Phosphorylation of SMC1 is a critical downstream event in the ATM-NBS1-BRCA1 pathway

The ATM protein kinase is activated by intermolecular autophosphorylation in response to DNA damage and initiates cellular signaling pathways that facilitate cell survival and reduce chromosomal breakage. Here, we show that NBS1 and BRCA1 are required for the recruitment of previously activated ATM to the sites of DNA breaks after ionizing irradiation, and that this recruitment is required for the phosphorylation of SMC1 by ATM. To explore the functional importance of SMC1 phosphorylation, murine cells were generated, in which the two damage-induced phosphorylation sites in SMC1 are mutated. Although these cells demonstrate normal phosphorylation and focus formation of ATM, NBS1, and BRCA1 proteins after IR, they exhibit a defective S-phase checkpoint, decreased survival, and increased chromosomal aberrations after DNA damage. These observations suggest that many of the abnormal stress responses seen in cells lacking ATM, NBS1, or BRCA1 result from a failure of ATM migration to sites of DNA breaks and a resultant lack of SMC1 phosphorylation.     

Investigation of albumin synthesis in rat livers during the perinatal period using immunocytochemistry andin situ hybridization

The immunoreactivity of albumin (ALB) was observed in the hepatocytes of fetal rats on day 18 of gestation, and was especially observable in immature rough endoplasmic reticulum (rER) and Golgi apparatus (GA); by then, a small amount of silver grains of ALB mRNA could already be detected. Just after birth, immunoreactivity of ALB could be observed in fine granules or diffusely in all hepatocytes, and was present in rER and GA. One week after birth immunoreactivity of ALB was observed in all hepatocytes and was visible in developed rER and GA; the grains of ALB mRNA were present in all hepatocytes.     

A case of mixed connective tissue disease developed into overlap syndrome of progressive systemic sclerosis, systemic lupus erythematosus, polymyositis and Sj?gren's syndrome

We encountered a patient who developed an overlap syndrome of progressive systemic sclerosis (PSS), systemic lupus erythematosus (SLE), polymyositis (PM) and Sj?gren's syndrome (SjS) while we were treating her for mixed connective tissue disease (MCTD). This 42-year-old woman had been photosensitive since 18 years of age. In 1986, Raynaud's phenomenon, swollen hands and arthralgia appeared; therefore, we started to treat this patient based on a diagnosis of MCTD. At that time, her anti-RNP antibody titer was 82,920, but she was negative to anti-Sm antibody. In 1988, she was admitted to our hospital with chief complaints of aggravation of polyarthralgia and myalgia. On physical examination, she showed difficulty in opening her mouth, systemic dermal sclerosis, a decrease in muscular strength and rales. In laboratory tests, her myogenic enzyme level was increased, and she was found to be positive to LE cells, antinuclear antibody, anti-DNA antibody, anti-ENA antibody and anti-SSA antibody. Furthermore, histological features clearly corresponding to those of PSS were found by skin biopsy, myogenic changes by electromyography, evidence of chronic inflammation of the salivary glands by lip biopsy, and proliferative changes in the mesangium were detected by renal biopsy. The concept of MCTD, especially the differences from overlap syndrome, is vague. Therefore we need further study about many cases. Since there have been no reports on cases having sufficient evidence of the development of the overlap syndrome of PSS, SLE, PM and SjS during a course of MCTD, our patient would provide very useful data contributing to the study of MCTD.     

Bruceine B, A Potent Inhibitor of Leukocyte-Endothelial Cell Adhesion

Leukocyte adhesion to vascular endothelial cells is an essential step in the development of inflammatory diseases. We have searched for inhibitors of leukocyte-endothelial cell adhesion that could be used as anti-inflammatory drugs and found that bruceine B (0.2 g/ml; 0.44 M) inhibited human neutrophil or T cell adhesion to tumor necrosis factor- (TNF) stimulated human umbilical vein endothelial cells (HUVEC). The inhibition of neutrophil adhesion to TNF-stimulated HUVEC by bruceine B was not derived from cytotoxic effects, as determined by measurement of the level of lactate dehydrogenase (LDH) activity in conditioned medium. The effect of bruceine B on neutrophil adhesion to HUVEC was not seen when the neutrophils were preincubated with bruceine B. However, inhibitory effects were evident when the HUVEC were preincubated with bruceine B. Bruceine B also inhibited neutrophil adhesion to lipopolysaccharide-stimulated HUVEC and T cell adhesion to TNF-stimulated HUVEC. These findings suggest that bruceine B may have anti-inflammatory activity.     

Effects of granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor on respiratory burst activity of neutrophils in patients with myelodysplastic syndromes.

The superoxide (O2-)-releasing capacity in response to N-formyl-methionyl-leucyl-phenylalanine (FMLP) and the priming effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) and granulocyte-macrophage colony-stimulating factor (rhGM-CSF) on FMLP-induced O2- release were investigated in neutrophils from 14 patients with myelodysplastic syndromes (MDS). The O2(-)-releasing capacity in MDS neutrophils varied from patient to patient. As compared with normal neutrophils, the O2(-)-releasing capacity in MDS neutrophils was increased in 9/14 patients, normal in three patients and decreased in two patients. There was no close relationship between the O2(-)-releasing capacity and the peripheral blood neutrophil count or the plasma concentration of C-reactive protein. The priming of neutrophils by rhG-CSF was not observed in five patients, whereas rhGM-CSF primed neutrophils from all patients. The priming effect of rhGM-CSF was consistently greater than that of rhG-CSF in each patient. The intravenous administration of rhG-CSF (300 micrograms/body) to two MDS patients showed an increase in the peripheral blood neutrophil count and enhancement of neutrophil O2- release. These findings demonstrate that the neutrophil O2(-)-releasing capacity in MDS varies from patient to patient and is not always impaired, and that rhGM-CSF is able to prime neutrophils which never respond to rhG-CSF.     

An anxiolytic agent, dihydrohonokiol-B, inhibits ammonia-induced increases in the intracellular Cl(-) of cultured rat hippocampal neurons via GABA(c) receptors

The effects of an anxiolytic honokiol derivative, dihydrohonokiol-B (DHH-B) [3'-(2-propenyl)-5-propyl-(1,1'-biphenyl)-2,4'-diaol], on ammonia-induced increases in the intracellular Cl(-) concentration ([Cl(-)](i)) were examined using primary cultured rat hippocampal neurons. DHH-B (1-100 ng/ml), but not an inactive isomer of honokiol, magnolol (100 ng/ml), dose-dependently inhibited the ammonia-induced increases in [Cl(-)](i) without any changes in the control [Cl(-)](i). Such an effect of DHH-B was blocked by a gamma-aminobutylic acid A (GABA(A)) and GABA(C) Cl(-) channel blocker, 100 microM picrotoxin, and a GABA(C) receptor blocker, 10 microM (1,2,5,6-tetrahydropyridine-4-yl)methylphosphinic acid, but not by a GABA(A) receptor blocker, 10 microM bicuculline. Further, a GABA(C) receptor agonist, 200 microM cis-4-aminocrotonic acid, but not a GABA(A) receptor agonist, 10 microM muscimol, mimicked the effect of DHH-B. Thus, DHH-B appears to protect neurons from the ammonia-induced increases in [Cl(-)](i) through GABA(C) receptor stimulation.     

Protease inhibitors (gebexate mesylate and ulinastatin) stimulate intracellular chemiluminescence in human neutrophils.

The effect of protease inhibitors on the intracellular production of free radicals was investigated by measuring chemiluminescence (CL) elicited from phagocytosed luminol-bound microspheres (Lumispheres) in human neutrophils stimulated with formylmethionyl-leucyl-phenylalanine (fMLP), interleukin-8 (IL-8), phorbol 12-myristate 13-acetate, or diacylglycerol. Both gabexate mesylate (Foy) and ulinastatin (Miraclid), urinary trypsin inhibitor, increased intracellular CL in a dose dependent manner. Compared to control buffer without protease inhibitor, gabexate mesylate (322 micrograms/ml) caused about a 10-fold increase in intracellular CL in stimulated neutrophils, and ulinastatin (3100 U/ml) a twofold increase in neutrophils stimulated with fMLP or IL-8. When the protease inhibitors were added to the cell suspension after the phagocytosis of lumispheres, CL responses rapidly increased again to the level which was observed when both protease inhibitors and neutrophil stimulants were incubated simultaneously. In contrast, extracellular release of oxygen metabolites from stimulated neutrophils, assayed by a conventional measurement of luminol-dependent CL, was reduced by the protease inhibitors in a dose dependent fashion. When luminol-unbound microspheres were incubated with neutrophils stimulated by fMLP in luminol solution, extracellular CL was almost completely inhibited by gabexate mesylate. These results indicate that the protease inhibitors enhance the generation of intracellular CL and suppress the extracellular release of free radicals.     

Activation of Human Monocytes for Enhanced Production of Interleukin 8 During Transendothelial Migration in Vitro

Interleukin-8 (IL-8) is a chemokine for polymorphonuclear leukocytes (PMNs) and lymphocytes, which promotes the extravasation of these inflammatory cells. In this study, we investigated IL-8 synthesis induced by the adhesive interaction between monocytes and endothelial cells during transmigration and the capacity of transmigrated monocytes to produce IL-8. Cocultured human monocytes and human umbilical vein endothelial cell (HUVEC) monolayers induced the synefgistic production of IL-8, compared with cultures of either monocytes or HUVEC monolayers alone. Coculture-induced IL-8 production almost doubled after HUVECs were stimulated with IL-1. The induced IL-8 mRNA expression was consistent with the protein data, indicating the de novo synthesis of IL-8 by the coculture. Monoclonal antibodies (mAbs) against IL-8 inhibited the transendothelial chemotactic activity of the supernatants for PMNs by 55%. Immunohistochemistry revealed that both adherent and transmigrated monocytes and unstimulated HUVECs expressed IL-8 protein, whereas nonadherent monocytes did little. Transmigrated monocytes spontaneously secreted a 3.8-fold greater amount of IL-8 than the initial monocytes. Coculture-induced IL-8 production was inhibited about 30% by polyclonal Abs against IL-, IL-1, or tumor necrosis factor , while it was not affected by mAbs against intercellular adhesion molecule 1 or vascular cell adhesion molecule 1. The results suggested that adhesive interaction during the transmigration of monocytes through HUVEC monolayers activates both cell types to produce IL-8 and that transmigrated monocytes are capable of producing ample IL-8.