Saturday, December 29, 2018

LIPID CHEMISTRY

•         LIPIDS ARE ORGANIC COMPOUNDS FOUND IN PLANTS AND ANIMALS.
–        INSOLUBLE IN WATER BUT SOLUBLE IN ORGANIC SOLVENTS, e.g. ETHER, BENZENE, CHLOROFORM, ACETONE
–        ARE ESTERS OF FATTY ACIDS OR SUBSTANCES CAPABLE OF FORMING SUCH ESTERS.
–        UTILIZATION BY THE LIVING ORGANISM
FUNCTIONS OF LIPIDS
•         COMPONENT OF ALL CELLS AND CELL ORGANELLES MEMBRANE
•         MAJOR STORAGE FROM OF CARBON AND ENERGY
•         METABOLIC FUEL AND EMULSIFYING AGENTS
•         PRECURSORS OF OTHER IMPORTANT COMPOUNDS (PROSTAGLANDINS)
•         INSULATING MATERIALS AGAINST ATMOSPHERIC HEAT OR COLD
•         PROTECT ORGANS AGAINST PHYSICAL SHOCK
•         PROTECTIVE COATING OF LIPID, PREVENT EXCESSIVE LOSS OF WATER AND INFECTIONS.
•         TRANSPORT OF FAT SOLUBLE VITAMINS AND OTHER FAT SOLUBLE MATERIALS ACROSS CELL MEMBRANE
•         FURNISHES ENERY TO BIOLOGICAL SYSTEM (9.1 KCAL/G)
FATTY ACIDS
•         MAJOR PHYSIOLOGICAL ROLES
–        BUILDING BLOCKS OF PL. AND GLYCO LIPID OF CELL MEMBRANS
–        FATTY ACID DERIVATIVES ACT AS
•         HORMONES
•         INTERCELLULAR MESSENGER
–        FATTY ACIDS ARE FUEL MOL & STORED AS TRIACYLGLYCEROL
CLASSIFICATION OF
FATTY ACIDS
•         CHAIN LENGTH DEPENDENT
–        SHORT CHAIN FATTY ACID                    [2-4 C]
–        MEDIUM CHAIN FATTY ACID                [6-10]
–        LONG CHAIN FATTYACID                       [12-26 C]
MOST OF FATY ACID IN BLOOD BELONG TO THIS CLASS
•         ESSENTIAL AND NON ESSENTIAL FATTY ACID
–        LINOLEIC ACID      =  W6 SERIES
–        LINOLENIC ACID = W3 SERIES
•         SATURATED AND UNSATURATED
–        MONO-ENOIC
–        DI-ENOIC
–        PLYUNSATURATED FATTY ACID
NOMENCLATURE OF FATTY ACIDS
•         NUMBERING OF FATTY ACIDS FROM–COOH  END ( D NUMBERING)
•         OMEGA (w) NUMBERING OF FATTY ACIDS
•         GREEK LETTERING SYSTEM a, b, g
•         POSITION OF DOUBLE BONDS IS SHOWN FROM w OR D
CLASSIFICATION OF LIPIDS
  1. SIMPLE LIPIDS
  2. COMPLEX LIPIDS
  3. PRECURSORS LIPIDS
  4. STEROIDS
SIMPLE LIPIDS:
ALCOHOL + FATTY ACID
a. FATTY ACID –  GLYCEROL
b. WAXES  –  HIGH MOL WT  ALCOHOL + FATTY ACID
2.   COMPLEX LIPIDS: ALCOHOL+F.A+OTHER GROUPS
I.          PHOSPHOLIPIDS
a. GLYCEROPHOSPHOLIPDS: (ALCOHOL  IS GLYCEROL)
•         PHOSPHATIDIC ACID
•         PHOSPHATIDYL GLYCEROL
•         PHOSPHATIDYL CHOLINE
•         PHOSPHATIDYL ETHANOLAMINE
•         PHOSPHATIDYL INOSITOL
•         PHOSPHATIDYL SERINE OR THREONIN
•         LYSOPHOSPHOLIPIDS
•         PLASMALOGENS. (ETHER LINKAGE)
b.   SPHINGO PHOSPHO LIPID – SPHINGOMYLIN
II.  GANGLIOSIDE
CERAMIDE – GLc – Gal – N. Acetylgalactosamine +Gal+Neuraminic acid
GMI GANGLIOSIDE
III. LIPOPOLYSACCHARIDES
–        LIPID + POLYSACCHARIDE
OCCURS IN CELL WALLS OF CERTAIN BACTERIA
IV. LIPOPROTEINS
–        LIPID CORE COVERED BY PROTEIN
OCCURS IN PLASMA
3.   PRECURSORS AND DERIVED LIPIDS
–        FATTY ACIDS
–        GLYCEROL
–        STEROIDS
–        ALCOHOLS
–        FATTY ALDEHYDES
–        KETONE BODIES
–        HYDROCARBONS
–        LIPID SOLUBLE VITAMINS.  VIT A, D, E & K
–        HORMONES OF STEROIDS IN NATURE
4.   STEROID/STEROLS
–        CHOLESTEROL
FUNCTIONS OF CHOELSTEROL
•         CELL MEMBRANES
•         BIL ACID
•         VITAMINE D
•         REGULATION OF GENE
•         STERIOD HORMONES
FUNCTIONS OF PROSTAGLANDIN
•         SMOOTH MUSCLES CONTRACTION (PGE2&PGF2a)
•         LOWER BLOOD PRESSURE
•         REGULATE MENSTRUATION AND FERTILITY
•         INDUCE LABOUR (PGE2 & PGF2a)
•         CONTROL INFLAMMATION
•         RELIEVE ASTHMA AND NASAL CONGESTION (PGE2 & PGI2)
•         INDUCE BLOOD CLOTTING TX A2
•         PREVENT BLOOD CLOTTING (PGI2)
•         PREVENT CONCEPTION
CEREBROSIDES
•         KERASIN
–        FATTY ACID IS LIGNOCERIC ACID
•         CEREBRON
–        FATTY ACID IS HYDROXYLIGNOCERIC ACID
•         NERVON
–        FATTY ACID IS UNSATURATED HOMOLOUG LIGNOCERIC ACID
•         OXYNERVON
–        FATTY ACID IS HYDROXY DERIVATIVES OF NERVONIC ACID

Motility Test -Methods, Procedures and Importance



Motility test is useful for identification of bacteria which possess similar biochemical reactions. Following methods are used for doing the motility test:motility test
  1. Hanging drop method
  2. By using motility medium like motility indole urea, motility indole ornithine.
Hanging Drop Method
Materials
Glass slide, cover slip, distilled water, normal saline, glass pipette, soft paraffin
Procedure
Place a drop of bacterial suspension on the center of cover slip, apply wax or soft paraffin over the corners of the cover slip. Put a glass slide gently over the cover slip and hold it upside down. It should be in such a manner that bacterial suspension should be hanging between the cover slip and glass slide. Examine under the microscope, first under 10x, then under 40x.
We should minimize the light to be giving a contrast in the background. Margins of drop are specially seen. True bacterial motility must be differentiated from non-motile particles, which may show Brownian movement.
Motility Detection by Motility Medium
Materials
Tube motility medium and a wire loop which is used to stab the medium
Non-motile organisms which lack flagella, are usually going to form a single line of growth that does not spread into the surrounding area. While a motile bacterium will grow and make a hazy zone around the stab line.
Some Important Motile and Non-motile Bacteria
  1. All enterobacteriaceae are motile, except Shigella species
  2. Klebsiella species are non-motile
  3. Pseudomonas species are motile with the help of a unipolar flagellum
  4. Vibrio colony has a shooting star motility
  5. Campylobacter has a darting motility
  6. Giardia lamblia has a falling leaf motility
  7. Listeria monocytogenes has a tumbling motility

Complete blood cell count tests

Why might I need a complete blood count?

A complete blood count (CBC) is a common blood test that your doctor may recommend for the following reasons:
  • To help diagnose some blood cancers, such as leukemia and lymphoma
  • Find out if cancer has spread to the bone marrow
  • Determine how a person’s body is handling cancer treatment
  • To diagnose other, noncancerous conditions
If you are receiving chemotherapy, your doctor will likely monitor your blood cell counts often using CBCs.

What does a complete blood count measure?

A CBC measures the amount of 3 types of cells in your blood:
  • White blood cell count. A white blood cell count, also called a leukocyte count, measures the total number of white blood cells in a sample of blood. These cells protect the body from infection by attacking invading bacteria, viruses, and other foreign materials in the body. Some white blood cells can also attack cancer cells.
  • White blood cell differential. A white blood cell differential measures the number of each type of white blood cell. There are 5 major types of white blood cells, and each type plays a different role in protecting the body. Your doctor can learn valuable information about your health by measuring the levels of these cells.
    • Neutrophils
    • Lymphocytes
    • Monocytes
    • Eosinophils
    • Basophils
  • Red blood cell count. Red blood cells carry oxygen throughout your body. A red blood cell count, also called an erythrocyte count, measures the number of red blood cells in a sample of blood. There are several ways to measure red blood cells. Two of the most common are:
    • Hematocrit (Hct), the percentage of your blood that is made up of red blood cells
    • Hemoglobin (Hgb), the amount of the protein in red blood cells that carries oxygen
  • Platelet count. A platelet count measures the number of platelets in a sample of blood. Platelets help to stop bleeding by forming blood clots.
The amounts of each of these types of cells have a normal range. Your health care team will note this range on your CBC lab results. A range is used instead of a specific number because a normal amount is different for each person.

What do the results mean?

Your health care team must carefully interpret CBC test results. Keep in mind that many factors, including noncancerous conditions, can lead to results that fall out of the normal range. Ask your doctor to help you understand what your results mean.
  • Low white blood cell count. Some cancer treatments, mainly chemotherapy, may cause a decrease in your body's white blood cells. Cancers that affect the blood and bone marrow can also cause a decrease in the count. These types of cancers include leukemia, lymphoma, and multiple myeloma.
  • Amounts of different white blood cells. Higher-than-normal numbers of lymphocytes or monocytes can indicate the possibility of certain types of cancers. Some cancers and their treatments may cause neutropenia. Neutropenia is a decrease in the number of neutrophils, which increases the chances of a bacterial infection. At times, your doctor may lower your chemotherapy dose to reduce your chance of developing a low neutrophil count. Your doctor may also recommend medication, such as white blood cell growth factors, to increase your body's production of neutrophils, especially if you develop a fever. Learn more about the use of white blood cell growth factors.
  • Low red blood cell count. Some cancer treatments, mainly chemotherapy and radiation therapy, may cause a decrease in red blood cells. This condition is known as anemia. Blood loss, either from surgery or specific cancers, and cancers that directly involve the bone marrow can also cause or worsen anemia. People whose red blood cell count falls too low may need a blood transfusion or medication to help increase it. 
  • Low platelet count. Some cancer treatments, such as chemotherapy or radiation therapy, may cause a decrease in platelets. Cancers that directly involve the bone marrow can also cause a decrease in platelets. An unusually low number of platelets is called thrombocytopenia. Patients with low platelet levels have a greater risk of serious bleeding or bruising. If your platelet count falls to very low levels, your doctor may recommend platelet transfusions.

Tuesday, December 18, 2018

A micro-niacin test for differentiating human tubercle bacilli from other mycobacteria

 

Mycobacterium smegmatis (negative for the niacin test)

TESTING PROCEDURES

A niacin test strip is similar in appearance to a pH test strip. It is small, thin, rectangular, and white in color. Water is placed onto the culture plate and touched with a test strip for 15–20 minutes inside a small, sterile tube. If excess amounts of niacin are detected, the liquid inside the tube will turn yellow, a positive test. If the liquid in the tube is clear, there are no excess amounts of niacin and the test is negative. It should be noted that a positive niacin test does not necessarily indicate the presence of M. tuberculosis because other Mycobacterium species can test positive for excess niacin.

Along with each batch of specimens being tested, a positive control of M. tuberculosis and a negative control with no organism will be included. If the positive control tests negative, there was probably an error with the batch, and likewise for a negative test showing positive.
Because lab samples that are determined to be acid-fast bacilli are possibly M. tuberculosis, a biosafety level 3 organism, all niacin tests must be conducted in a biosafety cabinet with a full gown, respirator, gloves, and sealed laboratory to ensure the safety of the lab technologist performing the test. All tests must also be conducted with sterile technique.

BIOCHEMICAL PROCESSES

Biochemical pathway

The nicotinamide adenine dinucleotide (NAD+) degradation pathway in M. tuberculosis has a blockade that the scavenging pathway resulting in an excess of niacin that cannot be processed by the organism.[3] Because of this abundance, the M. tuberculosis along with Mycobacterium canetti and varied types of Mycobacterium africanum release the excess niacin into their outside environment, in this case, the agar plate or another medium. Niacin is water-soluble, so the culture media can be tested for the presence of niacin to determine whether a Mycobacterium isolate is one of the three mentioned species.[3] Those three species are members of the Mycobacterium tuberculosis complex.

Test strip process

The niacin test strip is typically composed of potassium thiocyanate, chloramine-T, citric acid, and 4-Aminosalicylic acid.[5] In the presence of citric acid, chloramine-T and potassium thiocyanate will react to form cyanogen chloride. This chemical will break apart the pyridine ring of niacin to produce y-carboxy glutaconic aldehyde and joins an aromatic amine to form a yellow color.