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Biomedical subjects

S Nagarajan

Publications and source records attributed to S Nagarajan.

At least 19 recordsLinked to original sources
PubMed2006

Synthesis, in vitro antibacterial and antifungal evaluations of 2-amino-4-(1-naphthyl)-6-arylpyrimidines.

A series of 2-amino-4-(1-naphthyl)-6-arylpyrimidines have been synthesized and characterized by IR, NMR, MS, elemental analyses and evaluated for in vitro antibacterial and antifungal activities. Some of the compounds were found to be active against a limited panel of bacteria and fungi. In particular, compounds 4b and 4e were found to be the most effective analogs against the tested bacterial and fungal strains.

Anti-Bacterial Agents↗
PubMed2006

Automated localization of magnetoencephalographic interictal spikes by adaptive spatial filtering.

OBJECTIVE: Automated adaptive spatial filtering techniques can be applied to magnetoencephalographic (MEG) data collected from people with epilepsy. Source waveforms estimated by these methods have higher signal-to-noise ratio (SNR) than spontaneous MEG data, allowing identification and location of interictal spikes. The software tool SAM(g(2)) provides an adaptive spatial filtering algorithm for MEG data that yields source images of excess kurtosis and provides source time-courses in voxels exhibiting high excess kurtosis. The sensitivity and specificity of SAM(g(2)) in epilepsy is unknown. METHODS: Interictal MEG data from 36 patients with intractable epilepsy were analyzed using SAM(g(2)), and results compared with equivalent current dipole (ECD) fit procedures. RESULTS: When SNR of interictal spikes was high (compared to background) with a clear single focus, in most cases there was good agreement between ECD and SAM(g(2)). With multiple foci, there was typically overlap but imperfect concordance between results of ECD and SAM(g(2)). CONCLUSIONS: SAM(g(2)) may in some cases be equivalent to manual ECD fit for localizing interictal spikes with single locus and good SNR. Further studies are required to validate SAM(g(2)) with multiple foci or poor SNR. SIGNIFICANCE: In some cases, SAM(g(2)) might eventually assist or replace manual ECD analysis of MEG data.

Algorithms↗
PubMed2005

Kinetics of high strength phenol degradation using Bacillus brevis.

A strain of Bacillus brevis has been isolated and identified based on biochemical results. Phenol biodegradation in a batch reactor was studied using the pure culture of B. brevis. The isolated strain was optimized for various environmental conditions and the biodegradation of phenol was maximum at pH 8.0, 5% (v/v) of inoculum size and without any co-substrate. The kinetics of biodegradation according to Haldane's equation micro = micromaxS/(Ks + S + (S2/Ki)) adequately describes cell growth with kinetic constants in the ranges micromax = 0.026-0.078 h(-1), Ks =2.2-29.31 mg/l, Ki = 868.0-2434.7 mg/l. These values are specific for this organism and we have compared with literature for pure or mixed cultures degrading phenol.

Bacillus↗
PubMed2005

Isolation and identification of novel high strength phenol degrading bacterial strains from phenol-formaldehyde resin manufacturing industrial wastewater.

Phenols are toxic to all types of organisms. Two bacterial strains capable of utilizing phenol as a sole carbon source were isolated from the phenol bearing industrial wastewater. Based on the biochemical test results the organisms were identified as Pseudomonas cepacia and Bacillus brevis. The organisms were very efficient in phenol degradation, the lag phase increased with increase in phenol concentration. The well-acclimatized cultures of P. cepacia and B. brevis degraded 2500 and 1750 mg l(-1) of phenol in 144 h, respectively. The organisms degrade phenol even in the presence of toxicants like thiocyanate, sulphide and cyanide. The organisms can be effectively used for treating high strength phenol containing thiocyanate, sulphide and cyanide. The P. cepacia degrades phenol with a faster rate than B. brevis. P. cepacia can be used effectively for treating high strength phenolic wastewater.

Biodegradation, Environmental↗
PubMed2005

Synthesis and antibacterial activity of some 5-(4-biphenylyl)-7-aryl[3,4-d] [1,2,3]-benzothiadiazoles.

A series of 5-(4-biphenylyl)-7-aryl[3,4-d] [1,2,3]-benzothiadiazoles were synthesized, characterized by IR, NMR and elemental analysis and evaluated for in vitro antibacterial activity against some Gram-positive and Gram-negative bacteria. The antibacterial data revealed that compounds 7a-j had better activity against tested Gram-positive organisms than the reference ciprofloxacin and norfloxacin. However, the compounds were nearly inactive against Gram-negative bacteria. Compound 7c and 7d were the most active compounds against Gram-positive bacteria.

Anti-Bacterial Agents↗
PubMed2005

Management of methylmalonic acidaemia by combined liver-kidney transplantation.

Methylmalonic acidaemia (MMA) is a rare autosomal recessive inborn error of metabolism that typically presents in infancy with recurrent episodes of metabolic acidosis, developmental delay and failure to thrive. The disease course is complicated by the development of chronic tubulointerstitial nephritis progressing to end-stage renal disease in adolescence. We describe two adolescents with cobalamin-nonresponsive MMA (mut0) who developed polyuria, chronic tubulointerstitial nephritis, dystonia but normal synthetic liver function. Both patients received combined liver-kidney transplantation (CLKT), preceded by a single pretransplant haemodialysis for clearance of methylmalonic acid. Post CLKT there was 95-97% reduction in serum and urine methylmalonic acid, leading to significant liberalization of dietary protein intake and a consequent increase in body mass index, muscle strength and energy. In addition, renal function normalized and clinical neurological status stabilized. We propose that CLKT be considered as a therapeutic option early in the course of cobalamin-nonresponsive MMA. Progressive tubulointerstitial nephritis with disabling polyuria is a confounder in patient management even in the absence of end-stage renal disease. Successful CLKT restores methylmalonyl-CoA mutase enzyme levels in the liver and kidney, improves clearance of methylmalonic acid with resultant dietary protein liberalization, and offers excellent graft and patient outcomes with improvement in quality of life.

Adolescent↗
PubMed2005

Microwave-assisted synthesis and anti-bacterial activity of some 2-amino-6-aryl-4-(2-thienyl)pyrimidines.

Some novel 2-amino-6-aryl-4-(2-thienyl)pyrimidines were synthesized from 3-aryl-1-thien-2-ylprop-2-en-1-ones and guanidine hydrochloride in presence of alkali by conventional heating in alcoholic medium and microwave heating in solvent-free conditions. The compounds were evaluated for in vitro anti-bacterial activity. The anti-bacterial data revealed that compounds 5a-e had better activity against tested gram-positive organisms than the reference ciprofloxacin and norfloxacin. However, the compounds were nearly inactive against gram-negative bacteria. Compounds 5c and e were the most active compounds against gram-positive bacteria.

Anti-Bacterial Agents↗
PubMed2005

UV-vis spectroscopy for following the kinetics of homogeneous polymerization of diphenylamine in p-toluene sulphonic acid.

Kinetics of chemical oxidative polymerization of diphenylamine (DPA) was followed in aqueous 1M para-toluene sulphonic acid (p-TSA) using potassium peroxomonosulphate (PMS) or peroxodisulphate (PDS), independently as an oxidant. The medium was found to be homogeneous and became dark green in colour during the course of polymerisation. The course of polymerization was followed by UV-vis spectroscopy. Rate of polymerization (R(p)) was determined for various conditions by following the absorbance values corresponding to poly(diphenylamine) (PDPA) for different concentrations of DPA and PMS or PDS at various time intervals of polymerization. The observed dependences of DPA, PDS or PMS on R(p) were used to deduce rate equations for PDS or PMS initiated polymerization of DPA. The rate constant for the formation of poly(diphenylamine), was estimated. In situ spectroelectrochemical studies on the polymerization of DPA were also carried out on an ITO electrode in 1M p-TSA. The results are in accordance with the intermediates suggested in chemical oxidative polymerization.

Benzenesulfonates↗
PubMed2004

Production of 2-hydroxy-4-methoxybenzaldehyde in roots of tissue culture raised and acclimatized plants of Decalepis hamiltonii Wight & Arn., an endangered shrub endemic to Southern India and evaluation of its performance vis-a-vis plants from natural habitat.

Axillary buds obtained from field grown plants of D. hamiltonii were used to initiate multiple shoots on Murashige and Skoog's medium (MS) supplemented with 2 mg L(-1) 6-benzyl aminopurine (BA) and 0.5 mg L(-1) indole-3-acetic acid (IAA). Profuse rooting was achieved when the actively growing shoots were cultured on MS medium supplemented with 1.0 mg l(-1) indole-3-butyric acid (IBA). Regenerated plants were grown successfully in the plains, in contrast to wild growth in high altitudes and rocky crevices of hilly regions. Roots of different sizes from one-year-old tissue culture raised field grown plants had the same profile of 2-hydroxy-4-methoxybenzaldehyde as that of wild plants. A maximum of 0.14% and 0.12% 2-hydroxy-4-methoxybenzaldehyde was produced in roots of one year old tissue culture derived plants and greenhouse grown plants respectively.

Benzaldehydes↗
PubMed2002

Marker assisted detection of gene (1Dx5) and translocation (1B/1R) in wheat genotypes.

Detection of 1Dx5 gene and presence of 1B/1R wheat rye translocation were studied in nineteen elite Indian wheat genotypes using AS-PCR and STS markers, respectively. Fifteen genotypes had 1B/1R translocation whereas ten showed presence of 1Dx5 gene. More than 50 per cent of the genotypes tested were found positive for both 1Dx5 and 1B/1R translocation. The results are in conformity with HMW glutenin SDS-PAGE profile for 1Dx5 and cytological observations for 1B/1R translocation.

Genes, Plant↗
PubMed2001

Speech comprehension is correlated with temporal response patterns recorded from auditory cortex.

Speech comprehension depends on the integrity of both the spectral content and temporal envelope of the speech signal. Although neural processing underlying spectral analysis has been intensively studied, less is known about the processing of temporal information. Most of speech information conveyed by the temporal envelope is confined to frequencies below 16 Hz, frequencies that roughly match spontaneous and evoked modulation rates of primary auditory cortex neurons. To test the importance of cortical modulation rates for speech processing, we manipulated the frequency of the temporal envelope of speech sentences and tested the effect on both speech comprehension and cortical activity. Magnetoencephalographic signals from the auditory cortices of human subjects were recorded while they were performing a speech comprehension task. The test sentences used in this task were compressed in time. Speech comprehension was degraded when sentence stimuli were presented in more rapid (more compressed) forms. We found that the average comprehension level, at each compression, correlated with (i) the similarity between the frequencies of the temporal envelopes of the stimulus and the subject's cortical activity ("stimulus-cortex frequency-matching") and (ii) the phase-locking (PL) between the two temporal envelopes ("stimulus-cortex PL"). Of these two correlates, PL was significantly more indicative for single-trial success. Our results suggest that the match between the speech rate and the a priori modulation capacities of the auditory cortex is a prerequisite for comprehension. However, this is not sufficient: stimulus-cortex PL should be achieved during actual sentence presentation.

Auditory Cortex↗
PubMed2001

Plasmid-mediated extended-spectrum beta-lactamase (CTX-M-3 like) from India and gene association with insertion sequence ISEcp1.

Six non-clonally related enterobacterial isolates producing a same extended-spectrum beta-lactamase CTX-M-15 were isolated in 1999 from patients hospitalized in a New Delhi hospital. CTX-M-15 differed from CTX-M-3 by an asparagine to glycine substitution in position ABL238. Its gene was located on large plasmids varying in size. In each case, a same insertion sequence ISEcp1 was identified upstream of the 5' end of bla(CTX-M-15). Typical -35 and -10 promoter sequences of Enterobacteriaceae were identified in the 3' end of ISEcp1. The location of ISEcp1 upstream of plasmid-mediated CTX-M-type beta-lactamase genes may contribute to their spread or/and their expression.

Amino Acid Sequence↗
PubMed2001

Relations between the neural bases of dynamic auditory processing and phonological processing: evidence from fMRI.

Functional magnetic resonance imaging (fMRI) was used to examine how the brain responds to temporal compression of speech and to determine whether the same regions are also involved in phonological processes associated with reading. Recorded speech was temporally compressed to varying degrees and presented in a sentence verification task. Regions involved in phonological processing were identified in a separate scan using a rhyming judgment task with pseudowords compared to a lettercase judgment task. The left inferior frontal and left superior temporal regions (Broca's and Wernicke's areas), along with the right inferior frontal cortex, demonstrated a convex response to speech compression; their activity increased as compression increased, but then decreased when speech became incomprehensible. Other regions exhibited linear increases in activity as compression increased, including the middle frontal gyri bilaterally. The auditory cortices exhibited compression-related decreases bilaterally, primarily reflecting a decrease in activity when speech became incomprehensible. Rhyme judgments engaged two left inferior frontal gyrus regions (pars triangularis and pars opercularis), of which only the pars triangularis region exhibited significant compression-related activity. These results directly demonstrate that a subset of the left inferior frontal regions involved in phonological processing is also sensitive to transient acoustic features within the range of comprehensible speech.

Adult↗
PubMed2001

Designer cancer vaccines made easy: protein transfer of immunostimulatory molecules for use in therapeutic tumor vaccines.

Advances in the understanding of the immune response to tumors has led to the development of new strategies to design therapeutic vaccines. One of these strategies is the development of protein transfer of immunostimulatory molecules onto the surface of tumor cells, thereby directing the immune response to the tumor antigens carried by the modified tumor cells. This strategy has been developed as an alternative to gene transfer, the more classical technique of introducing immunostimulatory molecules onto tumors. In this report we briefly review current strategies for immunotherapy and then focus on several approaches to protein transfer and their historical basis. Finally, the application of these protein transfer approaches to develop cancer vaccines are reviewed and discussed.

Animals↗
PubMed2001

Development of therapeutic vaccines by direct modification of cell membranes from surgically removed human tumor tissue with immunostimulatory molecules.

The addition of immunostimulatory molecules to tumor cells has been proposed as a potentially useful strategy to induce anti-tumor immunity. In this report we have investigated the application of using isolated tumor membranes modified by transfer of a glycosyl-phosphatidylinositol (GPI)-anchored form of the costimulatory molecule, B7-1 (CD80), as a cell free cancer vaccine for clinical use. Isolated tumor cell membranes were prepared from established tumor cell lines and the optimum conditions necessary for modification and clinical application were determined. GPI-B7-1 transferred optimally onto isolated human tumor membranes at physiological temperature (37 degrees C) in a dose dependent manner. Transfer of GPI-B7-1 to isolated membranes resulted in stable expression and costimulatory function. These modified membranes could be stored for repeated immunizations while retaining expression of GPI-B7-1. Critically, isolated tumor membranes, prepared directly from surgically removed human tumor tissue, could be modified by GPI-B7-1 and costimulate T cells. Finally, membranes isolated from tumor tissue expressed MHC class II, unlike the cell line established in vitro from the same patient. This novel approach to express immunostimulatory molecules on isolated membranes derived from a patient's tumor tissue will make the preparation of autologous therapeutic cancer vaccines available to patients from which tumor cell lines can not be established.

Adjuvants, Immunologic↗