Immunity and Disease, Class 12, Biology (AIPMT) Chapter Notes PDF Download

IMMUNITY AND DISEASE

IMMUNE SYSTEM

System which protect the body from disease is called immune system.
(Immune = Letin term Exempt or Freedom)

•Some terms related to immunity :

1. Immunity : Resistance of the body against a pathogen or disease.
    
2. Antigen or Agglutinogen : Proteinous substance which stimulates the production of antibodies is called antigen.
    
3. Antibody or Agglutinin : It is a complex glycoprotein secreted by B-lymphocytes in response to an antigen. it is also called Agglutinin.
    
4. Antiserum : Serum of any animal which contains the antibody for a specific antigen is called antiserum.
    
5. Venom (poison) : Toxic substances secrete by snake and some insect.
    
6. Agglutination : Antigen antibody reaction is called agglutination and study of antigen-antibody reaction is called serology.
    
7. Toxoid : A bacterial exotoxin which is detoxicated by special procedures to allow its safe use in immunization against the disease.
    
8. Interleukin : It is a protein substances which stimulate the growth and activate certain kind of W.B.C.that are involved in Immune response, also act as a secondary messanger that activates the immune system. EX. IL-1, IL-2, IL-3, IL-4, IL-5

•Immunity (Two Types) :

1. Congenital immunity or innate Immunity or Non-specific immunity.
2. Acquired immunity or Adaptive or specific immunity

•Congenital Immunity :
It is present by birth and in most of animal. It is first line of defence of body. It is made up of following barriers.

•Anatomical Barrier : It is made up of two parts :-

1. Skin : Outermost layer of skin is dead (str. corneum). So the bacteria does not grow or enter into it.pH of skin destroy the bacteria, sebum of skin also have anti bacterial action.
    
2. Mucosal surface : Food and air passage lined by mucosa. Mucosa contain mucosal cells and cilia.Mucosa entraps the micro-organism and cilia propell the microbes.

•Physiologocal Barriers : Many physiological functions of body make the unfavourable environment for the
growth of microbes.

1. Fever : High temp. of body, inhibit the growth of microbes.
    
2. pH of body : Acidic pH of various part of body like oral cavity, stomach and Vagina inhibit the growthof microbes.
    
3. Secretions : Secretions of body like Eyes, sebum contain lysozyme enzyme. This enzyme destroys the microbes.
    
4. Interferon : Anti-viral protein made up to 270 amino acids secreated by virus infected cells and sitmulates the adjacent cells to produce the Translation inhibiting Protein (T.I.P.)
   
   By this mechanism interferon limits the infection of virus.
   
   Interferons make cells resistant to viral infection by synthesis of antiviral proteins in that cell.
   
   Vertebrate cells when infected with a virus respond by releasing a small amount of a class of glycoproteincalled interferons.
   
   Interferons are species specific i.e. interferons produced by one species can protect only cells of same species against viral infection.

Types of interferons :
α- produced by Leucocytes. (B-lymphocytes)
β - produced by Fibroblasts.
γ - produced by Lymphocytes. (T-lymphocytes)

Interferons can be used for prophylaxis and treatment of viral infections.

•Phagocytic Barrier :- In response to pathogenic infection, the total count of WBC in body increases.
Phagocytosis is exhibited by some types of WBC’s such WBC’s are called phagocytes.

Most important phagocytes are Macrophages and Neutrophils. Monocytes are liberated at the site of
infection these later converted into macrophages.

Macrophages are large irregular shaped cells that engulf microbes, virus, cellular debris etc in response
to an infection.

Steps of Phagocytosis -

1. Vasodilation (Blood stasis)
2. Adhesion
3. Migration or diapedesis
4. Chemotaxis (Neutrophils or Monocytes)
5. Phagocytosis

Steps of Phagocytosis -

1. Vasodilation : At site of entry - Increased diameter of blood vessels.
2. Adhesion : Accumulation of leucocytes at periphery of blood vessels due to decreased blood flow.
3. Diapedesis : Now the leucocytes (neutrophils or Monocytes) migrates from the blood vessel by Active movements (Amoeboid movement) into the E.C.F. This kind of active movement of cell, is called diapedesis.
4. Chemotaxis : Now this leucocyte cells move towards the pathogen by chemotactic movement (Active).
5. Phagocytosis :

Attachment (adherence) : The infective agent gets attracted to the membrane of the phagocyte.

Ingestion : Phagocyte engulfs the particular material into a vacuole (Phagosome). The membrane
of which fuses with a lysosome forming a phagolysosome. Lysosome contains hydrolytic enzymes
and other bactericidal substances.

Intracellular killing of bacterium : Most bacteria are slaughtered in the phagolysosome by the hydrolytic enzymes within a few minutes of phagocytosis.

•Inflammatory Barrier :

It is the resistance that an individual acquires during life. This is generated in response to an exposure to
the micro-organism in question.

•Features of Acquired immunity :

Types of Acquired Immunity :



 

Natural : Resistance pasively transferred from mother to baby. Mother milk gives passive immunity to the new born child by colostrum (first mother milk) – IgA type of antibody.

Artificial : Resistance passively transferred to a recepient by administration of antibodies.
Examples : human immunological administration.
Anti - tetanus serum (ATS)
Anti - rabies serum (ARS)
Anti - diptheria serum (ADS)

•Difference between active and passive immuntiy :

•Active Immunity :

Antigen Presenting Cells : In immune mechanism every antigen molecule is processed by antigen presenting cells like macrophages, B-lymphocyts etc. This processed antigen is presented on the surface of these cells. When a T-helper lymphocyte passes closely by the side of the antigen presenting cell bearing the antigen on its surface. It recognise the antigen and become activated. Now T-helper cells activate the B-cells and T-killer cells. These cells in turn develop clones by frequent divisions in themselves.

•A.M.I.S. (Antibody mediated immune system or humoral immunity)

Mostly intravascular
IgG – Protects body fluids.
IgA – Protects body surfaces.
IgM – Protects body blood stream.
IgE – Mediates regional hypersensitivity.
 

First line of Defence : Skin, Mucous membrane
Second line of Defence : Neutrophils, Monocytes, Macrophage, interferon, fever.
Third line of Defence : Specific immunity by T- and B-lymphocytes

VACCINE
Vaccine is suspension of inactivated pathogens or antigenic protein of pathogen which is taken orally or injected to provide immunity for that pathogen.

History :

Principle of vaccination :
It is based on memory of immune system. When a antigenic material is injected in a healthy person, it generate antibodies and memory cell as a primary immune respone. When this active pathogen enter second time inside this body of vaccinated person memory cells rapidly recognise and respond with massive production of lymphocytes and antibodoes. So it destroys pathogen rapidly and disease does not appear. Person become resistant for that disease after vaccination.

Types :

HLA System :

IMMUNE SYSTEM DISORDER
Improper functioning of immune system may cause discomfort (Allergy), disease (AIDS) or even death
(anaphylactic shock). Improper functioning divided into 3 classes.

Hyper sensitive disorder or Allergy :

Manifestations : (Effects) –
G Bronchial Asthma : It is common menifestation of allergy on (allergy of lungs) when an allergen enters inside the body by inhalation. It comes in contact with respiratory tube. This is characterised by the spasm of the smooth muscles present in the walls of the bronchiole. It is generally caused due to the hypersensitivity of the bronchiole to the foreign substances present in the air passing through it. The mucous memebranes on the wall of air passage start secreting excess amount of mucous, which may close the bronchi, as well as bronchiole.
 

Symptoms : coughing and difficulty in breathing mainly during expiration. (Wheezing)
 

Prevention and cure :
• Avoiding exposure to the foreign substance or allergens is the best preventive measure.
• Hyposensitisation (by exposing small doses of the specific allergen) is the other preventive meausre.
• Antibiotic therapy for removing the infection, and use of bronchodilator drugs, as well as inhalers for symptomatic relief.

I.D.D.M. : Insulin dependent diabetes mellitus.

Antibodies are formed against the B cell of pancreas that cause the deficiency of insulin in body
and this called I.D.D.M. Symptoms are hyperglycaemia, glycosuria, polyuria, polydipsia (excessive
thirst), polyphagia (increase food intake)

Multiple sclerosis : Antibodies are formed against the myline sheath of nerve cells. Destruction
of myline sheath causes neurological dysfunction.

Immuno deficiency disorder : May be due to gene mutation, gene deficiency, infection, nutritional
deficiency & accidents.

Immunotherapy
Immunotherapy is a treatment procedure that involves suppression or augmentation of immune responses,
to achieve therapeutic effects. Manipulation of the immune response can be carried out by modulating various components involved in it. Cytokines are natural immunomodulators secreted by one type of immune cell that elicits response in another type of immune cell these include interleukins, interferons and tumour necrosis factors.

Immunomodulators : Drugs that modulate the activity of a patient’s immune response. Either up or down, until a desired level of therapeutic effect is reached. There are two general clinical approaches of immunomodulation.

CANCER
Uncontroled, Abnormal and excessive mitotic division of cells is called cancer (Crab = cancer)
Study of cancer is called oncology
This abnormal and undifferentiated cells are called cancerous cells.

Tumour or neoplasm (new growth) :
Types of Tumours -

CANCER IS DIVIDED INTO 3 CLASSES ON BASIS OR ORIGIN :
Carcinoma : This tumour originate from the skin and epithelial tissue

Example -
Brain carcinoma

Oral carcinoma
Gastric carcinoma

Colon carcinoma
Lung carcinoma

Cervical carcinoma
Adeno carcinoma (gland tumour)

Breast carcinoma

Bone cancer - Osteosarcoderma
Muscle cancer - Myosarcoma
Lymph node cancer - Lymphosarcoma

Leukaemia (Leucocyte = W.B.C.) or Blood Cancer : This is cancer of white blood cells (WBC).

Causes of cancer -
Chemical or physical agents that can cause cancer are known as carcinogen. Depending on their mode
of action, carcinogens fall into the following main categories :

Agents that can cause alterations in the genetic material (DNA), resulting in oncogenic trasformation.

Agents that promote the proliferation of cells, which have already undergoes genetic alteration responsible
for oncogenic transformation. These agents are called tumour promoter e.g. some growth factors and
hormones.

Cancer causing DNA and RNA viruses (tumour viruses) have been shown to be associated with
oncogenic transformation.

Transformation of a normal cell into cancer cell if the regulation is upset.

Investigation -

Treatment :

Vincristine (weed - cantharanthus roseus = Vinca rosea)
Vinblastin (weed - cantharanthus roseus = Vinca rosea)
Cyclophosphamide

inhibit the DNA synthesis in cell cycle of cancerous cell but this has side effects.

DRUG ADDICTION & MENTAL HEALTH

DRUG DEPENDENCE

Meaning : Certain drugs are prescribed physicians for the prevention or treatment of diseases or for increasing
the physical and mental performance and are withdrawn as soon as the desired effect is achieved. Repeated
use of certain drugs on a periodic or continuous make the body dependent on them. This is called drug
dependence. The term. “drug-dependence” is now a-days preferred to ‘drug-addiction or drug habituation’
(WHO, 1964). Some people start taking drugs without medical advice due to one reason or the other and
become drug dependent.

Types : Drug dependence in of two types Psychological and Psysical or physiological.
 

Psychological dependence : If refer to the person’s belief that the normal state of well being can be
attained only with the drug’s action.
 

Physical (Physiological) Dependence : It refers to the person’s state when intake of a drug becomes
essential to maintain physiological equilibrium. In such a case, the nervous system functions normally in
the presence of the drug only. The physical dependence is, therefore, also called neuroadaptation.
 

Types of Habituating Drugs : The habituating drugs are gouped into two main categories. Psychotropic
drugs and psychodelic drugs

ADDICTIVE DISORDERS
If the body needs continuous presence of psychoactive substance within it, it is called addition. Psychoactive
drugs have the ability to alter the activity of nervous system. Different psychoactive drugs along with their category and effects are given below.
Major categories of psychoactive drugs (i) Psychotropic drug (ii) Psychedelic drug, their effects and
clinical uses

A person who is habitual user if abstains from a drug (abstinence), his body reacts i.e., ceases to function
normally. It is called physical dependence. The symptoms appearing in the body are withdrawal symptoms and range from mild tremors to convulsions, abdominal pain, diarrhoea, muscle cramps, anxiety, nausea, insomnia are called withdrawal symptoms. In many cases the withdrawal symptoms may be life threatening and needs medical supervision.

PSYCHOTROPIC DRUGS

Cannabinoid receptors present principally in the brain
Cannabinoid generally taken by inhalation and oral ingestion, these mainly affect cardiovascular system
of body.

Atropa belladona and Datura also have hallucinogenic properties.

ADOLESCENCE AND THEIR PROBLEMS
The transition period between 8–18 years for girls and 7–19 years for boys is called the adolescence. It is
poised between–childhood and adulthood which is characterised by rapid growth, and physical and mental
dvelopment. This period is marked by attainment of sexual maturity (puberty) and increased production of
hormones, including sex hormones. This results in frequent shifts of moods and emotional turbulence. The
most common problems of all adolescents of both sexes are.

Combinations of drugs :
Some addicts use mixtures of drugs to have immediate ‘kick’ or ‘charge’. Simultaneous use of drug (hemp
derivatives, barbiturates, aspirin or antihistamines) and alcohol may produce dangerous effects, including
death. When barbiturates and alcohol are taken together, each doubles the effect of the other. A mixture of
cocaine and heroin, called speed ball, gives spontaneous kick of cocaine and prolonged pleasure of heroin.

ALCOHOLISM
Alcoholism is a dependency of a person on regular consumption of alcohol either in low concentration (wine, bear etc) or in high concentration (rum, vodka etc)

Effect of Alcohol on an individual
 

Effects on liver : Absorbed alcohol is carried directly to the liver, where it becomes metabolised. Use of
moderate amounts of alcohol does not case liver damage, provided adequate nutrition is maintained. However,
chronic alcoholism causes the following diseased.

Effect on nervous system : These are characterised as

Effects on stomach : High doses of alcohol cause ill effect on gastric glands of stomach, these glands
secrete gestric juice in excess which cause the inflammation to gastric mucosa. This condition is known as
gastritis. It may also result gastric cacinoma, peptic ulcer, Dilute alcohol (optimum 10 %) stimulates gastric
secretion (specially acid). Acute alcoholic intake can result in inflammation of the oesophagus (esophagitis)
and stomach (gastritis). Chronic heavy drinking, if associated with violet vomiting, can produce a longitudinal
tear in the mucosa at the gastrointestinal junction- a Mallory- Weiss syndrome (also called mallory- weiss
Lesion).

Effect on heart : Due to deposition of alcoholic fat on the wall of blood vessels, the lumen of blood vessels
becomes reduced, this increases the blood pressure and hence, the activity of heart.

Effect on kidneys : Alcohol reduces the release of hormone ADH (Antidiuretic hormone) due to which the
excess amount of water is released from the body. So, alcoholism greatly causes dehydration condition.

Heavy drinking can cause an acute alcoholic myopathy characterized by painful and swollen muscless and
high levels of serum creatine phosphokinase (CK).

Alcohol increases RBC size causing a milk anaemia. Chronic heavy drinking can also decrease production
of white blood cells (WBCs). Alcohol may decrease platelet aggregation.

Effects on the skeletal system include alternations in calcium metabolism with an increased risk for fracture
and osteonecrosis (death of bone mass) of the head of femur.

Hormonal changes include an increase in cortisol levels, inhibition of vasopressin, reversible decrease in
serum thyroxine and a more marked decrease in serum triiodothyronine (T₃).

Heavy drinking during pregnancy results in serious consequences for foetal development. The foetal alcohol
syndrome (FAS) includes facial changes, poorly formed concha (cavity of pinna), small teeth with faulty
enamel, defects in atria and ventricles of heart.

Regular intake of small to moderate amounts has been found to raise HDL-high density lipoproteins (good
cholesterol) and lower LDL-low density lipoproteins (bad cholesterol) levels in the blood plasma. This may be
responsible for lower incidence of coronary artery disease in such persons. Alcohol also reduces blood sugar
level which is harmful to the functioning of brain.

Effect on immunity : Alcoholims losses resistance to infection. The alcoholics in most cases, are victims of
malnutrition and are easily susceptible to diseases like pneumonia.

Effect on family : The habit of drinking not only create problems to the drinker but directly or indirectly
affects the family and community life. Most drinkers do not think regarding needs of their children and other
members of the family.

Effect on society : Alcoholism is invariably associated with social crimes and dissolution of moral and
cultural inhibitions. Violence and other corrupt practices in the community are often directly or indirectly due
to the drinking of alcohol.

Metabolism of Alcohol
In body the alcohol passes to the stomach. Some amount of it also passes to proximal part of intestine.
Thus, stomach and proximal part of intestine absorb this alcohol and then transfer to blood and from blood to
liver. In liver, alcohol is converted to acetaldehyde with the help of enzyme alcohol dehydrogenase.

Acetaldehyde is oxidized by the enzyme acetaldehyde dehydrogenase. It liberates the heat. This heat is
utilized in the synthesis of fat. The excess of fat reduce the formation of glycogen, enzymes and structural
proteins. This condition is known as cirrhosis.

TOBACCO ADDICTION
Tobacco can be obtained from dried and cured leaves of young branches of two species of tobacco plant,
Nicotiana tobaccum and N. rustica. Tobacco plant belongs to angiospermic family Solanaceae.

The use of tobacco was started in America where Red Indians were started use it. It spreads to Europe and
other countries in early 1700s.

BLOOD BANK

Due to certain factors when blood flows out of the body of any person, then blood is required for performing the
vital activities.

It is essential to provide the blood to this person. This phenomenon is known as blood transfusion. For different
persons the blood of matching blood group is required for this purpose the storage of blood is essential.
The storage of blood of different blood groups in protected places are known as ‘Blood-bank’

DISEASE

1. Disease :- Any change from the normal state that causes discomfort or disability or impairs the health is called disease.
    
2. Health :- Health is a state of complete physical, mental and social well being. and not merely an absence of disease or infirmity (W.H.O. - 1948)
    
3. Prophylaxis or preventive measures :- Preventive measure for a disease is called prophylaxis.
    
4. Epidemiology :- The study of causes and spread of disease is called Epidemiology. (epi = among, demos = Human, logy = study)
    
5. Etiology :- Study the internal cause of disease is called Etiology.
    
6. Incubation period :- Time interval between the entry of pathogen and appearance of symptoms is called incubation period.
    
7. Window period :- Period between infection to the time when it can be laboratrically detected.

Chemotherapy : Treatment with chemicals (Medicine)

1. Antibiotics : Substances which are secreted by micro-organism that inhibit the growth or destroy the other micro-organism are called antibiotics. This term was given by Walksman (Streptomycin-first bacterial antibiotic obtained from bacteria-streptomycin griseus).
   Example- Bacteriostatic-Tetracycllin, Chloramphenicol,
   Bacteriolytic or Bacteriocidal-Streptomycin, Ciprofloxacin, Ampicillin.
    
2. Analgesics : Substance that relieves pain.
   Example - Opioid analgesics- Morphine, Codeine, Diclofenac sodium, Nimesulide.
    
3. Antipyretics (Antifebrile) : (Pyrexia - Fever) Substance that reduces temperature or fever of body. Example - Aspirin (Acetyl salicylic acid)- (It produces gastric ulcer so not extensively recommanded as a analgesic), Ibuprofen, Paracetamol, Nimesulide.
    
4. Antihistaminic drug : These drugs give relief from allergies by neutralizing histamines that is released from the ruptured mast cell. e.g. cetrizine.
    
5. Tranquillisers and Hypnotics and Sedative drug :
   Example - Diazepam, Alprazolum)
   
   a. Tranquilliser drug : A drug that act to reduce mental tension and anxiety without interfering with normal mental activity.
   
   b. Sedative drug : A drug that calms the subject without inducing sleep.
   
   c. Hypnotic drug : A drug that induces sleep.
    
6. Antiseptic and Disinfectant : Agent that inhibit or kill microbes on contact. Conventionally agents used on living surfaces are called antiseptics while those used for inanimate objects are called disinfectants.
   
   a. Disinfection : In this process, kill only vegetative form of bacteria.
   b. Sterlisation : In this process, kill all form of pathogens including spores.

MEDICAL TERMS

1. Arthro - Joint (Arthritis)
2. Aesthesia - Sensation (Anaesthesia means lack of sensation)
3. Bracy - Short (Bracydactyly)
4. Brady - Slow (Bradycardia)
5. Coronary or Cardia - Heart
6. Dropsy - Due to Argimone maxicana’s seeds. These seeds mix with mustard oil and produce poisoning.
7. Encephalon - Brain
8. Enteron - Intestine
9. .......emia - Blood (Anemia, protenemia, Hyperglycemia)
10. Gastric - Stomach
11. Hepatic - Liver
12. .......itis - Infection or inflammation
13. Myo - Muscles
14. Metastasis - Cancer cells or tissue spread from one part to another part of body.
15. Nephric/Renal - Kidney
16. Pulmonary - Lungs
17. Patho - Disease
18. .......Penia - Decrease (Neutropenia, Leucopenia)
19. .......Philia or Cytosis - Increase (Neutrophilia, Lymphocytosis)
20. Phobia - Acrophobia, Hydrophobia, Agoraphobia
21. Plegia - Paralysis, (Hemiplegia, Paraplegia, Quadriplegia)
22. Phrenic - Diaphargm
23. Rhine - Nose
24. Tachy - Fast (Tachycardia-fast heart rate)
25. .......uria - Urine (Haematuria)
     

SCIENTISTS :

1. Father of Medicine : Hippocrates – He gave scientific explaination of disease first time.
2. Father of Surgery : Susruta – He used non-poisonous leeches as an anti coagulant during surgery.
3. Father of Ayurveda : Charaka (Ayu – Life, Veda – Knowledge) He first gave concept of digestive, metabolism and immunity
4. Father of Modern Pathology : Rudolf virchow.
5. Father of Immunity : Edward Jenner (Small pox vaccine)
6. Father of Blood grouping : C. Landstainer.
7. Father of Modern Bacteriology : Robert Koch (Anthrax, T.B., Cholera)

Got nobel prize :

1. In 2004 for odourent receptor (olfaction) is given to Richard Axel and Linda B Buck.
2. In 2005 = Marshal and Warren for Helicobactor pylori bacterium
3. In 2006 = Fire and Melo for RNA interference.
4. In 2009 = V.Ramkrishan for antibiotic and ribosome relationship.
5. 26 June : International day against drug abuse and Illicit trafficking.

IMPORTANT DAYS :
30 January - Leprosy Day
24 March - Tuberculosis Day
07 April - World Health Day
01 July - Doctor’s Day
11 July - World Population Day
01 December - AIDS Day

1. Gene mutational disorder/Biochemical disorder :
  a. Autosomal Recessive gene mutation disorder :

1. Phenyl ketonuria : (12th chromosome) due to deficiency of phenyl alanine hydroxylase, phenylalanine increase in blood & it convert into phynyl pyruvic acid and phenyl ketone in liver this phenyl pyruvic acid accumulates in brain & destroy the brain cells. This causes mental retardation these individuals are called phenyl pyruvic idiots.
    
2. Alkaptonouria (16 Chromosomal) (Black urine disease) –
   This disorder is due to deficiency of enzyme homogentisic acid oxidase. So, homogentisic acid does not metabolised into tyrosine.  concentration of alkaptone or homogentisic acid in blood and tissue like joints, ligament, tendon, cartilage and also excreate in urine so it is called alkaptonuria.When this urine comes in contact with air, it turn black due to oxidation of homogentisic acid so it is also called black urine disease.
    
3. Albinism (11 Chromosome) : This disorder is due to deficiency of enzyme tyrosinase therfore the body parts like skin, iris of eye etc., they become melanin deficient. Melanin provide protection against U.V. rays.
    
4. Tay-sach’s disease or Infantile amourotic (Greek term – darkning – visionloss) 15 Chromosomal : This disease is first reported by tay and sac. This genetic disorder is due to deficiency of enzyme β-N acetyl hexose aminidase, this enzyme is involved in fat metabolism. So, the fat (conjugate lipid) accumulate in brain (ganglioside cell) and spinal cord and damage these cells. This cause mental retradation and paralysis of a normal born child and so child does not survive more than 3-4 years.There is no treatment of Tay-sach’s disease.
    
5. Thalassemia (Thalassa - sea) (Thomas Cooley – 1925) : (Mediterranean anemia or cooley’s anemia) This disorder was, first found in population of mediterranean region. Frame shift mutation causes the deficiency of β and αgenes present on 11th & 16th chromosomes respectively. So decrease synthesis of β and αpolypetide chain of hemoglobin, (Mainly β–chain is affected) abnormal type or decreased hemoglobin is formed in R.B.C. This deform the R.B.C. become hemolytic in nature.
   So hemolytic anemia appear in this disorder.
   
   Treatment : Blood transfusion or bone marrow transplantation
    
6. Sickle cell anemia (11th chromosome) : Glutamic acid is replaced by valine at the 6th position of β chain of hemoglobin. This abnormal Hb change the shape of RBC from spherical to sickle shape and these RBC’s become hemolytic in nature and produce haemolytic anemia. Sickle cell anemic patients are resistant against malaria (Falciparum malaria)

1. X-Linked recessive disorders :
   
   a. G-6-Phosphate dehydrogenase deficiency syndrome – G-6-PD enzyme present in RBC. This enzyme stabilize the membrane of R.B.C. Deficiency of this enzyme cause rupture of R.B.C. when it comes in contact with sulfa drug, chloroquine, Fava (Favism) bean legumes.
   
   b. Duchenne’s muscular dystrophy – Dystrophin protein is absent in muscles, this protein helps in conduction of Ca++ ion. Due to deficiency of dystrophin protein, muscles contraction do not occur properly.

Autosomal dominant gene mutational disorder

1. Polydactyly (7th chromosome) : Presence of extra fingers and toes
    
2. Brachydactyly : presence of abnormal short fingers & toes.
    
3. Huntington chorea : In this disorder dominant mutation occur on 4th chromosomes so the mental and muscle degeneration occurs in the patients. This causes abnormal movement of limbs and defective speech. This disease appears at the age of 25-55 yrs. (late onset) Nerve degeneration causing involuntary shaking of legs, arms and head).
    
4. Achondroplasia (4th Chromosome) : Defective formation of cartilagenous bones causing dwarfism.
    
5. Marfan syndrome (15th chromosome) : Long & thin body, Myopia, long Arachnodactyly (spide like) fingers. Mitral valve prolapes. Connective tissue disorder effect the skeleton, eye and cardiovascular system.

CHROMOSOMAL MUTATIONAL DISORDER

Autosomal Aneuploidy : (Change in no.)

1. Down’s Syndrome : (Mongolism or Mangolion Idiocy) 21 trisomy. This disorder first reported by Langdon down. It is first chromosomal mutational disorder to be discovered. It is most common cause of trisomy & mental retardation in children.
   
   Its frequency or incidence is 1 in 700 children. This abnormality or disorder is formed mostly by fusion of normal sperm with abnormal egg. This abnormal egg contains the extra chromosome on 21th position.
   
   Women around the age of 45 are more likely to produce the children having down syndrome This disorder is due to chromosomal non disjunction.
   
   Symptoms : Short stature, rounded face, extra folds in eye lids (epicanthus), broad forehead, retracted tongue and lower lips, flatened nasal bridge, open mount, short nack, flat hands, stubby fingers, undeveloped genital & gonads, mental retardation (I.Q. = 25 – 50).
   
   Amniocentesis is done to detect this syndrome in embryonic stage.
    
2. Edward’s syndrome (trisomy 18) (Incidence 1 in 8000 birth)
   In this disorder defective formation of ears and nervous system. They are mentally retarded small eyes– micropthalmia, micrognatha (small jaw).
    
3. Patauo’s syndrome (trisomy 13) (Incidence 1 in 15,000 birth)
   Cleft plate, polydactyly, small hands, tiny eyes, mentaly retarded.
    
4. Cat cry syndrome (Cri-du-cat)
   This disorder is due to partial deletion of short arm of Chromosome 5. Patients are mentally retarded and exhibit characteristic cat cry.

•Sex chromosomal (Aneuploidy)

 



AIDS (Aquired Immuno Deficiency Syndrome)

1. Also caled slim disease.
2. First detected in homosexual males in USA (1981) at Disease control centre Atlanta.
3. In India first AIDS case was reported in 1986 from chennai.
4. Virus was named variously HCLV-III = Humen cell Leukemia Virus-III
   HTLV-III = Human T-lymphotrophic Virus-III
   LAV = Lymphoadenophathy associated virus
   HIV-I = Most common in India (90 - 120 nm) and widly distributed throughout the world.
   HIV-II = Most common in West Africa (90 - 120 nm)

Transmission :

1. Sexual route : due to multiple sex partners, prostetuters, homosexuality, artificial insemination (Probability < 1%)
2. Parenteral route : through blood contact due to unsecreened blood transfusion, tattoeing, infected, poorly sterlised dentral instruments.
3. Trasplacentral route = from mother to fetus = Vertical transmission, by placenta (33%)
   = from mother to infants = perinatal transmission, by colostrum.

Misconceptions :

1. AIDS so not spread through more touch, physical contact, hugging, kissing, sharing meals, shaking hands, mosquito bites, coughing, sheezing looking after AIDS pateints.
2. HIV spreads only through body fluids.
    

Pathogenicity :

•Structure :

1. Retro virus (Lenti virus family)
2. Core has 2 identicle molecules of SSRNAs, enzymes (reverse transcriptase, protease)
   Core also has
   - Inner protein coat (P-24)
   - Outer protein coat (P-18)
3. Core is covered by lipoproteins (GP-120 and GP-41)
4. GP-120 has complementry sequence to CD-4 receptors present on Macrophages (HIV factory), helper T-cell etc.

•Symptoms :

1. Asymptomatic phase 2 - 10 yrs, There is no anitbody, protection in 1st (2 - 12 weaks) so infctivity of patients or activeness of virus is maximum is this period. This period is called window period (No specific symptom appear in this phase so ELISA test is negative in window period)
    
2. AIDS related complex (ARC) = mild form of HIV
   = Swollen lymph nodes, bouts of fever, repeated episodes ofdiarrhoea, weight loss prolonged cough.
   = Patient become fully immune deficient in this period. T-lymphocytes or CD4 count < 200 × 10⁶ / litre (normal CD₄ count > 900 × 10⁶ per/litre) and now this condition is called full blown AIDS.
    
3. Full blown AIDS = Tuberculosis by Mycobacterium avium.
   = Candidiasis of mouth and oesophagus by Candida albicans.
   = Pneumonia by fungus Pnemocystis carinii
   = Sores by Herpes simplex virus-II
   = Cancer of skin and lymphnodes (Kaposi’ sarcoma), HIV acts as an oncovius.
   = Dysentery by cryptosporidium
   = AIDS dementia (memory loss) by Herpes Zoster Virus.
   = Encephalitis by Toxoplasma gondii.
    
4. Most of infections are due to oppurtunistic infections, appear when immunity become weak.
    

•Investigation :

1. Screening test : (ELISA) Enzyme linked immuno sorbent assay.
2. Confirmatory tests : Western blot test which detects antibodies, in patient’s serum.

•Treatment :

1. Reverse transcriptase inhibitor = Zidovudin (previously called AZT), Stavudin, Trizivir, DDI (Didexymidine), Foscarnet, etc.
2. Protease inhibitor = Ritonavir, Nelfinavir, Sequinavir etc.
3. HAART (Highly Active Ant Retroviral Therapy) includes both reverse transcriptase inhibitor and protease inhibitor drugs.
   Dr. David Ho. - Cocktal treatment of AIDS in 1993 and research in USA 1995, man of the year.
   - Treatment is only partially effective, only prolong the life of the patients but cant prevent death, which is inevitable.
    

•Prevention :

1. Education : NACO (National AIDS control Organisation) has been set up under health family welfare ministry.
   (NGOs / Non government organisation also playing their important role)
2. Screening of blood.
3. Ban on prostetution, Safer sex and awareness about to use of condoms.
4. Use of disposables.
5. Sterlization of Ragors, blades and dentral equipments.
6. AIDS patients need help and sympathy instead of being shunned by society.

BIOCHEMICAL INVESTIGATION

Haemoglobin Estimation -

Methods of Haemoglobin Estimation :

Haemoglobin is a chromoprotein consisting of the colourless globin molecule attached to four red coloured
haem molecules. The globin molecules consist of two alpha-polypeptide chains and two beta-polypeptide
chains. Haem is a metal complex containing an iron atom in the centre of porphyrin structure. Haemoglobin
is formed in developing erythrocytes (normoblasts) in the marrow.

The biosynthesis of haemoglobin involves the tried of manufacture of haem, manufacture of globin and iron
metabolism. Methods of estimation of haemoglobin are as follows :

Sahli’s acid haematin method :

Principle :
Hb is converted into acid haematin by hydrochloric acid. The brown colour of the compound is matched
against a brown glass standard in a comparator.

1. One of the common method employed to determine Hb is Sahli method using as Haemoglobinometer (Brown complex - acid Haematin is formed).
    
2. Some indicators of disorders are :
   Low Hb - Anemia and leukemia.
   High Hb - Dehydration and polycythemia or erythrocytosis

Erythrocyte Sedimentation Rate (ESR)
It is the rate at which the erythrocytes or RBC sediment. when they are allowed to settle out from plasma.
ESR is measured in terms of milimeter per hour. It is useful in diagnosis of many diseases or non specific
infection, though it is not specific for any particular disease.

1. Lipid Profile : Blood Cholesterol Tests measure the levels of lipids (fatty acids). cholestrerol and triglycerides in the blood. Elevated lipid levels indicate heart disease or stroke overweight or diabetes mellitus.
    
2. Two important cholestrol types are HDL (high-density lipoprotein) and LDL (low-density lipoprotein) HDL have a protective effect against atherosclerosis where as high blood level of LDL is a risk factor HDL is good cholesterol and LDL is bed cholesterol.

1. Microsassay plate coated with HIV antigen. The sample suspected to contain the Ag immobilised on the surface of an ELISA plate.
2. Test serum is added and incubated. HIV antibody if present in the serum will attach to HIV antigen.
3. After washing, add goat antithuman immunoglobulin antibody conjugated with horse serum peroxidase enzyme. The conjugate will attach to HIV antibody in a positive test.
4. After washing, add substrate OPD (orthophenyl diamine HCI/paranitropheny phosphate). or (H₂O₂ + 4-chloronapthol)
5. A colour develops in the positive test, while there will be no colour in a negative test. ELISA is very quick diagnostic technique for detection of a wide variety of pathogens, disorders, allergens and hormones,
   Like–
   a. Pregnancy test throught presence of human chorionic gonadotropin (HCG) in urine or blood.
   b. AIDS or HIV infection
   c. Hepatitis
   d. STD or sexually transmitted disease
   e. Rubella virus
   f. Thyroid disorder

DEVICES