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.     

Antiangiogenic effect of KR-31372 by apoptosis via mediation of mitochondrial KATP channel opening and the phosphatase and tensin homolog deleted from chromosome 10 phosphorylation

Antiangiogenic action of (2R,3R,4S)-N"-cyano-N-(6-nitro-3,4-dihydro-hydroxy-2-methyl-2-dimethoxymethyl-2H-1-benzopyran-4yl)-N'-benzyl guanidine (KR-31372) was examined with its proapoptotic action in human umbilical vein endothelial cells (HUVECs) compared with diazoxide. KR-31372 as well as diazoxide significantly suppressed the neovascularization in mice induced by the Matrigel-containing recombinant human vascular endothelial growth factor (VEGF)165 in vivo and the basal tube formation of HUVECs in vitro with suppression of proliferation of HUVECs stimulated by VEGF165. KR-31372 and diazoxide enhanced DNA fragmentation associated with increase in phosphatase and tensin homolog deleted from chromosome 10 (PTEN) and decrease in serine/threonine kinase phosphorylation, which were accompanied by augmented Bax and cytochrome c release, and suppressed Bcl-2 in HUVECs. In the U87-MG cells, when transfected with expression vectors for sense PTEN, KR-31372 enhanced DNA fragmentation, but not in naive U87-MG cells. The suppression by KR-31372 and diazoxide of these variables was significantly antagonized by 5-hydroxydecanoic acid, a mitochondrial KATP channel blocker. Taken together, KR-31372 strongly inhibited angiogenesis in HUVECs by proapoptotic mechanism via mediation of 5-hydroxydecanoic acid-inhibitable mitochondrial KATP channel opening and PTEN phosphorylation.     

Annomolin and annocherimolin, new cytotoxic annonaceous acetogenins from Annona cherimolia seeds

Two new cytotoxic annonaceous acetogenins, annomolin (1) and annocherimolin (2), were isolated from an ethanolic extract of the seeds of Annona cherimolia. Annomolin has a mono-THF ring with one flanking hydroxyl and possesses a 1,2-diol at C-7/8 of the aliphatic chain. Annocherimolin has a mono-THF ring with two flanking hydroxyls and possesses a double bond at C-21/22. Their structures were elucidated by spectral data and chemical derivatization. Compound 1 showed cytotoxic selectivity for the human prostate tumor cell line (PC-3), with a potency of over 10,000 times that of adriamycin. Compound 2 showed cytotoxic potencies about 10,000 times those of adriamycin in the breast (MCF-7) and colon (HT-29) cancer cell lines.     

4-Hydroxy-6-oxo-6,7-dihydro-thieno[2,3-b] pyrimidine derivatives: synthesis and their biological evaluation for the glycine site acting on the N-methyl-D-aspartate (NMDA) receptor

Bioisostere approach has been shown to be useful to augment potency or to modify certain physiological properties of a lead compound. Based upon well documented bioisosterism, an isosteric replacement of benzene ring of 4-hydroxy-2-quinolone compound (L-695902) with a thiophene moiety was carried out to prepare the title compounds, 4-hydroxy-6-oxo-6,7-dihydro-thieno[2,3-b] pyrimidines 15. The resulting bioisosteric compounds 15 were evaluated for their antagonistic activity (binding assay) for NMDA receptor glycine site.     

Assessment of total energy expenditure in a Chinese population by a physical activity questionnaire: examination of validity

A physical activity questionnaire from which total daily energy expenditure (TEE) could be estimated was developed for adult Hong Kong Chinese subjects, and its reliability and validity examined. The questionnaire was based on questionnaires used in Caucasians, and adapted for local lifestyle after focus group meetings involving subjects of all age groups. The questionnaire was administered to 94 subjects, consisting of healthy adults, the elderly, and two patient groups (those with renal disease on continuous ambulatory peritoneal dialysis and those with cancer). Seventy-one subjects were reinterviewed within 14 days to test reliability. Validity was examined in 31 normal subjects by measuring the basal metabolic rate (BMR) by indirect calorimetry and multiplying by the physical activity level (PAL) obtained from published studies using the doubly labelled water method and also from FAO/WHO/UNU to obtain the TEE. The intraclass correlation coefficient of reliability rages from 0.7 to 0.8 for all subject groups. The mean estimated TEE from the questionnaire was not significantly different from the mean value derived from measured BMR x PAL. The mean bias ranged from an underestimation of 27 kcal to overestimation of 215 kcal. However, the limits of variability were wide. Age was inversely related to the energy expended for occupational activities, but was positively associated with energy expended in leisure activities. Women spent less energy on occupational and exercise activities, and more on caretaking activities. Those with disease were also less likely to participate in caretaking activities. We conclude that this questionnaire may be a useful tool for future studies where energy expenditure needs to be estimated in various settings in the Hong Kong Chinese population.     

Thermal—electrical finite element modelling for radio frequency cardiac ablation: Effects of changes in myocardial properties

Finite element (FE) analysis has been utilised as a numerical tool to determine the temperature distribution in studies of radio frequency (RF) cardiac ablation. However, non of the previous FE analyses clarified such computational aspects as software requirements, computation time or convergence test. In addition, myocardial properties included in the previous models vary greatly. A process of FE modelling of a system that included blood, myocardium, and an ablation catheter with a thermistor embedded at the tip is described. The bio-heat equation is solved to determine the temperature distribution in myocardium using a commercial soft-ware application (ABAQUS). A Cauchy convergence test (∈=0.1°C) was performed and it is concluded that the optimal number of elements for the proposed system is 24610. The effects of changes in myocardial properties (±50% electric conductivity, +100%/−50% thermal conductivity, and +100%/−50% specific heat capacity) in both power-controlled (PCRFA) and temperature-controlled RF ablation (TCRFA) were studied. Changes in myocardial properties affect the results of the FE analyses of PCRFA more than those of TCRFA, and the maximum changes in lesion volumes were −58.6% (−50% electric conductivity), −60.7% (+100% thermal conductivity), and +43.2% (−50% specific heat).     

Investigation of juxtasellar and cerebellopontine angle meningiomas and neurogenic tumours: two-phase helical CT

We performed two-phase helical CT in 31 patients with juxtasellar region and cerebellopontine angle tumours to evaluate its usefulness in differentiating meningiomas from neurogenic tumours. After the intravenous injection of 90 ml contrast medium at 3 ml/s, axial helical images were obtained with delays of 30 and 120 s. After the delayed axial images, we acquired coronal images. Changes in attenuation were assessed visually and quantitatively (by comparing the attenuation in Hounsfield units). There were 17 meningiomas and 14 neurogenic tumours, all pathologically proven. Two-phase helical CT showed a decrease in attenuation in 15 (88 %) meningiomas and an increase in 14 (100 %) neurogenic tumours from early to delayed axial images. Coronal images showed a decrease in attenuation in all 17 meningiomas and an increase in 13 (93 %) of the neurogenic tumours. The mean HU and their ratios were significantly different between meningiomas and neurogenic tumours. Received: 22 August 2000 Accepted: 13 October 2000