Phenanthrenoids from Juncus acutus L., new natural lipopolysaccharide-inducible nitric oxide synthase inhibitors

The novel natural product juncutol (1), 1,4,7-trimethyl-8,9-dihydro-4H-cyclopenta[def]phenanthrene-2,6-diol, along with the three related metabolites juncusol (2), dehydrojuncusol (3), and 6-hydroxymethyl-1-methyl-5-vinyl-9,10-dihydrophenanthrene-2-ol (4), were isolated from the rhizomes of Juncus acutus L. (Juncaceae) growing in Egypt. The structural identity of 1 was determined on the basis of spectroscopic analyses, including 2D NMR spectroscopy. The inhibitory effect of these natural products on the expression of inducible nitric oxide synthase (iNOS) in lipopolysaccharide-stimulated RAW264.7 macrophage cells was determined for the first time. The unprecedented symmetrical compound juncutol (1) was found to be the most potent inhibitor against the induction of the proinflammatory iNOS protein.     

Terpenoid-related metabolites from a formosan soft coral Nephthea chabrolii

Two new sesquiterpenoidal natural products chabrolidiones A and B (1 and 2), two C(18) terpenoid-related carboxylic acids, ketochabrolic acid (3) and isoketochabrolic acid (4), and one naphthoquinone derivative chabrolonaphthoquinone C (5), along with two known compounds (+)-aristolone (6) and teuhetenone A (7) were isolated from a Formosan soft coral Nephthea chabrolii. The structures of the new metabolites were determined on the basis of extensive spectroscopic analysis and by comparison of NMR data with those of related metabolites. Metabolite 1 has been synthesized previously, but was isolated for the first time from natural sources. Cytotoxic activity of metabolites 1-3 and 5-7 against a limited panel of cancer cell lines is also described.     

On decoding of both errors and erasures of a Reed-Solomon codeusing an inverse-free Berlekamp-Massey algorithm

In a previous article by Truong et al. (see ibid., vol.46, p.973-76, 1998), it was shown that an inverse-free Berlekamp-Massey (1968, 1969) algorithm can be generalized to find the error locator polynomial in a Reed-Solomon (RS) decoder for correcting errors as well as erasures. The basic idea of this procedure is the replacement of the initial condition of an inverse-free BM algorithm by the Forney (1965) syndromes. It is shown that the errata locator polynomial can be obtained directly by initializing an inverse-free BM algorithm with the erasure locator polynomial and the syndromes. An important ingredient of this new algorithm is a modified BM algorithm for computing the errata locator polynomial. As a consequence, the separate computation of the erasure locator polynomial and the Forney syndrome, needed in the decoder developed by Truong et al., are completely avoided in this modification of the BM algorithm. This modified algorithm requires fewer finite field addition and multiplication operations than the previous algorithm. Finally, the new decoding method was implemented on a computer using C++ language. It is shown in a simulation that the speed of this new decoder is faster than the decoder developed by Truong et al. An example using this program is given for an (255, 239) RS code for correcting errors and erasures with 2ν+s⩽10     

Chemical Constituents of a Formosan Soft Coral Sinularia sp.

A new marine sterol 7β-hydroperoxy-24-methylenecholesterol ( 1 ) along with five known compounds sarcophytol A ( 2 ), (Z)-N-[2-(4-hydroxyphenyl)ethyl]-3-methyldodec-2-enamide ( 3 ), 5α,7αH-eduesm-11(13)en-4α-ol ( 4 ), 24-methylenecholesterol ( 5 ) and 1β-hydroxy-α-cyperone ( 6 ) have been isolated from a Formosan soft coral Sinularia sp. The structures of the above compounds were determined by spectral analyses. Cytotoxicity of compounds 1–6 toward various cancer cell lines also is reported.     

5-epi-Sinuleptolide from Soft Corals of the Genus Sinularia Exerts Cytotoxic Effects on Pancreatic Cancer Cell Lines via the Inhibition of JAK2/STAT3, AKT,and ERK Activity

Pancreatic ductal adenocarcinoma is one of the most lethal malignancies: more than half of patients are diagnosed with a metastatic disease, which is associated with a five-year survival rate of only 3%. 5-epi-Sinuleptolide, a norditerpene isolated from Sinularia sp., has been demonstrated to possess cytotoxic activity against cancer cells. However, the cytotoxicity against pancreatic cancer cells and the related mechanisms are unknown. The aim of this study was to evaluate the anti-pancreatic cancer potential of 5-epi-sinuleptolide and to elucidate the underlying mechanisms. The inhibitory effects of 5-epi-sinuleptolide treatment on the proliferation of pancreatic cancer cells were determined and the results showed that 5-epi-sinuleptolide treatment inhibited cell proliferation, induced apoptosis and G2/M cell cycle arrest, and suppressed the invasion of pancreatic cancer cells. The results of western blotting further revealed that 5-epi-sinuleptolide could inhibit JAK2/STAT3, AKT, and ERK phosphorylation, which may account for the diverse cytotoxic effects of 5-epi-sinuleptolide. Taken together, our present investigation unveils a new therapeutic and anti-metastatic potential of 5-epi-sinuleptolide for pancreatic cancer treatment.     

Performance evaluation of uplink power control algorithm over TDMA systems

Future PCS (personal communication system) cellular networks will mainly be driven by high link quality, high bandwidth utilization, low power consumption and efficient network management. Power control is one of the several major techniques which could help to achieve these goals. By exploiting power control techniques, co-channel interference could be reduced and as many links as possible could be obtained with satisfactory link quality. SIR-based (signal-to-interference ratio-based) power control was proposed as a technique for managing co-channel interference in cellular radio systems. Furthermore, new distributed autonomous feedback power control methods were introduced to achieve excellent performance without the difficult centralized control used in SIR-based methods. Unfortunately, the implementation of those power control algorithms is still challenging owing to the precision of SIR. The main aim of this paper is to investigate an uplink power control algorithm which depends indirectly on the signal-to-noise ratio in the TDMA (time division multiple access) cellular system. Simulation of the prototype hardware implementation of the receiver baseband signal processing based on the PACS (personal access communications system) specification is used as the main approach to explore the performance evaluation of this power control technique. According to simulation results, suitable values of those parameters used in this power control algorithm are derived, and the minimum frequency reuse factor under different propagation environments is also obtained for PACS under power control. © 1998 John Wiley & Sons, Ltd.     

Sinugibberosides A-E, new terpenoids with cyclic peroxyhemiketal from the soft coral Sinularia gibberosa

The organic extract of the soft coral Sinularia gibberosa, collected from the northern Taiwan, has been investigated and resulted in the isolation of five new xeniaphyllane-type diterpenoids with a rare cyclic peroxyhemiketal (3,6-dihydro-1,2-dioxin-3-ol) moiety, sinugibberosides A-E (1-5). The structures of the new terpenoids, including their stereochemistries, were established on the basis of extensive spectroscopic analysis, including 1D and 2D NMR (¹H-¹H COSY, HMQC, HMBC, and NOESY), and by comparison of their NMR data with those of related compounds. Metabolites 1-5 represent the first example of marine terpenoids possessing a cyclic peroxyhemiketal moiety.     

Briarenolide E: the first 2-ketobriarane diterpenoid from an octocoral Briareum sp. (Briareidae)

A novel 2-ketobriarane diterpenoid, briarenolide E (1), was isolated from an octocoral Briareum sp. The structure of briarane 1 was elucidated by interpretations of spectral data. Compound 1 displayed modestly inhibitory effects on the generation of superoxide anions and the release of elastase by human neutrophils.     

Performance evaluation of a joint CDMA/NC-PRMA protocol forwireless multimedia communications

A joint code division multiple access and noncollision packet reservation multiple access (CDMA/NC-PRMA) technique is proposed and investigated as an uplink protocol for the third-generation (3G) mobile systems. Being the underlying time division multiple access (TDMA) architecture of the CDMA transmissions, NC-PRMA enables the base station (BS) to have a centralized control over the slot allocation policy. In order to reduce the multiple access interference (MAI) variation in a CDMA transmission, two different slot assignment schemes, referred to as load-balancing (LB) and power-grouping (PG) schemes, are proposed and evaluated. Simulation results show that considerable improvement can be achieved over the joint CDMA/PRMA scheme, in which the MAI variation is reduced by way of a dynamic permission probability for contending terminals. Especially when an imperfect power control mechanism is considered, the proposed PG assignment scheme achieves significant performance advantages     

Theoretical Analysis and Performance of NC-PRMA Protocol for Multichannel Wireless Networks

In this paper, we analyze the effect of duplexing schemes on the throughput and the average packet dropping probability of a new multichannel wireless access protocol which allows for non-collision packet reservation multiple access with multiple channel (NC-PRMA/MC). N _C equal-capacity, orthogonal, traffic channels are shared by M mobile users on the uplink. Transmission attempts on the uplink are made by using time-frequency signaling in every frame, which enables transmission attempts of mobile users to be conveyed to the base station without collisions. Two kinds of duplexing schemes, frequency division duplexing and shared time division duplexing, are considered in the performance analysis. Using a discrete-time Markov chain analysis, we derive the analytic expressions for the average per channel throughput and the average packet dropping probability. Computer simulation results verify the analysis. Analytical evaluation and computer simulation show that NC-PRMA/MC with shared time division duplexing improves the channel capacity, which approaches the theoretical upper bound. Jenn-Kaie Lain born in Taiwan, R.O.C., in 1973. He received the B.E. degree in engineering science from the National Cheng Kung University, Tainan, Taiwan, R.O.C., and the Ph.D. degree in electrical engineering from the National Chung Cheng University, Chiayi, R.O.C., in 1995 and 2001, respectively. Since August 2001, he joined the faculty of Department of Computer Science and Information Engineering at Shu-Te University, Kaohsiung, Taiwan, R.O.C., as an Assistant Professor. He has been on the Faculty at National Yunlin University of Science and Technology, Yunlin, Taiwan, R.O.C., since August 2002 and currently holds the position of Assistant Professor in the Institute of Electronic and Information Engineering. His current research interest is in the field of coding and modulation as well as efficient receiver designs for broadband wireless communications. Jyh-HorngWen received his B.S. degree in Electronic Engineering from the National Chiao Tung University, Hsing-Chu, Taiwan, in 1979 and the Ph.D. degree in Electrical Engineering from the National Taiwan University, Taipei, in 1990. From 1981 to 1983, he was a Research Assistant with the Telecommunication Laboratory, Ministry of Transportation and Communications, Chung-Li, Taiwan. From 1983 to 1991, he was a Research Assistant with the Institute of Nuclear Energy Research, Taoyun, Taiwan. Since February 1991, he has been with the Institute of Electrical Engineering, National Chung Cheng University, Chia-Yi, Taiwan, first as an Associate Professor and, since 2000, as a Professor. He was also the Managing Director of the Center for Telecommunication Research, National Chung Cheng University, from Aug. 2000 to July 2004. Currently, he is also the Dean of General Affairs, National Chi Nan University. He is an Associate Editor of the Journal of the Chinese Grey System Association. His current research interests include computer communication networks, cellular mobile communications, personal communications, spread-spectrum techniques, wireless broadband systems, and gray theory. Prof.Wen is a member of the IEEE Communication Society, the IEEE Vehicular Technology Society, the International Association of Science and Technology for Development,the Chinese Grey System Association, and the Chinese Institute of Electrical Engineering.