Biomedical subjects

S Joshi

Publications and source records attributed to S Joshi.

At least 19 recordsLinked to original sources

PubMed2006

Fluoroquinolone resistance in Salmonella typhi and S. paratyphi A in Bangalore, India.

Fluoroquinolone resistance in Salmonella typhi and S. paratyphi A is being increasingly reported. The minimum inhibitory concentrations (MICs) of ciprofloxacin, ofloxacin, levofloxacin and gatifloxacin against S. typhi and S. paratyphi A were compared. Fifty blood culture isolates, 25 S. typhi and 25 S. paratyphi A, were studied. The MICs were determined by the agar dilution method. Disc diffusion was done for the fluoroquinolones and other antibiotics. Nalidixic acid resistance was seen in 21/25 S. paratyphi A and 17/25 S. typhi isolates, and these had higher MICs to fluoroquinolones. Five S. typhi and six S. paratyphi A were fully resistant to ciprofloxacin (MIC >2 microg/l). No multidrug resistance was seen in S. typhi. The absence of multidrug resistance and presence of fluoroquinolone resistance warrants a review of therapy for enteric fever.

Ciprofloxacin↗

PubMed2006

Loose-patch-juxtacellular recording in vivo--a method for functional characterization and labeling of neurons in macaque V1.

We describe a method that uses a modified version of juxtacellular labeling [Pinault D. A novel single-cell staining procedure performed in vivo under electrophysiological control: morpho-functional features of juxtacellularly labeled thalamic cells and other central neurons with biocytin or neurobiotin. J Neurosci Meth 1996;65:113-36], which allows us to functionally characterize and subsequently label single neurons in vivo in macaque V1. The method is generally applicable in acute in vivo preparations. Extracellular recording is made with a patch electrode when the electrode is attached to the cell membrane. Initially a 'blind' search method is used as a guide to obtaining a cell attached configuration that we refer to as a loose-patch (LP). The neuron's receptive field properties are functionally characterized, the neuron is labeled and then characterization is confirmed, all in the LP configuration. There are a number of advantages of the method that we describe over other methods. First, we have found that we can obtain stable extracellular recordings for periods of hours that enable us to make a relatively comprehensive visual functional characterization of a neuron's receptive field properties. Second, because the electrode is closely apposed to the cell we obtain excellent isolation of the extracellular spike. Third, the method provides labeling that gives complete dendritic and axonal filling that survives over a number of days, which is an important feature in acute primate experiments. Fourth, the in vivo method of labeling and reconstructing neurons gives complete three-dimensional structure of the neuron including its intra-cortical axonal arbor. These features overcome known limits of the established methods of studying neuronal morphology including the Golgi stain (limited when adult tissue is used) and in vitro whole cell methods (incomplete axonal filling due to limited slice thickness). They also overcome the known limits of the established method of combined function-morphology studies i.e. intracellular recording in vivo. The modified juxtacellular method provides a reliable alternative to the difficult method of characterization by extracellular recording and subsequent intracellular labeling [Anderson JC, Martin KAC, Whitteridge D. Form, function and intracortical projections of neurons in the striate cortex of the monkey Macacus nemestrinus. Cerebral Cortex 1993;3:412-20]. We show the method can be used to record at a range of depths through V1 cortex allowing for sampling of neurons in the different layers and functional subpopulations. Links can then be made with existing knowledge about the anatomical organization of V1, the various morphological classes of neurons found therein, their functional connectivity and visual response properties.

Animals↗

PubMed2006

Retinoic acid receptors and tissue-transglutaminase mediate short-term effect of retinoic acid on migration and invasion of neuroblastoma SH-SY5Y cells.

Long-term treatment with all trans-retinoic acid (RA) induces neuronal differentiation and apoptosis. However, the effect of short-term RA treatment on cell proliferation, migration and invasion of neuroblastoma cell lines (SH-SY5Y and IMR-32) remains unclear. RA induces expression of tissue-transglutaminase (TGase) and promotes migration and invasion after 24 h of treatment in SH-SY5Y cells, but not in IMR-32 cells. RA receptor (RAR) agonist (4-(E-2-[5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl]-1-propenyl) benzoic acid) and RAR/retinoid X receptor (RXR) agonist (9-cis-RA) promote expression of TGase, migration and invasion of SH-SY5Y cells, while RXR agonist has no significant effect. RAR antagonist blocks RA effect on migration and invasion, indicating that RAR receptors are required. Retinoid receptors are expressed and activated by RA in both cell lines. However, only transient activation of RAR is observed in IMR-32 cells. These findings suggest that different responses observed in SH-SY5Y and IMR-32 cells could be due to differential activation of retinoid receptors. Overexpression of TGase has no effect on migration or invasion, while overexpression of antisense TGase blocks RA-induced migration and invasion, indicating that other molecules along with TGase mediate RA effects. In addition to the long-term effects of RA that are coupled with cell differentiation, short-term effects involve migration and invasion of neuroblastoma SH-SY5Y cells.

Alitretinoin↗

PubMed2006

Ethanol impairs Rho GTPase signaling and differentiation of cerebellar granule neurons in a rodent model of fetal alcohol syndrome.

Developmental exposure to ethanol impairs fetal brain development and causes fetal alcohol syndrome. Although the cerebellum is one of the most alcohol-sensitive brain areas, signaling mechanisms underlying the deleterious effects of ethanol on developing cerebellar granule neurons (CGNs) are largely unknown. Here we describe the effects of in vivo ethanol exposure on neurite formation in CGNs and on the activation of Rho GTPases (RhoA and Rac1), regulators of neurite formation. Exposure of 7-day-old rat pups to ethanol for 3 h moderately increased blood alcohol concentration (BAC) ( approximately 40 mM) and inhibited neurite formation and Rac1 activation in CGNs. Longer exposure to ethanol for 5 h resulted in higher BAC ( approximately 80 mM), induced apoptosis, inhibited Rac1, and activated RhoA. Studies demonstrated a regulatory role of Rho GTPases in differentiation of cerebellar neurons, and indicated that ethanol-associated impairment of Rho GTPase signaling might contribute to brain defects observed in fetal alcohol syndrome.

Animals↗

PubMed2006

Flow cytometric quantification of antigen D sites on red blood cells of partial D and weak D variants in India.

The D antigenic sites are diminished in weak D and partial D variants. The aim of this study was to estimate D antigen on RBC in weak D and partial D variants in Indian population by using flow cytometric method. Blood samples of 42 cases of partial D, eight cases of weak D and 123 normal Rh phenotypes identified by serological methods were used in the study. An indirect immunofluorescence method was employed using 29 monoclonal anti-D as primary antibody. The D antigenic sites were calculated using control RBC as internal standard. The D antigenic sites in weak D and partial D variants are less than that found in normal Rh phenotypes. In weak D, the D antigenic sites were between 1500 and 7000 D antigens per cell. Among partial D variants, DVI had minimum and DVa had maximum number of D sites. Flow cytometry is a very good tool for demonstrating minor variation in D antigen when serological methods are inconclusive. The D antigenic sites per RBC in partial D variants identified in Indian population are reported for the first time.

Antibodies, Monoclonal↗

PubMed2006

Evaluation of an automated deformable image matching method for quantifying lung motion in respiration-correlated CT images.

We have evaluated an automated registration procedure for predicting tumor and lung deformation based on CT images of the thorax obtained at different respiration phases. The method uses a viscous fluid model of tissue deformation to map voxels from one CT dataset to another. To validate the deformable matching algorithm we used a respiration-correlated CT protocol to acquire images at different phases of the respiratory cycle for six patients with nonsmall cell lung carcinoma. The position and shape of the deformable gross tumor volumes (GTV) at the end-inhale (EI) phase predicted by the algorithm was compared to those drawn by four observers. To minimize interobserver differences, all observers used the contours drawn by a single observer at end-exhale (EE) phase as a guideline to outline GTV contours at EI. The differences between model-predicted and observer-drawn GTV surfaces at EI, as well as differences between structures delineated by observers at EI (interobserver variations) were evaluated using a contour comparison algorithm written for this purpose, which determined the distance between the two surfaces along different directions. The mean and 90% confidence interval for model-predicted versus observer-drawn GTV surface differences over all patients and all directions were 2.6 and 5.1 mm, respectively, whereas the mean and 90% confidence interval for interobserver differences were 2.1 and 3.7 mm. We have also evaluated the algorithm's ability to predict normal tissue deformations by examining the three-dimensional (3-D) vector displacement of 41 landmarks placed by each observer at bronchial and vascular branch points in the lung between the EE and EI image sets (mean and 90% confidence interval displacements of 11.7 and 25.1 mm, respectively). The mean and 90% confidence interval discrepancy between model-predicted and observer-determined landmark displacements over all patients were 2.9 and 7.3 mm, whereas interobserver discrepancies were 2.8 and 6.0 mm. Paired t tests indicate no significant statistical differences between model predicted and observer drawn structures. We conclude that the accuracy of the algorithm to map lung anatomy in CT images at different respiratory phases is comparable to the variability in manual delineation. This method has therefore the potential for predicting and quantifying respiration-induced tumor motion in the lung.

Algorithms↗

PubMed2006

Primary anterior abdominal wall actinomycosis.

Actinomycosis of the anterior abdominal wall is rare. We report a 50-year-old diabetic man who presented with a left hypochondrial mass of three weeks duration associated with fever. Abdominal computed tomography showed a 2 x 4 cm mass projecting from the internal abdominal wall associated with surrounding inflammation. The mass did not decrease after a week of intravenous antibiotics. Excision of the mass and primary closure of the abdominal wall were performed. The mass involved the deep muscles of anterior abdominal wall. The omentum was adherent to the parietal peritoneum underneath the mass. Microscopical examination of the mass was consistent with actinomycosis. The postoperative period was uneventful and the patient recovered completely. The patient received penicillin for six months.

Abdominal Muscles↗

PubMed2005

Structure determination of CdS and ZnS nanoparticles: direct modeling of synchrotron-radiation diffraction data.

We introduce a modified method of powder-diffraction data analysis to obtain precise structural information on freestanding ZnS and CdS nanoparticles with diameters well below 5 nm, i.e., in a range where common bulk-derived approaches fail. The method is based on the Debye equation and allows us to access the crystal structure and the size of the particles with high precision. Detailed information on strain, relaxation effects, stacking faults, and the shape of the particles becomes available. We find significant size differences between our new results and those obtained by established methods, and conclude that a mixed zinc-blende/wurtzite stacking and significant lattice distortions occur in our CdS nanoparticles. Our approach should have direct impact on the understanding and modeling of quantum size effects in nanoparticles.

Journal Article↗

PubMed2005

Observation of resonant interatomic coulombic decay in Ne clusters.

We have measured the electron spectra of Ne clusters after excitation with photon energies around the 2s inner valence threshold. At two photon energies below threshold, a resonantly enhanced surplus of low kinetic-energy electrons is observed. The kinetic energy of the peak does not vary with the photon energy and is slightly larger than the transition energy of Interatomic Coulombic Decay (ICD) above threshold. This leads us to assume that an ICD-like process is present. In analogy to the Auger and the resonant Auger decay this new phenomenon is termed resonant ICD.

Journal Article↗

PubMed2005

Growth in children with Helicobacter pylori infection and dyspepsia.

AIMS: To compare the height, weight, and body mass index (BMI) of children presenting with dyspeptic symptoms and Helicobacter pylori infection, to those with dyspepsia but without the infection. METHODS: A retrospective chart review of 257 children was performed. 13C urea breath test was performed to detect H pylori infection; weight and height were recorded and BMI was calculated. Weight, height, and BMI SD scores were determined using the 1990 UK normative data. The Index of Multiple Deprivation 2004 (IMD 2004) scores, which measure deprivation at small area level, were calculated from the patients' postcodes. RESULTS: Ninety seven of the 257 children were H pylori positive. The mean age at diagnosis and presenting symptoms of H pylori positive and negative patients were similar. The mean IMD 2004 scores for children with H pylori infection were significantly higher compared to H pylori negative patients, suggesting that children with the infection came from relatively more deprived areas. The mean weight and height SD score were significantly lower for children with H pylori infection compared to those without. However, this difference was no longer significant after adjusting for socioeconomic deprivation and ethnic differences between the groups. CONCLUSION: Children with dyspepsia and H pylori infection were shorter and lighter than patients with similar symptoms but no infection. The differences in anthropometry may be due to socioeconomic and ethnic factors rather than H pylori infection.

Adolescent↗

PubMed2005

Automatic segmentation of intra-treatment CT images for adaptive radiation therapy of the prostate.

We have been developing an approach for automatically quantifying organ motion for adaptive radiation therapy of the prostate. Our approach is based on deformable image registration, which makes it possible to establish a correspondence between points in images taken on different days. This correspondence can be used to study organ motion and to accumulate inter-fraction dose. In prostate images, however, the presence of bowel gas can cause significant correspondence errors. To account for this problem, we have developed a novel method that combines large deformation image registration with a bowel gas segmentation and deflation algorithm. In this paper, we describe our approach and present a study of its accuracy for adaptive radiation therapy of the prostate. All experiments are carried out on 3-dimensional CT images.

Algorithms↗

PubMed2005

Prescription auditing and antimicrobial resistance at a tertiary care hospital in New Delhi, India.

This paper reports the antibiotic consumption data of Sir Ganga Ram Hospital, New Delhi and bacterial resistance over a seven-year period. Cephalosporins, penicillins and fluoroquinolones were the most widely prescribed antibiotics. A correlation was seen between Escherichia coli resistance to third-generation cephalosporins and increased cephalosporin use, as well as resistance to co-amoxyclav and its use.

Anti-Bacterial Agents↗

PubMed2005

Assessment of hypertension control in chronic kidney disease patients by ambulatory blood pressure monitoring.

BACKGROUND: Inadequate control of blood pressure (BP) increases cardiovascular mortality and morbidity in chronic kidney disease (CKD) and renal transplant patients. 24 hour ambulatory BP was recorded to evaluate the adequacy of BP control in these patients. METHODS: 60 CKD patients (25 conservative therapy, 16 maintenance hemodialysis, 19 renal transplant patients) were studied prospectively. After achieving clinic BP control, 24 hour ambulatory BP was recorded at 1 and 6 months. The patients were followed up for one year. RESULTS: Mean daytime and nighttime systolic blood pressure (SBP) both at 1 month and at 6 month was higher in non-survivors than in survivors. The survivors had better control of their daytime (p=0.018) as well as nighttime SBP levels (p=0.018) at 6 months compared to those at 1 month. Survivors achieved nocturnal dipping of SBP at 1 and 6 months (p=0.047, p=0.025, respectively). Non-survivors failed to achieve lower daytime (p=0.375) or nighttime SBP (p=0.254) at 6 months as compared to SBP at 1 month in spite of optimizing antihypertensive therapy. Daytime (p=0.022) and nighttime (p=0.029) diastolic BP (DBP) in the non-survivors was higher than in survivors. Nocturnal dip in DBP was not seen in either survivors at 1 (p=0.177) and 6 months (p=0.434) or non-survivors at 1 (p=0.408) and at 6 months (p=0.081). Renal transplant patients did not exhibit nocturnal dipping of BP. CONCLUSION: We conclude that, unlike survivors, there was worsening of 24 hour BP control in non-survivors. ABPM has a role in better management of total BP burden in CKD patients.

Adult↗

PubMed2004

Fluoroscope-aided retrograde placement of guide wire for tracheal intubation in patients with limited mouth opening.

Passing a retrograde catheter/wire into the pharynx through a cricothyroid puncture can facilitate tracheal intubation in difficult situations where either a flexible fibre-optic bronchoscope or an expert user of such a device is not available. Some mouth opening is essential for the oral and/or nasal retrieval of the catheter/wire from the pharynx. Two patients with temporo-mandibular joint (TMJ) ankylosis and extremely limited mouth opening required gap arthroplasty of the TMJ under general anaesthesia. Because we did not have a flexible fibre-optic bronchoscope, we performed fluoroscopy-assisted nasal retrieval of the guide wire passed up through a cricothyroid puncture and subsequently accomplished wire-guided naso-tracheal intubation. In the absence of a flexible fibre-optic bronchoscope, this technique is a very useful aid to intubation in patients with limited mouth opening.

Adult↗

PubMed2004

Monte Carlo as a four-dimensional radiotherapy treatment-planning tool to account for respiratory motion.

Four-dimensional (4D) radiotherapy is the explicit inclusion of the temporal changes in anatomy during the imaging, planning and delivery of radiotherapy. Temporal anatomic changes can occur for many reasons, though the focus of the current investigation was respiration motion for lung tumours. The aims of the current research were first to develop a 4D Monte Carlo methodology and second to apply this technique to an existing 4D treatment plan. A 4D CT scan consisting of a series of 3D CT image sets acquired at different respiratory phases was used. Deformable image registration was performed to map each CT set from the end-inhale respiration phase to the CT image sets corresponding with subsequent respiration phases. This deformable registration allowed the contours drawn on the end-inhale CT to be automatically drawn on the other respiratory phase CT image sets. A treatment plan was created on the end-inhale CT image set and then automatically created on each of the 3D CT image sets corresponding with subsequent respiration phases, based on the beam arrangement and dose prescription in the end-inhale plan. Dose calculation using Monte Carlo was simultaneously performed on each of the N (=8) 3D image sets with 1/N fewer particles per calculation than for a 3D plan. The dose distribution from each respiratory phase CT image set was mapped back to the end-inhale CT image set for analysis. This use of deformable image registration to merge all the statistically noisy dose distributions back onto one CT image set effectively yielded a 4D Monte Carlo calculation with a statistical uncertainty equivalent to a 3D calculation, with a similar calculation time for the 3D and 4D methods. Monte Carlo as a dose calculation tool for 4D radiotherapy planning has two advantages: (1) higher accuracy for calculation in electronic disequilibrium conditions, such as those encountered during lung radiotherapy, and (2) if deformable image registration is used, the calculation time for Monte Carlo is independent of the number of 3D CT image sets constituting a 4D CT, unlike other algorithms for which the calculation time scales linearly with the number of 3D CT image sets constituting a 4D CT.

Algorithms↗

PubMed2004

Unbiased diffeomorphic atlas construction for computational anatomy.

Construction of population atlases is a key issue in medical image analysis, and particularly in brain mapping. Large sets of images are mapped into a common coordinate system to study intra-population variability and inter-population differences, to provide voxel-wise mapping of functional sites, and help tissue and object segmentation via registration of anatomical labels. Common techniques often include the choice of a template image, which inherently introduces a bias. This paper describes a new method for unbiased construction of atlases in the large deformation diffeomorphic setting. A child neuroimaging autism study serves as a driving application. There is lack of normative data that explains average brain shape and variability at this early stage of development. We present work in progress toward constructing an unbiased MRI atlas of 2 years of children and the building of a probabilistic atlas of anatomical structures, here the caudate nucleus. Further, we demonstrate the segmentation of new subjects via atlas mapping. Validation of the methodology is performed by comparing the deformed probabilistic atlas with existing manual segmentations.

Algorithms↗

PubMed2004

Non-traumatic compression fractures of the thoracic spine following a seizure -- treatment by percutaneous kyphoplasty.

A 26-year-old male presented with acute mid-thoracic back pain following a witnessed grand mal seizure. There was no trauma and the patient was on steroids for systemic lupus erythematosus. X-rays and CT scans of the thoracic spine revealed compression fractures at T5 and T6, with 50 % loss of vertebral height and kyphosis. He underwent percutaneous kyphoplasty of both vertebrae, with symptomatic improvement. Non-traumatic compression fractures of the thoracic spine following seizures are a rare injury. This may be related to the compressive forces exerted on the vertebral column by the contractions of the truncal muscles, during a seizure. These compression fractures are suitable for treatment by minimally invasive techniques, such as kyphoplasty.

Adult↗

PubMed2004

The pp67 mRNA assay in treatment and monitoring of cytomegalovirus disease in renal transplant patients in India.

The present report describes use of nucleic acid sequence-based amplification (NASBA) technology to detect pp67 mRNA of cytomegalovirus (CMV) in transplant patients in India. In our experience, pp67 mRNA assay was an accurate, rapid, and effective diagnostic tool to detect active CMV disease in 40.7% (50/123) of symptomatic transplant cases. This assay also allowed us to monitor CMV therapy. As part of the immunosuppressive regimen mycophenolate mofetil was found to increase the risk of developing CMV disease. All positive cases with this assay were subjected to antiviral therapy, with complete remission of the disease. At our center CMV NASBA assay has become the gold standard for the diagnosis of CMV disease in transplant patients.

Antiviral Agents↗