Vaccinations

Inoculation, or vaccination, is a critical method in preventing disease. Vaccination dates back to 1000 CE where the Chinese utilized smallpox inoculation to prevent a future occurrence of the disease (History of Vaccines, 2017). A well-known use of vaccination was performed in 1796 where Edward Jenner inoculated a 13 year- old boy with cowpox to prevent the acquisition of smallpox (History of Vaccines, 2017). Since Jenner’s 18th centenary discovery, vaccination has been a critical method in the prevention of disease.

Vaccines create immunity to a disease by acting on the basic characteristics of immunity. The foundation of immunity to disease is the immune system, which consists of complementary organs, tissues, and cells that function in the body’s defense against pathogens. The immune system consists of two major components known as innate (non- specific) and adaptive (specific) immunity. These two components make up the three lines of defense that the body has against pathogens, which is described in the following image:

Screen Shot 2018-10-11 at 6.21.50 PM

Figure Taken from Kuby, Immunology 6th edition

       The first line of defense consists of mechanical, physical, and chemical defenses that are used to deter pathogens, such as saliva or the body’s acid mantel. The second line of defense consists of the complement system, fever, inflammation, and phagocytic cells. Inflammation and fever serve to deter pathogenesis and enhance the body’s immune response while the complement system and phagocytic cells serve to kill pathogens or infected cells.  Finally, the third line of defense is part of the adaptive immune response and is the mechanism in which vaccines function to stimulate to create pathogenic immunity. The third line of defense can be divided into two sub- categories, which are the humoral and cell- mediated responses. In the humoral response, B- cells recognize pathogens and release antibodies. The five major functions of antibodies are the following; Agglutination, or confinement of pathogens; Optimization, or enhancing phagocytosis via the coating of pathogens by antibodies; Neutralization, or blocking the receptors on toxins or pathogens; Complement activation, which yields cell lysis and inflammation; Antibody- dependent cell- mediated cytotoxicity, which causes destruction of target cells by natural killer cells and eosinophils.

In cell mediated, cytotoxic T- cells kill infected cells by direct cell- to- cell contact and T- helper cells aid in the activation of the humoral response and enhance other immune responses. During infection by a pathogen, B- cells differentiate into memory B- cells and plasma cells. Memory cells are B- cells that are specific for the pathogen that had initiated the primary infection and can secrete antibodies against that pathogen. Thereby, memory B- cells leads to a quicker and stronger response to a secondary infection of the same pathogen. Vaccines function by activating humoral and/or cell- mediated immunity.

Vaccines can be live- attenuated, inactivated, subunit, recombinant, conjugate, DNA, or toxoid. Each of these types of vaccines have attributes that should be considered prior to vaccination. For instance, live- attenuated vaccines may not be able to be given to immunocompromised individuals, as the vaccine most closely replicates a true infection. Also, there is a possibility for the pathogen to become reverted and infect the individual. Nonetheless, vaccines serve as an important mechanism to prevent disease. Vaccines can stimulate humoral and/or cell- mediated responses resulting in the production of memory cells. The memory cells are specific for the antigen that the vaccine contains. For example, the combination vaccine known as MMR contains antigens that replicate measles, mumps, and rubella. Thereby, although the vaccine does not contain pathogens that can cause disease, the vaccine can yield the production of memory B- cells and antibodies against an infectious measles, mumps, or rubella pathogen.

– Ron

Works Cited

  1. “All Timeline Overview.” Timeline | History of Vaccines, The College of Physicians of Philadelphia, 2017, http://www.historyofvaccines.org/timeline.
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Hemoglobin A1C and Diabetes

Diabetes mellitus is a metabolic disorder which is characterized by an elevated blood sugar level over a prolonged period of time. Type 1 diabetes is often referred to as juvenile diabetes or insulin-dependent diabetes mellitus. There is loss of the insulin producing cells in the pancreatic islets called the beta cells. This leads to insulin deficiency. The cause is most often idiopathic or sometimes is immune-mediated where the T-cells lead an autoimmune attack on the beta cells. Type 1 diabetes is often times inherited and occurs mostly in children which is why it is sometimes referred to juvenile diabetes.

Type 2 diabetes mellitus is characterized by insulin resistance, which sometimes can be coupled by decreased synthesis of insulin. There is a defective response to insulin by the bodies different cells. Often a problem with the insulin receptors of these cells. Type 2 diabetes is a life-style problem and some genetic variability. Physical stress, poor diet, stress and excessive BMI are correlated with type 2 DM. In the early stages of type 2 DM it is manageable and the high blood sugar can be reversed by medications and be controlled. As it progresses it may come with complications similar to type 1 DM and treatment may need to be changed and monitored.

Hemoglobin is a protein found in the red blood cells in the body. For an in depth look at what hemoglobin is exactly take a look at the previous article written, titled “Hemoglobin”. Hemoglobin A1C, which is going to be talked about today refers to the glycolated hemoglobin within the body. Glycolated hemoglobin refers to glucose that is bound to the hemoglobin in the red cells.

Hemoglobin A1C is used to monitor diabetes and can tell doctors whether the dose of insulin is sufficient enough to bring the patients glucose to a healthy level and it can also diagnose diabetes. It gives a snapshot of glucose control over a period of 3-4 months. What happens with diabetes is that  glucose builds up in the blood. When too much glucose is present it begins binding to the hemoglobin within the red cells. This is called glycolated hemoglobin. It gives a fairly accurate analysis of glucose control over a period of 3-4 months because red cells live for 120 days.

a1c-in-relation-to-blood-glucose

The test is measured as a percentage. The percentage is pertaining to how much hemoglobin is saturated with glucose. The reference range is 4-5.6% although levels between 5.7% and 6.4% raise the risk of developing diabetes. A acceptable range for everyone is different when they have diabetes, but typically the individuals physician will work to keep the A1C level below 7%.  Its standard practice to order the hemoglobin A1C test every 3 months as a good way to monitor therapy and change doses, brands, etc. if needed. As the A1C levels rise or remain high it means that either the patient is non-compliant to their treatment regimen or that the treatment itself is not working and puts the patient at a higher risk of diabetic complications. Such complications include eye disease, heart disease, kidney disease, nerve damage and strokes.

Its important as a physician to recognize that certain conditions can alter the results of the test. Chronic anemias, kidney disease or specific blood disorders such as thalassemia can affect the results of the test and must be taken into consideration when using the A1C test to guide treatment.

-Caleb

What Is Medical Laboratory Science?

According to the American Society for Clinical Laboratory Science (ASCLS) medical scientists are vital in healthcare, uncovering and providing important laboratory analyses that assist physicians in patient diagnosis and treatment. Scientists have a role in monitoring disease progression and treatment monitoring as well.

Laboratory scientists utilize technologically advanced biomedical instrumentation and computers to perform laboratory testing across a wide range of disciplines. Such disciplines include clinical chemistry, hematology, immunology, immunohematology, microbiology and molecular biology.

Without clinical laboratory scientists Physicians would not be able to see patients, they would not be able to test them or treat them. A hospital really runs on the expertise of its laboratory professionals. The behind the scenes work done by the lab professionals is just as important as the patient interaction done by other healthcare professionals.