Role of GTP-binding proteins in the polyunsaturated fatty acid stimulated proliferation of mouse mammary epithelial cells

Polyunsaturated fatty acids enhance the proliferation of mouse mammary epithelial cells stimulated by epidermal growth factor (EGF) by modulating the post-receptor signaling pathways. The growth stimulatory effect of these fatty acids is completely inhibited by pertussis toxin, whereas the inhibition of EGF and insulin stimulated growth is only partial. The treatment of cell cultures with 12-O-tetradecanoyl-phorbol-13 acetate (TPA) reverses the growth inhibitory effect of pertussis toxin and fully restores the growth as was in the control cultures untreated with the toxin suggesting a role for PKC in this reversal. It appears that the functions of Gi-proteins are required in the mediation of fatty acid effect on growth. The predominant types of Gi alpha in mammary epithelial cells are Gi alpha 1, Gi alpha 2, and Gi alpha 3. Among these, the levels of Gi alpha 1 and 2 appears to be regulated by steroid hormones. Linoleic acid raises the level of GTP-bound Ras in the cells above the levels induced by EGF. Pertussis toxin reduces the level of Ras-GTP and inhibits phosphorylation of MAP kinase by EGF. It has been speculated that Gi-proteins interact with the receptor bound nucleotide exchange factor and the membrane anchored Raf kinase and constitute two sites for pertussis toxin action. The phosphorylation by PKC may uncouple Gi-protein interaction with these effectors and enable the agonist-induced signals to bypass the inhibitory action of PT on growth.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dietary supplementation of nucleotides and arginine promotes healing of small bowel ulcers in experimental ulcerative ileitis

We previously showed that intravenous total parenteral nutrition supplemented with nucleosides and nucleotides (NS/NT) promoted ulcer healing in rats with indomethacin-induced ileitis. The present study evaluated whether dietary NT supplementation would similarly affect ulcer healing in this model. Female Lewis rats were randomized into either control or experimental groups receiving yeast RNA containing NT or arginine, glutamine, fish oil, guar gum, or a combination of yeast RNA+arginine diets. Ileitis was induced by two doses of indomethacin (7.5 mg/kg) administered subcutaneously 24 hr apart. Ulcer number and length were determined at 4, 8, and 14 days after induction of ileitis. Ileal villous and crypt length, crypt-villous ratio, and bromodeoxyuridine (BrdU) labeling were studied in the control and yeast RNA-supplemented diet groups. Ileal ulceration was present in all groups at 4 and 8 days and was almost healed by 14 days. Rats receiving yeast RNA, arginine, and yeast RNA + arginine diets showed a significant decrease in ulcer number (56%, 28%, and 34%, respectively) and length (67%, 41%, and 48%, respectively) compared to controls at 8 but not at 4 days. Glutamine, fish oil, and guar gum had no effect on ulcer healing at 4, 8, or 14 days. Among the histological parameters, a significant decrease in crypt length in the yeast RNA-supplemented group at 8 days suggested an acceleration of the healing process and restoration to a near-normal crypt-villous architecture. We conclude that the yeast RNA, arginine, and yeast RNA + arginine diets accelerated ulcer healing, as indicated by decreased ulcer number and length. We postulate that the underlying mechanism(s) contributing to ulcer healing may be related, in part, to increased cell proliferation.     

Ecological observations on the anopheline mosquitoes of Jalpaiguri Duars, West Bengal

OBJECTIVES: To assess the impact of Vitamin A supplementation to the mother soon after delivery and to the infant at six months on morbidity in infancy. DESIGN: Randomized double blind placebo controlled field trial. SETTING: 51 villages in two contiguous Primary Health Centers in Villupuram Health Unit District of Tamil Nadu, South India. SUBJECTS: 909 newly delivered mother-and-infant pairs. INTERVENTIONS: Both mother and infant received Vitamin A (300,000 IU for mothers and 200,000 IU for children) in 311 instances (AA); mother received Vitamin A but infant received Placebo in 301 instances (AP); and both mother and infant received Placebo in the remaining 297 instances (PP). MAIN OUTCOME MEASURES: Incidence of diarrhea and Acute Respiratory Infection (ARI); distributions of infants by frequency of episodes and number of infected days. RESULTS: 233 in the AA Group and 228 each in the AP and PP Groups were followed up regularly. The incidence of diarrhea in these infants was 97.4%, 96.9% and 94.7% in the three groups, mean number of diarrheal episodes was 4.4, 4.6 and 4.2 and median number of days in infancy with diarrhea was 26, 26 and 22 days, respectively. For ARI, the incidences were 96.6%, 95.6% and 96.1%, means were 4.8, 5.1 and 4.8 episodes, and the medians were 32, 34 and 34 days, respectively. CONCLUSIONS: Prophylactic administration of mega doses of Vitamin A to the mother soon after delivery and to the infant at six months do not have any beneficial impact on the incidence of diarrhea and ARI in infancy.     

Electro-Discharge Machining of Inconel 825 Super alloy: Effects of Tool Material and Dielectric Flushing

Aspects of machinability of Inconel 825 super alloy during electro-discharge machining was attempted in this work. The extent of machinability was investigated in purview of process performance (i.e. material removal rate), surface integrity (morphology as well as topography) of the EDMed work surface including surface roughness, surface crack density, white layer thickness, and micro-indentation hardness. Effects of variation of tool material (graphite, tungsten, brass and copper) were analyzed in this work. Metallurgical characteristics of the EDMed work surface were studied in view of phase information (matrix and precipitates), grain refinement (crystallite size, micro-strain and dislocation density) etc. Results were further interpreted in support of EDS, and micro-hardness test data. Additionally, effects of flushing condition (with and without flushing) of the dielectric medium were examined on influencing EDM performance on Inconel 825 work material. Moreover, effects of peak discharge current on EDM responses were discussed.

     

Study of transition metal ion doped mullite by positron annihilation techniques

Mullite, an extremely useful ceramic material, is doped with transition metal ions. The changes in the electronic properties of these doped materials have been studied by positron annihilation lifetime spectroscopy as well as Doppler broadened line shape analysis. The results on the positron annihilation parameters are characteristic of ionic size, oxidation state and the d-electron configuration of the respective transition metals doped in the parent lattice of the mullite. These results, along with the resistivity measurements are suggestive of transition of the parent mullite from an insulator to a semimetal in the modified structure.     

Temporal link prediction in multi-relational network

Link prediction problem in complex networks has received substantial amount of attention in the field of social network analysis. Though initial studies consider only static snapshot of a network, importance of temporal dimension has been observed and cultivated subsequently. In recent times, multi-domain relationships between node-pairs embedded in real networks have been exploited to boost link prediction performance. In this paper, we combine multi-domain topological features as well as temporal dimension, and propose a robust and efficient feature set called TMLP (Time-aware Multi-relational Link Prediction) for link prediction in dynamic heterogeneous networks. It combines dynamics of graph topology and history of interactions at dyadic level, and exploits time-series model in the feature extraction process. Several experiments on two networks prepared from DBLP bibliographic dataset show that the proposed framework outperforms the existing methods significantly, in predicting future links. It also demonstrates the necessity of combining heterogeneous information with temporal dynamics of graph topology and dyadic history in order to predict future links. Empirical results find that the proposed feature set is robust against longitudinal bias.     

$$C^3$$-index: a PageRank based multi-faceted metric for authors’ performance measurement

Ranking scientific authors is an important but challenging task, mostly due to the dynamic nature of the evolving scientific publications. The basic indicators of an author’s productivity and impact are still the number of publications and the citation count (leading to the popular metrics such as h-index, g-index etc.). H-index and its popular variants are mostly effective in ranking highly-cited authors, thus fail to resolve ties while ranking medium-cited and low-cited authors who are majority in number. Therefore, these metrics are inefficient to predict the ability of promising young researchers at the beginning of their career. In this paper, we propose \(C^3\)-index that combines the effect of citations and collaborations of an author in a systematic way using a weighted multi-layered network to rank authors. We conduct our experiments on a massive publication dataset of Computer Science and show that—(1) \(C^3\)-index is consistent over time, which is one of the fundamental characteristics of a ranking metric, (2) \(C^3\)-index is as efficient as h-index and its variants to rank highly-cited authors, (3) \(C^3\)-index can act as a conflict resolution metric to break ties in the ranking of medium-cited and low-cited authors, (4) \(C^3\)-index can also be used to predict future achievers at the early stage of their career.     

Failure Analysis of High-Pressure Compressor Blade in an Aero Gas Turbine Engine

Failure of high-pressure compressor rotor blade in an aero gas turbine engine is analyzed to determine its root cause. Forensic and metallurgical investigations are carried out on the blade and failed parts. The failure of the platform ladder is found to the first in the chain of events that led to the compressor blade failure. The mode of failure in the blade is found to be fatigue and has originated from the damaged region on the leading edge caused by dislodgement of platform ladder. The failure has caused extensive damages in high-pressure compressor module and also in downstream turbine blades as a secondary effect.     

Intrusion Detection System for PS-Poll DoS Attack in 802.11 Networks Using Real Time Discrete Event System

Wi-Fi devices have limited battery life because of which conserving battery life is imperative. The 802.11 Wi-Fi standard provides power management feature that allows stations (STAs) to enter into sleep state to preserve energy without any frame losses. After the STA wakes up, it sends a null data or PS-Poll frame to retrieve frame(s) buffered by the access point (AP), if any during its sleep period. An attacker can launch a power save denial of service (PS-DoS) attack on the sleeping STA(s) by transmitting a spoofed null data or PS-Poll frame(s) to retrieve the buffered frame(s) of the sleeping STA(s) from the AP causing frame losses for the targeted STA(s). Current APproaches to prevent or detect the PS-DoS attack require encryption, change in protocol or installation of proprietary hardware. These solutions suffer from expensive setup, maintenance, scalability and deployment issues. The PS-DoS attack does not differ in semantics or statistics under normal and attack circumstances. So signature and anomaly based intrusion detection system (IDS) are unfit to detect the PS-DoS attack. In this paper we propose a timed IDS based on real time discrete event system (RTDES) for detecting PS-DoS attack. The proposed DES based IDS overcomes the drawbacks of existing systems and detects the PS-DoS attack with high accuracy and detection rate. The correctness of the RTDES based IDS is proved by experimenting all possible attack scenarios.