c-Myc alters the DNA damage-induced G2/M arrest in human mammary epithelial cells

Effects of c-Myc overexpression on the DNA damage-induced G2/M checkpoint were studied in finite lifespan, normal human mammary epithelial cells (HMECs). Previously, we showed that c-Myc attenuates G1/S arrest and leads to an inappropriate entry of cells with damaged DNA into the S phase, following treatment with ionising radiation (IR). Here we show that, in striking contrast to control cells, c-Myc-overexpressing HMECs demonstrate a significant attenuation of the G2/M arrest, following IR, and enter into inappropriate mitoses. At the molecular level, ectopic overexpression of c-Myc leads to an unusually high level of expression of cyclin B1, and the elevated levels of cyclin B1 were maintained, after gamma-irradiation. Introduction of DNA damage in c-Myc-overexpressing, normal mammary epithelial cells eventually induces apoptosis, indicating a dramatic sensitisation by c-Myc of DNA damage-induced apoptosis. These two remarkable phenotypes, checkpoint attenuation and sensitisation to apoptosis, resulting from a deregulation of the protooncogene c-myc, may produce a unique pattern of alternating cycles, consisting first of amplification of DNA damage, followed by apoptosis-assisted selective pressure. The result of this alternating pattern of damage apoptosis could facilitate the selection of certain genomic alterations required for cellular survival and cellular transformation.     

Oncolytic vesicular stomatitis virus for treatment of orthotopic hepatocellular carcinoma in immune-competent rats

Tumor-targeted replicating viruses are being developed as a novel class of oncolytic agents. Vesicular stomatitis virus (VSV) is a negative-strand RNA virus with inherent specificity for replication in tumor cells due to their attenuated antiviral responses. VSV as an oncolytic virus is particularly appealing for its exceptionally rapid replication rate in tumor cells, such that the oncolytic effects could be maximally manifested before the onset of potentially neutralizing antiviral immune responses in the host. To easily monitor VSV replication, we have rescued a recombinant VSV (rVSV) vector expressing the green fluorescent protein (GFP) gene (rVSV-GFP). Using this GFP-expressing virus, we have demonstrated the oncolytic potential of VSV against human and rat hepatocellular carcinoma (HCC). We found that rVSV-GFP replicated efficiently in cultured human and rat HCC cells, whereas normal human and rat hepatocytes were refractory. When a single dose of the vector was injected intratumorally into large orthotopically implanted HCC in immune-competent rats, rVSV-GFP effectively and selectively replicated throughout the solid tumor mass without apparent hepatotoxicity, caused tumor destruction, and inhibited tumor growth, which led to significant prolongation of animal survival. Our results show that VSV is an effective oncolytic agent against HCC in immune-competent hosts and warrants further development for future therapy in patients with HCC.     

Effect of lifetime lactation on breast cancer risk: a Korean women's cohort study

The objective of our study was to examine the effect of lifetime lactation on breast cancer risk among premenopausal women. The data were from a prospective cohort study with a follow-up period of 6 years in Korea (1995-2000). The cohort was composed of 110,604 premenopausal parous Korean women, aged 20 years and older, who received health insurance from the Korea Medical Insurance Corporation and who had medical evaluations in 1992 and 1994. Multivariate Cox proportional hazard models were tested, controlling for age, age at menarche, number of children, age at first pregnancy, oral contraceptive use, smoking, exercise and obesity. At baseline, 57,440 (51.9%) reported breastfeeding and 4,584 (4.1%) reported breastfeeding more than 24 months. From 1995-2000, 360 incident cases of breast cancer (61.8/100,000 person-years) occurred. Compared to parous women who had no history of lactation, a period of lactation of 13-24 months decreased the risk of breast cancer (RR, 0.7; 95% CI, 0.5-1.1), and this risk was decreased even further for those who breastfed for more than 24 months (RR, 0.6; 95% CI, 0.3-1.0). There was a clear trend of decreasing breast cancer risk with the duration of lactation (p for trend <0.001). In conclusion, our study of a large Korean cohort provides additional empirical evidence to current theoretical conjecture that lactation decreases the risk of breast cancer among premenopausal women.     

New guaianolides from leaves and stems of Chrysanthemum boreale

The 8-acetoxy-2-methoxy-10-hydroxy-3,11(13)-guaiaden-12,6-olide 1 and 8,10-diacetoxy-2-methoxy-3,11(13)-guaiadiene-12,6-olide 2 were isolated from Chrysanthemum boreale Makino. Compound 1 inhibited the etoposide-induced apoptosis in U 937 cells with an IC50 value 8.6 microg/mL.     

Acquired subglottic stenosis caused by methicillin resistant Staphylococcus aureus that produce epidermal cell differentiation inhibitor

Local infection of the trachea in intubated neonates is one of the main risk factors for development of acquired subglottic stenosis, although its role in the pathogenesis is unclear. Methicillin resistant Staphylococcus aureus (MRSA) is often the cause of critical illness in neonatal patients. Two cases are reported of acquired subglottic stenosis following bacterial infection of the trachea, suggesting an association with the staphylococcal exotoxin, epidermal cell differentiation inhibitor (EDIN). EDIN-producing MRSA were isolated from purulent tracheal secretions from both infants. Acquired subglottic stenosis in both cases was probably caused by delayed wound healing as the result of EDIN inhibition of epithelial cell migration.     

Matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-3 mRNA expression in ectopic and eutopic endometrium in women with endometriosis: a rationale for endometriotic invasiveness

OBJECTIVE: To investigate mRNA expression of metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-3 (TIMP-3) in ectopic endometriosis tissue and uterine endometrium from women with and without endometriosis throughout the menstrual cycle. DESIGN: Molecular studies in human tissue. SETTING: Department of Gynecology and Obstetrics, Reproductive Immunology Laboratory, Stanford University Medical Center. PATIENT(S): Fifty-three premenopausal woman (23 women with endometriosis and 30 women without endometriosis undergoing laparoscopic surgery). Endometrium and ectopic endometriosis tissue were obtained at the time of surgery. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): mRNA expression from eutopic and ectopic endometrium was analyzed by quantitative, competitive PCR. RESULT(S): Both uterine endometrium and ectopic endometriotic tissue from women with endometriosis expressed significantly (P<.05) lower levels of TIMP-3 than endometrium from normal women. Also, ectopic endometrium expressed higher levels of MMP-9 and a higher ratio of MMP-9/TIMP-3 than eutopic endometrium from normal and endometriosis patients. CONCLUSION(S): These results suggest that ectopic and eutopic endometrium from endometriosis patients may be more invasive and prone to peritoneal implantation because of greater MMP and less TIMP-3 mRNA expression than endometrium from women without endometriosis. Thus, increased proteolytic activity may be one of the reasons for the invasive properties of the endometrium, resulting in the development of endometriosis.     

Minimally invasive video-assisted graft replacement of a descending thoracic aortic aneurysm

Standard surgical therapy of descending thoracic aortic aneurysms entails obligate extensive operative exposure that is associated with significant postoperative pain and morbidity. A 70-year-old patient with multiple significant comorbidities including severe chronic obstructive pulmonary disease (force expiratory volume at 1 second, 0.66 L) presented with a highly symptomatic, eccentric, descending thoracic aortic aneurysm. The patient underwent successful minimally invasive video-assisted graft repair of this aneurysm. This report represents the first known clinical application of this operative approach.     

Destruxins,cyclodepsipeptides, block the formation of actin rings and prominent clear zones and ruffled borders in osteoclasts

Bone-resorbing osteoclasts exhibit polarized morphological structures such as actin rings, clear zones, and ruffled borders. To gain insight into the mechanism of bone-resorbing activity of osteoclast and to discover new types of anti-resorptive agents, we have screened for natural compounds that inhibit the bone-resorbing activity of osteoclast-like multinucleated cells (OCLs). Destruxin B (DestB) and E (DestE), cyclodepsipeptides, were found to inhibit pit formation without affecting osteoclast differentiation and survival. Destruxins reversibly induced morphological changes in OCLs in a dose-dependent manner (DestB, 0.2-1 microM; DestE, 0.01-0.05 microM) and inhibited pit formation. Destruxin-induced morphological changes were accompanied by disruption of the actin rings in OCLs. The formation of actin rings in OCLs after adhesion was also inhibited by destruxins. Electron microscopical analysis revealed that destruxin-treated OCLs on dentine slices have no prominent clear zones and ruffled borders. The effective concentrations of destruxins on the morphological changes were almost the same as those that inhibited bone resorption in organ culture system. These results suggest that the anti-resorptive effects of destruxins result from induction of a disorder of the morphological structures in polarized OCLs.     

Change in endothelial nitric oxide synthase in the rat retina following transient ischemia

Patterns of endothelial nitric oxide synthase (eNOS) expression in retinal ischemia were studied utilizing a transient high intraocular pressure (HIOP) model. We investigated neuronal cell damage and changes in eNOS immunoreactive expression in the ischemic retina, and its relationship to the neuroprotection of betaxolol treatment after ischemic injury. Immunohistochemical staining for eNOS was performed at 3, 7, 14 and 28 days after ischemia/reperfusion. In controls, eNOS immunoreactivity was detected in retinal vessels, but was not detected in neurons. After ischemia/reperfusion, the intensity of eNOS immunoreactivity increased in both retinal vessels and the ganglion cell layer (GCL) compared with controls. eNOS-positive neurons were induced first in the inner nuclear layer (INL) 7 days after reperfusion. However, when experiments were carried out on animals that had been treated with betaxolol after ischemia/reperfusion, the intensity of eNOS immunoreactivity decreased compared to the untreated ischemic retinas. These results suggest that an increase in eNOS expression could be associated with the degenerative changes in the ischemic retina, and that betaxolol treatment appears to protect retinal tissue from ischemic damage.