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G Ganesh

Publications and source records attributed to G Ganesh.

11 recordsLinked to original sources
PubMed2006

Neural correlates of internal-model loading.

Skilled object manipulation requires knowledge, or internal models, of object dynamics relating applied force to motion , and our ability to handle myriad objects indicates that the brain maintains multiple models . Recent behavioral studies have shown that once learned, an internal model of an object with novel dynamics can be rapidly recruited and derecruited as the object is grasped and released . We used event-related fMRI to investigate neural activity linked to grasping an object with recently learned dynamics in preparation for moving it after a delay. Subjects also performed two control tasks in which they either moved without the object in hand or applied isometric forces to the object. In all trials, subjects received a cue indicating which task to perform in response to a go signal delivered 5-10 s later. We examined BOLD responses during the interval between the cue and go and assessed the conjunction of the two contrasts formed by comparing the primary task to each control. The analysis revealed significant activity in the ipsilateral cerebellum and the contralateral and supplementary motor areas. We propose that these regions are involved in internal-model recruitment in preparation for movement execution.

Adult↗
PubMed2006

Accurate real-time feedback of surface EMG during fMRI.

Real-time acquisition of EMG during functional MRI (fMRI) provides a novel method of controlling motor experiments in the scanner using feedback of EMG. Because of the redundancy in the human muscle system, this is not possible from recordings of joint torque and kinematics alone, because these provide no information about individual muscle activation. This is particularly critical during brain imaging because brain activations are not only related to joint torques and kinematics but are also related to individual muscle activation. However, EMG collected during imaging is corrupted by large artifacts induced by the varying magnetic fields and radio frequency (RF) pulses in the scanner. Methods proposed in literature for artifact removal are complex, computationally expensive, and difficult to implement for real-time noise removal. We describe an acquisition system and algorithm that enables real-time acquisition for the first time. The algorithm removes particular frequencies from the EMG spectrum in which the noise is concentrated. Although this decreases the power content of the EMG, this method provides excellent estimates of EMG with good resolution. Comparisons show that the cleaned EMG obtained with the algorithm is, like actual EMG, very well correlated with joint torque and can thus be used for real-time visual feedback during functional studies.

Adult↗
PubMed2006

Shock wave lithotripsy in solitary functioning kidneys: is prophylactic stenting necessary?

OBJECTIVE: To assess the safety of shock wave lithotripsy (SWL) without prophylactic stents in solitary functioning kidneys. PATIENTS AND METHODS: Sixteen solitary functioning kidneys with 23 renal stones with a size of <15 mm were treated with SWL as the primary modality. All patients were counseled about the possibility of obstruction, and treatment was offered to those who consented. The safety of SWL was assessed by the need for interventions and the posttreatment renal function. RESULTS: In 14 patients lithotripsy was uneventful. The duration of treatment ranged from 5 to 35 days. One patient with a 15-mm pelvic calculus presented with anuria which resolved before intervention. In 1 patient fragmentation failed, and percutaneous nephrolithotomy was performed. CONCLUSIONS: In solitary functioning kidneys, SWL is safe without prophylactic stents in properly selected and closely monitored patients. Avoiding stents decreases costs, duration of treatment, and stent-related morbidity without unduly compromising safety.

Adult↗
PubMed2005

Corpora cavernositis caused byActinomycetes.

We present the case of a 58-year-old diabetic who developed corpora cavernositis following drainage of a perianal abscess. To our knowledge this is the first such case caused by Actinomycetes, which spread from the perianal abscess by direct extension through Buck's fascia, which was probably breached during drainage of the abscess.

Abscess↗
PubMed2000

Rapid staining of proteins on polyacrylamide gels and nitrocellulose membranes using a mixture of fluorescent dyes.

The present work describes a novel, fluorescence-based method for staining proteins on SDS-PAGE and membrane(s). In this method, proteins are stained using a mixed-dye (sulfo-rhodamine B and 1-anilino-8-naphthalene sulfonic acid (NH(4)(+))) solution. The mixed-dye staining protocol can detect proteins up to a concentration of 15 ng. This method is generally applicable to all proteins and is more sensitive than the conventional Coomassie blue method. The staining method is rapid and efficient. Staining-destaining of proteins using the mixed-dye protocol takes less than half an hour. Another interesting feature of the staining protocol described here is the applicability to the staining of proteins on nitrocellulose membranes.

Anilino Naphthalenesulfonates↗
PubMed2000

Proline inhibits aggregation during protein refolding.

The in vitro refolding of hen egg-white lysozyme is studied in the presence of various osmolytes. Proline is found to prevent aggregation during protein refolding. However, other osmolytes used in this study fail to exhibit a similar property. Experimental evidence suggests that proline inhibits protein aggregation by binding to folding intermediate(s) and trapping the folding intermediate(s) into enzymatically inactive, "aggregation-insensitive" state(s). However, elimination of proline from the refolded protein mixture results in significant recovery of the bacteriolytic activity. At higher concentrations (>1.5 M), proline is shown to form loose, higher-order molecular aggregate(s). The supramolecular assembly of proline is found to possess an amphipathic character. Formation of higher-order aggregates is believed to be crucial for proline to function as a protein folding aid. In addition to its role in osmoregulation under water stress conditions, the results of this study hint at the possibility of proline behaving as a protein folding chaperone.

Animals↗
PubMed2000

The dyad gene is required for progression through female meiosis in Arabidopsis.

In higher plants the gametophyte consists of a gamete in association with a small number of haploid cells, specialized for sexual reproduction. The female gametophyte or embryo sac, is contained within the ovule and develops from a single cell, the megaspore which is formed by meiosis of the megaspore mother cell. The dyad mutant of Arabidopsis, described herein, represents a novel class among female sterile mutants in plants. dyad ovules contain two large cells in place of an embryo sac. The two cells represent the products of a single division of the megaspore mother cell followed by an arrest in further development of the megaspore. We addressed the question of whether the division of the megaspore mother cell in the mutant was meiotic or mitotic by examining the expression of two markers that are normally expressed in the megaspore mother cell during meiosis. Our observations indicate that in dyad, the megaspore mother cell enters but fails to complete meiosis, arresting at the end of meiosis 1 in the majority of ovules. This was corroborated by a direct observation of chromosome segregation during division of the megaspore mother cell, showing that the division is a reductional and not an equational one. In a minority of dyad ovules, the megaspore mother cell does not divide. Pollen development and male fertility in the mutant is normal, as is the rest of the ovule that surrounds the female gametophyte. The embryo sac is also shown to have an influence on the nucellus in wild type. The dyad mutation therefore specifically affects a function that is required in the female germ cell precursor for meiosis. The identification and analysis of mutants specifically affecting female meiosis is an initial step in understanding the molecular mechanisms underlying early events in the pathway of female reproductive development.

Arabidopsis↗
PubMed1994

Morphological and molecular characterization of Frankia sp. isolates from nodules of Alnus nepalensis Don.

Nodules collected from Alnus nepalensis growing in mixed forest stands at three different sites around Shillong, were crushed in various culture media to obtain isolates of Frankia. The isolates were found to have typical Frankia morphology as revealed by the scanning electron microscope. Seedlings inoculated with isolates or crushed nodules formed nitrogen fixing nodules. Frankia specific DNA probes amplified the DNA of the tested isolate AnpUS4. Partial nucleotide sequence of the 16S rRNA gene indicated that AnpUS4 was phylogenetically distinct from all other Frankia strains characterized so far.

Actinomyces↗
PubMed1993

Aspects of hypertension in renal allograft recipients. A study of 1000 live renal transplants.

A retrospective study of 1000 live renal transplants was performed in order to assess the factors associated with hypertension in renal transplant recipients. The prevalence of hypertension prior to transplantation was 48%. The need for antihypertensive drugs decreased in 43%, increased in 31% and remained the same in 26%. The presence of hypertension before transplantation, rejection episodes, transplant renal artery stenosis and native kidney disease were the main factors associated with post-transplant hypertension. An algorithm for the management of post-transplant hypertension is suggested.

Algorithms↗