Category Health and Medicine

   In general, bacteria use a number of different genetic mechanisms to develop, optimize and spread the genes that give them resistance. This includes the following:

• They suddenly change their genetic information (mutation).
• They exchange plasmids. Plasmids are additional, ring-shaped deoxyribonucleic (DNA) structures in bacterial cells.
• They spread by cloning. This means that they reproduce one cell whose daughters are transferred from one person to another.

Resistance genes develop when genes in the bacterial chromosome are modified by mutation. This generally requires more than one step. Mutation normally has to take place in several genes to achieve clinically effective resistance.

The selection caused by the way antibiotics are used is contributing to the rapid pace with which resistance is increasing. Massive use of certain antibiotics can lead particularly quickly to the spread of resistant strains. Without the selection pressure exerted by antibiotics, resistance genes could develop but they would never be able to spread sufficiently to gain dominance. Individual bacteria can only become dominant if they enjoy a persistent selective advantage over the rest of the bacterial population.

            Cloning is the process of ‘deriving’ an organism or a group of cells from another organism or from a single cell asexually. Members of a clone are identical in their inherited characteristic that is, in these genes except for any differences caused by mutation. Identical twins who originate by the division of a single fertilized egg are members of a clone, whereas non identical twins that derive from two separate fertilized eggs are not, according to the Encyclopedia.

            Through recent advances of genetic engineering, scientists can isolate one or more genes from one organism and grow it in another organism belonging to a different species. The species chosen as a recipient is usually one that can reproduce asexually, such as a bacterium or yeast. Thus it is able to produce a clone of organisms, or of cell, that all contain the same foreign gene or genes. They make many copies of a particular gene.

            The copies can then be isolated and used to study. As this procedure involves clones of organisms or cells it is called cloning.

Identical twin animals can also be produced by cloning. An embryo in the early stage or development is removed from the uterus and split, and then each separate part is placed in a surrogate uterus. This method has been used to produce mice and sheep.

 Another development has been the discovery that a whole nucleus, containing an entire set of chromosomes, can be taken from a cell and injected into a fertilized egg whose own nucleus has been removed. The division of the egg brings about the division of the nucleus, and the descendant nuclei can, in their turn, be injected into eggs.

 After several such transfers, the nuclei may become capable of directing the development of eggs into complete new organisms genetically identical to the organism from which the original nucleus was taken. This cloning technique is thus, capable of producing large numbers of genetically identical individuals. Such experiments have been carried out with frogs, mice and now with sheep and monkey. 

Keloid is a scar that does not know when to stop forming, becoming large, shiny, smooth, and often pink and dome-shaped, according to The Merck Manual of Diagnosis and Therapy. It is not known why some people get overgrown scars after injuries, surgery or acne, but keloids are more common among people of black and Asian descent, so a genetic factor is suspected.

In normal scarring, after the inflammation that follows an injury subsides, scar tissue begins to form, along with tiny new blood vessels.

Cells in the skin around the injury, called fibroblasts, produce collagen, a fibrous connective tissue. As more and more of the fibers link up, the scar becomes harder. In a keloid, the process continues long after the wound is covered over, and the scar can become quite large.

Keloids are not dangerous but can be disfiguring, tender and sometimes itchy. Removal of a keloid by surgery or the use of lasers, followed by corticosteroid injections at the site, is sometimes but not always successful, and can cause even worse scarring.

            Someone with a tendency to form keloids may want to avoid plastic surgery, though doctors can sometimes use hidden incisions in facial surgery or avoid making cuts in the periphery of the face, where keloids are more likely to form.

Our body muscle tissue can be classified as skeletal, cardiac, and visceral.

–  Skeletal muscles in all instances are attached to osseous tissues (bones).

–  Cardiac muscles form the muscular body of the heart.

–  Visceral muscles are present in all hollow viscera such as gastro-intestinal tract, blood vessels, ducts of glands, respiratory, urogenital and lymphatic systems of the body.

Certain changes occur in the functions of various organs when exercise is repeated over a period of time. The magnitude of change depends on many factors, the most important being the intensity and frequency of exercise. Age and heredity also play a role. The nature of the change depends on the type of exercise, the muscles used and the previous training of the individual.

Changes that are produced by training disappear after some time if the person stops training. The primary effects of training occur in skeletal muscle. There is an increased number of capillaries in muscle tissue, leading to increased blood flow, and therefore more oxygen is brought to the muscle cells.

There is also an increase in asteriovenus oxygen difference, which means more extraction of oxygen by muscle cells and lower lactate concentration (lactate is a product from anaerobic oxidation of glycogen of our body during insufficient supply of oxygen by blood to the muscle cells which leads to the phenomenon called muscle cramp) in muscle and blood at a given work load. This indicates that the muscles depend more on aerobic mechanism – a mechanism that uses up oxygen to oxidize glycogen to carbon dioxide and water and yield energy.

Myoglobin content: Myoglobin content stores oxygen in a manner similar to that of haemoglobin inside RBC. Training increases the Myoglobin content of skeletal muscle.

            Energy Stores: There is up to a 100 per cent increase in the glycogen storage fuel of our body. A high carbohydrate diet enhances the storage glycogen in muscle. The amount of glycogen is an important factor in endurance sports eg: long distance running. It is also found that the activity of the enzyme systems required for oxidative metabolisms are also increased. This results in about a 45 per cent increase in the rate of oxidation.

Mitochondria: Size and number of mitochondria in skeletal muscle cells increases. Also there is an increase in the concentration of enzymes needed for utilization of fuel substances to obtain energy.

 

Continue reading “How does regular physical exercise improve our muscles?”

    A mole is a concentration of melanin pigments deposited in the inner layer of the skin (dermis). It may or may not be raised slightly above the skin surface. It is also called nevus. It is usually congenital, hence also known as birth mark.

            At times hairs grow on them. They may appear suddenly or change their size and colour suddenly. These changes may be an indication of cancer.

            Melanin pigments are found in all animals, particularly in mammals. Several physiological and congenital conditions may induce formation of melanin in animals. Hence moles are found in animals also but they cannot be seen distinctly on them due to the presence of hairs.

The scientific name of mole is Nevus. Medically the moles or nevi are instructive tumours of the skin. The term nevus denotes any congenital lesion of skin. Common acquired nevi are tan-to-brown, uniformly pigmented solid regions of elevated skin with well defined rounded borders. They are usually less than 6mm across. They are formed when single cells which are normally interspersed among basal Keratinocytes are transferred in to round to oval melanocytes called nevus cells that grow in aggregates or nests along the dermal-epidermal junction.

The nuclei of nevi cells are uniform and rounded, contain inconspicuous nucleoli and show little or no mitotic activity. The early developmental stages in nevi are called junctional nevi. When they grow in to underlying dermis as nests or cords of cells they are called compound nevi. When they are still older the epidermal nests may be lost entirely but dermal nests develop further. Now they are called dermal nevi. Clinically, compound and dermal nevi are often more elevated than junctional nevi. Although nevi are common, their clinical and histological diversity necessitates thorough knowledge of their appearance and natural evolution. Otherwise they become confused with other skin conditions notably malignant melanoma (skin cancer tumour). There are numerous clinical and histological types of nevi. The following are important ones: 1. Congenital nevi: These are present at birth and are called acquired nevi. 2.

Spindle and epitheloid cell nevi: They are red-pink nodules and contain large plump cells with pink blue cytoplasm.3. Blue nevi: These are black blue nodules and are dendritic with heavily pigmented nevus cells.4. Halo nevi: These are identical to ordinary acquired nevi but provided with lymphocytic infiltration surrounding nevus cells. So they have host immune response.

Mole consists of cells containing melanin, a dark pigment. Moles may occur at any part of the body and can number as high as forty and may be flat or raised. Colouration could be light brown to blue black. Basically moles are harmless and are just formations on the skin, like say, hair. But these are vital indications of cancer’s onset. Any change in size or colour should be taken seriously and medical attention sought.

 

 

 

 

 

Two sudden and involuntary contractions within the diaphragm cause hiccups. You can get hiccups if you eat too much or too fast or if you eat victuals disagreeable to your system Hiccups, occasionally, can indicate serious conditions which include pneumonia, pancreatitis, bladder irritation, uremia, stomach disorders etc. Mild ones not lasting more than thirty minutes are never cause for concern.

Granny’s gambols for mild attacks comprise holding your breath for a tolerably long spell, drinking a glass of water while holding your breath and swallowing in rapid successions three times a glass of water duly holding your breath.

If these methods do not work hold a paper bag tightly over your nose and mouth and breathe in and for a minute or two. The relatively high level of carbon dioxide in blood shall inhibit hiccups. 

 

Continue reading “What causes hiccups?”

Infants born with congenital heart defects turn blue and such babies are ‘blue babies’. It occurs when the blood carried to the body contains, a less than normal amount of oxygen due to congenital heart defects. The most common defect is a hole in the septum separating two ventricles (ventricular septal defect – VSD). Normally, deoxygenated blood returns from the body to right atrium from where it flows to the right ventricle. From the right ventricle deoxygenated blood flows to the lungs where it is oxygenated.

The oxygenated blood from the lungs flows to the left atrium then to the left ventricle from where it is distributed to all parts of the body. In the case of VSD, deoxygenated blood instead of flowing to the lungs from the right ventricle, flows to the left ventricle (through the septal hole) from where is distributed to the body parts. Deoxygenated blood causes the body to turn blue (oxygenated blood is red). Blue baby disease was discovered by an American cardiologist, Hellen Brooke Taussig (1898-1986).

Infants who are fed on milk containing water contaminated with high ,nitrate content turn blue and is commonly referred to as ‘Blue baby syndrome’ (BBS). The skin of infants turn blue when there is insufficient oxygen supply to the body through the blood. Nitrates reduce the oxygen carrying capacity of haemoglobin present in the red blood corpuscles (RBC). Infants of less than six months of age are more prone to BBS. Their haemoglobin has poor chemical equilibrium and hence restoration of haemoglobin cannot take place as quickly as in adults.

 

Atrial fibrillation is the most common sustained cardiac arrhythmia. In arrhythmia the atria beats rapidly, chaotically and ineffectively. It is a kind of heart malformation that occurs due to abnormal rhythm of the heart.

A coordinate contraction of all the heart muscles at once, which is required for the pumping cycle leads to a normal rhythm of the heart. But abnormal rhythm of the heart results from cardiac impulses that have gone wild and violent with the auricular muscle mass and ventricular muscle mass, which are respectively called Atrial fibrillation and Ventricular fibrillation.

 Since auricular muscle mass is entirely separated from the ventricular muscle mass and insulated from each other by fibrous tissue, these two fibrillations are entirely independent of each other.

 The mechanism of atrial fibrillation is identical with that of ventricular fibrillation except that the process occurs in the atrial muscle mass instead of ventricular mass. A very frequent cause of atrial fibrillation is atrial enlargement. It results due to heart valve lesions that prevent the atria from emptying adequately into the ventricles.

 In atrial fibrillation the atria become useless as primer pumps for the ventricles. Even so, blood flows positively through the atria into the ventricles and the efficiency of ventricular pumping is decreased only 20 to 30 percent.

 Therefore in contrast to the lethality of ventricular fibrillation, a person can live for months together or even years with atrial fibrillation though at a reduced efficiency of overall heart pumping. The onset of atrial fibrillation can cause palpitation. It may precipitate or aggravate cardiac failure in, patients with an abnormal heart, especially that with mitral stenos is or poor left ventricle function. 

Continue reading “What is atrial fibrillation?”

Pulse and heart beat are checked primarily to have a simple and quick assessment of the condition of the heart and other system of the body. By checking the pulse the doctor can know the rate, rhythm and wave pattern of the arterial pulse. The normal arterial pulse will have certain characteristic features and any deviation from this pattern suggests an underlying problem.

For example normal, adult resting person’s pulse rate/heart rate is around 72 beats per minute. Here the words normal, adult resting all have significance as children’s heart rate is more compared to adults and a person who did some exercise like running, cycling and swimming will have a higher pulse/heart rate compared to other persons at rest. These are all physiological variations.

 Even at rest if a person’s pulse rate grossly deviates from the beat it signifies some underlying problem. In the same way if the rate of the rhythm or wave pattern of the pulse deviates from the normal it also denotes some underlying problem. Normal heartbeat consists of two heart sounds. In addition if any other sounds or murmurs (peculiar noises heard in between or along with the heart sounds) are heard, it also signifies some problem in the heart.

The arterial pulse can be felt at several places viz near the wrist, elbow, armpit, neck, groin, popletial fossa (area behind the knee joint) and foot. The wrist and neck are the most easily accessible places for the doctor to check the pulse with little discomfort to the patient. Hence these regions are usually preferred. In certain special conditions or diseases the pulse at the other regions are also checked.