Hyperthyroidism

        The hormones required for the body’s functions such as growth, reproduction, metabolism, homeostasis, some immunological functions, etc. are produced by endocrine glands which constitute the endocrine system. The endocrine system regulates all body processes by releasing necessary hormones. If this system fails to function or doesn’t perform rightly, it causes endocrine disorders. 

The hormone imbalance (too high amount of hormones or very little amount of hormones) can lead to disorders. Examples are acromegaly, diabetes mellitus, pituitary disorders, thyroid disorders (hypo & hyperthyroidism), etc.

Let us learn about one of the examples of hyperthyroidism.

What is Hyperthyroidism?

It is a condition in which the thyroid glands release an excess amount of thyroid hormones {triiodothyronine(T3) and thyroxine(T4)} than the body requires. This happens when the thyroid glands are overactive. Females are more prone to this disorder compared to males.

What are the causes?

    1. Inflammation of thyroid gland – thyroiditis

    2. Thyroid nodules

    3. Grave’s disease, an autoimmune disease

    4. Intake of excess iodine

    5. Some medications

Symptoms

    1. Weight loss 

    2. Increased appetite

    3. Rapid heartbeat

    4. Recurrent bowel movement

    5. Fatigue

    6. Nervousness

    7. Problems in sleeping

    8. Swelling in the neck (Goiter – enlarged thyroid glands)

    9. Uncontrolled sweating

    10.  Changes in vision

    11.  Muscle Weakness

Diagnosis

• Blood test - The levels of thyroid stimulating hormone (TSH), T3 and T4 in blood are checked. This is called thyroid functioning test. The low levels of TSH and high levels of T3 and T4 indicate the disorder.
• Thyroid scan and ultrasound - To check for the lumps present in the thyroid gland

Treatment

• Antithyroid medications – Methimazole (inhibit the overproduction of thyroid               hormones)
•  Beta-blockers – To reduce the symptoms of the hyperthyroidism
•  Radioactive iodine – Radiotherapy method to demolish the cells in the thyroid gland 
•  Surgery – Removal of thyroid gland

References

• Written By Healthgrades Editorial Staff Updated on May 27. (2022, May 29). Endocrine disorders: Types, causes, treatments. Healthgrades. Retrieved January 15, 2023, from https://www.healthgrades.com/right-care/endocrinology-and-metabolism/endocrine-disorders

• NHS website. (2021a, November 18). Overactive thyroid (hyperthyroidism). nhs.uk. https://www.nhs.uk/conditions/overactive-thyroid-hyperthyroidism

Central Dogma

Hi Everyone, 

        What is the term Central Dogma? The process of conversion of DNA into RNA and then into functional protein is known as central dogma. In simple terms, the flow of information in the DNA into a functional protein. This term was introduced by Francis Crick in 1958. This involves,

1. Replication - Making new DNA from the existing one.

2. Transcription - Conversion of DNA to RNA.

3. Translation - Conversation of RNA to proteins. 

    Our DNA carries all information needed to produce the required proteins. During transcription, the information in the DNA is converted to small RNA messages. These messages are converted to specific proteins in ribosomes during translation. The process of transcription and translation together is called gene expression.

Note:

    Although central dogma explains how genetic information flows, there are some deviations in this concept. An example is non-coding RNA (ncRNA). This transcribed RNA doesn't convert into proteins. The role of ncRNA is being studied. 

Let us study more about non-coding RNA in our next blog.

Thank you!

Reference:

• What is the ‘Central Dogma’? (n.d.). @Yourgenome · Science Website. https://www.yourgenome.org/facts/what-is-the-central-dogma/

Antigens and Antibodies

Hi Everyone, 

        Let us continue our learning process. In this blog, we are going to learn about antigens and antibodies. We have already learned about pathogens.

 

        Well, pathogens are the infectious foreign microbes that cause diseases. The immune system persistently checks for foreign molecules. Once the foreign pathogens attack, the immune response is developed by white blood cells.  These white blood cells can differentiate their own cells and foreign cells by surface molecules. Foreign molecules that activate immune responses are called antigens. The surface of pathogens has different antigens which have different shapes. Moreover, different pathogens have different antigens. 

        White blood cells specifically B-lymphocytes produce antibodies when antigens attack the human body. Antibodies are Y-shaped protein molecules that recognizes specific antigens and bind with them in lock and key manner. These B-lymphocytes eliminate antigens and halt the infection.

Important points:

1. Since the antigens have different shapes, antibodies produced against one particular pathogen won't able to attack other pathogens.

2. Vaccine shots produce immunity by producing Antibodies against a particular pathogens.

Thank you!

References:

• What’s the Difference Between Antigens and Antibodies? (2021, March 4). Healthline. https://www.healthline.com/health/infection/antigen-vs-antibody

Pathogens

Here comes a brief elucidation about pathogens!

        Pathogens are the foreign infectious microbes that make you sick or cause disease. These are microscopic disease-causing agents from outside of our body which can spread from one person to another. Types of pathogens are,

• Virus
• Bacteria
• Parasite
• Fungi

But some of the above are harmless. Examples for beneficial bacteria are soil decomposers and bacteria in digestive system. Pathogens enter our body through nose, ear, mouth, eyes, any cut and any other openings to the body. Pathogens disrupt the normal functioning by using human body as host to replicate and infect others. Our immune system is designed to attack and abolish them. 

Some diseases caused by the pathogens are

• Viral diseases - flu, common cold, hepatitis, AIDS
• Bacterial diseases - Salmonella food poisoning, Strep throat, Tuberculosis
• Fungal diseases - Fungal nail infection, vaginal infections
• Diseases caused by parasites - malaria, intestinal worms

Thank you!

Enzymes

        Enzymes are the biological catalysts (also called biocatalysts) which accelerate the biological processes in living organisms. Enzyme lowers the activation energy of the reaction, hence speed up the reaction. Enzymes are must for the systematic functioning of biological processes such digestion, respiration, muscle activities, nerve function, excretion and few other metabolic activites. 

Enzymes are proteins which made up of one or more aminoacids. They react with the molecule called substrate and convert the substrate into products. Also, enzymes are highly specific in nature. 

Some examples of enzymes in human body are,

• Lactase - converts lactose into glucose and galactose
• Maltase - breaks down maltose into glucose
• Lactate dehydrogenase - converts lactate into pyruvate
• Rennin - converts milk proteins into peptides
• Protease - breaks down protein into amino acids

The enzymes has also got many industrial applications. Some examples are, 

• Amylase and protease - baking
• Rennin - cheese production
• Cellulase, protease, oxidases, amylase and peroxidase - detergent industry

Read more details about enzymes in the following book.

Enzymes

Thank you!

What is Factor-V gene mutation?

What is Factor-V?

        Blood clotting is a multi-step process which involves many proteins. Factor V is one of such protein. This protein is also known as labile factor, and which is derived from liver and platelets. Factor-V helps in the conversation of prothrombin to thrombin which is one of the vital steps in the blood clotting cascade. 

Difference between Factor-V and Factor-V Leiden

        Factor-V is one of the proteins involved in blood clotting and Factor-V Leiden is the mutation or gene change which produces in the abnormal blood clots.

Factor-V Leiden

        This is a genetic disorder, and which develops abnormal clots (thrombosis) mostly in legs called deep vein thrombosis (DVT). If this clot moves to lung through bloodstream and blocks the blood flow in lung, this condition is called as pulmonary embolism (PE) which is a lethal condition.

        The clotting activity of Factor-V is controlled by activated protein C (APC), which turn off Factor-V to prevent blood clotting. But APC cannot work with Factor-V Leiden which lead to abnormal blood clotting. Hence, this Factor-V Leiden is also known as APC resistance. Factor-V Leiden mutation results from the G to A transition in 1601 position of nucleotide (c.1601G>A). This transition results in arginine to glutamine substitution (p.Arg534Gln) at amino acid 534 of protein.

Diagnosis of Factor-V Leiden

        If you have a family history of thrombosis or if you are experiencing unnecessary blood clots or to know the inherited risk of having this mutation or if you are having DVT during pregnancy, the doctor suggests getting tested for Factor-V mutation. A simple blood test can be done by polymerase chain reaction to find out the mutation.

Genetics in Factor-V Leiden

        This is an autosomal dominant disorder means one copy of the mutated gene can cause the increased risk of thrombosis. 

• Factor-V Leiden heterozygous condition (GA, one variant) - having one mutated gene inherited from one parent and one normal gene from another parent.
• Factor-V Leiden homozygous condition (AA, two variants) - having two mutated gene inherited from both parents. No normal factor-V gene is present.
• GG, Leiden mutation is absent.

        Heterozygous condition increases the risk of developing abnormal clots whereas having homozygous condition makes the situation worse means higher the chances of producing clots.

References

• Factor V Leiden - Symptoms and causes. (2020, August 1). Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/factor-v-leiden/symptoms-causes/syc-20372423#:%7E:text=Factor%20V%20Leiden%20(FAK%2Dtur,Leiden%20never%20develop%20abnormal%20clots.
• Kirshman, M. (2019, November 22). Factor V Leiden Mutation and PT 20210 Mutation. Testing.Com. https://www.testing.com/tests/factor-v-leiden-mutation-and-pt-20210-mutation/.
• Hanna Rennert PhD, Robert A. DeSimone MD, in Transfusion Medicine and Hemostasis (Third Edition), 2019

Hope this information helps you!

What is inside a chromosome?

We have already studied the definitions of chromosome, genome, and DNA in the previous blogs. Now, let us have a look on what is there inside the chromosome.

Each human cell contains 46 chromosomes except eggs and sperms, and which is present inside the nucleus. 23 chromosomes come from the father and other 23 chromosomes from the mother. The DNA associated with histone proteins are wrapped inside the structure called chromosome and it is replicated in the time of cell division. These chromosomes are visible under microscope only during the cell division! 

Why the DNA packaging is so important? Chromosome has plethora of genetic information which stored in DNA. If the DNA present in a cell uncoil, it comes to six feet long!

 Related Terms:

• Histone - These are the proteins which helps the DNA packaging inside the cell's nucleus. Moreover, which helps the DNA to condenses in chromatin. These proteins are rich in lysine and arginine. 
• Nucleosome - It is the repeating unit of chromatin. DNA along with histone proteins form nucleosome. The core histones such as H3, H4, H2A and H2B form H3-H4 tetramer and H2A-H2B dimer. The negatively charged DNA wraps around the positively charged histone octamer. As an outcome, the nucleosomes are stabilized. 
• Chromatin - Nucleosomes packed together to form chromatin. The chromatin loops fold around each other to form chromosome.
• Centromere - The structure which holds the sister chromatids together. Each chromosome has two p and q arms which held together by centromere.
• Telomeres - The repetitive sections of DNA present at the end of each eukaryotic chromosome, which plays a vital role in chromosome replication and maintenance. Telomeres protect the chromosome from becoming impaired. During each cell division, some part of telomeres may lose in some of the cells. If the telomeres completely gone, the cell dies.

References:

• The Jackson Laboratory. (n.d.). Minute to Understanding: What is a chromosome? https://www.jax.org/news-and-insights/minute-to-understanding/what-is-a-chromosome.
• What is a chromosome? (2016, January 25). Yourgenome. https://www.yourgenome.org/facts/what-is-a-chromosome.
• NHGRI. (2019, March 9). Chromosomes Fact Sheet. Genome.Gov. https://www.genome.gov/about-genomics/fact-sheets/Chromosomes-Fact-Sheet.

Thank you!

Genetics and its divisions

Genetics

Genetics is the study of genes and heredity. It also deals with how the traits or certain characteristics are being passed to offsprings from parents. Gene is the basic unit of heredity, and it is the part of DNA which has the information for protein synthesis. The entire set of genes in an organism is called genome. The genome is present in the nucleus in the case of human, animal and plant cell.

Genetics plays a major role in disease diagnosis, personalized treatment for diseases and to identify the likelihood of getting a particular ailment. This all can be understood based on the genetic information. Any changes in the gene can prevent the certain protein synthesis which affect the specific functions. Genome sequencing technology is being used to identify the changes in the gene, and this information can be used for the betterment of human life.

Divisions

Primarily, there are 3 following subdivisions for genetics.

• Transmission genetics (Classical genetics)
• Molecular genetics
• Population genetics

Transmission genetics deals with how the genes are being transferred from one generation to other generation. It mainly focuses on an individual's genetic make up and how it inherits to the following generation. Molecular genetics emphasis on the structure and function of gene. It includes processes such as replication, transcription, translation and gene regulation. Whereas, population genetics studies the genetic makeup of individual members of the same species. It mainly deals with the evolution that is how the genetic make is being changed over time and space.

Other branches of genetics

• Microbial genetics - The study of genetics of microorganisms such as bacteria, viruses, unicellular plants and animals
• Immunogenetics - The study of the effect of genes on immune response
• Behavioral genetics - The study of the impact of genetic composition on one's behavior
• Human genetics - The study of human hereditary processes and inheritance
• Animal genetics - The study of genes and heredity in animals
• Plant genetics - The study of genes and heredity in plants
• Viral genetics - The study of genetics of viruses
• Cytogenetics - The microscopic study of chromosomes to understand the changes in the chromosome like extra or missing chromosome, broken etc. which lead to genetic diseases
• Clinical genetics - The study of causes and inheritance of genetic disorders

References

• Winchester, A. (2020, May 15). genetics. Encyclopedia Britannica. https://www.britannica.com/science/genetics.
• Branches and Importance of Genetics, study&Score. (n.d.). STUDYANDSCORE. https://www.studyandscore.com/studymaterial-detail/branches-of-genetics-importance-of-genetics
• Genetics. (2000). NIGMS. https://www.nigms.nih.gov/education/fact-sheets/Pages/genetics.aspx.
• Genetics, A Conceptual Approch by Benjamin.A.Pierce

               

                Hope you all like the information!

T             Thank you!😊

All about Hepatitis B

        One of the common liver diseases found worldwide is Hepatitis B caused by Hepatitis B virus. It can cause liver cirrhosis (scarring of the liver) and hepatocellular carcinoma (HCC). For some people, it is a short-term illness and for others it can cause chronic conditions and put their lives at high risk. This Hepatitis B can be prevented by vaccination and many other drug therapies. And also, by taking proper safety measures can prevent the spreading of virus.

Transmission

Disease can be transmitted by the following ways,

• Mother to child
• Unprotected sex
• Misuse of contaminated needles
• Exchange of infected bodily fluids such as blood, plasma, menstrual, vaginal and seminal fluid

Symptoms

Some people do not show any symptoms in both acute and chronic conditions. In chronic conditions, their liver is being silently destroyed and they also spread the disease to others without knowledge. However, some people show symptoms such as,

• Yellowing of eyes and skin
• Extreme fatigue
• Dark urine
• Abdominal Pain
• Fever
• Loss of appetite 
• Vomiting and Nausea

About Hepatitis B Virus (HBV)

Hepatitis B is a small partially double-stranded DNA virus (3.2kb in size) which infects hepatocytes present in the liver. It consists of an outer lipid envelope and an icosahedral nucleocapsid core, which is made up of protein. Hepatitis B virus exists in 3 forms such as spherical (most common form), tubular, and Dane particle (complete form, rare). 

• They have an outer envelope, made up of the HBsAg (Hepatitis B Surface Antigen/Australia Antigen). 
• HBcAg (Hepatitis B Core Antigen) is present in the inner core.
• HBeAg (Hepatitis B precore Antigen) is present in between the core and outer envelope. This is secreted and hence present in blood.

Hepatitis B Virus structure. Image Credit : Shutterstock

Life Cycle

The complex life cycle includes the following steps,

• Attachment of HBV to the hepatic cell
• HBV enters the hepatic cell via phagocytosis
• Fusion of viral envelope and hepatic cellular membrane
• Releasing of viral capsid into the cytoplasm
• Viral capsid moves to liver cell nucleus and viral genome imports into nucleus (nuclear import)
• The relaxed circular DNA (rcDNA) converts to covalently closed circular DNA (cccDNA)
• Transcription of cccDNA to pre-genomic RNA
• Translation of RNA to HBV antigens (inside the cytoplasm)
• HBeAg releases into blood
• HBcAg performs encapsidation of HBV polymerase and pre-genomic RNA
• Pre-genomic RNA converts to DNA (DNA synthesis)
• Encapsidated nucleocapsid again repeats the steps from nuclear import
• HBsAg assembles to form viral envelope
• Viral envelope wraps up the capsid (assembly)
• Release of virus

Treatment of Hepatitis B

People diagnosed with chronic hepatitis B infection need treatment to prevent the progression of liver diseases such as cirrhosis and HCC. This disease can not be completely cured. Treatment can prevent the transmission of disease to others.

1. Antiviral drugs - Adefovir, Entecavir, Tenofovir, lamivudine and Telbuvidine

2. Interferon alpha injections 

3. Liver Transplantation - If the liver is completely damaged, liver transplantation is the option

4. Everyone should get a hepatitis B vaccine to prevent the disease

Prevention and Control

• Vaccination
• Avoid sharing of needles to take drugs
• Use condom for sex
• Don't use infected person's belongings
• Verify the safety of the instruments used for tattooing and body piercing
• If you are a healthcare worker, then follow all safety precautions while handling samples

References

• Hepatitis B - Diagnosis and treatment - Mayo Clinic. (2020, September 4). Mayoclinic. https://www.mayoclinic.org/diseases-conditions/hepatitis-b/diagnosis-treatment/drc. 20366821#:%7E:text=Treatment%20for%20chronic%20hepatitis%20B%20may%20include%3A,ability%20to%20damage%20your%20liver.
• Schädler, S., & Hildt, E. (2009). HBV life cycle: entry and morphogenesis. Viruses, 1(2), 185–209. https://doi.org/10.3390/v1020185.
• What is Hepatitis B. (n.d.). Hepatitis B Foundation. https://www.hepb.org/what-is-hepatitis-b/what-is-hepb/.