ABOUT MEDICINE

What Is Medicine?

Medicine has two basic meanings, it refers to 1. The Science of Healing; the practice of the diagnosis, treatment and prevention of disease, and the promotion of health. 2. Medications, drugs, substances used to treat and cure diseases, and to promote health. This collection of articles focuses on the science of healing, its history from prehistoric times until today, and the medications and healing methods used. 

Some people might call medicine a regulated patient-focused health profession which is devoted to the health and well-being of patients.
Modern medicine includes many fields of science and practice, including:

• Clinical practice - the physician assesses the patient personally; the aim being to diagnose, treat, and prevent disease using his/her training and clinical judgment.
• Healthcare science - a multidisciplinary field which deals with the application of science, technology, engineering (mathematics) for the delivery of care. A healthcare scientist is involved with the delivery of diagnosis, treatment, care and support of patients in systems of healthcare, as opposed to people in academic research. A healthcare scientist actively combines the organizational, psychosocial, biomedical, and societal aspects of health, disease and healthcare
• Biomedical research - a broad area of science that seeks ways to prevent and treat diseases that make people and/or animals ill or causes death. It includes several areas of both physical and life sciences. Biomedical scientists use biotechnology techniques to study biological processes and diseases; their ultimate objective is to develop successful treatments and cures. Biomedical research requires careful experimentation, development and evaluations involving many scientists, including biologists, chemists, doctors, pharmacologist, and others. It is an evolutionary process.
• Medications - drugs or medicines and their administration. Medications are chemical substances meant for use in medical diagnosis, treatment, cure, or prevention of disease.
• Surgery - a branch of medicine that focuses on diagnosing and treating disease, deformity and injury by instrumental and manual means. This may involve a surgical procedure, such as one that involves removing or replacing diseased tissue or organs. Surgery usually takes place in a laboratory, operating room (theater), a dental clinic, or a veterinary clinic/practice.
• Medical devices - instruments, implants, in vitro reagents, apparatuses, or other similar articles which help in the diagnosis of diseases and other conditions. Medical devices are also used to cure disease, mitigate harm or symptoms, to treat illness or conditions, and to prevent diseases. They may also be used to affect the structure or function of parts of the body. Unlike medications, medical devices achieve their principal purpose (action) by mechanical, thermal, physical, physic-chemical, or chemical means. Medical devices range from simple medical thermometers to enormous, sophisticated and expensive image scanning machines.
• The History of Medicine - humans have been practicing medicine in one way or another for over a million years. In order to understand how modern medicine got to where it is now, it is important to read about the history of medicine. In this series of articles, you can read about:

Immunodeficiencies(AIDS)

Immunodeficiencies can be divided into the primary immunodeficiency disorders, which are almost always genetically determined, and secondary immunodeficiency states, which may arise as complications of cancers, infections, malnutrition, or side effects of immunosuppression, irradiation, or chemotherapy for cancer and other diseases. The primary immunodeficiency syndromes are accidents of nature that provide valuable insights into some of the critical molecules of the human immune system. Here we briefly discuss the more important primary immunodeficiencies, to be followed by a more detailed description of acquired immunodeficiency syndrome (AIDS), the most devastating example of secondary immunodeficiency.
Morphology. The anatomic changes in the tissues (with the exception of lesions in the brain) are neither specific nor diagnostic. In general, the pathologic features of AIDS include those of widespread opportunistic infections, KS, and lymphoid tumors. Most of these lesions are discussed elsewhere, because they also occur in individuals who do not have HIV infection. Lesions in the central nervous system are described in Chapter 28 .
Biopsy specimens from enlarged lymph nodes in the early stages of HIV infection reveal a marked follicular hyperplasia. The mantle zones that surround the follicles are attenuated, and hence the germinal centers seem to merge with the interfollicular area. These changes, affecting primarily the B-cell areas of the node, are the morphologic reflections of the polyclonal B-cell activation and hypergammaglobulinemia seen in patients with AIDS. Under the electron microscope and by in situ hybridization, HIV particles can be detected within the germinal centers. Here they seem to be concentrated on the processes of follicular dendritic cells, presumably trapped in the form of immune complexes. During the early phase of HIV infection, viral DNA can be found within the nuclei of CD4+ T cells located predominantly in the parafollicular regions. The B cell hyperplasia is also reflected in the bone marrow, which typically contains increased numbers of plasma cells, and in peripheral blood smears, which often demonstrate rouleaux, the abnormal stacking of red cells that results from hypergammaglobulinemia. With disease progression, the frenzy of B-cell proliferation subsides and gives way to a pattern of severe follicular involution. The follicles are depleted of cells, and the organized network of follicular dendritic cells is disrupted. The germinal centers may even become hyalinized. During this advanced stage viral burden in the nodes is reduced, in part because of the disruption of the follicular dendritic cells. These “burnt-out” lymph nodes are atrophic and small and may harbor numerous opportunistic pathogens. Because of profound immunosuppression, the inflammatory response to infections both in the lymph nodes and at extranodal sites may be sparse or atypical. For example, mycobacteria may not evoke granuloma formation because CD4+ cells are deficient. In the empty-looking lymph nodes and in other organs, the presence of infectious agents may not be readily apparent without special stains. As might be expected, lymphoid depletion is not confined to the nodes; in later stages of AIDS, the spleen and thymus also appear to be “wastelands.”

Tuberculosis

Tuberculosis:


•One person is infected with Tuberculosis (TB) 

every second.

•

•There are an estimated 4,400 deaths per 

day caused by TB.

•

•It is estimated that 2 million deaths resulted 

from TB in 2012.

•One-third of the world’s population, or 

approximately

  

2 billion people, is currently infected with TB.

•

•5-10% of the people infected with TB will 

develop the active stage of the disease 

becoming infectious during their life.

•Left untreated, each person with active TB 

will infect on average between 10 and 15 

individuals every year

Morphology of Mycobacteria.

•slender,

•curved,

•nonmotile,

•nonsporing rods

•often are beaded or banded, coccoid or 

filamentous.

•They may produce L-forms.

•

•They are acid fast and

resistant to acids, alkalis,

and dehydration.

Sites of infection

•Lungs – primary site, > 80% of infections

•CNS

•Lymphatic system

•Genitourinary tract

•Gastrointestinal tract

•Bones and joints

•Disseminated (milliary TB)

Diagnosis

•Clinical specimens: sputum, bronchial or gastric washings, pleural fluid, urine, or cerebrospinal fluid.

1. Microscopy: detection of acid-fast bacilli via the Ziehl-Neelsen method.

2. Bacteriological method.

–M. tuberculosis can be differentiated from most other mycobacteria by the production of niacin.

3. PCR.

4. Tuberculin skin test.

Treatment

•First line: isoniazid, rifampin, pyrazinamide, ethambutol, streptomycin (injectables only)

•Second line : cycloserine, kanamycin, capreomycin, rifabutin, fluoroquinolones (levofloxacin), viomycin, clarithromycin,

  azithromycin

HUMAN HERPERVIRUSES

Human Herperviruses:

•Subfamily Alphaherpesvirinae

Herpes simplex virus 1 (HSV-1)

Herpes simplex virus 2 (HSV-2)

Varicella-zoster virus (VZV=HHV-3)

•Subfamily Betaherpesvirinae

Cytomegalovirus (CMV=HHV-5)

Human herpes viruses 6,

  7 (HHV-6, HHV-7)

•Subfamily Gammaherpesvirinae

Epstein-Barr virus (EBV=HHV-4)

Human herpes virus 8 (HHV-8).

Gamma herpesviruses:

•Infection specific to T or B lymphocytes;

•Latent in lymphoid tissue, lymphocytes, salivary glands, epithelial cells of mouth and pharynx.

•Proliferation of B-lymphocytes.

  EBV

  HHV 8

•Transmission:

  - Contact of infected lesions;

  - HSV 1 = oral-oral; oral-genital;

  - HSV 2 = primarily genital-genital.

•Local multiplication:

  - Mucous membranes;

  - No systemic illness.

•Virus spread along neurons.

•Latent infection – sensory cranio-spinal ganglia