Friday, 24 July 2015

Medical Ultrasonography

Medical Ultrasonography is a medical diagnostic technique used to visualize inner body  structures like muscles and other soft tissues as well as  organs like the liver, gallbladder and various other  structures.  It helps to identify  any pathology in the tissues   and record any lesion.

The Ultrasound Machine

The word ‘ultrasound’ refers to sound waves  with a frequency too high for human ears to hear. In medical ultrasound, sound waves  in frequencies ranging from 1.6 to 10 megahertz are employed. Superficial structures like muscles, tendons, thyroid etc  are at a higher frequency (7–18 MHz) while deeper structures such as the liver and kidney are imaged at a lower frequency 1–6 MHz.

Ultrasonography  utilizes sound waves which are  sent into the body in pulsatile waves with the help of a transducer or probe. The sound waves bounce off the structures and the echo is received  by the probe and displayed on screen on a monitor.

Ultrasonography used during pregnancy to monitor the growth and health of the fetus  and other pregnancy tissues like the placenta and amniotic fluid is known as Obstetrical ultrasound and is widely used. Nowadays, it is a routine procedure performed in all pregnancies in the first trimester  to help identify any anatomical defects in the fetus.

Ultrasonography is also used  as an aid in  treatment procedures – for example,  draining of fluid or pus or in ultrasound guided biopsies. This procedure is known as interventional ultrasonography.
Other types of ultrasonography include cardiac ultrasonography (echocardiography), dental ultrasonography, Doppler ultrasonography to study blood flow and muscle motion as well as high intensity focused ultrasonography. Lithotripsy , a procedure used to break up kidney stones is a type of high intensity focused ultrasonography.

Compared to other medical devices, ultrasound has many advantages – it is safe because it does not use any ionizing radiation, the device is portable and can be easily carried to the patient’s bedside,  it is not very expensive and the results are obtained in real time, meaning that the result is available instantly at the time of the test and the patient does not need to wait for a long time for the report to be available.

The main disadvantage of ultrasound is that it requires a skilled operator  for an accurate report. Another disadvantage is that structures behind bones may not be readily seen.

Ultrasonography is one of the most widely used diagnostic aids in medical care today.

Monday, 8 June 2015

How Life Began on Earth

Life on earth began in a primordial soup  of chemicals  about 3.6 billion years ago.  Specific chemicals combined to form amino acids – the basic building blocks of life. The amino acids combined to form proteins and the proteins combined to form the first  single celled living organism. And these cells developed to form the multicellular plants and animals that we know today.

The Primordial Soup

  The first single celled organism is also known as the LUCA or the Last Universal  Common Ancestor. It  resembled a modern day cell with its own nucleic acid, lipids, and genes capable of reproduction. It also had the complete blueprints for DNA replication, RNA transcription and protein synthesis.

There is widespread scientific consensus on how  the LUCA  developed into the multicellular complex life forms we see on earth today. But for a long time, it was not known how or what caused the amino acid blocks in the primordial soup to combine to form the LUCA.

A common theory to explain this phenomenon is the ‘RNA world’ theory. Ribonucleic acid (RNA) is a polymeric molecule implicated in coding, decoding, regulation, and expression of genes. Together with DNA and proteins, it is one of the main macromolecules  essential for all forms of life.

 The RNA world theory suggests that RNA lifted itself from the primordial soup of chemicals to form short peptides which then formed the fist cell. But recent research by two long-time University of North Carolina scientists — Richard Wolfenden, PhD, and Charles Carter, PhD  suggests that RNA did not work alone – that RNA and amino acids developed simultaneously.
“Our work shows that the close linkage between the physical properties of amino acids, the genetic code, and protein folding was likely essential from the beginning, long before large, sophisticated molecules arrived on the scene,” Carter said in a statement. “This close interaction was likely the key factor in the evolution from building blocks to organisms.”

Protein must fold in specific way to function properly.  The complex process of protein folding depends on  both the polarities of the  amino acids (how they distribute between water and oil) and their sizes.  It is during the process of protein folding that the amino acids arrange themselves into 3-dimensional structures capable of a particular biological function.

Protein folding  is brought about by the tRNA – a type of RNA known as the transcriptor RNA. One end of the tRNA selected the amino acids by size while the other end selected the  amino acids by polarity. This helped to transfer the genetic code  accurately to the messenger RNA which could then make the correct amino acid.

“Dr. Wolfenden established physical properties of the 20 amino acids, and we have found a link between those properties and the genetic code,” Carter said. “That link suggests to us that there was a second, earlier code that made possible the peptide-RNA interactions necessary to launch a selection process that we can envision creating the first life on Earth.”

“The collaboration between RNA and peptides was likely necessary for the spontaneous emergence of complexity,” Carter added. “In our view, it was a peptide-RNA world, not an RNA-only world.”

The National Institutes of Health funded this work. Dr. Wolfenden holds a joint appointment in the department of chemistry in the College of Arts and Sciences at UNC-Chapel Hill.

Monday, 12 January 2015

Almonds can Reduce Belly Fat

Can eating a handful of almonds daily reduce belly fat?

A study  carried out in the Pennsylvania State University and published in the  Journal of  the American Heart Association suggests that including 42 gms (1.5 ounces) of almonds daily can not only cut down on the risk of heart diseases but also reduce belly fat,  producing a trimmer waistline.

In a 12 week randomized, controlled clinical study, the scientists compared 52 overweight, middle aged adults who had high cholesterol but were otherwise healthy. All the paticipants were put on an identical  cholesterol lowering diet, with all meals and snacks in amounts necessary to maintain their body weight.

But while  half of the  group was given a snack of 42 gms of almonds daily, the other group was allowed to snack on a banana muffin. This was the only difference in the diet. The almonds and the banana muffin contained the same amount of calories.  There is 160 calories in an ounce of almonds as well as protein, fibre, vitamin and minerals. A single almond weighs approximately 2 gms.

After six weeks, it was noted that the  participants on the diet with almond snacks had  significantly reduced  central adiposity with resultant decrease in waist circumference and belly fat.Leg fat was also considerably reduced. There was no difference in total weight between the two groups. Central adiposity is  a well known risk factor for heart disease.

Not only that, there was reduction in the total cholesterol,   LDL cholesterol and remnant lipoproteins.

Belly fat not only makes the body unsightly, but it  is also linked to metabolic syndrome - a disorder characterized by a combination of diabetes, high blood pressure, high cholesterol levels and central obesity. The nuts moderate blood sugar level - particularly beneficial for people with diabetes.

Almonds are also high in monounsaturated fatty acids and vitamin E which protect against Alzheimer's disease, The flavonoids in the almond skin act as anti-oxidants and  together with Vitamin  E decreases wrinkles and age spots.

"Our research found that substituting almonds for a high-carbohydrate snack improved numerous heart health risk factors, including the new finding that eating almonds reduced belly fat," said Claire Berryman, lead researcher of the study. 

"Choosing almonds as a snack may be a simple way to help fight the onset of metabolic and cardiovascular diseases," said Berryman. 

The study provides evidence that snacking on almonds instead of a high carbohydrate snack helps to limit belly fat and has overall benefits on body composition.