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R C Naidu

Publications and source records attributed to R C Naidu.

7 recordsLinked to original sources
PubMed2001

Longitudinal coupling in the basilar membrane.

A systematic and detailed study of the longitudinal coupling exhibited by the basilar membrane (BM) was performed in the excised gerbil cochlea. Contrary to the notion that the adjacent regions of the BM are decoupled from each other, the data indicate that: (a) the BM exhibits longitudinal coupling; (b) the length of the coupled region increases from base to apex of the cochlea; and (c) the cells of the organ of Corti (OC) increase the overall coupling exhibited by the BM. Modeling results show that, at a given location, longitudinal coupling increases the effective stiffness of the OC near the characteristic frequency. Therefore, the effect of longitudinal coupling cannot be neglected in the region of the peak of the traveling wave.

Acoustic Stimulation↗
PubMed1998

Measurements of the stiffness map challenge a basic tenet of cochlear theories.

The cochlear frequency map is believed to depend on the progressive decrease in partition stiffness from base to apex. Measurements on cochleae from human cadavers by von Békésy (1960) suggested that the elasticity of the partition increases by a factor of 100 from the stapes to the helicotrema. However, conventional models require a factor of nearly 10,000 to support the frequency range of normal hearing if entirely determined by partition stiffness. To test this assumption, we measured point stiffness along the width and length of the partition in the gerbil cochlea. Two major findings result from this study: (1) contrary to von Békésy's results, both cellular and extracellular elements of the sensory epithelium exhibit stiffness gradients; and (2) the stiffness changes by only a factor of 100 over the whole cochlea. Our results imply that present ideas regarding partition vibration need to be significantly revised.

Anatomy, Artistic↗
PubMed1981

AMP-deaminase activity in denervation atrophy of the amphibian skeletal muscle.

The substrate (AMP) and co-factor (ATP)-dependent kinetic parameters of AMP-deaminase have been studied in the contralateral and denervated gastrocnemius muscles of frog, Rana hexadactyla. An increasing in apparent affinity (Km) and maximal velocity (V) were found with denervated muscle enzyme as compared to the contralateral muscle enzyme. The activation energy (delta E) values were found to be decreased on denervation suggesting increased catalytic efficiency of denervated muscle enzyme.

AMP Deaminase↗