What is Pathology and What Does a Pathologist Do?

A pathologist is a medical professional who examines bodies and body tissue. They are also responsible for conducting lab tests. A clinical pathologist is an essential part of medical teams who reach diagnoses for patients. After completing medical school, an individual must also complete three years of advanced medical education in a residency program before they are eligible to take board certification exams. Most pathologists are trained in both anatomical and clinical pathology.

The Role of Blood and Pathology Tests

Blood and pathology tests are essential for detecting, diagnosing, and treating disease. The term, “pathology” means the study of disease as well as causes and progression. There are a variety of pathology tests including blood tests, urine, stool (feces), and body tissue testing. Pathologists interpret the results of blood and pathology tests. They are looking for abnormalities in the samples that may indicate the presence of disease or health risks like cancer, chronic illnesses, or pre-diabetes. 

Why Blood and Pathology Tests Are Ordered

While pathology plays a role in detecting and diagnosing diseases, the tests are also important for other reasons including:

·   Properly treating a disease

·   Monitoring the progression of disease

·   Preventing disease

·   Determining the future risk of disease

·   Aiding research for new treatment options

·   Ensure the safety of treatment and procedures

When a doctor or specialist requests pathology tests it’s usually due to a concern about your health risks. A pathology test is effective for discovering if a problem or concern exists.

Types of Tissue Pathologists Examine

A pathologist is trained to examine tissue samples including samples as small as a dozen cells. Tissue cells may be obtained by aspiration or a needle biopsy. Larger tissue samples are surgically removed.

What do clinical pathologists do?

A clinical pathologist examines blood, urine, and other types of bodily fluids under a microscope. They are watching for the presence of certain chemicals or other substances. Their test results often determine a diagnosis or treatment option. Specimens used in clinical pathology include:

·   Blood Samples are used in many tests and can be checked in a variety of ways whole, plasma (the remaining fluid after red and white blood cells are removed), or serum (the clear fluid that separates from the blood during clotting).

·   Urine Samples are collected in a variety of ways including catheterization, clean catch specimen, or randomly.

·   Sputum Samples or phlegm samples are coughed into a clean container.

·   Stool Samples are often examined for the presence of blood.

·   Other Bodily Fluid Samples may include spinal fluid, pleural fluids, belly fluids, joint fluids, or bone marrow.

Clinical pathologists are often responsible for blood banks at hospitals. Their duties include collecting and processing blood products. They may also look at transfusion reactions or check tissue compatibility for transplants.

Conclusion

Pathology is a medical field that is quickly becoming more specialized. Pathologists provide experience and expertise when it comes to interpreting laboratory test results and evaluating cells, tissue, and organs in order to diagnose disease. A pathologist may determine a specific type of cancer and what stage it is in so that appropriate treatment can be recommended. In a quickly advancing technological age, their work is far from done and their importance continues to become apparent.

https://www.mskcc.org/cancer-care/diagnosis-treatment/diagnosing/role-pathology

https://pathology.uic.edu/understanding-your-pathology-report/

https://www.rcpath.org/discover-pathology/what-is-pathology.html

https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=85&contentid=P00955

https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/Blood-and-pathology-tests

https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/the-pathologist

The Incredible MicroRNA's

What is microRNA?

MicroRNAs (miRNAs) are a group of small non-coding RNAs that are found in tissue samples of animals, plants, and some viruses. Since the discovery of circulating and extracellular miRNAs, there has been a rapid expansion of studies on miRNAs in biofluids like cerebrospinal fluid, plasma, serum, and urine. miRNAs are similar to small interfering RNAs (siRNAs). However, miRNAs originate from RNA transcripts forming short hairpins while siRNAs are from longer parts of double-stranded RNA. miRNAs are plentiful in mammalian cells and seem to target approximately 60% of these genes. miRNAs are thought to have important biological functions as they are evolutionary conserved. A good example is where there is conservation of 90 families of miRNAs as seen in the common ancestor of fish and mammals. The majority of these conserved miRNAs have been shown to play important roles.

Roles of miRNA

miRNA plays a role in RNA silencing and gene expression as post-transcriptional regulators. Within mRNAs, miRNAs function by base-pairing with the complementary molecules causing mRNA molecules to be silenced through cleavage of mRNA strand, destabilization of mRNA, or reduced efficiency of mRNA translation by ribosomes. Despite the low numbers of miRNA, it is estimated that the miRNAs regulate approximately more than 33% of the cellular transcriptome. Therefore, it should be no surprise that the miRNAs have crucial functions in the developmental and cellular processes that have been thought to be involved in many human diseases.

Since miRNAs are relatively stable in biofluids and have a wide range of biological potential, these molecules are suited to be used as non-invasive biomarkers in diagnosis, drug safety, and pre-clinical toxicity. Many studies have proven that secreted miRNAs are involved in conditions such as organ damage, cancers, and coronary heart disease. While the exact role of circulating miRNAs is mostly unknown, they have been observed to be protected from RNAse degradation through the inclusion in membranous particles or protein complexes.

Disease

Since miRNA plays a role in the normal functioning of eukaryotic cells, miRNA dysregulation is therefore linked to disease. For example:

a)       Hereditary Diseases

• It has been found that a mutation in the region of miR-96 results in progressive hearing loss.

• Hereditary keratoconus with anterior polar cataract is seen in mutation in the region of miR-184.

• Growth and skeletal defects can be seen in those with deletion of miR-17 to 92 cluster.

b)      Cancer

• Chronic lymphocytic leukemia was one of the first human diseases that has been associated with miRNA dysregulation. Other miRNAs that have also been linked to cancer are called “oncomirs”. miRNAs are involved in pathways that are crucial in B-cell development such as B-cell receptor signaling, cell-cell interaction, B-cell migration or adhesion, and production or class-switching of immunoglobulins. They also influence the generation of marginal zone, follicular, plasma, B1, and memory B cells.

• Another clinical trial is using miRNA as a screening assay for the detection of colorectal cancer in the early stages.

• miRNAs can also be used to determine prognosis in cancers based on their expression level. For example, a study on non-small-cell lung carcinoma determined that a low level of miR-324a levels is an indication of poor prognosis. In colorectal cancer, a low level of miR-133b and high level of miR-185 is linked with metastasis resulting in poor prognosis.

c)       Heart Disease

• Studies have found that there are specific changes in the expression levels of miRNAs in diseased hearts which points to the involvement of miRNAs in cardiomyopathies.

• miRNAs can also be used to determine the prognosis and risk stratification of cardiovascular diseases.

• In animal models, miRNAs have been associated with the regulation and metabolism of cholesterol.

d)      Nervous System

• miRNAs are thought to be involved in the function and development of the nervous system.

• Neural miRNAs such as miR-124, miR-132 and miR-134 are involved in dendritogenesis.

• Other neural miRNAs are involved in the formation of the synapses. miR-134 and miR-138 are thought to be included in the process of synapse maturation.

• Studies have found that conditions such as bipolar disorder, schizophrenia, anxiety disorders, and major depression have altered miRNA expression.

e)      Obesity

• miRNAs have a vital role in the differentiation of stem cell progenitors into adipocytes. Studies have found that the expression of miRNAs 155, 221, and 222 can inhibit adipogenesis paving a possible genetic treatment for obesity.

• miRNAs of the let-7 family was found to accumulate in tissues as aging occurs. Based on animal models, the excessive expression of let-7 class miRNAs resulted in accelerated aging, insulin resistance, and therefore increases the risk of obesity and diabetes. When let-7 was inhibited, it resulted in an increase in insulin sensitivity and resistance to high-fat-diet-induced obesity. This means the inhibition of let-7 may prevent, reverse, and cure obesity and diabetes.

Conclusion

Although miRNAs have great promise in the screening, diagnosis, treatment, and prevention of various pathological conditions, more research, and clinical trials will be needed in the study of miRNAs to further explore and discover the potential of miRNAs.

References:

1. microRNA. Wikipedia. Accessed 8/22/2018. https://en.wikipedia.org/wiki/MicroRNA#Disease

2. Blondal T, Nielsen SJ, Baker A, et al. Assessing sample and miRNA profile quality in serum and plasma or other biofluids. Methods. 2013; 59(1): S1-S6.