Structural Studies of the Atypical Rio2 Kinase and N-Acetylglutamate Synthase

Rio2 is required for small subunit ribosomal RNA (rRNA) maturation. It is specifically involved in site D cleavage of the 20S rRNA to produce the mature 18S rRNA. Loss of Rio2p is lethal and a decrease of Rio2p activity results in 20S accumulation in the cytoplasm. One of the goals of this thesis was to crystallize Rio2 from a eukaryotic organism in order to determine the structural differences between eukaryotic and archaeal versions. Another goal was to define the importance of individual domains. Yeast Rio2 was the first eukaryotic protein purified, but it formed only microcrystals. Human Rio2 was purified next, but the solubility was too low to set up crystal trays. Finally, Rio2 from Chaeotomium thermophilum was purified and crystals were obtained. The structure revealed a possibly inhibitory alpha helix blocking the active site. The role of the N-terminal winged helix domain of Rio2 in yeast was investigated and found not to be necessary for binding of Rio2p to the ribosome. The crystal structure of the first N-acetylglutamate synthase (NAGS) was also determined. The crystal structure of NAGS complexed with acetyl-CoA and with CoA plus N-acetylglutamate was determined at 2.5 and 2.6-Å resolution. Each NAGS consists of an N-terminal amino acid kinase domain (AAK) domain and a C-terminal N-acetlyltransferase (NAT) domain connected by three amino acids. The monomers form a six membered ring with a trimer of dimers symmetry. The AAK domains form two dimeric contacts with other AAK domains. Each AAK domain interacts with the NAGS domain of another monomer at the polar ends of the ring. The NAGS domain contains the active site. The AAK domain is believed to bind arginine and also helps to bind acetyl-CoA. Structural insights suggest a one step mechanism in which both substrates bind and the acetyl group is directly passed from acetyl-CoA to the alpha amino group of gluatamate. In addition, collaborative work on the structural characterization of the MphR(A) protein is reported

Functional analysis of UDP-sugar: sterol glucosyltransferases

Glycosyltransferases (GTs) are essential for the biosynthesis and diversification of many therapeutically important natural products. Of these, UDP-sugar: sterol glucosyltransferases (UGTs) (2.4.1.173) catalyse the synthesis of therapeutically important steryl glycosides (SGs). Guided by the sequence similarity with a previously characterised N-terminally truncated UGT from Saccharomyces cerevisiae (UGT51), this study reports the cloning of the gene fragment encoding the C-terminal catalytic domains from related yeasts and the expression and characterisation of their encoded products produced. N-terminally histidine tagged proteins were purified for in vitro assays against a panel of sterol and steroidal acceptors. Liquid chromatography-mass spectrometry (LC-MS) and kinetic analysis led to the successful characterisation of two novel UGTs from Pichia angusta and Kluyveromyces lactis. In addition, testosterone was shown to be utilized by all UGTs, including the previously characterised S. cerevisiae UGT51. Random mutagenesis of UGTs and homology modelling of the S. cerevisiae UGT revealed structural similarities with family 1 bacterial glycopeptide GTs. Given the structural and mechanistic similarities among GT family 1 UGTs, this approach may provide a template for genetic manipulation of novel UGTs from other members of the GT superfamily with a better understanding of catalytic domains and for broadening their scope in drug development. It may also aid the development of a generic process in the synthesis of SGs

General uniqueness and monotone iterative technique for fractional differential equations

AbstractIn this paper, the general existence and uniqueness result is proved which exhibits the idea of comparison principle. This result is also valid for fractional differential equations in a Banach space. The well-known monotone iterative technique is then extended for fractional differential equations which provides computable monotone sequences that converge to the extremal solutions in a sector generated by upper and lower solutions

The Generalized Quasi-linearization Method for Reaction Diffusion Equations on an Unbounded Domain

AbstractThe method of generalized quasi-linearization has been well developed for ordinary differential equations. In this paper, we extend the method of generalized quasi-linearization to reaction diffusion equations on an unbounded domain. The iterates, which are solutions of linear equations starting from lower and upper solutions, converge uniformly and monotonically to the unique solution of the nonlinear reaction diffusion equation in an unbounded domain. Initially an existence theorem for the linear nonhomogeneous reaction diffusion equation in an unbounded domain has been proved under improved conditions. The quadratic convergence has been proved by using a comparison theorem of reaction diffusion equations with ordinary differential equations. This avoids the computational complexity of the quasi-linearization method, since the computation of Green's function at each stage of the iterates is avoided

In vitro studies on effects of plant growth regulators on callus and suspension culture biomass yield from Gymnema sylvestre R.Br

Callus cultures were initiated from nodal segments and leaf explants of Gymnema sylvestre on Murashige and Skoog (1962) medium containing basic salts and 30 g/l sucrose supplemented with different concentrations (0.10, 0.25, 0.5, 1.0, 2.0 and 5.0 mg/l) of 2,4-dichlorophenoxy acetic acid (2,4-D), -naphthalene acetic acid (NAA), indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), kinetin (KN) and 6-benzyladenine (BA). Callus induction was observed in 0.5 mg/l of 2, 4-D supplemented medium for both explants. At the initial stage, some parts of explants enlarged and gave raise to pale yellowish calli after 2-3 weeks of incubation. The harvested cell biomass was subjected to extraction of active principles. In this study, cell biomass extracts were compared with extracts from leaves of naturally growing gymnema plants. HPLC analysis of these extracts showed that the main components of the active principles namely gymnemic acids and gymnemagenin were present in sufficiently large amounts in the cultured undifferentiated cell

Cross sectional study to determine the cognitive impairment among epilepsy patients

Background: The study was aimed to screen cognitive impairment and assess its levels among epilepsy patients, also study the prevalence and the relationships between specific seizure subtype and determine the correlation between seizure frequency, seizure duration and abnormal EEG finding with cognitive impairment among epilepsy patients.Methods: The study was conducted in a tertiary care hospital over a period of 1yr after taking informed consent from 100 patients by random sampling after fulfilling the inclusion criteria.Results: Out of 100 patients 64% did not have cognitive impairment, 36% had cognitive impairment. Among 36%, 7% had definitive cognitive impairment and 29% had mild cognitive impairment. It was observed that the other group of seizure subtypes which included atonic, myoclonic, focal sensory, focal motor, absence seizure with secondary generalization had low mean cognitive scores signifying cognitive impairment, where as those with complex partial seizure with secondary generalization group had high mean cognitive scores signifying no cognitive dysfunction. However, the observed difference is statistically significant (p<0.05). Patients who had higher seizure frequency had low mean cognitive scores indicating cognitive decline and those with very low seizure frequency had high mean cognitive scores indicating no cognitive decline. However, the observed difference is statistically significant. It was observed that the mean cognitive score for abnormal EEG patients was 24.68 indicating mild cognitive decline whereas for normal EEG patients the mean cognitive score was 26.27 indicating no cognitive decline however the observed difference is statistically significant since P<0.05.Conclusions: The high prevalence of cognitive impairment among epilepsy patients calls for early neuropsychological assessment soon after the diagnosis of epilepsy beyond that, the baseline screening may also guide treatment plan and serve as an early indicator for rehabilitative care

Comparison of external and endoscopic endonasal dacryocysto-rhinostomy: a hospital based retrospective study

Background: The aim of the study was to compare and analyze the surgical outcome in doing external dacryocystorhinostomy (Ex-DCR) and endoscopic endonasal dacryocystorhinostomy (En-DCR), at our tertiary care referral hospital of this hilly region of northern India. Design was retrospective and comparative.Methods: A retrospective review of total 106 patients with unilateral or bilateral primary nasolacrimal duct obstruction (NLDO), who had undergone either Ex-DCR or En-DCR surgery that included revision surgeries, with or without silicone tube intubation (STI), for a period of two years from October 2013 to September 2015, were enrolled in this study. Consecutive six months follow up was observed, in all. Surgical outcome was evaluated at each follow up, objectively and subjectively. Statistical data was analyzed using IBM SSPS 23.0 version software. P-value <0.05 was considered statistically significant.Results: Total 111 DCR surgeries (55 Ex-DCR, 56 En-DCR), were performed on 106 primary NLDO patients, including 5 bilateral En-DCR. Mean age for Ex-DCR and En-DCR was 52±17years, 36±18years, respectively. Female preponderance was seen in both the groups (F:M=41:14 in Ex-DCR, 32:14 in En-DCR). Overall, the success rate of DCR surgery was 92.80% (n=103 out of 111). Intergroup success rate was found to be almost similar (Ex-DCR 52/55; 94.54%; En-DCR 51/56; 91.07%, P=1.00), whereas, ultimate success rate considering repeat /revision surgeries following failed DCR (n=8, Ex-DCR-3,En-DCR-5) was 100%. Commonest perioperative and late complication in both the groups were, hemorrhage and rhinostomy scarring, respectively.Conclusions: Success and complication rate of both Ex-DCR and En-DCR surgeries are almost similar after primary DCR surgeries. We emphasize the advantage of doing En-DCR in bilateral NLDO, repeat/revision DCR, NLDO associated with additional intranasal disease, other than its esthetic advantage over Ex-DCR. However, further multicentric randomized controlled studies are required to substantiate our findings.

A comparative study on the investment preferences of retail investors towards risky vs. non risky investment options

Increasing presence of retail investors, in the Indian financial markets, calls for extensive study on their investment habits and behavior. The current study tries to understand the impact of the demographic characteristics of the individual investor on risk appetite, investment habits and selection of mutual funds as an investment choice. The study also investigates the impact of the demographic characteristics on choice of risky investment options Vs. Non risky options and all the investment options together. Statistical tests used have been used to conclude that the demographic variables age and income have an influence on the investment choice of mutual funds. Based on the results of tests conducted on the data collected it was found that income levels of a respondent have an influence on the selection of the risky investment choices. It has been found that the previous literature has mainly focused on the relation between the demographics and selection of mutual funds alone or only single class of financial instruments. The current paper has categorized the investment into risky and non-risky, to study the association of the categories with the demographics of the sample. However the test was conducted with a sample size of 100. The sample selection method used in the study was convenience sampling. Similar studies can be conducted with a larger sample size. Stratified sample or cluster sampling method or stratified sampling method could be used to have a better representation of the population. It would be interesting to study how the data would behave on a larger scale. Further studies in the same line are very important on many fronts .Considering the importance of the retail investor in a developing economy like India; the current study would help us to understand the retail investor better. A better understanding of the behavior of the end user, will help the finance professionals to design more custom made financial products in the coming future