Cytotoxic effects of topotecan combined with various anticancer agents in human cancer cell lines

BACKGROUND: Topotecan (TPT) is a topoisomerase I poison that exhibits antineoplastic activity. Analysis of the cytotoxic effects of combinations of TPT and other anticancer agents has been limited. PURPOSE: We assessed the cytotoxic effects produced by combinations of TPT and other antineoplastic agents in experiments involving multiple human cancer cell lines of diverse histologic origins. METHODS: The cytotoxic effects of various antimetabolites (fluorouracil, methotrexate, or cytarabine), antimicrotubule agents (vincristine or paclitaxel [Taxol]), DNA alkylating agents (melphalan, bis[chloroethyl]nitrosourea [BCNU], or 4-hydroperoxycyclophosphamide [4HC]), and a DNA-platinating agent (cisplatin), alone and in combination with TPT, were measured in clonogenic (i.e., colony-forming) assays. HCT8 ileocecal adenocarcinoma, A549 non-small-cell lung carcinoma, NCI-H82ras(H) lung cancer, T98G glioblastoma, and MCF-7 breast cancer cell lines were used in these assays. The data were analyzed by the median effect method, primarily under the assumption that drug mechanisms of action were mutually nonexclusive (i.e., completely independent of one another). For each level of cytotoxicity (ranging from 5% to 95%), a drug combination index (CI) was calculated. A CI less than 1 indicated synergy (i.e., the effect of the combination was greater than that expected from the additive effects of the component agents), a CI equal to 1 indicated additivity, and a CI greater than 1 indicated antagonism (the effect of the combination was less than that expected from the additive effects of the component agents). RESULTS: When the mechanisms of drug action were assumed to be mutually nonexclusive, virtually all CIs for combinations of TPT and either antimetabolites or antimicrotubule agents revealed cytotoxic effects that were less than additive. The CIs calculated at low-to-intermediate levels of cytotoxicity for combinations of TPT and the DNA alkylating agents melphalan, BCNU, and 4HC also showed drug effects that were less than additive; in most cases, however, nearly additive or even synergistic effects were observed with these same drug combinations at high levels of cytotoxicity (i.e., at > or = 90% inhibition of colony formation). Results obtained with combinations of TPT and cisplatin varied according to the cell line examined. With A549 cells, less than additive effects were seen at low-to-intermediate levels of cytotoxicity, and more than additive effects were seen at high levels of cytotoxicity. With NCI-H82ras(H) cells, synergy was observed over most of the cytotoxicity range. CONCLUSIONS AND IMPLICATIONS: TPT cytotoxicity appears to be enhanced more by combination with certain DNA-damaging agents than by combination with antimetabolites or antimicrotubule agents. Interactions between TPT and other drugs can vary depending on the cell type examined. Further investigation is required to determine the basis of the observed effects and to determine whether these in vitro findings are predictive of results obtained in vivo.     

Development of a recurrent Sigma-Pi neural network rainfall forecasting system in Hong Kong

At the moment, weather forecasting is still an art — the experience and intuition of forecasters play a significant role in determining the quality of forecasting. This paper describes the development of a new approach to rainfall forecasting using neural networks. It deals with the extraction of information from radar images and an evaluation of past rain gauge records to provide shortterm rainfall forecasting. All of the meteorological data were provided by the Royal Observatory of Hong Kong (ROHK). Preprocessing procedures were essential for this neural network rainfall forecasting. The forecast of the rainfall was performed every half an hour so that a storm warning signal can be delivered to the public in advance. The network architecture is based on a recurrent Sigma-Pi network. The results are very promising, and this neural-based rainfall forecasting system is capable of providing a rain storm warning signal to the Hong Kong public one hour ahead.     

CMV colitis masquerading as colon cancer--an unusual presentation of acquired immunodeficiency syndrome

To determine whether there is any correlation between sudden decrease in barometric pressure and onset of labor, a non-experimental, retrospective study at a 948-bed tertiary care hospital was done. Pregnant patients of 36 weeks gestation or more who presented with spontaneous onset of labor during the 48 hours surrounding the 12 occurrences of significant drop in barometric pressure in 1992 were included in the study. Significantly more occurrences of onset of labor were identified in the 24 hours after a drop in barometric pressure than were identified in the 24 hours prior to the drop in barometric pressure (P < 0.05). Therefore, the overall number of labor onsets increased in the 24 hours following a significant drop in barometric pressure.     

CT of appendicitis in children

PURPOSE: Our goal was to review the CT findings and to help define the role of CT in the evaluation of appendicitis in children. METHOD: Of 730 children with surgically proven appendicitis, 22 underwent preoperative CT evaluation. Their CT scans and operative and pathology records were retrospectively reviewed. The CT scans were evaluated for appendiceal wall thickness, diameter, and location, appendicoliths, pericecal inflammation, phlegmon, abscess, free fluid, small bowel dilatation, and bowel wall thickening. Criteria for diagnosing appendicitis were (a) appendiceal wall thickening (> 1 mm) or (b) presence of abscess, phlegmon, or pericecal inflammation associated with appendicolith(s). Prospective reports of ultrasound examinations performed within 2 days of the CT scans were available in 14 children and were correlated with the CT findings. RESULTS: An abnormally thickened appendix, with a diameter ranging from 9 to 18 mm, was seen in four children. Three appendices were retrocecal and one was near the cecal tip, anterior to the iliac vessels. Appendicoliths were present in 10 children, multiple in 1. Abscesses were seen in 13 of 22 children, multiple in 5. Phlegmon was seen in five children and pericecal inflammation in two. Bowel wall thickening was present in seven children and small bowel dilatation was noted in six. Other findings included free fluid, hydronephrosis, thickening of urinary bladder wall, air in the uterus and vagina, adenopathy, and thickening of the abdominal wall musculature. CT was diagnostic of appendicitis in 11 of 22 children (50%). In 14 children with both ultrasound and CT studies, CT was slightly better in diagnosing appendicitis and visualizing the abnormal appendix and was superior in defining the presence and extent of abscess and inflammation in 9 of 14 children. CONCLUSION: CT is a useful adjunct in diagnosing appendicitis in children, with a major role in cases of complicated appendicitis.     

Power Distribution Fault Cause Identification With Imbalanced Data Using the Data Mining-Based Fuzzy Classification E-Algorithm

Power distribution systems have been significantly affected by many outage-causing events. Good fault cause identification can help expedite the restoration procedure and improve the system reliability. However, the data imbalance issue in many real-world data sets often degrades the fault cause identification performance. In this paper, the E-algorithm, which is extended from the fuzzy classification algorithm by Ishibuchi to alleviate the effect of imbalanced data constitution, is applied to Duke Energy outage data for distribution fault cause identification. Three major outage causes (tree, animal, and lightning) are used as prototypes. The performance of E-algorithm on real-world imbalanced data is compared with artificial neural network. The results show that the E-algorithm can greatly improve the performance when the data are imbalanced     

Plasmid DNA is protected against ultrasonic cavitation-induced damage when complexed to cationic liposomes

Cationic liposomes bound to plasmid DNA are currently used for in vitro and in vivo gene therapy applications, but such complexes readily form large, heterogeneous aggregates that are not appropriate for pharmaceutical development. More importantly, size heterogeneity makes studies focused on optimizing gene transfer to cells difficult to conduct or understand. For this reason we have evaluated the effect of microprobe sonication on these complexes in an effort to achieve process-controlled size homogeneity. Complexes were prepared using a 7.2 kb reporter plasmid and the following liposomal lipid combinations: DDAB/DOPE (50:50 mol %), DDAB/DOPE/PEG-PE (50:45:5 mol %), DDAB/EPC (50:50 mol %), DDAB/EPC/PEG-PE (50:45:5, 50:40:10, 50:35:15 mol %), DODAC/DOPE (50:50 mol %), and DODAC/EPC (50:50 mol %) (DDAB, dimethyldioctadecylammonium bromide; DOPE, dioleoylphosphatidylethanolamine; PEG-PE, monomethoxypolyethylene glycol2000 succinate- distearoylphosphatidylethanolamine; EPC, egg phosphatidylcholine; DODAC, dioleoyldimethylammonium chloride). The influence of complex composition and lipid:DNA ratio was evaluated. Particle size was determined before and after complexation and again after sonication using the quasi-elastic light scattering technique. DNA integrity was assessed via agarose gel electrophoresis. Finally, gene transfection was evaluated using CHO cells that were transfected in vitro with sonicated and unsonicated complexes. It is established in this study that size reduction can occur, but this is dependent on cationic and neutral lipid composition and, in some cases, lipid:DNA ratio. Surprisingly, the process of sonication leaves a significant percentage of the plasmid DNA intact and capable of in vitro transfection. This study shows that plasmid DNA can be protected from damage due to sonication by liposome complex formation. This may indicate that more common pharmaceutical methods for size reduction which subject particles to mechanical stress may be applicable in preparation of liposome/DNA formulations for in vivo application.     

Improved accuracy of burn wound assessment using laser Doppler

The utility of the laser Doppler for determining burn depth has been questioned because of problems with technology and methodology. This study prospectively evaluates the ability of a new laser Doppler technique to predict burn healing time. Using the Periflux System 4000 laser Doppler, readings were taken on 305 burns (147 patients) on postburn day 3 or 4. Sixty-six wounds were used to derive a predictive function (phase I) and 152 wounds were used to test the function (phase II). Blood flow dynamics (flux), microvascular dilation capacity of the wounds to beat stress, and flow motion wave pattern (vasomotion) were studied using the laser Doppler, and seven parameters were evaluated to determine their relative contribution to the prediction of healing time. These parameters are hyperemic flux (flux value after heating to 42 degrees C), average hyperemic wave amplitude (AHWA), number of average flux units >100(F100), number readings with wave amplitude 75 (A5), average flux change (AFC), percentage of average flux increase, and relative flow capacity (RFC = AFC/average hyperemic flux). After readings were made, the wounds were observed and divided into two groups: those that healed in less than 14 days and those that healed or were grafted after 14 days. A step-wise discriminant analysis was used to assess the relative contribution of the Doppler-derived measures to healing time prediction. AHWA, F100, and RFC were included in the final discriminant function explaining 72% of the healing time variance (Wilks' lambda value 0.28; p value <0.0001). Predicted outcome = 0.05(AHWA) + 0.31(F100) + 5.0(RFC) - 2.3. With this derived function, there is 94% accuracy in the prediction of burn wound healing time compared with a physician predictive accuracy of 70%.     

The Transmogrifier-2: a 1 million gate rapid-prototyping system

This paper describes the Transmogrifier-2 (TM-2), a second-generation multifield programmable gate array (FPGA) rapid-prototyping system. The largest version of the system will comprise 16 boards that each contain two Altera 10K50 FPGA's, four I-Cube interconnect chips, and up to 8 Mbytes of memory. The inter-FPGA routing architecture of the TM-2 uses a novel interconnect structure, a nonuniform partial crossbar, that provides a constant delay between any two FPGA's in the system. The TM-2 architecture is modular and scalable, meaning that systems of various sizes can be constructed from copies of the same board, while maintaining routability and the constant delay feature. Other features include a system-level programmable clock that allows single-cycle access to off-chip memory, and programmable clock waveforms with edge resolution of 10 ns. The first Transmogrifier-2 boards have been manufactured and are functional. They have recently been used successfully in some simple graphics acceleration applications