Clinical Chemistry Blog Notes 08

DRUG TESTING!!

2009-09-08T21:41:00.000-07:00

DO YOU AGREE THAT DRUG TESTING SHOULD BE DONE AS A REQUIREMENT FOR ADMISSION TO SCHOOL? Why OR Why not?

Yes, I agree that drug testing must be done in schools before the admission of the students, because it is very important to know if the student is a drug user or not. Drug testing is useful for all students, not just those taking a medical course.

We all know that drugs have adverse effects on human. They can bring euphoria and sometimes physical and emotional dependence if people use them for a long time. Many crimes in our world today are due to drug addiction and unfortunately drug users can do something that is evil. Crimes then can be prevented in the school campus if it is a drug free place without worries about safety and security.

The question is, "What will happen to those people who would be positive in the Drug Test? Will they or will they not be allowed to enter School?". These questions I think should be answered by the school administration. Then they will decide what to do with these people, because some who might be positive for drugs may want to have a new life and they deserve a chance to prove themselves. I don't want to comment further about these questions.

Students do not have to use drugs in order for them to be good in school. They just have to believe in themselves. Drugs bring bad things to people instead of good things. I think Drug Testing will benefit the school, the faculty members and the students as well.

Get High on Life, Not on Drugs!!!

Photo by: jenniferlawler

Answers to Questions on Type 1 Hormone Mechanism

2009-09-01T02:30:00.000-07:00

Identification:

1. Enzymes (catalyst) will act with the hormones which will serve as the messengers to invoke changes in the target cell.
2. The two types of receptor in cell are the cell surface receptor and intracellular receptor.
3. The cell surface receptor only acts outside of the cell while the intracellular receptor will go inside the cell and will act there.
4. Examples of hormone in type 1 mechanism are peptide hormone, proteins, catecholamines and eicosanoids.
5. Examples of hormone for type 2 mechanism are the steroids and thyroid hormones.
6. Example of 2nd messenger is the adenylate cyclase.

Fill in the blanks:

Hormones in the type 1 mechanism find their receptor on the plasma membrane of the target cells.

The binding of hormone to the receptor will result to the production of second messengers within the cell.

This then will trigger a series of molecular interactions that will alter the physiologic state of the cell.

Each of the hormones will bind to the receptor protein that are embedded in the cytoplasmic membrane of the target cell.

Near the receptor protein is adenylate cyclase which is in inactive form and will act as the 2nd messenger.

It is important to know the type of receptor a hormone utilize to know its action. If it is steroid or non-steroid hormone.

The type 1 mechanism acts faster because it just reacts on the cell surface unlike the type 2 it will first go inside the cell then will have the reaction there.

STOP and THINK for Awhile!!

2009-08-25T19:44:00.000-07:00

Identification:

1. What is the function of an enzyme in the type 1 hormone mechanism?

2. What are the two types of receptor in the cell?

3. What is the difference of the two types of receptors in the cell?

4. What are examples of hormones in type 1 Mechanism?

5. What are examples of hormones in type 2 Mechanism?

6. Give examples of 2nd messengers?

Fill in the blanks:

Hormones in the type 1 mechanism found their receptor on the _______ of the target cell.

The binding of hormone will result in the production of ________ within the cell.

This will then trigger a series of _______ that will alter the physiologic state of the cell.

Each of the hormone will bind to a receptor protein that are embedded in the _____________ of the target cell.

Near the receptor protein is the ________ which is in inactive form and will act as the 2nd messenger.

Essay:

Discuss the importance of knowing the type of receptor a hormone utilizes.

Discuss which type of hormone mechanism reacts faster.

Photos by: krista baugham photo

Type 1 Hormonal Mechanism

2009-08-20T02:22:00.001-07:00

Hormonal Mechanism Type 1

The endocrine system release hormones that trigger the actions in a target cell. Target cell membrane receptor will bind only to one type of hormone. Hormones (messengers) act with enzymes (catalyst) to invoke changes within the target cells. Hormonal action can be gained by knowing the type of receptor it uses. The receptors can be categorized into two types based on the location on the cell:

Cell surface receptors

Hormones: Peptide hormones, proteins, catecholamines and eicosanoids
The Principle Mechanism of Action is the generation of second messengers which reacts the activity of other molecules within the cell

Intracellular receptors

Hormone: Steroids and thyroid hormones
The Principle Mechanism of Action is alter the activity of responsive genes in the hormones

Cell Surface Receptors or Hormonal Mechanism of Action Type 1

In type 1 hormonal mechanism, only the receptor found on the surface of the cell will come in contact with the specific hormone. This receptor when in combination with the hormone will initiate biochemical processes such as muscle contraction and relaxation, digestion, etc.

Peptide hormones, proteins, catecholamines and eicosanoids find their receptor on the plasma membrane of the target cells. The binding of hormone to the receptor will initiates a series of events that will leads to production of second messengers within the cell. Second messengers then will trigger a series of molecular interactions that will alter the physiologic state of the cell.

Each of the hormones has unique structure that will bind to the receptor protein that are embedded in the cytoplasmic membrane on the target cell. Near the receptor protein is adenylate cyclase which is in inactive form before the hormone will arrive at the target cell and will bind to its receptor.

Photo by: users.rcn.com

References: Clinical Chemistry by Bishop

http://www.cartage.org.lb/en/themes/Sciences/LifeScience/GeneralBiology/Physiology/EndocrineSystem/MechanismsHormone/MechanismsHormone.htm

TSH what a wonderful hormone!!=)

2009-07-14T06:19:00.000-07:00

Thyrotropin what a wonderful glycoprotein hormone

Secreted by the anterior pituitary gland in the brain

You encourage the thyroid gland to make more thyroid hormone

Thyroid hormones that act in nearly every cell in the body

T3 and T4 acts on development and differentiation of cells

They increase the basal metabolic rate and affect protein synthesis

They also regulate protein, fat and carbohydrate

What a truly important hormones they are

Two subunits make up this wonderful hormone

Alpha subunit is identical to that of HCG, LH and FSH
Beta subunit is unique to the TSH.

These hormones essentially have biological activity.

Excess and deficiency of this hormone can cause problems

Elevated level of it confirms a diagnosis of hypothyroidism

Decreased level of it confirms hyperthyroidism

Thyrotropin what a really significant hormone

Thyroid Disease

Video Thanks to: http://www.youtube.com/watch?v=0GSCECqc8U8

ANSWERS to the questions =)

2009-06-30T04:16:00.000-07:00

Answers:
Identification
1. Which cells secrete T3 and T4? Thyroid follicular cells
2. What is the most common cause of hypothyroidism? Grave's disease
3. What hormone does the parafollicular cells or C cells produce? Calcitonin
4. What substance is needed for the synthesis of thyroid hormone? Iodine
5. TSH is release from what endocrine gland? Anterior Pituitary Gland
6. Release of TRH and TSH is due to an elevated level of T3.
7. High iodine levels suppresses what hormone secretion? T3/T4
8. TSH promotes normal development and activity of the thyroid gland.
9. Low blood levels of T3 and T4 stimulate the Hypothalamus to secrete TRH.
10. What is the other name for thyroxine? Tetraiodothyronine

Case Analysis

11-20.
Grace is a new freshmen college student who hates herself for she's been gaining weight and her neck looks fat. She also has odd butterfly shaped swelling across the front of her neck under her chin. She's also been feeling tired and mentally dull.

The probable diagnosis of the patient is that she has enlarged thyroid gland or goiter. The goiter is probably due to hypothyroidism which is causing the weight gain, fatigue and mental dullness. Thyroid gland does not produce enough thyroid hormone that cause the hypothyroidism of the patient. Hypothyroidism means that T3 and T4 are lessen in number and these two hormones are needed for the normal development of the brain causing the mental dullness of the patient.

Take the Quiz and have some fun!! =)

2009-06-16T19:50:00.000-07:00

IDENTIFICATION
1. Which cells secrete T3 and T4?
2. What is the most common cause of hyperthyroidism?
3. What hormone does the parafollicular cells or C cells produced?
4. What substance is needed for the synthesis of thyroid hormones?
5. TSH is release from which endocrine gland?
6. Release of TRH and TSH is due to an elevated level of _______.
7. High iodine levels suppresses what hormone secretion?
8. _____ promotes normal development and activity of the thyroid gland.
9. Low blood levels of T3 and T4 stimulate the _______ to secrete TRH.
10. What is the other name for thyroxine?

CASE ANALYSIS

Grace is a new freshmen college student who hates herself for she's been gaining weight and her neck looks fat. She also has odd butterfly shaped swelling across the front of her neck under her chin. She's also been feeling tired and mentally dull.

What is the probable cause of her symptoms?
What probable cause does Grace is suffering from?
What test would you recommend to diagnose her?

THYROID STIMULATING HORMONE

2009-06-02T00:32:00.000-07:00

Thyroid Stimulating Hormone

The thyroid is a unique organ of the endocrine glands because it has a large store of hormone and a slow rate of normal turnover. Stimulation of the thyroid gland by the TSH, which is produced by the anterior pituitary gland, causes the release and distribution of stored thyroid hormones. TSH stimulate secretion of T4 and T3. TSH secretion is physiolologically regulated by T3 and T4 (feedback inhibition) and is stimulated by thyrothropin-releasing hormone (TRH) from the hypothalamus. TSH is the single most sensitive test for primary hypothyroididsm. If there is clear evidence of hypothyroidism and the TSH is not elevated, then an implication of possible hypopituitarism.

This test is used in the diagnosis of primary hypothyroidism when there is thyroid gland failure owing to intrinsic disease, and it is used to differentiate primary from secondary hypothyroidism by determining the circulatory level of TSH. High TSH levels are seen in primary hypothyroidism and low TSH levels are seen in hyperthyroidism.

TSH measurements will distinguish low levels from normal levels which have become the preferred test for hyperthyroidism. The high-sensitivity TSH test is useful for diagnosing sick euthyroid patients and in differentiating mild hyperthyroidism from Grave’s disease.

Reference Values:

Adults: 0.4-4.2 mIU/L
Neonates: 3-20 µIU/L by day 3 of life

Clinical Implications

1. ↑ TSH levels are seen in the following conditions:
a. Adults and Neonates with primary hypothyroidism
b. Thyrothropin-producing tumor (ei. ectopic TSH secretion from lung, breast tumors)
c. Hashimoto’s thyroiditis
d. Thyrotoxicosis due to pituitary tumor
e. TSH antibodies
f. Hypothyroid patients receiving insufficient thyroid replacement hormone or thyroid hormone resistance

2. ↓TSH levels are associated with the following conditions:
a. Primary hyperthyroidism
b. Secondary and tertiary hypothyroidism
c. Treated Grave’s disease
d. Euthyroid sick disease
e. Overreplacement of thyroid hormone in treatment of hypothyroidism

Interferring Factors
• Values are normally high in neonatal cord blood because of hypersecretion of TSH in newborns. This level will be normal after 1st week of life.
• Treatment with thyroxine and corticosteroids will decrease level of TSH.
• Iodine containing drugs will increase level of TSH in the body.
• TSH values are decreased in the first trimester of pregnancy.
• TSH values are increased in older people (>80 yrs. old)

TSH subunits

TSH consists of two subunits, the alpha and the beta subunit.
- The alpha subunit is identical to that of human chorionic gonadotropin (HCG), luteinizing hormone (LH) and follicle stimulating hormone (FSH).
- The beta subunit is unique to the TSH.

The TSH receptor

The TSH receptor is found mainly on thyroid follicular cells. Stimulation of the receptor increases the T3 and T4 secretion and production.

Therapeutic Use

A drug which is a recombinant human TSH, called Thyrogen is used in patients with thyroid cancer.

References:
• Fischbach, Frances, A manual of Laboratory and Diagnostic test, 7th edition

• http://en.wikipedia.org/wiki/Thyroid-stimulating_hormone

Welcome

2009-05-26T04:58:00.000-07:00

Hi, I'm Lindsey, welcome to my blog.