Tuesday, December 30, 2008

Happy New Year - 2009

Let us pray for the Peace, Happiness and Prosperity throughout the World. Let God decorate every ray of the sun reaching you with the fragrance of success and prosperity for you.
Keep smiling and rocking in 2K9.
Wish you a “Very Happy New Year”
Dr. Rayat

Monday, December 29, 2008

Physical Properties Of Some Radioisotopes Used In Medical Field

There are about two dozen radioisotopes finding their use in medical diagnosis and treatment. Here is a list of physical properties of these radioactive isotopes. The list could be beneficial for the students of radiation science.

Physical Properties of some Radioisotopes

The radioisotopes available as mixed with stable isotope from the same element and are called carrier radioisotopes and those available as free from any stable isotope are called carrier free radioisotopes. The carrier free radioactive chemical may contain many milliCuries (mCi) of radiation energy in a few milligrams (mg) of chemical. The radioactive iodine (131I) used in the treatment of hyperthyriodism (hyperactivity of thyroid gland) and evaluation of thyroid function should be carrier free or nearly so.

Friday, December 26, 2008

Penetration Power Of Radiation Energies

The penetration power of the radiation energy is related to the type of radiation. The radioactive chemicals emit radiation in the form of particles or rays and the penetration power of these particles or rays in the tissues of our body varies due to variation in the energy of these particles or rays. The alpha (α) particles can not penetrate more than a few micrometers in our body tissue, and are of little practical importance in medicine. The beta negative (β-) and beta positive (β+) particles have penetrating power varying from 100 to 500 micrometers (mm) as in case of radiations of Carbon-14 (14C) and Sulphur-35 (35S) to over a centimeter (cm) as in case of Yttrium-90 (90Y) radioisotope. The beta negative (β-) particles from Gold-198 (198Au), Gold-199 (199Au) and Iodine (Iodine-125, 130, 131, 132 etc) have a penetration power in tissues ranging from 1 to 3 millimeters (mm). The gamma rays (g-rays) are like x-rays and are usually very penetrating. The energy range of gamma rays (g-rays) is almost equal to that from 40 kilovolt (KV) to 3 megavolt (MV) x-ray machines. Negative beta (b-) particles may or may not have accompanying gamma rays (g-rays). The gamma rays (g-rays) emitted by a particular radioisotope would always have the same penetrating power or energy. The positrons or positive beta (b+) particles in addition to possible gamma rays (g-rays) are always accompanied by 50 KV x-rays.

Quantity of radioactive material is always expressed in terms of radioactive disintegrations per second. The major unit of expression of radioactivity represents 37 billion (37 x109) disintegrations per second and is called Curie (Ci). One thousandth (1/1000) part of a Curie is called milliCurie (mCi) and one thousandth (1/1000) part of a milliCurie is called microCurie (mCi). Brief description of these units is as below:

  1. Curie (Ci): 37x109 disintegrations per second

  2. milliCurie (mCi): 37x106 disintegrations per second

  3. microCurie (mCi): 37x103 disintegrations per second

There are quite many radioisotopes used in medical practice as a therapy and also in medical diagnostic procedures. The quantities of radioactive materials used in therapy are in milliCuries (mCi) and those used in diagnostic procedures is in microCuries (mCi).

Tuesday, December 23, 2008

What Is Radioactive Decay Or Half Life Of A Radioisotope

Radioactive isotopes or radioisotopes of an element are always in the process of nuclear disintegration in order to acquire the stable form. The major unit of radioactivity is Curie (Ci) which means 37x109 disintegrations per second. One thousandth (1/1000) part of a Curie is called milliCurie (mCi) and one thousandth (1/1000) part of a milliCurie is called microCurie (mCi). Other units of the radioactivity will be discussed in some other article. The radioactive chemical is being expressed in terms of radioactivity it possessed at the time (0 hour) of evaluation and labeling. Every radioisotope undergoes decay or nuclear disintegration at a uniform rate and the time after which it loses the half of its activity is called its Half Life.

Radioactivity is linked to per unit mass or volume of radioactive chemical. The radioactive Half Life could be a few hours, days or many years. For example 24Na has a Half Life of 15 hours, 125I has a Half Live of 60 days, 60Co has a Half Live of 5.2 years and 14C has a Half Live of 5730 years. If 1gram of a radioactive chemical has 2Ci radioactivity at 0-hour, it would be reduced to 50% (1Ci) after the completion of 1st Half Life, 25% after completion of 2nd Half Life, 12.5% after the completion of 3rd Half Life and 6.25% after the completion of 4th Half Life and goes on reducing to 50% on the completion of successive Half Lives as depicted below, through the Radioactivity Decay Graph.

However the mass or volume of the radioisotope would not under go any change with the reduction in radioactivity due to passage of time and completion of successive Half Lives one after the other. Preparation of Radioactivity Decay Graph is must for the radioisotope users to workout the radioactivity at a particular time or date with respect to the Half Life of a radioisotope.

Saturday, December 20, 2008

What Is Meant By Radioactive Disintegration

Radioactive disintegration is a process of nuclear disintegration of a radioisotope in its effort to achieve a stable nucleus. We know that in the naturally available radioactive elements there are only two kinds of particles which could be ejected from its atoms:

  1. The alpha (a) particle, which is really the nucleus of a Helium atom (4He) and carries away 4 mass particle and 2 atomic particles.

    ZXA - 2a4 = Z-2XA

    Here X represents chemical symbol, Z is atomic number and A is mass number.

  2. The other particle which could be ejected is beta (b) particle, which is an electron. It does not however, comes from an orbit, but from a neutron, which under certain circumstances, dissociates into a proton and an electron. The electron is not tolerated in the nucleus and is ejected immediately, but an extra positive charge (neutron replaced by a proton) is left in the nucleus. The new atom now has the same mass but the atomic number one higher than the old or previously possessed by it.

    ZXA - -1b0 = Z+1XA

Uranium, Thorium and Radium are the best known naturally occuring radioactive elements. In 1934 it was documented that it was possible to create isotopes and radioisotopes by bombarding the stable elements with high energy subatomic particles. Except Hydrogen and Helium more than two isotopes have been created from every element by artificial manipulations. There are 21 isotopes of Iodine ranging from 119I to 139I and out of these 20 are radioactive isotopes or radioisotopes except 127I.

The artificially created radioactive isotopes or radioisotopes have the same radiations as those of natural ones. Some of them also emit protons or beta+ (b+) particles.

ZXA - +1b0 = Z-1XA

Radioactive disintegration of radioisotopes results in the emission of only one type of above mentioned particles and radiation like x-rays called gamma (g) rays. The atoms of any particular radioactive element are destined to emit the same kind of radiation till its total disintegration; there is no way to switch on to any other type of radiation.

How The Structure Of Matter Is Associated With Radioactivity

We know that the matter is made up of elements. The smallest part of any element is its atom. Atoms are composed of a positively charged nucleus containing protons (positively charged subatomic particles) and neutrons (inert particles), and around the nucleus, there are orbital electrons (negatively charged subatomic particles). In 1896 Bacquerel discovered the phenomenon of radioactivity in the atoms of some elements. The mass of an atom is represented by its nucleus that is the sum of protons (positively charged subatomic particles) and neutrons (inert particles) in the nucleus. Each element has been allotted a chemical symbol and its atomic number is fixed. The number of electrons is always equal to the number of protons in the nucleus of an atom and this number stands for the atomic number of an atom. Mass of an electron is 1/1800 of the mass of a proton on atomic scale. The atoms in some of the elements have natural variation in mass number and that made them unstable or radioactive.

Isotopes: Atoms of a particular element not have to be exactly alike in terms of mass number. In such atoms the things that must be alike are the number of protons (positively charged subatomic particles) in the nucleus or the nuclear charge and the number of orbital electrons (negatively charged subatomic particles). But the number of neutrons (inert particles) may vary and hence atomic mass may vary in a narrow range. Atoms of the same element with same atomic number but with different number of neutrons (inert particles) are called isotopes. A single chemical symbol of an element is not sufficient to represent an isotope. The chemical symbol along with a superscript at the upper left or right, depicting the mass number and lower left depicting the atomic number, represents an isotope; however, it is not necessary to mention atomic number to depict an isotope, as 51Cr represents an isotope of Chromium. Each element has a unique atomic number but the mass number may vary depending on the number of the isotopes of that element. An element generally has only one stable isotope.

Radioactivity: Majority of the elements found naturally have stable atoms. The atoms of the elements never change unless they are attacked with subatomic particles from outside; however, some of the atoms in some heavy elements are inherently unstable. The unstable atoms are called radioactive isotopes or radioisotopes. The nucleus of the radioactive atom or radioisotope undergoes disintegration with the ejection of tiny particle accompanied by electromagnetic radiation. After disintegration the rest of the material of the nucleus rearranges itself and becomes the nucleus of a different element.

Are We Born Vegetarian Or Non-vegetarian

The natural features of an animal are considered to define its vegetarian of non-vegetarian instinct. The cattle eat grass, plant leaves and soft branches rich in cellulose. Cellulose is digested by these animals as their digestive system secrete cellulase enzyme required for the breakdown of cellulose. So, cattle are vegetarian in nature as they are capable of digesting cellulose rich food due to the presence of cellulase in their stomach where as cellulose is not produced in our stomach, so, we are not vegetarian. On the contrary the teeth of non-vegetarian animals are pointed and sharp but human beings do not have such teeth, so, we are not non-vegetarian also. If you go through the theory of evolution you would find that man had been evolved out of monkey, so our dietary habits and instinct should be like those of monkeys. Monkeys eat fruits and are fruitarian, so we are also fruitarian like our ancestors.

If we eat only fresh fruits like monkeys, we would be more healthy, active and energetic. Fruits are rich in good quality sugar, the fructose which is quickly metabolized. Fruits are the natural and the richest source of minerals and vitamins. Citrus fruits like orange and lemon are rich source of vitamin-C. Red and yellow fruits and vegetables like papaya, tomatoes and carrots are rich in vitamin-A. Vitamin-B, C, folic acid and minerals are almost in all fruits. Bananas are rich in calcium. Grapes are a natural source of calcium, magnesium, potassium, phosphorus, iron, sugar and antioxidants. If you go through the history of mankind, you would find that ancient saints used to live in forests and eat lot of fresh fruits and raw vegetables (salad) instead of cooked food and lived longer than us. Antioxidants present in fruits are known to slow down the ageing process, so it is always beneficial to eat fruits for health and longevity.

Eating fruits is better than drinking fruit juice since the chewing action would add saliva to the fruit pulp in our mouth and initiate digestive process. Eating fruits is good for the health of our gums and teeth since fruits are non sticky. Dry fruits are rich source of good fat and minerals also. Diabetics can eat dry fruits and less sweet fruits like melons and oranges in addition to salad (tomatoes, cucumber, onions, radish and cabbage). Apples and guavas are available through out the year and are rich source of vitamin-C, iron and other minerals. People suffering from chronic constipation should eat fruits and salad before any cooked meal for the beneficial effect of fruits in alleviating the constipation.

Tuesday, December 16, 2008

What Is The Cause Of Dengue Fever And How Can We Prevent It

Malaria, Dengue and Chikungunya are post rainy season maladies and are spread by mosquitoes. Dengue fever is caused by a virus called Dengue virus and is transmitted from an infected person to a normal person by Aedes aegypti mosquitoes. Aedes aegypti mosquitoes are more active during the morning hours. The Dengue infection could be a serious problem and need hospitalization if platelet count of the blood patient falls below 30000/ml
leading to bleeding in side the body. There may also be a fall in blood pressure of the patient during dengue fever. Chikungunya is also transmitted by Aedes aegypti mosquitoes. Chikungunya is characterized by rash, fever and severe joint pains like dengue fever. However, chikungunya is not as severe as dengue fever. Incubation period between the infected mosquito bites and dengue fever or chikungunya is 10 to 12 days and the course of fever runs for a week generally.

Suspect dengue in case of sudden onset of high grade fever and chills associated with headache and pain in muscles, joints and back. In some cases there could be purplish-red rash on lower limbs and chest. There may also be abdominal pain and diarrhea. The key to accurate and effective treatment is accurate, quick and early diagnosis. If anybody has fever with above cited symptoms, quickly get investigated for dengue. In malaria we look for the direct evidence of malarial parasites in the peripheral blood films but in case of dengue fever, indirect diagnosis is made based on the exploration of anti-dengue antibodies in the patient's blood or serum by ELISA (Enzyme Linked Immuno-sorbent Assay) or viral DNA by PCR (Polymerase Chain Reaction). The aforesaid methods need at least one day to make a diagnosis of dengue infection. A technique called Loop Mediated Isothermal Amplification Procedure (LAMP) is probably under developmental stage and could be helpful in achieving the diagnosis of dengue within one hour. Use mosquito net at night as well as mosquito repellent vaporizers to save your self from mosquito bites in endemic areas. Wear protective clothing and keep your feet covered while on a morning or evening walk. All mosquito borne diseases could be prevented through coordinated efforts of the public and the vector control organizations through out the world.

Thursday, December 11, 2008

Malaria: Prevention Is Better Than Cure

Malaria could be a serious and life threatening disease if not diagnosed and treated properly. Treatment of malaria had been known to general physicians even before the discovery of causative organism, the Plasmodium, a parasite. The parasite of malaria was discovered by Laveran in 1880 and in 1898, Sir Ronald Ross worked out the mosquito cycle with parasite of birds. There are four known species of malarial parasite causing malaria in human beings. These species are Plasmodium vivax, Plasmodium ovale, Plasmodium falciparum and Plasmodium malariae. Infection is caused by bites of infected female Anopheles mosquitoes. The incubation period for P. vivax and P. ovale is around two weeks, for P. falciparum 8-12 days and for P. malariae incubation period is three to four weeks. The surest way of diagnosing malaria is through microscopic examination of peripheral blood film. Anyone having high grade fever (around 104 to 105o F) and chills should get tested for malaria. Febrile paroxysm (bout of fever) starts generally in the early afternoon however it may start at any time if mixed infection (infection of two or more malarial parasite species). Malarial parasites of animals (P. berghei of rats and mice, P. knowlesi of monkeys etc) do not infect human beings. Each paroxysm shows a succession of three stages:

  1. The cold stage: Lasting 20 minutes to one hour.

  2. The hot stage: Lasting one hour to 4 hours.

  3. The sweating stage: Lasting 2 to 3 hours.

The total duration of the febrile cycle could be from 6 to 10 hours. The febrile cycle may vary with the species of malarial parasite. Malarial parasites are found in all countries extending from 40o south to 60o north. The tropical zone is the endemic home of all malarial parasites infecting man. Prevention: Malaria eradication could only be possible through coordinated efforts of the people and the government agencies involved in the control of mosquitoes since malaria is a serious public health problem in all the tropical and subtropical regions of the world. If you go through the pages of the history of science and malaria, you would find that malaria had taken more human lives than any other disease. To control mosquito breeding always keep storage water tanks covered with mosquito tight lids. Larvae eating fish (gambusia or guppy) should be introduced in stagnant water ponds. Insecticides should be sprayed regularly at home, the work place and drains. Use mosquito nets at night and protective clothing during the day time. Consult your physician and take prophylactic medicine if malaria is endemic. Prevention is always better than cure since it saves our money, time and health.

Astronomy: A Heritage Of The Mankind

The Astronomy and astrology had remained fascinating and distinct achievements of the mankind form the time immemorial. Ever since the days of Aryabhata, Indian astronomers been remained in the fore front in the world, who could predict the lunar eclipse as well as the solar eclipse with an accuracy of a few hours. The solar eclipse fair at Kurukshetra (Haryana State, India) has been held from the days of Mahabharta with an accurate prediction of the day of the solar eclipse year after year. The United Nations has declared the year 2009 as the International year of Astronomy (IYA 2009) to commemorate the 400th anniversary of the astronomical use of telescope by Galileo Galilei, the inventor of the telescope. However the history of science for the chance invention of the telescope goes in favor of a Dutch spectacle maker, Hans Lippershey who in 1608, by chance combined a convex and a concave lens and noticed the magnification of the image of an object. Hans Lippershey failed to get his product patented well in time. International Astronomical Union shall be celebrating IAY 2009 throughout the world with its strong team of over 1000 astronomers. There is a great enthusiasm among the astronomers the world over. The event would provide an opportunity to the young astronomers to learn the scientific revelations of the parallel universes. Over 100 nations are probably going to participate in the mega events of the 400th anniversary of the astronomical use of telescope, the IYA 2009.

Monday, December 8, 2008

Nerve Injuries And Repair Of Nerves

Nerve injuries are very common in accidental cases and may cause significant morbidity in patients. There are two types of nerves in our body: a) sensory nerves and b) motor nerves. Sensory nerves are associated with the feeling of touch, pressure, hot, cold, taste, vision and smell whereas the motor nerves control the contraction of muscles and mobility of our body parts under the control of our will. Peripheral nerve injuries may lead to lack of muscular control and mobility of our arms, legs, hand or feet. Nerve fibre regeneration and reconstruction is there in clinical practice since the late 19th Century. Nerve fibre regeneration after focal nerve injury varies with age, site and type of lesion. If the nerve ends could be approximated without any difficulty, end to end repair is possible. End to end repair is routinely practiced procedure for the repair of injured nerves. The situation becomes difficult in case of gap between the ends of the injured nerve. In such cases the options available are nerve graft or end to side repair using an adjoining nerve or nerve conduits.

In case of peripheral nerve injuries restoration of motor functions is considered useful for the patient. There may be needed to sacrifice a sensory nerve for restoring motor function by nerve grafting. Harvesting of sensory nerve for nerve graft to restore a motor function will create a non sensory zone in the patient. In cases of facial nerve reconstruction, the procedure of choice is end to side neurorrhaphy. Neurorrhaphy is a procedure wherein injured nerve is sutured to an intact nerve in its vicinity after transecting the distal segment provided the nerve is close to the neuromuscular junction. There is a great role of cellular and biochemical factors as myelin required for ensheathment of nerves undergoing repair and regeneration is produced by Schwann cells. End to side anastomosis with an adjoining healthy nerve is a new technique coupled with plastic surgery features and inputs. Only an experienced plastic surgeon with expertise in nerve repair surgical procedure or neurorrhaphy could be helpful.

Friday, December 5, 2008

Eat Less And Live Longer Than Expected

The quality of life is most important aspect of our life. It is a proven fact that if we eat less, we would definitely live longer than expected. The average life expectancy is around 70 years but health fitness and mobility is important to cherish the comforts of life. Human body is like an industrial town capable of processing and synthesizing a number of products for the propagation of life and heath. Each organ in our body has been assigned a particular function required to be performed for maintaining homeostasis. Proper vaccination is the very first important responsibility in life to save ourselves from infectious diseases. If you are adequately immunized only then you could think of the measures for improving your life expectancy.

Regular exercise and diet control minimize load on our organs and this way retard the aging process. The less we eat the less will be the requirement of digestive juices or enzymes for digestion; so our organs would not be exhausting in their respective actions. In this way we conserve the potency of our internal organs which leads to longevity. Brisk walking and cycling could be the best choice for exercise as it does not involve major expenditure and good for all age groups. The strategy of eating less is also known as calorie restriction protocol. Intake of low calorie diet in rats has shown marvelous results it terms of longevity and reduction in susceptibility to diseases like diabetes and cancer and controlling obesity. Optimal nutrition is must for all but calorie restriction protocol advocates the need to eat less, in the range of 25 to 40 percent less than what your body needs daily as per your body mass. As a rough estimate an adult needs 1800 to 2000 calories daily and 25 percent of the same would be 1350 to 1500 calories.

Fresh fruits and vegetables are a rich source of low calorie diet with high fibre content. Fruits and vegetables contain hundreds of known and unknown substances capable of protecting us from cancer and premature aging. Almost all fruits contain vitamin C, an antioxidant and immunopotentiator. Pomegranates are rich in antioxidant and immunopotentiator substances. Antioxidants reduce inflammation and the risk of heart disease. Tomatoes must be included in your daily diet. Tomatoes contain a substance called lycopene which has anti cancer properties. Tomatoes are also a rich source of vitamins A, C and E and potassium. Eat less, sleep well, exercise regularly and care your body to live longer than expected. Health awareness is a key to fitness and longevity.

Tuesday, December 2, 2008

Look Young And Pretty In Minutes

There is nothing bad if you want to look younger than your age. In fact all men and women have this feeling of looking younger. Medical science has the answer to fulfill your desire and you will look young and pretty in minutes. Cosmetics are just for artificial beauty and face lift, but sustainable beauty and healthy skin could be achieved with Botox and dermal filler treatment. Facial lines and wrinkles are the most visible signs of aging and it is possible to correct these with Botox and dermal filler treatment. Frown lines above your nose, crow's feet lines at the corners of your eyes and fore head lines now can be treated successfully with Botox. Botox is derived from a microorganism called Clostridium botulinum and comes in an inject-able form. Botox is injected into tiny facial muscles. It is not so painful procedure. Botox relax the facial muscles and gives you the young look. However, the procedure should be done by a trained medical professional. Dermal filler contains hyaluronic acid, a natural substance. Hyaluronic acid is also present in our body and is not a harmful substance. There are other dermal fillers also. The effect of dermal fillers lasts for 9 months to one year. Consult an expert dermatologist for best results and look young for ever.