The biological clock or circadian rhythm is found in all organisms that keeps pace with the rotation of earth that takes 24 hours time. This biological clock controls all the biological functions like sleeping, waking up, release of hormones produced by the body organs, detoxification, digestion and the functions of heart and kidneys that make the body to adjust and adopt. Any events that disturb this biological clock like going to sleep late in the night, night shifts disturb this rhythm and leads to ill health.
Most of the biological functions are controlled by circadian rhythm. Athletic performance tends to reach peak in the afternoon where as cognitive abilities are high late in the morning which suggests that we can benefit from knowing their clock.
For the past 50 years scientists have been studying this circadian rhythm to find way to meet the situation. It has been discovered that circadian rhythm is maintained by hypothalamus region of the brain called supra-chiasmatic nucleus which is controlled by light. The important aspect is that each cell in the living body has its own inherent cycle that works independently but synchronizes with circadian rhythm.
A research team in Japan has shown that measurement of certain metabolites in the blood samples taken with a gap of 12 hours can produce an accurate clock. This study was published in PNAS in August, 2012 with a small sample size. But further studies are needed to be done in a larger sample size to prove this aspect of circadian rhythms.
Biologists from Newyork University have uncovered that biological clocks neurons use electrical activity to keep behaviour rhythm in order. The electrical activity of the clock neurons produced changes in the expression of genes in fruit flies. By increasing electrical activity in the evening, when clock neurons are normally inactive, they found that clock neurons developed a circadian gene expression profile more typically found in morning hours.
In contrast by diminishing electrical activity in the morning, gene expression was shifted to look more like it does in the evening as published in October, 2012 in Current Biology that may provide new direction to study sleep disorders and other related diseases.
Dr. John O’neil of the cell biology division of the MRC Laboratory of Molecular biology in Britain with his colleagues have studied the mechanism of circadian rhythm and found an interesting aspect that the body clock is desynchronized with environment leads to diseases which can be controlled by balancing the circadian rhythm. Chronotherapeutics is based on the premise that the time of drug consumption determines the efficacy as well as side effects.
The best examples are statins that control cholesterol and cut the risk of cardio-vascular disease. The enzyme that makes cholesterol in liver is regulated by the clock of liver and it is most active in the night. Therefore statins that inhibit are most efficacious if taken before going to bed in the night.
Prof.Ueli Schibler at the department of molecular biology of the University Of Geneva, Switzerland has given another example. Certain anti-tumor drugs administered to sick mice in the morning lead to 100 per cent mortality while the mice that are administered with the drug in the evening have all survived. This example shows that the actions of internal clocks have on the drug efficacy. This shows the influence of internal clocks on the efficacy or toxicity of drugs.
There is another interesting aspect of chronotherapy. There is evidence that circadian rhythms are disrupted in women undergoing chemotherapy for breast cancer. A study published in Behavioural sleep medicine has shown that bright light could be used to strengthen the rhythms. An experiment was conducted in a group of women numbering 39 that were divided into two groups. One group received 30 minutes bright white light and another group received dim red light during the first four cycles of chemotherapy. The result has shown that bright white light was better in maintaining the circadian rhythm.
Thus chronotherapy will improve the cancer therapeutics in future and has to be tested. One of the biggest problems is how to manipulate the body clock as well as the type of cell response to environment, body temperature besides healthy life styles that have to be analyzed. The research has to be intensified in this field.
The basis of wound healing
All the cells in our body follow an electric field. When there is a wound the electric field changes and a new field is created attracting surrounding cells into the injured tissue. How this happens is not yet clearly known.
A study on keratocytes, the cells that form scales of fish, has shown that a change in the electric field makes certain electrically charged proteins in the edge of cell membrane. These proteins act as tiny electro-magnetic compasses and propel cells towards a wound. This study can be further intensified to develop better healing techniques.