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HEALTH AND DISEASES. Mrs. SHEEJA M.P PGT Biology KV PORT TRUST. AIDS. AIDS stands for Acquired Immuno Deficiency Syndrome. Acquired means you can get infected with it;
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HEALTH AND DISEASES Mrs. SHEEJA M.P PGT Biology KV PORT TRUST.
AIDS AIDS stands for Acquired Immuno Deficiency Syndrome. • Acquired means you can get infected with it; • Immune Deficiency means a weakness in the body's system that fights diseases. • Syndrome means a group of health problems that make up a disease.
Causal Organism • AIDS is caused by a virus called HIV, the Human Immunodeficiency Virus . • The Human Immunodeficiency Virus (HIV) is not spread easily. You can only get HIV if you get infected blood or sexual fluids into your system. You can't get it from mosquito bites, coughing or sneezing, sharing household item .
To infect someone, the virus has to get past the body's defenses. These include skin and saliva. If your skin is not broken or cut, it protects you against infection from blood or sexual fluids. Saliva contains chemicals that can help kill HIV in your mouth. • If HIV-infected blood or sexual fluid gets inside your body, you can get infected. This can happen through an open sore or wound, during sexual activity, or if you share equipment to inject drugs
Transmission • One can get infected with HIV from anyone who's infected, even if they don't look sick and even if they haven't tested HIV-positive yet. The blood, vaginal fluid, semen, and breast milk of people infected with HIV has enough of the virus in it to infect other people. Most people get the HIV virus by: • having sex with an infected person . • sharing a needle (shooting drugs) with someone who's infected . • being born when their mother is infected, or drinking the breast milk of an infected woman .
Symptoms • The symptoms of HIV infection include fever, headache, sore muscles and joints, stomach ache , flu, swollen lymph glands, or a skin rash for one or two weeks. Some people may have no symptoms.
The virus will multiply in your body for a few weeks or even months before your immune system responds. During this time, you won't test positive for HIV, but you can infect other people. Being HIV-positive, or having HIV disease, is not the same as having AIDS. • Many people are HIV-positive but don't get sick for many years. As HIV disease continues, it slowly wears down the immune system. Viruses, parasites, fungi and bacteria that usually don't cause any problems can make you very sick if your immune system is damaged. These are called "opportunistic infections
Structure Of HIV • HIV-1 is composed of two copies of single-stranded RNA enclosed by a conical capsid comprising the viral protein p24, typical of lentiviruses (Figure 1). The RNA component is 9749 nucleotides long[5]. This is in turn surrounded by a plasma membrane of host-cell origin. The single-strand RNA is tightly bound to the nucleocapsid proteins, p7 and enzymes that are indispensable for the development of the virion, such as reverse transcriptase and integrase.
The nucleocapsid (p7 and p6) associates with the genomic RNA (one molecule per hexamer) and protects the RNA from digestion by nucleases. A matrix composed of an association of the viral protein p17 surrounds the capsid, ensuring the integrity of the virion particle. Also enclosed within the virion particle are Vif, Vpr, Nef, p7 and viral protease (Figure 1). The envelope is formed when the capsid buds from the host cell, taking some of the host-cell membrane with it. The envelope includes the glycoproteins gp120 and gp41 .
Life cycle of HIV • HIV enters the body and binds to dendritic cells (orange cells with projections) which carry the virus to CD4+ T cells in lymphoid tissue establishing the infection. Virus replication accelerates producing massive viremia and wide dissemination of virus throughout the body's lymphoid tissues. • An immune response against virus causes some protection but a chronic persistent infection is established. The production of cytokines and cell divisions that regulate the immune response for protection also cause HIV replication.
There is a rapid turnover of CD4+ T cells that ultimately leads to their destruction and to a cHIV is stopped by innate defenses. HIV cannot penetrate unbroken skin. HIV is transmitted through direct exchange of body fluids. • Sexual intercourse is the most common mode of transmission. Blood to blood contact, such as through sharing needles for intravenous injection or blood transfusion can also transmit HIV. Infected mothers can pass HIV to their infants during pregnancy, birth and breastfeedinghange in lymphoid tissues that prevent immune responses.
HIV Tests • A human immunodeficiency virus (HIV) test detects antibodies to HIV in the blood. This determines whether an HIV infection is present (HIV-positive). HIV infects white blood cells called CD4+ cells, which are part of the body's immune system that help fight infections . • After the original infection, it takes between 2 weeks and 6 months for antibodies to HIV to appear in the blood. The period between becoming infected with HIV and the point at which antibodies to HIV can be detected in the blood is called the seroconversion or "window" period
Enzyme Linked Immuno-sorbent Assay (ELISA test):This test is usually the first one used to detect infection with HIV. If antibodies to HIV are present (positive), the test is usually repeated to confirm the diagnosis. If ELISA is negative, other tests are not usually needed. This test has a low chance of having a false result after the first few weeks that a person is infected. • Western blot. :This test is more difficult than the ELISA to perform, but it is done to confirm the results of two positive ELISA tests. • Polymerase chain reaction (PCR). This test finds either the genetic material RNA of HIV.
The PCR test is very useful to find a very recent infection, determine if an HIV infection is present when antibody test results were uncertain, and screen blood or organs for HIV before donation. • Indirect fluorescent antibody (IFA). This test detects HIV antibodies. Like a Western blot test, it is used to confirm the results of an ELISA. However, it is more expensive than a Western blot test and not commonly used.
PREVENTION OF AIDS • ABC of AIDS prevention • A bstinence for youth, including the delay of sexual debut and abstinence until marriage • B eing tested for HIV and being faithful in marriage and monogamous relationships • C orrect and consistent use of condoms for those who practice high-risk behaviours.
An abstinence-based approach to sex education focuses on teaching young people that abstaining from sex until marriage is the best means of ensuring that they avoid infection with HIV, other sexually transmitted infections and unintended pregnancy. As well as seeing abstinence from sex as the best option for maintaining sexual health, many supporters of abstinence-based approaches to sex education also believe that it is morally wrong for people to have sex before they are married.
THERE is no vaccine to cure AIDS , but can be used to slow down infection of HIV. • 1. Nonnucleoside Reverse Transcriptase Inhibitors (NNRTIs) • 2. Nucleoside Reverse Transcriptase Inhibitors (NRTIs) • 3. Protease Inhibitors (PIs) • 4. Fusion Inhibitors
CANCER • Cancer (medical term: malignantneoplasm) is a class of diseases in which a group of cells display uncontrolled growth (division beyond the normal limits), invasion (intrusion on and destruction of adjacent tissues), and sometimes metastasis (spread to other locations in the body via lymph or blood).
Most cancers form a tumor but some, like leukemia, do not. • The branch of medicine concerned with the study, diagnosis, treatment, and prevention of cancer is oncology. • Cancer may affect people at all ages, even fetuses, but the risk for most varieties increases with age.Cancer causes about 13% of all deaths. • According to the American Cancer Society, 7.6 million people died from cancer in the world during 2007. Cancers can affect all animals .
Tumors are of 2 types • 1) Benign Tumors – Remain confined to their original location and do not spread to other parts of the body • 2) Malignant Tumors - are mass of proliferating cells which grow very rapidly and damage surrounding normal tissues. • Malignant Tumors show property of metastasis (spread to other locations in the body via lymph or blood).
Causes of Cancer • Nearly all cancers are caused by abnormalities in the genetic material of the transformed cells. • These abnormalities may be due to the effects of carcinogens, such as tobacco smoke, radiation, chemicals, or infectious agents. • Other cancer-promoting genetic abnormalities may be randomly acquired through errors in DNA replication, or are inherited, and thus present in all cells from birth. • The heritability of cancers are usually affected by complex interactions between carcinogens and the host's genome. • New aspects of the genetics of cancer pathogenesis, such as DNA methylation, and microRNAs are increasingly recognized as important.
Chemical carcinogens. • Ionizing radiation. • Infectious diseases. • Hormonal imbalances. • Immune system disfunction. • Oncogenes. • Heredity.
Genetic abnormalities found in cancer typically affect two general classes of genes. • Cancer-promoting oncogenes are typically activated in cancer cells, giving those cells new properties, such as hyperactive growth and division, protection against programmed cell death, loss of respect for normal tissue boundaries, and the ability to become established in diverse tissue environments. • Tumor suppressor genes are then inactivated in cancer cells, resulting in the loss of normal functions in those cells, such as accurate DNA replication, control over the cell cycle, orientation and adhesion within tissues, and interaction with protective cells of the immune system.
Symptoms of Cancer • Persistent cough or blood-tinged saliva. • Continuous diarrohea . • Frequent anemia. • Breast lump or breast discharge . • Indigestion or difficulty swallowing . • Persistent lumps or swollen glands . • Hoarseness . • Hematuria
Cancer Detection And Diagnosis • Diagnosis usually requires the histologic examination of a tissue biopsy specimen by a pathologist, although the initial indication of malignancy can be symptoms or radiographic imaging abnormalities. • Most cancers can be treated and some cured, depending on the specific type, location, and stage. Once diagnosed, cancer is usually treated with a combination of surgery, chemotherapy and radiotherapy. • There has been significant progress in the development of targeted therapy drugs that act specifically on detectable molecular abnormalities in certain tumors, and which minimize damage to normal cells.
Treatment Of Cancer • Cancer can be treated by surgery, chemotherapy, radiation therapy, immunotherapy, monoclonal antibody therapy or other methods. • The choice of therapy depends upon the location and grade of the tumor and the stage of the disease, as well as the general state of the patient (performance status). A number of experimental cancer treatments are also under development.
SURGERY • In theory, non-hematological cancers can be cured if entirely removed by surgery, but this is not always possible. When the cancer has metastasized to other sites in the body prior to surgery, complete surgical excision is usually impossible . • Examples of surgical procedures for cancer include mastectomy for breast cancer and prostatectomy for prostate cancer.
RADIATION THERAPY • Radiation therapy (also called radiotherapy, X-ray therapy, or irradiation) is the use of ionizing radiation to kill cancer cells and shrink tumors. • Radiation therapy can be administered externally via external beam radiotherapy (EBRT) or internally via brachytherapy. The effects of radiation therapy are localised and confined to the region being treated. • Radiation therapy injures or destroys cells in the area being treated (the "target tissue") by damaging their genetic material, making it impossible for these cells to continue to grow and divide.
Radiation therapy may be used to treat almost every type of solid tumor, including cancers of the brain, breast, cervix, larynx, lung, pancreas, prostate, skin, stomach, uterus, or soft tissue sarcomas. • Radiation is also used to treat leukemia and lymphoma. • Radiation dose to each site depends on a number of factors, including the radiosensitivity of each cancer type and whether there are tissues and organs nearby that may be damaged by radiation.
CANCER IMMUNOTHERAPY • Cancer immunotherapy refers to a diverse set of therapeutic strategies designed to induce the patient's own immune system to fight the tumor. • Contemporary methods for generating an immune response against tumours include intravesical BCG immunotherapy for superficial bladder cancer, and use of interferons and other cytokines to induce an immune response in renal cell carcinoma and melanoma patients • Vaccines to generate specific immune responses are the subject of intensive research for a number of tumours, notably malignant melanoma and renal cell carcinoma .
HORMONAL THERAPY • The growth of some cancers can be inhibited by providing or blocking certain hormones. Common examples of hormone-sensitive tumors include certain types of breast and prostate cancers. Removing or blocking estrogen or testosterone is often an important additional treatment. In certain cancers, administration of hormone agonists, such as progestogens may be therapeutically beneficial.
CHEMOTHERAPY • Chemotherapy is the treatment of cancer with drugs ("anticancer drugs") that can destroy cancer cells. • Chemotherapy drugs interfere with cell division in various possible ways, e.g. with the duplication of DNA or the separation of newly formed chromosomes. Most forms of chemotherapy target all rapidly dividing cells and are not specific for cancer cells . • The treatment of some leukaemias and lymphomas requires the use of high-dose chemotherapy, and total body irradiation
