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Search Results: 1 - 10 of 224614 matches for " Ranga R. Krishnan "
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Hippocampus Shape Analysis and Late-Life Depression
Zheen Zhao, Warren D. Taylor, Martin Styner, David C. Steffens, K. Ranga R. Krishnan, James R. MacFall
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0001837
Abstract: Major depression in the elderly is associated with brain structural changes and vascular lesions. Changes in the subcortical regions of the limbic system have also been noted. Studies examining hippocampus volumetric differences in depression have shown variable results, possibly due to any volume differences being secondary to local shape changes rather than differences in the overall volume. Shape analysis offers the potential to detect such changes. The present study applied spherical harmonic (SPHARM) shape analysis to the left and right hippocampi of 61 elderly subjects with major depression and 43 non-depressed elderly subjects. Statistical models controlling for age, sex, and total cerebral volume showed a significant reduction in depressed compared with control subjects in the left hippocampus (F1,103 = 5.26; p = 0.0240) but not right hippocampus volume (F1,103 = 0.41; p = 0.5213). Shape analysis showed significant differences in the mid-body of the left (but not the right) hippocampus between depressed and controls. When the depressed group was dichotomized into those whose depression was remitted at time of imaging and those who were unremitted, the shape comparison showed remitted subjects to be indistinguishable from controls (both sides) while the unremitted subjects differed in the midbody and the lateral side near the head. Hippocampal volume showed no difference between controls and remitted subjects but nonremitted subjects had significantly smaller left hippocampal volumes with no significant group differences in the right hippocampus. These findings may provide support to other reports of neurogenic effects of antidepressants and their relation to successful treatment for depressive symptoms.
Frontal White Matter Anisotropy and Antidepressant Remission in Late-Life Depression
Warren D. Taylor, Maragatha Kuchibhatla, Martha E. Payne, James R. MacFall, Yvette I. Sheline, K. Ranga Krishnan, P. Murali Doraiswamy
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0003267
Abstract: Introduction Neuroanatomic features associated with antidepressant treatment outcomes in older depressed individuals are not well established. This study used diffusion tensor imaging to examine frontal white matter structure in depressed subjects undergoing a 12-week trial of sertraline. We hypothesized that remission would be associated with higher frontal anisotropy measures, and failure to remit with lower anisotropy. Methods 74 subjects with Major Depressive Disorder and age 60 years or older were enrolled in a twelve-week open-label trial of sertraline and completed clinical assessments and 1.5T magnetic resonance brain imaging. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were measured in regions of interest placed in the white matter of the dorsolateral prefrontal cortex, anterior cingulate cortex, and corpus callosum. Differences in ADC and FA values between subjects who did and did not remit to treatment over the study period were assessed using generalized estimating equations, controlling for age, sex, medical comorbidity and baseline depression severity. Results Subjects who did not remit to sertraline exhibited higher FA values in the superior frontal gyri and anterior cingulate cortices bilaterally. There were no statistically significant associations between ADC measures and remission. Conclusions Failure to remit to sertraline is associated with higher frontal FA values. Functional imaging studies demonstrate that depression is characterized by functional disconnection between frontal and limbic regions. Those individuals where this disconnection is related to structural changes as detected by DTI may be more likely to respond to antidepressants. Trial Registration ClinicalTrials.gov NCT00339066
Pharmacometabolomics of Response to Sertraline and to Placebo in Major Depressive Disorder – Possible Role for Methoxyindole Pathway
Hongjie Zhu, Mikhail B. Bogdanov, Stephen H. Boyle, Wayne Matson, Swati Sharma, Samantha Matson, Erik Churchill, Oliver Fiehn, John A. Rush, Ranga R. Krishnan, Eve Pickering, Marielle Delnomdedieu, Rima Kaddurah-Daouk, Pharmacometabolomics Research Network
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0068283
Abstract: Therapeutic response to selective serotonin (5-HT) reuptake inhibitors in Major Depressive Disorder (MDD) varies considerably among patients, and the onset of antidepressant therapeutic action is delayed until after 2 to 4 weeks of treatment. The objective of this study was to analyze changes within methoxyindole and kynurenine (KYN) branches of tryptophan pathway to determine whether differential regulation within these branches may contribute to mechanism of variation in response to treatment. Metabolomics approach was used to characterize early biochemical changes in tryptophan pathway and correlated biochemical changes with treatment outcome. Outpatients with MDD were randomly assigned to sertraline (n = 35) or placebo (n = 40) in a double-blind 4-week trial; response to treatment was measured using the 17-item Hamilton Rating Scale for Depression (HAMD17). Targeted electrochemistry based metabolomic platform (LCECA) was used to profile serum samples from MDD patients. The response rate was slightly higher for sertraline than for placebo (21/35 [60%] vs. 20/40 [50%], respectively, χ2(1) = 0.75, p = 0.39). Patients showing a good response to sertraline had higher pretreatment levels of 5-methoxytryptamine (5-MTPM), greater reduction in 5-MTPM levels after treatment, an increase in 5-Methoxytryptophol (5-MTPOL) and Melatonin (MEL) levels, and decreases in the (KYN)/MEL and 3-Hydroxykynurenine (3-OHKY)/MEL ratios post-treatment compared to pretreatment. These changes were not seen in the patients showing poor response to sertraline. In the placebo group, more favorable treatment outcome was associated with increases in 5-MTPOL and MEL levels and significant decreases in the KYN/MEL and 3-OHKY/MEL; changes in 5-MTPM levels were not associated with the 4-week response. These results suggest that recovery from a depressed state due to treatment with drug or with placebo could be associated with preferential utilization of serotonin for production of melatonin and 5-MTPOL.
Development of a liposomal nanodelivery system for nevirapine
Lakshmi N Ramana, Swaminathan Sethuraman, Udaykumar Ranga, Uma M Krishnan
Journal of Biomedical Science , 2010, DOI: 10.1186/1423-0127-17-57
Abstract: According to the World Health Organization, more than 40 million people have been presently infected with Human Immunodeficiency Virus type 1 (HIV-1) globally. Highly Active Antiretroviral Therapy (HAART), which consists of a combination of a minimum of three antiretroviral (ARV) drugs, is the primary treatment currently available for efficient management of AIDS [1,2]. The various types of ARVs that are used in HAART could be categorized into nucleoside reverse transcriptase inhibitors (NRTIs), nucleotide reverse transcriptase inhibitors (nRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), protease inhibitors (PIs), viral fusion inhibitors, integrase inhibitors, maturation inhibitors and fixed dose combination [1]. These drugs have a potential to manage the chronic infection but not to treat the disease [3]. The bioavailability of many of the ARV drugs is considerably low and erratic due to the substantial first pass metabolism and degradation in the gastrointestinal tract. Given the short half-life of the drugs, frequent administration of the drugs is required at relatively higher doses, often leading to low patient compliance [4]. If adherence falls below 95% level, the therapeutic effectiveness is reduced below 50% [3]. Immunologically privileged compartments of the body including the central nervous system, lymphatic system and the macrophages are characteristically inaccessible to a majority of the ARV drugs thus serving as viral reservoirs [5]. The inability to maintain therapeutic concentration of the drugs for longer durations significantly contributes to multidrug-resistance [6]. Furthermore, the prolonged use of ARVs frequently leads to toxic side effects resulting in the deterioration in the quality of life and incompliance to therapy [7]. Nevirapine is a hydrophobic NNRTI that non-competitively binds to an allosteric non-substrate binding site of the reverse transcriptase (RT) [8,9]. Nevirapine, the first ARV member of non-nucleoside rever
Influence of Specialization on Entrepreneurial Intentions of the Students Pursuing Management Program  [PDF]
Vivek Ranga, R. Raghunath Reddy, Deepal N. Perera, P. Venkateswarlu
Theoretical Economics Letters (TEL) , 2019, DOI: 10.4236/tel.2019.92025
This paper was conceptualized with an objective to ascertain the entrepreneurial intentions amongst the students pursuing management program and to assess the influence of respective specialization such as HR, Operations, Finance and Marketing on the entrepreneurial intentions. Ajzen’s [1] Theory of Planned Behaviour was applied to explicate the behavioural intentions. The results indicated that Personal Attitude and Perceived Behaviour Control had significant influence on the entrepreneurial intentions while Subjective Norms did not have any influence. It was identified that overall specialization had no significant influence on the entrepreneurial intentions. However, the students who have taken Marketing as their domain for Specialization in their management program have shown interest to choose entrepreneurship as their career with complete knowledge and larger intent to have control on their business comparatively followed by the students who have taken Finance as specialization. Students of HR and Operations specialization were identified to be lowest in having entrepreneurial intentions.
Preliminary Study on the Antibacterial Activity of Six Medicinal Plants against Two Naso-Pharyngeal Pathogens—Streptococccus pyogenes and Pseudomonas aeruginosa  [PDF]
R. Jithesh Krishnan, S. Resmy Nair
American Journal of Plant Sciences (AJPS) , 2016, DOI: 10.4236/ajps.2016.76086
Abstract: Objective: The objective is to study the antibacterial activity of six medicinal plants against two naso-pharyngeal pathogens and determination of total phenol contents in ethanol extracts of those plants. Methods: Different serial concentrations (0.05 g/mL, 0.1 g/mL, 0.2 g/mL, 0.4 g/mL) of ethanolic and acetone extracts of Piper nigrum L. (Piperaceae), Ocimum sanctum Linn., Plectranthus amboinicus L. (Lamiaceae), Ayapana triplinervis M.Vahl. (Asteraceae), Cinnamomum zeylanicum L. (Lauraceae), Allium schoenoprasum Linn. (Liliaceace) were evaluated for the antibacterial activity using disc diffusion method against gram positive Streptococcus pyogenes and gram negative Pseudomonas aeruginosa. The extracts were prepared from different parts of the plants. The total phenol content was estimated using folin-ciocaltau reagent in catechol equivalents. Results: Majority of the extracts had inhibitory effect against the tested bacteria at different concentrations. In ethanol extracts, Plectranthus amboinicus exhibited the maximum zone of inhibition (14 mm) at 0.05 g/mL concentration against Streptococcus pyogenes, and Ocimum sanctum showed highest zone of bacterial inhibition (19 mm) at 0.05 g concentration against Pseudomonas aeruginosa. In acetone extracts, Piper nigrum had the maximum zone of bacterial inhibition (17 mm) in 0.4 g/mL concentration against Streptococcus pyogenes and Cinnamomum zeylanicum and Allium schoenoprasum exhibited the highest zone of bacterial inhibition (0.4 g/mL) against Pseudomonas aeruginosa. The ethanol extract of Plectranthus amboinicus contained the highest amount of phenol (0.8 mg/mL) and Allium schoenoprasum contained the lowest amount (0.62 mg/mL). In acetone, Cinnamomum zeylanicum contained highest phenol content (0.78 mg/mL). Conclusion: All these investigations pave way to the molecular modeling of the lead phyto compounds present in the studied plants, and also in finding out their biochemical action in various metabolic pathways and reactions of infection.
Preprocessing and Image Enhancement Algorithms for a Form-based Intelligent Character Recognition System.
Dipti Deodhare,NNR Ranga Suri,R. Amit
International Journal of Computer Science & Applications , 2005,
Management of postoperative choroidal detachment
Krishnan M,Baskaran R
Indian Journal of Ophthalmology , 1985,
Multiple Cross-Layer Design Based Complete Architecture for Mobile Adhoc Networks
R. Venkatachalam,A. Krishnan
Computer Science , 2009,
Abstract: Different cross layer design for mobile adhoc network focuses on different optimization purpose, different Quality of Service (QoS) metric and the functions like delay, priority handling, security, etc. Existing cross layer designs provide individual solution for congestion control, fault tolerance, power conservation, energy minimization and flow control and the major drawback is of high cost and overhead. In this paper, we propose to design multiple cross layer design based architecture to provide a combined solution for link failure management, power conservation, congestion control and admission control. By simulation results, we show that the average end to end delay, average energy consumption and the packet loss are considerably reduced with the increase in high throughput and good delivery ratio.
Bipolar Disorder, Brain-Derived Neurotrophic Factor (BDNF) Val66Met Polymorphism and Brain Morphology
Cheryl Ann Teh, Tih-Shih Lee, Margaratha Kuchibhatla, Allison Ashley-Koch, James MacFall, Ranga Krishnan, John Beyer
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0038469
Abstract: In this study of the effect of bipolar status and presence of BDNF Val66Met polymorphism on differences in regional brain volumes, we hypothesized based on previous studies that 1) bipolar subjects will have smaller regional brain volumes than healthy controls; 2) BDNF Met66 allele carriers within the same population are likely to have smaller regional brain volumes as compared to Val66 homozygyotes. In our Caucasian sample of 166 bipolar subjects and 64 gender-matched healthy controls, we found significant decreases in total (p = 0.005) and regional gray matter volumes in bipolar patients compared to healthy controls, more pronounced in the inferior and posterior parts of the brain, together with a concomitant increase in total CSF (p = 0.012) particularly in the lateral ventricles (p = 0.023). However, there was no difference in white matter volumes noted by other studies. Furthermore we did not find significant differences in other brain regions that have been reported by other authors. Nor did we find a significant effect of BDNF on these measurements.
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