Before cell division, the chromosomes duplicate themselves and coil up with the 2 copies joined together. The doubled chromosomes line up in the centre of the cell and are pulled apart to opposite ends of the cell, which then divides. Each daughter cell therefore has the same chromosome content as the original cell. (See also meiosis.)
Meiosis produces egg (see ovum) and sperm cells that differ from their parent cells in that they have only half the normal number of chromosomes.... cell division
During meiosis in humans, a cell containing 23 pairs of chromosomes (46 in total) divides to form 4 sperm or egg cells, each with 23 single chromosomes.
First, the chromosomes are duplicated to produce 4 copies of each chromosome (92 in total).
Matching pairs of chromosomes line up and exchange genetic material.
The cell then divides twice to form 4 daughter cells, with each taking 1 copy of each chromosome.
Egg and sperm cells therefore have only half the usual chromosome content of a body cell, so that each parent contributes half of the child’s genetic material.
The exchange between chromosomes means that each daughter cell has a unique genetic make-up.
(See also mitosis).... meiosis
Habitat: The temperate Himalayas from Kashmir to Chamba. Major supplies of the drug are received from Kashmir.
English: Hermodactyls, Colchicum, Meadow Saffron, Golden Collyrium (Indian substitute). (C. luteum is a good substitute for C. autumnale L. which is official in the B.P.)Ayurvedic: Hiranyatuttha.Unani: Suranjaan Talkh.Action: Non-steroidal antiinflammatory, anti-gout (relieves inflammation and pain of acute gout but does not increase expulsion of uric acid, is used with an alkaline diuretic), emetic, cathartic. Anti-chemotactic, antiphlogistic, inhibitor of mitosis. Highly toxic. Used for external application to lessen inflammation and pain.
Key application: In acute gout attack. (German Commission E.)The fresh corms and aerial parts of a sample from Jammu yielded 0.94% and 070% of total alkaloids, the major being colchicine 0.40% and 0.20% respectively. Colchicine analogs— decteyl thiocolchicine (DTC), decetyl- methylcolchicine (DMC) and tri- methylcolchicinic acid (TMCA) were effective in the treatment of gout; DTC may elicit agranulocytosis.Colchicine binds to tubulin, the protein subunit of microtubules. Its most important biological effect is the inhibition of processes that depend upon microtubule function by blocking polymerization. In preventing micro- tubule formation, colchicine has been shown to inhibit catecholamine secretion from adrenal medulla, iodine secretion from thyroid gland and pro- lactin secretion from pituitary tumour cells. It inhibits stimulated insulin secretion from isolated perfused pancreas and islets in vitro.The use of Colchicum for long periods is not recommended owing to its toxicity in larger doses (even 7 mg of colchicine has caused death) and its depressant action upon central nervous system.Prolonged use of Colchicum autum- nale may cause agranulocytosis, aplas- tic anaemia and peripheral nerve inflammation. (Sharon M. Herr.)... colchicum luteumGenes fulfil these functions by directing the manufacture of proteins. Many proteins have a structural or catalytic role in the body. Others switch genes “on” or “off”. The genes that make these regulatory proteins are called control genes. The activities of control genes determine the specialization of cells; within any cell some genes are active and others idle, according to its particular function. If the control genes are disrupted, cells lose their specialist abilities and multiply out of control; this is the probable mechanism by which cancers form (see carcinogenesis; oncogenes).Each of a person’s body cells contains an identical set of genes because all the cells are derived, by a process of division, from a single fertilized egg, and with each division the genes are copied to each offspring cell (see mitosis; meiosis). Occasionally, a fault occurs in the copying process, leading to a mutation. The gene at any particular location on a chromosome can exist in any of various forms, called alleles. If the effects of an allele mask those of the allele at the same location on its partner chromosome, it is called dominant. The masked allele is recessive. (See also genetic code; inheritance.)... gene
Constituents: allantoin, pyrrolizidine alkaloids (fresh young leaves and roots), mucilage, phenolic acids, steroidal saponins (root).
Action: astringent-demulcent, haemostatic, vulnerary. Rapid healer of flesh and bones by its property to accelerate mitosis (cell-division). Useful wherever a mucilaginous tissue restorative is required (repairing broken bones and lacerated flesh), especially in combination with Slippery Elm powder which prevents excess fluidity.
Uses: Ulceration anywhere along the gastrointestinal tract; colitis, hiatus hernia.
Bleeding from stomach, throat, bowel, bladder and lungs (haemoptysis) in which it reduces blood clotting time. Once used extensively for tuberculosis (pulmonary and elsewhere). Irritating cough, ‘dry’ lung complaints; pleurisy. Increases expectoration. Should not be given for oedematous conditions of the lungs.
Bones – fractures: to promote formation of a callus; rickets, wasting disease. Skin – varicose ulcers and indolent irritating sores that refuse to heal. Promotes suppuration of boils and gangrene as in diabetes. Bruises. STD skin lesions, internally and externally. Blood sugar control: assists function of the pancreas. Urine: scalding. Rheumatoid arthritis: improvement reported. Malignancy: cases of complete regression of sarcoma and carcinoma recorded. Rodent ulcer, (as a paste).
Preparations: thrice daily.
Tea: dried herb, one heaped teaspoon to each cup; or, 1oz to 1 pint boiling water; infuse 15 minutes, half- 1 cup for no more than 8 weeks.
Tincture (leaf). 1 part to 5 parts alcohol: dose 2.5-5ml. Maximum weekly dosage – 100ml for no more than 8 weeks.
Tincture (root). 1 part to 5 parts alcohol. Maximum weekly dosage – 80ml, for 8 weeks.
(National Institute of Medical Herbalists)
Poultice. A mucilage is prepared from fresh root in a liquidiser or by use of a rolling pin. For sprains, bruises, severe cuts, cleaning-out old ulcers and wounds.
Compress. 3 tablespoons crushed root or powder in 1 pint (500ml) water. Bring to boil; simmer gently 10 minutes. Saturate linen or suitable material and apply. Renew 2-3 times daily as moisture dries off. Ointment. 1 part powder, or liquid extract, to 10 parts base (cooking fat, Vaseline, etc).
Oil (external use). Ingredients: powdered Comfrey root in peanut oil and natural chlorophyll. (Henry Doubleday Research Association)
Notes. Contains trace element germanium, often given for cancer and arthritis. (Dr Uta Sandra Goodman) Helps eliminate toxic minerals. Neutralises free radicals that are created by toxic substances entering the body. Restores the body’s pH balance disturbed by highly acid foods such as meat, dairy products, refined foods and alcohol.
Dr H.E. Kirschner, well-known American physician, reported being called to the bedside of a patient with a huge advanced cancer of the breast. The odour was over-powering and the condition hopeless, but he advised poultices of fresh crushed Comfrey leaves several times daily to the discharging mass. Much to the surprise of all, the vile odour disappeared. The huge sore scaled over and the swelling subsided. Within three weeks the once-malignant sore was covered with a healthy scale and the pain disappeared. Unfortunately, treatment came too late; metastases had appeared in the liver which could not be reached by the poultices.
Claims that Comfrey is a toxic plant are unsubstantiated by a mass of clinical evidence to the contrary. Attempts to equate the effects of its isolated compounds apart from the whole plant yield conflicting results. For thousands of years the plant has been used by ancient and modern civilisations for healing purposes. Risks must be balanced with benefits.
There is a growing body of opinion to support the belief that a herb which has, without ill-effects been used for centuries and capable of producing convincing results is to be recognised as safe and effective.
Experiments reveal that in sufficient doses Comfrey can cause liver disease in laboratory animals. Its risk to humans has been a matter of serious debate since the 1960s, and is still unresolved. Although the overall risk is very low, a restriction has been placed on the plant as a precautionary measure. Fresh Comfrey leaves should not be used as a vegetable which is believed to be a health risk. It is believed that no toxicity has been found in common Comfrey (Symphytum officinale L). No restriction has been placed on use of dried Comfrey leaves as a tea. The debate continues.
It would appear that use of the root of Symphytum officinale may be justified in the treatment of severe bone diseases for which it has achieved a measure of success in the past, such as rickets, Paget’s disease, fractured bones, tuberculosis, etc, its benefits outweighing risks. Few other medicinal plants replenish wasted bone cells with the speed of Comfrey. (external use only) ... comfrey
Goldenseal, Mistletoe, Red Clover, Violet leaves. See also: ANTI-NEOPLASTIC. ... cytostatic
There are 2 types of nucleic acid: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). In all plant and animal cells, including human cells, DNA permanently holds the coded instructions, which are translated and implemented by RNA. DNA is the main constituent of chromosomes, which are carried in the nucleus (central unit) of the cell.
DNA and RNA are similar in structure, both comprising long, chain-like molecules. However, DNA usually consists of 2 intertwined chains, whereas RNA is generally single-stranded.
The basic structure of DNA has been likened to a rope ladder, the chains forming the 2 sides, with interlinking structures in between forming the rungs.
The ladder is twisted into a spiral shape called a double helix.
Each DNA chain has a “backbone” consisting of a string of sugar and phosphate chemical groups. Attached to each sugar is a chemical called a base, which can be any of 4 types (adenine, thymine, guanine, and cytosine) and forms half a rung of the DNA ladder. The 4 bases can occur in any sequence along the chain. The sequence, which may be many millions of individual bases long, provides the code for the activities of the cell (see genetic code).
RNA is like a single strand of DNA; the main difference is that the base thymine is replaced by another base, uracil.
Complex organisms are built up of millions of cells that are specially adapted to carry out particular functions. The process of cell differentiation begins early on in the development of the embryo and cells of a particular type (e.g. blood cells, liver cells) always give rise to cells of the same type. Each cell has a particular number of *chromosomes in its nucleus. The sex cells (sperm and ova) always contain half the number of chromosomes of all the other cells of the body (see meiosis); at fertilization a sperm and ovum combine to form a cell with a complete set of chromosomes that will develop into the embryo.... cell
Health Encyclopedia