Validation of fluorescence transition probability calculations

A systematic and quantitative validation of the K and L shell X-ray transition probability calculations according to different theoretical methods has been performed against experimental data. This study is relevant to the optimization of data libraries used by software systems, namely Monte Carlo codes, dealing with X-ray fluorescence. The results support the adoption of transition probabilities calculated according to the Hartree-Fock approach, which manifest better agreement with experimental measurements than calculations based on the Hartree-Slater method.Comment: 8 pages, 21 figures and images, 3 tables, to appear in proceedings of the Nuclear Science Symposium and Medical Imaging Conference 2009, Orland

Role of a Conserved Glutamate Residue in the \u3cem\u3eEscherichia coli\u3c/em\u3e SecA ATPase Mechanism

Escherichia coli SecA uses ATP to drive the transport of proteins across cell membranes. Glutamate 210 in the “DEVD” Walker B motif of the SecA ATP-binding site has been proposed as the catalytic base for ATP hydrolysis (Hunt, J. F., Weinkauf, S., Henry, L., Fak, J. J., McNicholas, P., Oliver, D. B., and Deisenhofer, J. (2002) Science 297, 2018–2026). Consistent with this hypothesis, we find that mutation of glutamate 210 to aspartate results in a 90-fold reduction of the ATP hydrolysis rate compared with wild type SecA, 0.3 s–1versus 27 s–1, respectively. SecA-E210D also releases ADP at a slower rate compared with wild type SecA, suggesting that in addition to serving as the catalytic base, glutamate 210 might aid turnover as well. Our results contradict an earlier report that proposed aspartate 133 as the catalytic base (Sato, K., Mori, H., Yoshida, M., and Mizushima, S. (1996) J. Biol. Chem. 271, 17439–17444). Re-evaluation of the SecA-D133N mutant used in that study confirms its loss of ATPase and membrane translocation activities, but surprisingly, the analogous SecA-D133A mutant retains full activity, revealing that this residue does not play a key role in catalysis

Asymmetric ATP Binding and Hydrolysis Activity of the \u3cem\u3eThermus aquaticus\u3c/em\u3e MutS Dimer Is Key to Modulation of Its Interactions with Mismatched DNA

Prokaryotic MutS and eukaryotic Msh proteins recognize base pair mismatches and insertions or deletions in DNA and initiate mismatch repair. These proteins function as dimers (and perhaps higher order oligomers) and possess an ATPase activity that is essential for DNA repair. Previous studies of Escherichia coli MutS and eukaryotic Msh2−Msh6 proteins have revealed asymmetry within the dimer with respect to both DNA binding and ATPase activities. We have found the Thermus aquaticus MutS protein amenable to detailed investigation of the nature and role of this asymmetry. Here, we show that (a) in a MutS dimer one subunit (S1) binds nucleotide with high affinity and the other (S2) with 10-fold weaker affinity, (b) S1 hydrolyzes ATP rapidly while S2 hydrolyzes ATP at a 30−50-fold slower rate, (c) mismatched DNA binding to MutS inhibits ATP hydrolysis at S1 but slow hydrolysis continues at S2, and (d) interaction between mismatched DNA and MutS is weakened when both subunits are occupied by ATP but remains stable when S1 is occupied by ATP and S2 by ADP. These results reveal key MutS species in the ATPase pathway; S1ADP−S2ATP is formed preferentially in the absence of DNA or in the presence of fully matched DNA, while S1ATP−S2ATP and S1ATP−S2ADP are formed preferentially in the presence of mismatched DNA. These MutS species exhibit differences in interaction with mismatched DNA that are likely important for the mechanism of MutS action in DNA repair

Mismatch Recognition-Coupled Stabilization of Msh2-Msh6 in an ATP-Bound State at the Initiation of DNA Repair

Mismatch repair proteins correct errors in DNA via an ATP-driven process. In eukaryotes, the Msh2-Msh6 complex recognizes base pair mismatches and small insertion/deletions in DNA and initiates repair. Both Msh2 and Msh6 proteins contain Walker ATP-binding motifs that are necessary for repair activity. To understand how these proteins couple ATP binding and hydrolysis to DNA binding/mismatch recognition, the ATPase activity of Saccharomyces cerevisiae Msh2-Msh6 was examined under pre-steady-state conditions. Acid-quench experiments revealed that in the absence of DNA, Msh2-Msh6 hydrolyzes ATP rapidly (burst rate = 3 s-1 at 20 °C) and then undergoes a slow step in the pathway that limits catalytic turnover (kcat = 0.1 s-1). ATP is hydrolyzed similarly in the presence of fully matched duplex DNA; however, in the presence of a G:T mismatch or +T insertion-containing DNA, ATP hydrolysis is severely suppressed (rate = 0.1 s-1). Pulse-chase experiments revealed that Msh2-Msh6 binds ATP rapidly in the absence or in the presence of DNA (rate = 0.1 μM-1 s-1), indicating that for the Msh2-Msh6·mismatched DNA complex, a step after ATP binding but before or at ATP hydrolysis is the rate-limiting step in the pathway. Thus, mismatch recognition is coupled to a dramatic increase in the residence time of ATP on Msh2-Msh6. This mismatch-induced, stable ATP-bound state of Msh2-Msh6 likely signals downstream events in the repair pathway

Cost variation analysis of antihypertensive drugs acting through renin angiotensin aldosterone axis modulation

Background: Several brands of antihypertensive drugs are available in the Indian market with huge price variations. This study was undertaken to find out the percentage cost variation and cost ratio of antihypertensive drugs acting through renin angiotensin aldosterone axis modulation.Methods: Costs of different brands of renin angiotensin aldosterone axis modulatory drugs with antihypertensive action for the same dosage form and strength were found out using current index of medical specialties-134, July-October 2016. The maximum and minimum price of different brands of each drug was noted. Data was entered in Microsoft excel 2010. Percentage cost variation and cost ratio was calculated for each drug.Results: 16 antihypertensive drugs were analysed. Most of them were tablets. Ramipril and Valsartan were available as capsules also. Among tablets, percentage cost variation was highest for Atenolol 12.5 mg (683.93%) and least for Bisoprolol 2.5 mg (3.6538%). Valsartan capsules (160 mg) had no difference in the costs between the available 2 brands. Cost ratio ranged from 1.04 to 7.84 among the tablet form of drugs.Conclusions: There is a huge difference in the cost of antihypertensive drugs manufactured by different companies in the same strength and dosage form. To promote rational drug use and cost effective therapy, it is essential to create an awareness among clinicians regarding the availability of multiple brands for these drugs and the discrepancies in their costs

Efficient Three Party Key Exchange Protocol

Key exchange protocols allow two or more parties communicating over a public network to establish a common secret key called a session key. In 1976, Diffie and Hellman proposed the first practical key exchange (DH key exchange) protocol. In 2005, Abdalla and Pointcheval suggested a new variation of the computational DH assumption called chosen based computational Diffie Hellman (CCDH) and presented simple password based authenticated key exchange protocols. Since then several three party password authenticated key agreement protocols have been proposed In 2007, Lu and Cao proposed a simple 3 party authenticated key exchange (S-3PAKE) protocol. Kim and Koi found that this protocol cannot resist undetectable online password guessing attack and gave fixed STPKE' protocol as a countermeasure using exclusive-or operation. Recently, Tallapally and Padmavathy found that STPKE' is still vulnerable to undetectable online password guessing attack and gave a modified STPKE' protocol. Unfortunately, we find that, although modified STPKE' protocol can resist undetectable online password guessing attack but it is vulnerable to man in the middle attack. Also, we propose and analyze an efficient protocol against all the known attacks

A Modified Weight Balanced Algorithm for Influential Users Community Detection in Online social Network (OSNs)

In the modern era online users are increasing day by day. Different users are using various social networks in different forms. The behavior and attitude of the users of social networking sites varies U2U (User to User). In online social networking users join many groups and communities as per interests and according to the groups'/Communities' influential user. This paper consist of 7 sections , first section emphasis on introduction to the community evelotion and community. Second section signify movement between communities ,third section involve related work about the research.. Fourth section includes Problem Definition and fifth section involve Methodology (Proposed Algorithm Process ,Get Community Matrix, Community detetcion).Sixth section involve Implementation. Furthermore implementation include Datasets ,Quantitative performance, Graphical Results, Enhancement in the existing work..Last section include Conclusion and then references. In this paper,we are implementing and proposing the community detection in social media .In the proposed we have deployed a Longest Chain Subsequence metric for finding the number of connections to the kernel community

Evolution of excitation wavelength dependent photoluminescence in nano-CeO2 dispersed ferroelectric liquid crystals

The optical properties of nano-ceria (nano-CeO2) dispersed ferroelectric liquid crystals (FLCs) have been investigated by excitation wavelength dependent photoluminescence (PL) spectroscopy. The PL spectra of nano-ceria exhibited a strong excitation wavelength dependence in the 255-370 nm range. The red shift in the violet emission band of ceria i.e. from 368 nm to 396 nm with increasing excitation wavelength, has been attributed to the recombination of electrons trapped in the defect band and the deeply trapped holes in oxygen vacancies. This excitation wavelength dependence of ceria has noticeably been manifested in the PL response of FLC-CeO2 nanocomposites as well. PL emission recorded at an excitation wavelength where host and guest materials show intense emission, i.e. 340 nm, exhibits a quenching effect connected to the overlapping of emission and absorption bands of the host FLC and guest ceria NPs respectively. No blue/red shift in the spectral energy band was observed at 310 and 340 nm excitations. On the other hand, emission spectra at a lower excitation wavelength followed a reverse trend: an increase in the emission intensity, with a large blue shift in spectral energy band. The mechanisms involved in the changes of the PL spectrum of FLC-ceria nanocomposites with varying ceria concentration and excitation wavelengths are discussed in detail

A study on association of preoperative anaemia and obesity with causes and postoperative outcome in women undergoing hysterectomy for abnormal uterine bleeding

Background: Abnormal uterine bleeding is most commonly encountered in 10-20% of women in reproductive age.  The objectives of the study are to assess the proportion and association with causes and postoperative outcome of preoperative anaemia and obesity in women with abnormal uterine bleeding who underwent hysterectomy.Methods: This was a retrospective observational record-based study conducted in the Dept. of Obstetrics and Gynaecology of Sri Manakula Vinayagar Medical College and Hospital(SMVMCH), Pondicherry. The study population consisted of 169 patients who were admitted for abnormal uterine bleeding and underwent hysterectomy from January 2016 to December 2016 for a period of one year.Results: The mean age was 43years.The mean value of haemoglobin on admission was 9.89g/dl. The distribution frequencies of patients by WHO BMI classification as underweight, normal, overweight and obesity are 8, 59, 78 and 24 respectively. The distribution frequencies of patients by WHO anaemia classification as no anaemia, mild, moderate are 34, 37 and 98 respectively. Seventy-six patients had blood transfusion. Six patients had urinary tract infection and all of them were anaemic and obese. Two patients had developed respiratory tract infection and none of the patients had developed deep vein thrombosis.  Conclusions: Preoperative anaemia was more common in patients with fibroid and associated with increased morbidity in immediate postoperative period. There is more prevalence of SSI among overweight and obese women

PRELIMINARY PHYTOCHEMICAL AND ANTIBACTERIAL STUDIES ON LEAF EXTRACTS OF ALTERNANTHERA BRASILIANA (L.) KUNTZE

Objectives: The present study was to study the phytochemical and antibacterial properties of Alternanthera brasiliana leaf extracts using three different solvents (hexane, chloroform and methanol) against human pathogenic microorganism. Methods: Preliminary phytochemical screening of leaf extracts (in different solvents) of A. brasiliana were qualitatively tested using standard procedures. Thin Layer Chromatography (TLC) was performed to detect the phytochemical compounds present in A. brasiliana. Antibacterial activity of crude extract was determined by disc diffusion method. Minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were also performed for the hexane extract. Results: The preliminary qualitative phytochemical screening of hexane extracts revealed the presence of alkaloids, phenols, flavonoids, saponins, tannins, phytosterols and carbohydrates. In chloroform and methanolic extracts, all the tested phytochemicals were present except flavanoids and saponins. Alkaloids were not present in the chloroform extract. TLC analysis revealed the presence of seven compounds with Rf values ranging from 0.173 to 0.933. Promising antibacterial activity was observed in the hexane extract with an inhibition zone of 22 mm against E. coli. Chloroform and methanolic extracts showed negligible antibacterial activities. Conclusion: The results revealed that the hexane leaf extract of A. brasiliana alone exhibited potential antibacterial activity specifically against pathogenic E. coli (MTCC 729)