Albumin transport function analysis by EPR spectroscopy is an ''

in vitro ''In vitro'' (meaning ''in glass'', or ''in the glass'') Research, studies are performed with Cell (biology), cells or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in ...

blood test A blood test is a medical laboratory, laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a hypodermic needle, or via fingerprick. Multiple tests for specific blood components, such as a glucose ...

that detects changes to the transport and molecular conformation of

serum albumin Serum albumin, often referred to simply as blood albumin, is an albumin (a type of globular protein) found in vertebrate blood. Human serum albumin is encoded by the ''ALB'' gene. Other mammalian forms, such as bovine serum albumin, are chem ...

using the method of EPR spectroscopy. The test is used for

diagnosis Diagnosis (: diagnoses) is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in a lot of different academic discipline, disciplines, with variations in the use of logic, analytics, and experience, to determine " ...

cancer Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...

sepsis Sepsis is a potentially life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage of sepsis is followed by suppression of the immune system. Common signs and s ...

and toxemia.

Principles

The test is based on the interaction of spin-labeled

fatty acid In chemistry, in particular in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an ...

s with serum albumin by means of EPR spectroscopy. A sample of

blood serum Serum () is the fluid and solvent component of blood which does not play a role in clotting. It may be defined as blood plasma without the clotting factors, or as blood with all cells and clotting factors removed. Serum contains all proteins ex ...

is subjected to a spin probe 16-doxyl stearate. Spin probe molecules bind specifically to albumin

molecule A molecule is a group of two or more atoms that are held together by Force, attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemi ...

s where they occupy two main positions: * primary

binding site In biochemistry and molecular biology, a binding site is a region on a macromolecule such as a protein that binds to another molecule with specificity. The binding partner of the macromolecule is often referred to as a ligand. Ligands may includ ...

s located in albumin domains, where their mobility is restricted * the relatively spacious

hydrophobic In chemistry, hydrophobicity is the chemical property of a molecule (called a hydrophobe) that is seemingly repelled from a mass of water. In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, thu ...

area between the protein domains in the interior of the albumin globule. The spin probe molecules bound on albumin have restricted mobility that changes the EPR spectrum, which reflects characteristics of the protein site where the spin probe is located and allows estimating the conformation of the albumin globule. Some part of the spin probe remains in the serum in the unbound state. The ratio of the fractions of bound and unbound spin probes allows estimating the functional activity of albumin molecules. Analysis of the EPR spectrum allows assessment of the conformation and functional activity of albumin molecules. The test material is 100 μL serum or plasma. The procedure includes mixing a serum sample with a spin probe

reagent In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a ...

, incubating the mixture, measuring the EPR spectrum of a serum with a spin probe, and analyzing the EPR spectrum by calculating the conformation and functional indicators of albumin molecules.

Applications

Cancer diagnosis

A specific change to the conformation of albumin molecules that is associated with the growth of a

malignant tumor Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal ...

is caused by (or associated with) changes in the composition of

metabolite In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...

s carried by serum albumin during the growth of a malignant tumor (proliferating cancer cells uptake and release metabolites in abnormal quantities). Clinical studies of the EPR test of serum albumin showed diagnostic

sensitivity and specificity In medicine and statistics, sensitivity and specificity mathematically describe the accuracy of a test that reports the presence or absence of a medical condition. If individuals who have the condition are considered "positive" and those who do ...

of 90%. Clinical applications: * as a screening test to detect cancer-specific metabolic alterations in patients; * to determine whether the cancer growth has stopped or the disease is progressing; * to determine when cancer treatment is effective or needs to be changed.

Sepsis and toxemia

Reduced functional activity of serum albumin (reduced binding efficacy) is associated with toxemia (an increase in the

concentration In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', '' molar concentration'', '' number concentration'', ...

of toxic molecules in the blood) and is manifested before other clinical symptoms. Clinical applications: * prognosis and early diagnosis of sepsis (1 to 2 hours after

surgery Surgery is a medical specialty that uses manual and instrumental techniques to diagnose or treat pathological conditions (e.g., trauma, disease, injury, malignancy), to alter bodily functions (e.g., malabsorption created by bariatric surgery s ...

); * diagnosis of severe

preeclampsia Pre-eclampsia is a multi-system disorder specific to pregnancy, characterized by the new onset of high blood pressure and often a significant amount of protein in the urine or by the new onset of high blood pressure along with significant end- ...

(gestosis) in women in the 2nd and 3rd trimesters of pregnancy; * diagnostics of the functional status of a

kidney transplant Kidney transplant or renal transplant is the organ transplant of a kidney into a patient with end-stage kidney disease (ESRD). Kidney transplant is typically classified as deceased-donor (formerly known as cadaveric) or living-donor transplantat ...

* early diagnosis of

congenital A birth defect is an abnormal condition that is present at childbirth, birth, regardless of its cause. Birth defects may result in disability, disabilities that may be physical disability, physical, intellectual disability, intellectual, or dev ...

pneumonia Pneumonia is an Inflammation, inflammatory condition of the lung primarily affecting the small air sacs known as Pulmonary alveolus, alveoli. Symptoms typically include some combination of Cough#Classification, productive or dry cough, ches ...

newborns In common terminology, a baby is the very young offspring of adult human beings, while infant (from the Latin word ''infans'', meaning 'baby' or 'child') is a formal or specialised synonym. The terms may also be used to refer to juveniles of ...

References

{{Reflist Medical diagnosis Cancer research