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14 results on '"Kumar, Ratna"'

7. Acquired neuromyotonia in children with CASPR2 and LGI1 antibodies

Author

Surana, Snehal, Kumar, Ratna, Pitt, Matthew, Hafner, Patricia, Mclellan, Ailsa, Davidson, Joyce, Prabakhar, Prab, Vincent, Angela, Hacohen, Yael, and Wright, Sukhvir

Abstract

Acquired neuromyotonia is a form of peripheral nerve hyperexcitability. In adults, pathogenic antibodies that target the extracellular domains of leucine-rich glioma-inactivated protein 1 (LGI1) and contactin-associated protein-like 2 (CASPR2) have been reported. We describe three paediatric patients with acquired neuromyotonia and CASPR2 and LGI1 serum antibodies. They all presented with acute-onset myokymia and pain in the lower limbs; one patient also had muscle weakness. Electromyography was suggestive of peripheral nerve hyperexcitability. Two patients improved without immunotherapy; one treated patient remained immunotherapy-dependent. Although not fatal, acquired paediatric neuromyotonia can be disabling. It is amenable to symptomatic treatment or may undergo spontaneous recovery. More severe cases may require rational immunotherapy. What this paper adds: The symptoms of neuromyotonia may resolve spontaneously or may require sodium channel blockers. Patients with debilitating symptoms who are refractory to symptomatic therapy may require immunotherapy.

Published
2019

12. Investigations of Effect of Rotary EDM Electrode on Machining Performance of Al6061 Alloy

Author

Robinson, D S, Jenish, Joses, Periasamy, C, Samuel, P S, and Kumar, Ratna

Abstract

Electric Discharge Machining is an essential process which is being used for machining desired shape using electrical discharges which creates sparks. There will be electrodes subjected to electric voltage and which are separated by a dielectric liquid. Removing of material will be due to the continuous and rapid current discharges between two electrodes.. The spark is very carefully controlled and localized so that it only affects the surface of the material. Usually in order to prevent the defects which are arising due to the conventional machining, the Electric Discharge Machining (EDM) machining is preferred. Also intricate and complicated shapes can be machined effectively by use of Electric Discharge Machining (EDM). The EDM process usually does not affect the heat treat below the surface. This research work focus on the design and fabrication of rotary EDM tool for machining Al6061alloy and investigation of effect of rotary tool on surface finish, material removal rate and tool wear rate. Also the effect of machining parameters of EDM such as pulse on & off time, current on material Removal Rate (MRR), Surface Roughness (SR) and Electrode wear rate (EWR) have studied. Al6061 alloy can be used for marine and offshore applications by reinforcing some other elements. The investigations have revealed that MRR (material removal rate), surface roughness (Ra) have been improved with the reduction in the tool wear rate (TWR) when the tool is rotating instead of stationary. It was clear that as rotary speed of the tool is increasing the material removal rate is increasing with the reduction of surface finish and tool wear rate.

Published
2018

13. Evaluation of Mechanical Properties of MWCNT / Nanoclay Reinforced Aluminium alloy Metal Matrix Composite

Author

Samuel, P S, Kumar, Ratna, Robinson, D S, and, Smart, and John, S

Abstract

Aluminium alloy 5083 (AA5083) is a widely used material in aerospace, marine, defence and structural applications were mechanical and corrosion resistance property plays a vital role. For the present work, MWCNT / Nanoclay (montmorillonite (MMT) K10) mixed with AA5083 for different composition in weight percentage to enhance the mechanical property. Semi-solid state casting method (Compo-casting) was used to fabricate the composite materials. By using Field-emission scanning electron microscope (FESEM) the uniform dispersion of the reinforcement and microstructure were studied. Finally, the addition of Nanoclay shows decrease in tensile strength compared to the AA5083 / MWCNT composites and hardness value of the composites (AA5083 / MWCNT and AA5083 / Nanoclay) was found to increase significantly.

Published
2018

14. Acquired neuromyotonia in children with CASPR2 and LGI1 antibodies.

Author

Surana S, Kumar R, Pitt M, Hafner P, Mclellan A, Davidson J, Prabakhar P, Vincent A, Hacohen Y, and Wright S

Subjects
Adolescent, Antibodies immunology, Child, Preschool, Humans, Immunotherapy, Isaacs Syndrome therapy, Male, Treatment Outcome, Intracellular Signaling Peptides and Proteins immunology, Isaacs Syndrome diagnosis, Isaacs Syndrome immunology, Membrane Proteins immunology, Nerve Tissue Proteins immunology
Abstract

Acquired neuromyotonia is a form of peripheral nerve hyperexcitability. In adults, pathogenic antibodies that target the extracellular domains of leucine-rich glioma-inactivated protein 1 (LGI1) and contactin-associated protein-like 2 (CASPR2) have been reported. We describe three paediatric patients with acquired neuromyotonia and CASPR2 and LGI1 serum antibodies. They all presented with acute-onset myokymia and pain in the lower limbs; one patient also had muscle weakness. Electromyography was suggestive of peripheral nerve hyperexcitability. Two patients improved without immunotherapy; one treated patient remained immunotherapy-dependent. Although not fatal, acquired paediatric neuromyotonia can be disabling. It is amenable to symptomatic treatment or may undergo spontaneous recovery. More severe cases may require rational immunotherapy. WHAT THIS PAPER ADDS: The symptoms of neuromyotonia may resolve spontaneously or may require sodium channel blockers. Patients with debilitating symptoms who are refractory to symptomatic therapy may require immunotherapy., (© 2019 Mac Keith Press.)

Published
2019
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