R P Tripathi

All India Institute of Medical Sciences, New Dilli, NCT, India

Are you R P Tripathi?

Claim your profile

Publications (47)83.93 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Neuroimaging studies have reported an association between white matter integrity and cognitive performance in normal aging and various neuropathological conditions. We compared alcoholics with controls and hypothesized that the degree of disconnection of white matter fibers would be negatively correlated with memory dysfunction scores. Diffusion tensor imaging (DTI) based tractography and PGI-memory scale (PGIMS) test was performed in 10 abstinent chronic alcoholic and 10 demographically equivalent control men. DTI measures [fractional anisotropy (FA), and mean diffusivity (MD)] from all of the major cerebral tracts were calculated and a comparison was done between patient group and controls. Spearman's rank correlation coefficient was computed between memory dysfunction score and DTI measures. Compared to controls alcoholic participants had significantly reduced FA in corpus callosum (CC), fornix (FX), and right hemispheric arcuate fasciculus (AF), anterior thalamic radiation (ATR) and inferior longitudinal fasciculus (ILF). A significant inverse correlation with memory dysfunction score was observed with right cingulum, right uncinate fasciculus, right ILF and left ILF. The inverse correlation of memory dysfunction score with FA of white matter tracts suggest that white matter deficit in these white matter fibers may contribute to underlying dysfunction in memory in alcoholism.
    Behavioural brain research 05/2013; 250. DOI:10.1016/j.bbr.2013.05.001 · 3.39 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Heavy metals are known for their associated nephrotoxicity and nickel is no exception. An integrated metabonomic approach, based on high-resolution 1H NMR spectroscopy, was applied to determine the acute biochemical effects of NiCl2 on the renal tissues of rats. Kidney homogenates from rats treated with NiCl2 at two dose levels (4 and 20 mg kg−1 b.w., i.p.) and those from controls were analysed using 1H NMR spectroscopy and also assessed for antioxidant parameters at days 1, 3 and 5 post-dose. The major metabolite changes corresponding to nickel exposure were related to amino acids, osmolytes and energy metabolites. Differential responses were observed in 1H NMR spectra with exposure to low and high doses of NiCl2. For high doses, 1H NMR spectral analysis revealed alterations in renal tissues, along with damage to the cortical and papillary region and depletion of renal osmolytes such as betaine, trimethyl amine oxide, myo-inositol and taurine, which persisted until day 5 post-dose. The metabolite profile of 1H NMR spectra obtained from animals treated with lower dose of NiCl2 initially increased as an immediate stress response and then showed signs of recovery with the passage of time. NMR spectral analysis was well corroborated with histopathological and oxidative stress results. Nickel-induced oxidative stress was observed in both groups of animals with increased levels of antioxidant parameters at initial time points, but continued to increase in the high-dose group. The present study shows a huge potential of metabonomics for mapping organ-based metabolic response during heavy metal toxicity. Copyright © 2011 John Wiley & Sons, Ltd.
    Journal of Applied Toxicology 02/2013; 33(2). DOI:10.1002/jat.1730 · 3.17 Impact Factor
  • Sonia Gandhi, Subash Khushu, Rajendra P. Tripathi
    [Show abstract] [Hide abstract]
    ABSTRACT: The field of metabolomics continues to grow rapidly over the last decade and has proven to be a powerful technique in predicting and explaining complex phenotypes in various biological systems. As one of the ‘omic’ technology, metabolomics has exciting applications in varied fields including medical science, synthetic biology, medicine and predictive modelling of plant, animal and microbial systems. Integrated application with genomics, transcriptomics and proteomics provide greater understanding of global system biology. Metabolomics is often considered a powerful tool to provide an instantaneous snapshot of the physiology of a cell. It is increasingly being used to characterize the interaction of organism with their environment. Although thermal conditions influence the development of living organism in a wide variety of ways, this topic has been recently ignored in humans. This review reintroduces thermal conditions as a topic of importance by presenting an example of how thermal conditions influence various metabolic pathways. The first section highlights the advances in metabolomics technologies followed by the effects and recent studies of organism function and metabolic responses to thermal stress, including investigations of heat and cold stress are reviewed. This review forms the basis for future studies to detect early biomarkers for thermal stress in humans and identifying population at risk. Furthermore, it can be used to develop methods to provide protection to the body against environmental insult, thereby, reducing the adverse response to thermal stress.
    01/2013; 1(4). DOI:10.2174/2213235X01666131212230658
  • [Show abstract] [Hide abstract]
    ABSTRACT: Trait anxiety, a personality dimension that measures an individual's higher disposition to anxiety, has been found to be associated with many functional consequences viz. increased distractibility, attentional bias in favor of threat-related information etc. Similarly, volumetric studies have reported morphological changes viz. a decrease in the volume of left uncinate fasciculus (fiber connecting anterior temporal areas including the amygdala with prefrontal-/orbitofrontal cortices) and an increase in the volume of the left amygdala and right hippocampus, to be associated with trait anxiety. The functional and morphological changes associated with trait anxiety might also be associated with the changes in the integrity of WM tracts in relation with the trait anxiety levels of the subjects. Therefore, in the present diffusion tensor tractography (DTT) study, we investigated the possible relationship between the diffusion tensor imaging (DTI) derived indices of a wide array of fiber tracts and the trait anxiety scores in our subject group. A positive correlation between trait anxiety scores and the mean fractional anisotropy (FA) value was obtained in fornix and left uncinate fasciculus. The study provides first account of a positive relation between sub-clinical anxiety levels of subjects and the FA of fornix thereby providing interesting insights into the biological foundation of sub-clinical anxiety.
    Behavioural brain research 10/2012; 238. DOI:10.1016/j.bbr.2012.10.007 · 3.39 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The nuclear arsenal and the use of nuclear technologies have enhanced the likelihood of whole-body/partial-body radiation exposure. The central nervous system is highly susceptible to even low doses of radiation. With the aim of detecting and monitoring the pathologic changes of radiation-induced damage in brain parenchyma, we used serial diffusion tensor magnetic resonance imaging (DTI) with a 7T magnetic resonance unit and neurobehavioral assessments mice irradiated with 3-, 5-, and 8-Gy doses of radiation. Fractional anisotropy (FA) and mean diffusivity (MD) values at each time point (baseline, day 1, day 5, and day 10) were quantified from hippocampus, thalamus, hypothalamus, cudate-putamen, frontal cortex, sensorimotor cortex, corpus callosum, cingulum, and cerebral peduncle. Behavioral tests were performed at baseline, day 5, and day 10. A decrease in FA values with time was observed in all three groups. At day 10, dose-dependent decreases in FA and MD values were observed in all of the regions compared with baseline. Behavioral data obtained in this study correlate with FA values. Radiation-induced affective disorders were not radiation dose dependent, insofar as the anxiety-like symptoms at the lower dose (3 Gy) mimics to the symptoms with the higher dose (8 Gy) level but not with the moderate dose. However, there was a dose-dependent decline in cognitive function as well as FA values. Behavioral data support the DTI indices, so it is suggested that DTI may be a useful tool for noninvasive monitoring of radiation-induced brain injury.
    Journal of Neuroscience Research 10/2012; 90(10):2009-19. DOI:10.1002/jnr.23073 · 2.73 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Radiation accidents are rare events that induce radiation syndrome, a complex pathology which is difficult to treat. In medical management of radiation victims, life threatening damage to different physiological systems should be taken into consideration. The present study was proposed to identify metabolic and physiological perturbations in biofluids of mice during different phases of radiation sickness using 1H nuclear magnetic resonance (1H NMR) spectroscopy and pattern recognition (PR) technique. The 1H NMR spectra of the biofluids collected from mice irradiated with 5 Gray (Gy) at different time points during radiation sickness were analysed visually and by principal components analysis. Urine and serum spectral profile clearly showed altered metabolic profiles during different phases of radiation sickness. Increased concentration of urine metabolites viz. citrate, α ketoglutarate, succinate, hippurate, and trimethylamine during prodromal and clinical manifestation phase of radiation sickness shows altered gut microflora and energy metabolism. On the other hand, serum nuclear magnetic resonance (NMR) spectra reflected changes associated with lipid, energy and membrane metabolism during radiation sickness. The metabonomic time trajectory based on PR analysis of 1H NMR spectra of urine illustrates clear separation of irradiated mice group at different time points from pre dose. The difference in NMR spectral profiles depicts the pathophysiological changes and metabolic disturbances observed during different phases of radiation sickness, that in turn, demonstrate involvement of multiple organ dysfunction. This could further be useful in development of multiparametric approach for better evaluation of radiation damage as well as for medical management during radiation sickness. KeywordsRadiation sickness– 1H NMR spectroscopy–Serum–Urine–Metabonomics
    Metabolomics 12/2011; 7(4):583-592. DOI:10.1007/s11306-011-0277-4 · 3.97 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Thallium (Tl) is a toxic heavy metal and its exposure to the human body causes physiological and biochemical changes due to its interference with potassium-dependent biological reactions. A high-resolution (1)H NMR spectroscopy based metabonomic approach has been applied for investigating acute biochemical effects caused by thallium sulfate (Tl(2)SO(4)). Male strain A mice were divided in three groups and received three doses of Tl(2)SO(4) (5, 10 and 20 mg kg(-1) b.w., i.p.). Urine samples collected at 3, 24, 72 and 96 h post-dose time points were analyzed by (1)H NMR spectroscopy. NMR spectral data were processed and analyzed using principal components analysis to represent biochemical variations induced by Tl(2)SO(4). Results showed Tl-exposed mice urine to have distinct metabonomic phenotypes and revealed dose- and time-dependent clustering of treated groups. The metabolic signature of urine analysis from Tl(2)SO(4)-treated animals exhibited an increase in the levels of creatinine, taurine, hippurate and β-hydroxybutyrate along with a decrease in energy metabolites trimethylamine and choline. These findings revealed Tl-induced disturbed gut flora, membrane metabolite, energy and protein metabolism, representing physiological dysfunction of vital organs. The present study indicates the great potential of NMR-based metabonomics in mapping metabolic response for toxicology, which could ultimately lead to identification of potential markers for Tl toxicity.
    Journal of Applied Toxicology 10/2011; 31(7):663-70. DOI:10.1002/jat.1617 · 3.17 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The metabolomic approach has been widely used in toxicology to investigate mechanisms of toxicity. To understand the mammalian system’s response to nickel exposure, we analysed the NiCl2 induced metabolomic changes in urine of rats using 1H nuclear magnetic resonance (1H NMR) spectroscopy together with clinically relevant biochemical parameters. Male Sprague–Dawley rats were administered intraperitoneally with NiCl2 at doses of 4, 10 and 20 mg/kg body weight. Urine samples were collected at 8, 16, 24, 72, 96 and 120 h post treatment. The metabolomic profile of rat urine showed prominent changes in citrate, dimethylamine, creatinine, choline, trimethylamine oxide (TMAO), phenyl alanine and hippurate at all doses. Principal component analysis of urine 1H NMR spectra demonstrated the dose and time dependent development of toxicity. The metabolomic time trajectory, based on pattern recognition analysis of 1H NMR spectra of urine, illustrated clear separation of pre and post treatments (temporal). Only animals treated with a low dose of NiCl2 returned to normal physiology. The 1H NMR spectral data correlated well with the clinically relevant nephrotoxic biomarkers. The urinary metabolomic phenotyping for NiCl2 induced nephrotoxicity was defined according to the predictive ability of the known metabolite biomarkers, creatinine, citrate and TMAO. The current approach demonstrates that metabolomics, one of the most important platform in system biology, may be a promising tool for identifying and characterizing biochemical responses to toxicity.
    Metabolomics 10/2011; 8(5):940-950. DOI:10.1007/s11306-011-0390-4 · 3.97 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The study was aimed to test the feasibility of utilizing an algorithmically determinable stable fiber mass (SFM) map obtained by an unsupervised principal eigenvector field segmentation (PEVFS) for automatic delineation of 18 white matter (WM) tracts: (1) corpus callosum (CC), (2) tapetum (TP), (3) inferior longitudinal fasciculus (ILF), (4) uncinate fasciculus (UNC), (5) inferior fronto-occipital fasciculus (IFO), (6) optic pathways (OP), (7) superior longitudinal fasciculus (SLF), (8) arcuate fasciculus (AF), (9) fornix (FX), (10) cingulum (CG), (11) anterior thalamic radiation (ATR), (12) superior thalamic radiation (STR), (13) posterior thalamic radiation (PTR), (14) corticospinal/corticopontine tract (CST/CPT), (15) medial lemniscus (ML), (16) superior cerebellar peduncle (SCP), (17) middle cerebellar peduncle (MCP) and (18) inferior cerebellar peduncle (ICP). Diffusion tensor imaging (DTI)-derived fractional anisotropy (FA) and the principal eigenvector field have been used to create the SFM consisting of a collection of linear voxel structures which are grouped together by color-coding them into seven natural classes to provide PEVFS signature segments which greatly facilitate the selection of regions of interest (ROIs) for fiber tractography using just a single mouse click, as compared with a manual drawing of ROIs in the classical approach. All the 18 fiber bundles have been successfully reconstructed, in all the subjects, using the single ROIs provided by the SFM approach, with their reproducibility characterized by the fact that the ROI selection is user independent. The essentially automatic PEVFS method is robust, efficient and compares favorably with the classical ROI methods for diffusion tensor tractography (DTT).
    Magnetic Resonance Imaging 06/2011; 29(8):1088-100. DOI:10.1016/j.mri.2011.04.014 · 2.02 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Acute cold stress may trigger systemic biochemical and physiological changes in the living organisms, which leads to rapid loss of homeostasis. These changes may reverse due to self-regulatory mechanism of the organism or by the intervention of suitable medication in the form of herbs. The present study was undertaken to assess the alterations in metabolites levels arising due to acute cold stress and to monitor the restoration of these changes by suitable herb intervention. Male Sprague-Dawley rats were exposed to acute cold stress of −10°C for 3 h and urine samples were collected and analyzed by NMR spectroscopy in conjugation with Principal Component Analysis (PCA). The study revealed highly significant biochemical changes in urinary metabolites and also demonstrated the protective effects of Tinospora Cordifolia (Tc) extract on the stressed rats. These changes suggest the involvement of various metabolic pathways such as Tricarboxylic Acid (TCA) cycle, gut microbiota, renal function, catecholamines and muscle metabolism in the metabolic alterations induced by cold stress and the compensation required to restore homeostasis. The present study forms the basis of future studies to establish potential biomarkers for cold stress in humans and lay down the optimum dosage of Tc to be administered for providing immunity to the body as prophylactic and mitigating agent against environmental insult such as cold stress.
    Metabolomics 06/2011; 8(3):444-453. DOI:10.1007/s11306-011-0326-z · 3.97 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Acute heat stress may trigger systemic biochemical and physiological changes in living organisms leading to rapid loss of homeostasis. Metabolic regulatory process during heat stress has been poorly understood therefore the present study was undertaken in order to have an insight of alterations in various metabolites due to acute heat stress exposure using nuclear magnetic resonance (NMR) spectroscopy. Male sprague-dawley (SD) rats were exposed to acute heat stress of 45±2°C for 3 h and urine samples were collected from control (n=6) and heat stress group (n=6) on day 0 and 1. Metabolites excreted in urine were analyzed using NMR spectroscopy in conjugation with principal component analysis (PCA). The biochemical response to acute heat stress was characterized by decreased levels of citrate, succinate, 2-oxoglutrate, phenylalanine, creatinine, hippurate and elevation in formate levels. Hence, some biological pathways such as tricarboxylic acid (TCA) cycle, catecholamine activity and gut microbiota were transiently affected due to heat stress exposure. NMR based metabonomic studies in conjugation with statistical analysis permits non-invasive and simultaneous monitoring of entire metabolic pathways. This reveals the subtle interplay of functional metabolites and pathways leading to an understanding of the systemic response to external stimuli such as heat stress. These studies form the basis for future studies to detect early biomarkers for heat stress in humans and identifying the population at risk. Furthermore, it can be used to develop methods to provide protection to the body against environmental insult, thereby reducing the adverse response to heat stress.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Subclinical hypothyroidism (sHT) is considered to be a milder form of thyroid dysfunction. Few earlier studies have reported neuromuscular symptoms as well as impaired muscle metabolism in sHT patients. In this study we report our findings on muscle bioenergetics in sHT patients using phosphorous magnetic resonance spectroscopy (31P MRS) and look upon the possibility to use 31P MRS technique as a clinical marker for monitoring muscle function in subclinical thyroid dysfunction. Seventeen normal subjects, 15 patients with sHT, and 9 patients with hypothyroidism performed plantar flexion exercise while lying supine in 1.5 T magnetic resonance scanner using custom built exercise device. MR Spectroscopy measurements of inorganic phosphate (Pi), phosphocreatine (PCr), and ATP of the calf muscle were taken during rest, at the end of exercise and in the recovery phase. PCr recovery rate constant (kPCr) and oxidative capacity were calculated by monoexponential fit of PCr vs time (t) at the beginning of recovery. We observed that changes in some of the phosphometabolites (increased phosphodiester levels and Pi concentration) in sHT patients which were similar to those detected in patients with hypothyroidism. However, our results do not demonstrate impaired muscle oxidative metabolism in sHT patients based upon PCr dynamics as observed in hypothyroid patients. 31P MRS-based PCr recovery rate could be used as a marker for monitoring muscle oxidative metabolism in sub clinical thyroid dysfunction.
    Journal of endocrinological investigation 04/2011; 35(2):129-34. DOI:10.3275/7676 · 1.55 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: SSPE is a persistent infection of the central nervous system caused by the measles virus. The correlation between the clinical staging and conventional MR imaging is usually poor. The purpose of this study was to determine whether tract-specific DTI measures in the major white mater tracts correlate with clinical grades as defined by the Jabbour classification for SSPE. Quantitative DTT was performed on 20 patients with SSPE (mean age, 9 years) and 14 age- and sex-matched controls. All patients were graded on the basis of the Jabbour classification into grade II (n=9), grade III (n=6), and grade IV (n=5) SSPE. The major white matter tracts quantified included the CC, SLF, ILF, CST, CNG, SCP, MCP, ICP, ATR, STR, and PTR. Although a successive decrease in mean FA values was observed in all the fiber tracts except for the SCP and ICP, moving from controls to grade IV, a significant inverse correlation between clinical grade and mean FA values was observed only in the splenium (r=-0.908, P<.001), CST (r=-0.663, P=.013), SLF (r=-0.533, P=.050), ILF (r=-0.776, P=.001), STR (r=-0.538, P=.047), and PTR (r=-0.686, P=.035) fibers. No significant correlation of mean MD values from these white matter tracts was observed with clinical grades of the disease. We conclude that the grade of encephalopathy correlates inversely with the tract-specific mean FA values. This information may be valuable in studying the disease progression with time and in assessing the therapeutic response in the future.
    American Journal of Neuroradiology 02/2011; 32(4):714-20. DOI:10.3174/ajnr.A2380 · 3.68 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Radiation exposure induces change in many biological compounds. It is important to assess the physiological and biochemical response to an absorbed dose of ionising radiation due to intentional or accidental event and to predict medical consequences for medical management. In the present study, nuclear magnetic resonance (NMR) spectroscopy-based metabolic profiling was used in mice serum for identification of radiation-induced changes at metabolite level. Mice were irradiated with 3, 5 and 8 Gray of γ-radiation dose and serum samples collected at day 1, 3 and 5 post irradiation were analysed by proton nuclear magnetic resonance (¹H NMR) spectroscopy. ¹H NMR spectra of serum were analysed by pattern recognition using principal component analysis. Irradiated mice serum showed distinct metabonomic phenotypes and revealed dose- and time-dependent clustering of irradiated groups. ¹H NMR spectral analysis exhibited increased lactate, amino acids, choline and lipid signals as well as decreased glucose signals. These findings indicate radiation-induced disturbed energy, lipid and protein metabolism. The information obtained from this study reflects multiple physiological dysfunctions. The study promises the application of NMR-based metabonomics in the field of radiobiology, for development of metabolic-based markers for screening of risk populations and medical management in these cases.
    International Journal of Radiation Biology 11/2010; 87(1):91-7. DOI:10.3109/09553002.2010.518211 · 1.84 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Region of interest based morphometric diffusion tensor imaging analysis, has been used extensively for the assessment of age-related changes in human brain, is limited to two dimensions and does not reflect the whole fiber bundle; however, diffusion tensor tractography (DTT) offers an overall view of individual fiber bundle in three-dimensional spaces. Quantitative DTT was performed on 51 healthy subjects of pediatric age range and young adults to compare age-related fractional anisotropy (FA) changes in corpus callosum, sensory and motor pathways, limbic tracts [cingulum (CNG) and fornix (Fx)], and superior and inferior longitudinal fascicules. In corpus callosum, inferior longitudinal fascicules, limbic tracts (CNG and Fx), sensory pathways, and motor pathways, an initial sharp increase in FA was observed up to the age of 2 y followed by a gradual increase up to 21 y. In superior longitudinal fascicules, sharp increase in FA was observed up to 3 y followed by a gradual increase. The FA value of the left CNG (p = 0.01, sign test) was observed to be significantly greater than that of the right CNG. We conclude that white matter fiber tracts mature with age and can be assessed by using DTT that may greatly improve our understanding of the human brain development.
    Pediatric Research 09/2009; 66(6):636-41. DOI:10.1203/PDR.0b013e3181bbc6b5 · 2.84 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: High fractional anisotropy (FA) usually reflects the orientation and integrity of white matter (WM) fibers. Other regions of increased FA have been described, such as brain abscesses, developing cortex, and areas of hemorrhage. It may not be possible to differentiate true fibers from the pseudofibers found inside an abscess cavity on the basis of FA and mean diffusivity (MD). The aim of this study was to differentiate true WM fibers from pseudo WM tracts inside the abscess cavity using geometrical diffusion tensor imaging metrics [linear anisotropy (CL), planar anisotropy (CP), and spherical anisotropy (CS)]. Diffusion tensor imaging was performed in 42 patients with brain abscess and 10 age/sex-matched controls. Automated segmentation using Java-based software divided the abscess cavity into two sub-regions with FA < 0.20 and FA ! 0.20. Quantitation was carried out on the sub-regions of the abscess cavity with FA ! 0.20. In healthy controls, regions of interest were placed on the corpus callosum, posterior limb of the internal capsule, and periventricular and subcortical WM. Significantly increased CP values were observed inside the abscess cavity compared with various normal WM regions. Significantly increased FA and CL values were observed in the abscess cavity compared with subcortical WM only. However decreased FA and CL values were observed in the cavity compared with the corpus callosum, posterior limb of the internal capsule, and periventricular WM. The 95% confidence intervals of means for the abscess cavity were well separated from those for WM in the case of CL and CP; however, they overlapped in the case of FA, MD, and CS. High CP with low CL inside the abscess cavity suggests that the shape of the diffusion tensor is predominantly planar, whereas it is linear in WM tracts. These geometrical indices may have advantages over FA for differentiating true from pseudo WM tracts inside the abscess cavity.
    NMR in Biomedicine 11/2008; · 3.56 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: It has been previously hypothesized that the high fractional anisotropy (FA) values in leptomeningeal cortical subcortical white matter (LCSWM) regions of neonatal brain with bacterial meningitis is due to the presence of adhesion molecules in the subarachnoid space, which are responsible for adherence of inflammatory cells over the subarachnoid membrane. The aim of this study was to look for any relationship between FA values in LCSWM regions and various neuroinflammatory molecules (NMs) in cerebrospinal fluid (CSF) measured in neonates with bacterial meningitis. Diffusion tensor imaging was performed on 18 term neonates (median age, 10.5 days) having bacterial meningitis and 10 age-/sex-matched healthy controls. CSF enzyme-linked immunosorbent assay was performed to quantify NMs [soluble intracellular adhesion molecules (sICAM), tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta)]. Significantly increased FA values were observed in LCSWM regions of the patients compared to controls. A significant positive correlation was observed between FA values in LCSWM regions and NMs [sICAM (r=0.67, P=.006), TNF-alpha (r=0.69, P=.005) and IL-1beta (r=0.82, P=.000)] in CSF of these patients. No difference in FA values (P=.99) in LCSWM regions was observed between patients with sterile (0.12+/-0.02) and culture-positive CSF study (0.12+/-0.02). FA may be used as noninvasive surrogate marker of NMs in neonatal meningitis in assessing therapeutic response in future.
    Magnetic Resonance Imaging 09/2008; 27(2):214-21. DOI:10.1016/j.mri.2008.06.010 · 2.02 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: High fractional anisotropy (FA) usually reflects the orientation and integrity of white matter (WM) fibers. Other regions of increased FA have been described, such as brain abscesses, developing cortex, and areas of hemorrhage. It may not be possible to differentiate true fibers from the pseudofibers found inside an abscess cavity on the basis of FA and mean diffusivity (MD). The aim of this study was to differentiate true WM fibers from pseudo WM tracts inside the abscess cavity using geometrical diffusion tensor imaging metrics [linear anisotropy (CL), planar anisotropy (CP), and spherical anisotropy (CS)]. Diffusion tensor imaging was performed in 42 patients with brain abscess and 10 age/sex-matched controls. Automated segmentation using Java-based software divided the abscess cavity into two sub-regions with FA < 0.20 and FA > or = 0.20. Quantitation was carried out on the sub-regions of the abscess cavity with FA > or = 0.20. In healthy controls, regions of interest were placed on the corpus callosum, posterior limb of the internal capsule, and periventricular and subcortical WM. Significantly increased CP values were observed inside the abscess cavity compared with various normal WM regions. Significantly increased FA and CL values were observed in the abscess cavity compared with subcortical WM only. However decreased FA and CL values were observed in the cavity compared with the corpus callosum, posterior limb of the internal capsule, and periventricular WM. The 95% confidence intervals of means for the abscess cavity were well separated from those for WM in the case of CL and CP; however, they overlapped in the case of FA, MD, and CS. High CP with low CL inside the abscess cavity suggests that the shape of the diffusion tensor is predominantly planar, whereas it is linear in WM tracts. These geometrical indices may have advantages over FA for differentiating true from pseudo WM tracts inside the abscess cavity.
    NMR in Biomedicine 08/2008; 21(6):581-8. DOI:10.1002/nbm.1228 · 3.56 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The metabolic changes in the brain of patients affected with Type 2 diabetes mellitus (DM) alone, both Type 2 DM and hypothyroidism and hypothyroidism only were investigated using proton magnetic resonance spectroscopy ((1)H MRS). Single-voxel spectroscopy was carried out in right and left frontal lobe white matter, left parietal white matter and left occipital gray matter. Choline (Cho)/creatine (Cr) value was found to be increased in the left occipital gray matter of the subjects affected with Type 2 DM and both Type 2 DM and hypothyroidism as compared to controls. No significant change in the Cho/Cr value in the occipital gray matter was observed in hypothyroid subjects as compared to controls. However, they showed an increased level of Cho/Cr in the frontal white matter. High Cho is associated with altered membrane phospholipid metabolism. The high Cho in frontal white matter in hypothyroids and occipital gray matter in diabetic patients suggests that, though both the diseases are endocrine disorders, they differ from each other in terms of regional brain metabolite changes.
    Magnetic Resonance Imaging 05/2008; 26(3):420-5. DOI:10.1016/j.mri.2007.08.011 · 2.02 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: PurposeThe objective of this article is to review the sources, effects and remedies of the artifacts that are controlled by operator variable parameters. Protocol error artifacts include susceptibility, ferromagnetic, truncation, aliasing, chemical shift, black boundary, cross-talk, partial volume averaging, and saturation artifacts. All these artifacts are simulated/developed in-house along with a few uncommonly seen artifacts. Also, the effectiveness of various remedial measures for all these artifacts has been demonstrated.ResultsSusceptibility, ferromagnetic, and black boundary artifacts can be reduced by using spin echo (SE) pulse sequence. Susceptibility and ferromagnetic artifacts are minimized by altering time-to-echo (TE), though chemical shift artifact (CSA) may turn into black boundary artifact and vice versa when TE is varied. By employing three-dimensional (3D) volume acquisitions susceptibility, ferromagnetic and partial volume averaging (PVA) artifacts can be reduced. Field of view (FOV) has an effect on aliasing, CSA and PVA artifacts, whereas by proper selection of phase encoding and frequency-encoding axes, susceptibility, ferromagnetic, aliasing and CSA can be overcome.ConclusionsThese artifacts can usually be ameliorated or avoided by altering parameters that are under operator control and employing remedial measures, thus maintaining good image quality and avoiding diagnostic errors, thereby enhancing the usefulness of MRI in clinical practice.
    Radiography 11/2007; DOI:10.1016/j.radi.2006.03.011

Publication Stats

303 Citations
83.93 Total Impact Points

Institutions

  • 1991
    • All India Institute of Medical Sciences
      New Dilli, NCT, India