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Spectroscopy to detect muscular weakness at an early stage

Myopathies are muscular diseases where muscle fibres do not function optimally, resulting in muscular weaknesses. For effective therapy, it is important to diagnose the myopathies early. Scientists from Indian Institute of Science have shown for the first time that a technique generally used to analyse atomic structure of chemicals, Raman spectroscopy, can be utilized as a diagnostic tool to differentiate between different types of myopathies.

Spectroscopy is the study of the interaction between matter and energy. When radiation falls on a particular material, the component atoms absorb some parts of the radiation and reflect others, forming a unique pattern called the “spectrum”. This spectrum can be analysed to find out the components of materials. For instance, a spectroscopic analysis of water can tell us it is made of hydrogen and oxygen.

Raman spectroscopy is a special type of spectroscopy, which uses lasers. Laser light interacts with molecular vibrations in the system, and the information obtained can be used to identify the components of a sample and to quantify the relative amount of components.

This study used Raman spectroscopy to classify different myopathies based on molecular changes, initially on commonly available fruitfly, Drosophila. Flies with two types of myopathy were used: nemaline myopathy and cardiomyopathy. In humans, nemaline myopathy is a birth defect that leads to weak leg and body muscles and cardiomyopathy is a condition with abnormal heart muscles. Drosophila individuals exhibiting similar abnormalities make an excellent model system to simulate the human condition.

Muscle defects in these flies could be very well distinguished using Raman spectroscopy. Interestingly, Raman spectra obtained from Drosophila affected by nemaline myopathy overlapped with Raman spectra from humans suffering from the same disorder.

In mutant conditions, the levels and properties of different molecules like nucleic acids, proteins, carotenoids and carbohydrates could vary; these changes can be read by using Raman spectroscopy.

“Now, it is required to generate a standard Raman spectra based classification of different types of myopathies in humans”, said Upendra Nongthomba, a co-author on the study. “Though it is difficult to obtain validated human samples, we are working towards it”.

The existing technique to diagnose myopathy is the use of biopsies, which require sample size of 1.5*0.5 cm2, which take a long time to heal. Raman spectroscopy uses just 0.5mm long fibres. The technique can also detect early onset of myopathies, which provide useful information to start early therapy.

“We are also trying to find out using Drosophila model if this technique can be used to study other human diseases like neurodegenerative diseases”, added Prof. Nongthomba.

"Medical diagnosis and prognosis non-invasively in a short time requires latest technologies to be developed with an inter disciplinary approach. These results on myopathy studies is an example how Lasers can effectively be utilised", said Prof. Umapathy.

About the Authors:

Rekha Gautam was a PhD student in Department of Inorganic and Physical Chemistry, Indian Institute of Science. Sandeep Vanga was a visiting student with Prof. Siva Umapathy. Aditi Madan is a PhD student in Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science.

Upendra Nongthomba is Associate Professor at Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science.

Narayanappa Gayathri is Professor at Department of Neuropathology, National Institute of Mental Health and Neuro Sciences.

Siva Umapathy is Professor at Department of Inorganic and Physical Chemistry and Department of Instrumentation and Applied Physics, Indian Institute of Science.

Contact:

Upendra Nongthomba: upendra@mrdg.iisc.ernet.in; 080-22933258/3262

Siva Umapathy: umapathy@ipc.iisc.ernet.in; 080-22932595

The paper appeared in Analytical Chemistry published by American Chemical Society. http://pubs.acs.org/doi/abs/10.1021/ac503647x