 h, respectively. The gene product is also detectable in thymic large dendritic cells of pleurisy-induced rats as well as normal control rats. COX-2 became detectable in stellar dendritic cells of the enlarged draining lymph nodes from 14 h. Thus, these gene products were induced in the immediate proximity of regional lymph nodes, and even at a considerable distance of liver by the local inflammatory stimulus. Although their expression pattern was quite different from each other, these gene products were detectable in phagocytic cells.