M.S. Swaminathan: Biology and Human Welfare

• Unit VIII focuses on the application of biology to improving human welfare
• Chapters cover human health and disease, food production enhancement, and the role of microbes in human welfare
• Modern advancements have highlighted biology's role in health and agriculture

M.S. Swaminathan

• Born in August 1925, in Kumbakonam, Tamil Nadu
• Graduated and completed his Botany post-graduation at Madras University
• Developed expertise in genetics and plant breeding through work at various institutions in India and abroad
• Enabled the development of short-duration, high-yielding rice varieties, including scented Basmati, at the School of Cytogenetics and Radiation Research (IARI)
• Known for developing the concepts of crop cafeteria, crop scheduling, and genetically improving yield and quality
• Initiated collaboration with Norman Borlaug, resulting in the "Green Revolution" through the introduction of Mexican wheat to India
• Initiated "Lab-to-Land", food security, and other environmental programs
• Honored with Padma Bhushan and other prestigious awards and fellowships

Human Health and Disease

• Health is defined by physical, mental, and social well-being, not just the absence of disease
• Good health increases efficiency, productivity, longevity, and reduces mortality
• Balanced diet, hygiene, exercise, and practices like yoga are crucial for maintaining good health
• Awareness about diseases, vaccination, waste disposal, vector control, and food/water hygiene are also important
• Disease occurs when the body's functions are negatively affected with signs and symptoms
• Diseases are either infectious (transmissible) or non-infectious
• AIDS and cancer are deadly
• Health is affected by genetic disorders, infections, and lifestyle choices like diet/exercise/habits
• Drug and alcohol abuse can also affect health

Common Human Diseases

• Diseases can be caused by bacteria, viruses, fungi, protozoans, or helminths
• Pathogens are organisms that cause diseases by harming the host
• Pathogens enter the body, multiply, and interfere with bodily functions, causing morphological and functional damage
• Pathogens adapt to survive in the host's environment

Typhoid

• Salmonella typhi is a bacterium that causes typhoid fever
• Pathogens enter the small intestine via contaminated food and water, then migrate to other organs via the blood
• Symptoms: sustained high fever (39-40°C), weakness, stomach pain, constipation, headache, loss of appetite
• Intestinal perforation and death can result from severe cases
• "Typhoid Mary" spread typhoid for years through the food she prepared as a cook and typhoid carrier

Pneumonia

• Streptococcus pneumoniae and Haemophilus influenzae cause pneumonia
• Affects alveoli, which become filled with fluid, causing respiratory problems
• Symptoms: fever, chills, cough, headache; severe cases can cause bluish lips and fingernails
• Infection spreads through inhaling droplets/aerosols from an infected person or sharing utensils

Common Cold

• Rhino viruses cause the common cold which only affects the nose and respiratory passage, not the lungs
• Symptoms: nasal congestion/discharge, sore throat, hoarseness, cough, headache, tiredness, lasts 3-7 days
• Infection spreads through inhaling droplets from coughs or sneezes of the infected; it can also spread by contaminated objects

Malaria

• Plasmodium, a protozoan, causes malaria
• Different species of Plasmodium (P. vivax, P. malaria, P. falciparum) cause different types of malaria
• P. falciparum causes malignant malaria, which is the most serious and can be fatal
• Plasmodium's life cycle includes humans and mosquitoes
• A sporozoite (infectious form) enters the human body through the bite of an infected female Anopheles mosquito
• Parasites multiply in liver cells, then attack and rupture red blood cells (RBCs)
• Rupture of RBCs releases haemozoin, causing recurring chills and high fever
• Malarial Parasites enter a mosquito body during a mosquito bite; the parasites multiply to form sporozoites that reside in salivary glands
• Female Anopheles mosquito is the vector (transmitting agent).

Amoebiasis (Amoebic Dysentery)

• Entamoeba histolytica is a protozoan parasite in the large intestine causing amoebiasis
• Symptoms include constipation, abdominal pain/cramps, stools with mucus and blood clots
• Houseflies act as mechanical carriers transmitting the parasite from feces to food

Ascariasis

• Caused by Ascaris (roundworm), which is an intestinal parasite
• Symptoms: internal bleeding, muscular pain, fever, anemia, blockage of the intestinal passage
• Infection spreads, as eggs of the parasite are excreted with feces, contaminating soil, water, and plants and then a healthy person contracts it through contaminated resources

Elephantiasis/Filariasis

• Wuchereria (W. bancrofti and W. malayi), filarial worms, cause chronic inflammation of organs, especially lymphatic vessels of lower limbs
• The results are gross deformities
• Transmitted by the bite of female mosquito vectors

Ringworms

• Fungi like Microsporum, Trichophyton and Epidermophyton cause ringworm
• Symptoms: dry, scaly lesions on skin, nails, and scalp with intense itching
• Heat and moisture promote growth, especially in skin folds
• Infection spreads through the soil or by sharing towels, clothes, or combs of infected individuals

Hygiene

• Personal and public hygiene are important for preventing/controlling infectious diseases
• Personal hygiene measures include keeping the body clean
• Public hygiene includes proper waste disposal, disinfection of water resources, and hygiene in public catering
• Precautions especially important in cases of typhoid, amoebiasis, ascariasis, pneumonia, and common cold

Immunity

• Defends against infectious agents
• Overall ability of the host to fight disease-causing organisms
• Two types: innate (present at birth) and acquired (developed)

Innate Immunity

• Non-specific defense with different types of barriers:
• Physical: skin, mucus coating in respiratory/gastrointestinal/urogenital tracts, which prevents the entry of micro organisms
• Physiological: acid in the stomach, saliva, tears prevent microbial growth
• Cellular: leukocytes (PMNL-neutrophils), monocytes, and natural killer cells which phagocytose and destroy microbes
• Cytokine: Interferons (proteins secreted by virus-infected cells) protect non-infected cells from further viral infection

Acquired Immunity

• Pathogen specific and characterized by memory
• Primary response is produced the first time
• It encounters a pathogen and this response is low intensity
• A subsequent encounter elicits a highly intensified secondary response
• It uses B-lymphocytes and T-lymphocytes
• B-lymphocytes produce antibodies (proteins) to fight pathogens in blood
• T-cells help the B cells to produce antibodies
• An antibody molecule has two light and two heavy peptide chains represented as H2L2

Antibodies

• Antibodies such as IgA, IgM, IgE, IgG; produced in the blood
• Response is called humoral immune response
• Cell-mediated immune response (CMI) is mediated by T-lymphocytes
• Transplantation requires tissue and blood group matching
• Patients have to take immunosuppressants
• The body is able to differentiate 'self' and 'nonself.
• The cell-mediated immune response is responsible for graft rejection.

Active and Passive Immunity

• Active immunity develops from encountering antigens (living or dead microbes, proteins), and then producing antibodies
• Active immunity develops fully and is slow
• Microbes are injected deliberately during immunization or get access into the body and then active immunity develops
• Passive immunity is when ready-made antibodies directly protect the body, such as the colostrum (yellowish milk) secreted by the mother
• The foetus also receives some antibodies from their mother through the placenta during pregnancy

Vaccination and Immunisation

• An antigenic Proteins or Inactivated and weakened pathogen (vaccine) are introduced into the body
• Antibodies produced against these antigens would neutralise the pathogenic agents during actual infection.
• The vaccines also generate memory B and T-cells
• In tetanus infections, preformed antibodies or antitoxin (a preparation containing antibodies to the toxin) are directly injected
• Snakebites are given preformed antibodies against venom.
• Recombinant DNA technology allows the production of antigenic polypeptides/vaccines to create greater availability for immunsation

Allergies

• Allergy is an exaggerated immune response to certain antigens (allergens) in the environment that causes symptoms such as sneezing, watery eyes, running nose and difficulty in breathing
• Antibodies are of IgE type such as mites in dust, pollens and animal dander
• Allergy is due to chemicals being released like histamine and serotonin from the mast cells
• The patient who is exposed or injected with very small doses of possible allergens and is reactions studied is used to determine the cause
• The use of drugs like anti-histamine, adrenalin and steroids quickly reduce the symptoms of allergy

Auto Immunity

• Memory-based acquired immunity evolved enables to differentiate between foreign organisms and self-cells which higher vertebrates can do
• Two, is sometimes the body attacks self-cells which Results in autoimmune diseases; e.g., Rheumatoid arthritis
• Experimental immunology tends to focus predominantly on the capacity for higher vertebrates to differentiate foreign molecules and organisms.

Immune System

• The human immune system has lymphoid organs, tissues, cells and soluble molecules like antibodies
• Recognizes foreign antigens, responds to these and remembers them
• Organs where origin and/or maturation and proliferation of lymphocytes occur
• Primary lymphoid organs: bone marrow and thymus; and secondary lymphoid organs: Spleen, lymph nodes, tonsils, Peyer's patches
• Bone marrow: main lymphoid organ where all blood cells including lymphocytes are produced
• Thymus a lobed organ located near the heart where Both bone-marrow and thymus provide micro-environments for the development
• and maturation of T-lymphocytes.
• The spleen mainly contains lymphocytes and phagocytes.
• Lymph nodes serve to trap the micro-organisms or other antigens that are responsible for the activation of lymphocytes

AIDS (Acquired Immuno Deficiency Syndrome)

• AIDS is caused by HIV (Human Immuno deficiency Virus) virus called retrovirus and it is Not a congenital disease
• Transmission generally occurs:
• (i) sexual contact with infected person,
• (ii) transfusion of contaminated blood and blood products,
• (iii) sharing infected needles as in the case of intravenous drug abusers and
• (iv) from infected mother to her child through placenta
• HIV attacks helper T-lymphocytes leading to progressive decrease in T-lymphocytes; sufferers' from infections becomes so immuno-deficient that he/she is unable to protect.

HIV Mechanism

• HIV enters into macrophages where RNA genome replicates to form viral DNA with the help of reverse transcriptase
• The viral DNA gets incorporated into host cell DNA and directs the infected cells to produce virus particles
• Macrophages produce virus and acts like a HIV factory, simultaneously, HIV enters into helper T-lymphocytes (TH), replicates and produces viruses.
• Progeny viruses attack other T-lymphocytes, decreasing number in the body and the person suffers from fever, diarrhea and weight loss

Diagnosis and Prevention of AIDS

• Enzyme linked immuno-sorbent assay (ELISA) is a widely used diagnostic test conducted.
• Treatment with anti-retroviral drugs and has has no cure, then prevention is the best option.
• National AIDS Control Organisation (NACO) and other non-governmental organisation (NGOs) are doing a lot to educate people and Blood (from blood banks) have to be safe from HIV and free distribution of condoms.

Cancer

• Uncontrolled cell growth and differentiation
• Regulator mechanisms break down which lead to Cancer cells
• Cancer cells lose "contact inhibition", which causes normal cells to stop growth when it touches another cell and therefore divides forming masses of cells called tumors.
• Tumors can be benign and malignant based.
• Caused by physical, chemical or biological agents
• Carcinogens are the agents such as ionising radiations, chemical carcinogens and oncogenic viruses

Prevention and Diagnosis of Cancer

• Early detection is essential through biopsy, histopathological studies of the tissue and blood samples, radiography( use of X-rays) and Magnetic resonance imaging( MRI)
• Antibodies against cancer-specific antigens are also used for detection of certain cancers.
• Treated by surgery, radiation therapy and immunotherapy through substances such as a-interferon which activates their immune system and helps in destroying the tumor
• Surveys show drugs are on the increase especially among the youth
• Opioids are the drugs binding to specific opioid receptors
• Heroin (diacetylmorphine) is a white, odourless, bitter crystalline compound and its a depressant

Cannabinoids, Cocaine, and Drug/Alcohol Prevention

• Cannabinoids are a group of chemicals and that used in the plant Cannabis sativa to effect the cardiovascular system of the body - Flower tops, leaves and the resin of cannabis plant are used in various combinations to produce marijuana, hashish, charas and ganja.
• Cocaine or coca is obtained from coca plant interferes with the transport of the neurotransmitter dopamine.
• Adolescence accompanied by several biological and behavioural changes
• Proper education and guidance would safeguard themselves against dangerous behaviour patterns and follow healthy lifestyles
• Addiction is a psychological attachment drive people to take when these are not needed because it provides - euphoria and a temporary feeling of well-being.
• Undue peer pressure, Parents and teachers have a special responsibility and it should be Avoided