Imagine a glass of water near a window through which a beam of sunlight comes in. When light illuminates an object, it scatters it (light is also absorbed, transmitted and scattered by any object on which light is incident, depending on the nature of object). Generally the wavelength (frequency) of the incident and scattered lights remains the same. This scattering is called Rayleigh scattering and constitutes nearly the entire part of the scattering process. But a small percentage of scattered light does differ in frequency from the incident frequency. This Raman Effect, also referred to as Raman scattering, is very weak and constitutes only 0.001% of total scattering, usually obscured by the Rayleigh scattering.

When a chemical substance is dissolved in solvent like water, the dissolved molecules have a specific motion called vibrational motion. This vibrational motion is caused by the substance’s molecular structure, its atomic constituents and the bonds between the atoms in the molecule. The feeble Raman Effect is caused by the vibrational motions of the molecules, due to which, unlike Rayleigh scattering, the wavelength of the scattered light is different from the incident light. The intensity of Raman scattering and associated wavelength shift in the resulting Raman spectrum, are specific for each molecule. This is the basis of application of Raman Effect. Though Sir C.V. Raman originally used focused sunlight for his observation in the 1920s, modern Raman spectroscopy uses high intensity laser beams.

In modern industrial processes, be it pharmaceutical drug production or polymer production in plastic industry, the purity and chemical composition of substances are monitored by Raman spectrum analysis. The non-destructive nature of the analysis (meaning sample being studied is unaltered after the study) allows the technique to be used in biomedical research and diagnosis (such as cancer screening). This is a more recent development in the ever widening ‘effect’ of Raman scattering.

More on Rare Disease Day…

With the participation of 18 nations the first Rare Disease Day was celebrated in Europe by EURORDIS in 2008 to highlight the cause of rare disease affected population. Including India now over 85 nations celebrate the event. ‘Join us in making the voice of rare diseases heard’ is the slogan Rare Disease Day uses to create awareness of existence of over 7000 disparate diseases and disorders affecting some 72 million Indians. Lack of awareness not only among patients but also in treating clinicians, scientists and those in the government are the multiple constraints that cripple rare disease patients. Lack of law at state or union level for rare diseases also discourages pharmaceutical industry from paying attention to the issue.

Corpus callosum dysgenesis, Wilsons disease, Noonan’s syndrome, Williams syndrome, Gouchers disease, Kyasanur forest disease, Madras motor neuron disease are names of a few rare diseases. While most rare diseases are of genetic origin, several have environmental and infectious causes. While several rare diseases do not have medicine and are untreatable, some of them require lifelong treatment, which are very expensive.

The focus of this day and the need at this time is to highlight the necessity for all stakeholders to pool their resources for the sake of largely neglected rare disease patients.

Images: Anandhi N.