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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5535_Библиотеки_им_академика_М_И_Перельмана.pdf
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Medical Laboratory Technology: Volume 3
Multiplex PCR
It is a PCR designed to detect more than one target sequence in a single PCR reaction. The assay uses
two or more sets of primers. Each set of primers is specic for a different target sequence. The assay is
most commonly used for simultaneous detection of multiple viral genes and differentiation of genotypes
or subtypes of related microorganisms.
Differential PCR
Differential PCR can sometimes be used to distinguish closely related targets. Differential PCR is done
either in a multiplex format using two or more sets of primers or by running two separate PCR assays.
Applications of PCR
PCR technique has vast applications. It can be used for DNA cloning application for sequencing, gene
cloning and manipulation, gene mutagenesis; construction of DNA-based phylogenies, functional
analysis of genes, diagnosis and monitoring of hereditary diseases, amplication of ancient DNA,
analysis of genetic ngerprints for DNA proling (e.g. in forensic science and parentage testing), and
nally it has a huge impact in the detection of pathogens for infectious disease diagnosis.
Advantages of PCR Over Conventional Techniques
a. Quick, accurate, more sensitive and specic
b. Has fast turnaround time as compared to other tests such as culture
c. Has more wider application such as detecting infectious diseases, genetic testing, forensics, drug
resistance, and tumour marker detection and monitoring.
Limitations/difficulties
Technique Related Limitations
While a very powerful technique, PCR can also be very tricky. The polymerase reaction is very sensitive
to the levels of divalent cations (especially Mg2+) and nucleotides, and the conditions for each particular
application must be worked out. Primer design is extremely important for effective amplication. The
primers for the reaction must be very specic for the template to be amplied. Cross reactivity with nontarget DNA sequences results in nonspecic amplication of DNA. Also, the primers must not be capable
of annealing to themselves or each other, as this will result in the very efcient amplication of short
nonsense DNAs. The reaction is limited in the size of the DNAs to be amplied (i.e. the distance apart
that the primers can be placed). The most efcient amplication is in the 300–1000 bp range, however,
amplication of products up to 4 Kb has been reported. Also, Taq polymerase has been reported to make
frequent mismatch mistakes when incorporating new bases into a strand.
PCR reagents are very sensitive to heat and are stored at temperatures between –20oC and –80oC and
cannot be subjected to multiple freeze thaw cycles. Laboratories running PCR are typically equipped
with good sample storage facilities and skilled technicians.
The most important consideration in PCR is contamination. If the sample that is being tested has
even the smallest contamination with DNA from the target, the reaction could amplify this DNA and
report a falsely positive identication. For example, if a technician in a crime lab sets up a test reaction
(with blood from the crime scene) after setting up a positive control reaction (with blood from the
suspect) cross contamination between the samples could result in an erroneous incrimination, even if the
technician changed pipette tips between samples. A few blood cells could volatilise in the pipette, stick
to the plastic of the pipette, and then get ejected into the test sample. The powerful amplication of PCR
may be able to detect this cross contamination of samples. Modern labs take account of this fact and
devote tremendous effort to avoiding this problem, while strictly following good laboratory practices to
ensure accurate reporting of results.
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Polymerase Chain Reaction in Clinical Diagnosis
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Because of the high capex and opex involved in the above, clinical diagnostic applications of PCR have
been highly centralised and limited to large hospitals and laboratories having specialised infrastructure
and resources. Samples hence have to be transported to these centralised facilities, maintaining a cold
chain. These and the need for batch testing often lead to long turn around time for results thus severely
limiting the clinical value of the test.
New innovations in recent times have come up with solutions that enable decentralisation of PCR
testing by reducing/eliminating dependence on laboratory infrastructure and skilled man power and
bringing PCR testing closer to the patient.
Point of Care PCR for Clinical Diagnosis
In order to cater to the need for PCR based diagnosis in distributed settings, PCR devices are becoming
smaller, simpler, more accurate, and easy to handle. The introduction of GeneXpert by Cepheid,
Sunnyvale, California paved the way for more affordable and less complicated real time PCR testing.
However, infrastructure dependence resulted in this platform being restricted to district level settings.
Recently, Molbio Diagnostics, Goa, India has introduced Truenat, a portable, battery operated, real
time PCR platform for point of care use that enables the end user to perform molecular tests at the rst
point of patient contact even in primary health settings. With ready to use, room temperature stable
reagents, multi-disease testing capability and turnaround time of 1 hour from sample to result, Truenat
has brought in a paradigm shift in PCR testing by removing all the bottlenecks of a conventional PCR
and making it accessible and affordable at all levels of the healthcare chain.
Truenat™ Real Time Micro PCR Chips
Products Available
MTB screening CE Chikungunya CE Gonorrhoea CE
MTB-RIF CE Dengue/Chikungunya CE Chlamydia/Gonorrhoea
HBV with VL Malaria Pf CE Trichomonas CE
HV-1 with EID+VL Malaria Pv/Pf Rabies
HCV with VL Salmonella CE HPV-HR CE
H1N1 CE Chlamydia Influenza A/B CE
Dengue CE HLA-B27 CE GBS CE
HAV CE HEV CE Beta CoV CE
SARS CoV-2 CE COVID-19 CE Leptospira CE
Figure 40.6:
TruenattestforMTBandRifresistencehasbeenendorsedbyWHOandrecommendedforuseas
theinitialtestforTBasareplacementtosmearmicroscopy
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Products coming soon
Samrsa
H3N2/H1N1 SA/PA
ZIKA
Staphylococcus aureus
(SA)
MTB/NTM Leishmania Kyasanur Forest disease (KFD)
MTB-INH MTB-FQ Mycoplasma
MTB-BDQ Cholera
Products Pipeline
Klebsiella BCR-ABL for chronic myeloid
HIV-2 Rubella
CMV Rubeola Rotavirus
EBV Rubula Syphillis
HSV (1/2) H5N1 Mumps
HHV-6 (A/B) Japanese encephalitis virus (JEV) MERS (middle east respiratory syndrome)
Yellow fever virus Measles
Medical Laboratory Technology: Volume 3
Neisseria meningitidis (Nm) Pseudomonas aeruginosa (PA)
Streptococcus pneumoniae (SP)
Haemophilus influenzae B (HIB)
Shigella Sickle cell anemia screening
leukaemia
Nipah
Bordetella pertussis
Toxoplasma gondii
Clostridium difficile
Truenat test for Covid-19 is endorsed by ICMR and has played a major role in RTPCR testing during
the pandemic.
Section 9
MISCELLANEOUS
INFORMATION
• Medical Terminology
• Glossary of Technical Terms
• Appendices
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Medical Terminology
Maya Chattoraj and Kanai L Mukherjee
SuffixeS and PrefixeS in Medical TerMinology
Suffix
Sux is a leer or group of leers (ax) added to the end of a word to change its meaning. For
example, adding the sux “ter” to the adjective “hot” turns it into the comparative adjective
“hoer”. Similarly, adding sux “ly” to the adjective “quick” turn it into the adverb quickly.
Other examples include willing, management, serviceable, joyful, etc. Some of the suxes
used in medical terminology are shown in the table below. The following are a few medical
suxes, along with their meanings, and English examples.
Remember: Sux goes at the end of a word and Prex goes at the beginning of a word.
Sux Meaning Application (example)
-aemia in the or of the blood Bilirubinaemia
-algia pain Neuralgia
-ase enzyme Lactase, Oxidase
-ation process Medication
-blast primitive, germ Erythroblast
-centesis puncture, aspiration Amniocentesis
-cide death, killer Bacteriocide
-ectomy excision, cut out Gastrectomy
-ferent carry Aerent
-genie origin, producing Pyogenic
-itis inammation Pharyngitis
-lysis free, breaking down Haemolysis
-oma tumour Hepatoma
-opathy disease Adenopathy
-osis state or increase Leukocytosis
Contd.
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-otomy cut into Phlebotomy
-paenia lack of Leukopaenia
-pathy denotes a disease, or disorder Neuropathy
-poiesis production Haematopoiesis
-troph(y) nourishment Hypertrophy
Medical Laboratory Technology: Volume 3
Prefix
A prex is placed at the beginning of a word to modify or change its meaning. Following is
a list of the most common prexes in English, together with their basic meaning and some
examples. You can nd more detail or precision for each prex in any good dictionary.
In medical terminology many prexes are used in the literature, like “algia” (pain) and
“neuralgia” (pain from damaged nerve). Few other examples are given in the following table.
The following are a few medical prexes, along with their meanings, and English examples.
Prex Meaning Application (example)
A-, An- not, without Analgesic, Apathy
Ab- from; away from Abduction
Aden(o)-, aden(i)- of or relating to a gland Adenocarcinoma
Alge(si)- pain Analgesic
All(o)- denoting something as dierent, or
as an addition
Andr(o)- pertaining to a man Androgen
Aniso- unequal Anisocytosis
Ante-. before Antecedent, Ante-Room
Anti- ‘against’ or ‘opposed to’ another Antibody
Aur(i)- of or pertaining to the ear Aural
Auto- self Automobile
Baso- blue Basophil
Bi- two Bilateral
Cardi(o)- of or pertaining to the heart Cardiology
Contra- against, opposite Contraceptive
Di -
Dipl(o)- double Diplococcus
Idio- self, one’s own Idiopathic
Melan(o)- black colour Melanin
Ost(e)-, Oste(o)- bone Osteoporosis
Phago- eating, devouring Phagocyte
Pneum(o)- of or pertaining to the lungs Pneumonia
Pre- denotes something as ‘before’ Premature Birth
two Dimorphic
Alloantigen
Contd.
Medical Terminology
Pulmon-, pulmo- of or relating to the lungs Pulmonary
Trans- denoting something as moving Transfusion
Uter(o)- of or pertaining to the uterus Uterus, Womb
Dis (also di-) apart, away from, removal Disadvantage, Dimount
Dys- bad, dicult, painful Dysentry
E-, Ecto-, Ex- out from Ectoblastic, Ectoderm
En-(also Em-) put into or on Engulf, Enmesh
End(o)- inside, within Endoscope
Enter(o)- intestine Enteric Fever
Epi- upon, aer Epidermis, Epicardium
Ex- out, completely Exclude, Excruciate
Hyper- above, excessive Hyperactive
Hypo- under, decient Hypothermia
Infra- below Infrared
Inter- among Interact, Interchange
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Intra- within, inside, between Intravenous
Iso- equal Isotonic
Macr(o)- large Macrophage
Mega- huge, great Megameter
Meta- aer, next Metcarpus
Micro- small Microscope
Necro- dead Necrosis
Neo- new Neoplasm
Neutro- neutral Neutrophil
Olig- few Oligotrophy
Pan- all Panophobia, Panic
Peri- around Perimeter
Phago- to eat Phagocyte
Poly- many Polymyositis
Post- aer Post-mortem
Pre-, Pro- before Precondition, Premature
Pseudo- false Pseudoephedrine
Py(o)- pus Pyoretra
Quad(r)- four Quadriceps
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Medical Laboratory Technology: Volume 3
Glossary of Technical Terms
Maya Chattoraj and Kanai L Mukherjee
A
ABO blood group: The basic blood group system in humans, which is determined by the
antigenic characters of red cells. The cells agglutinate when mixed with corresponding
antibody.
Abscess: A localized collection of pus in a cavity produced by the breakdown of tissues.
Absorbance: Applied in photometry; it expresses the amount of light absorbed by a solution;
also called optical density (O.D.); it is related to Beer’s Law (an optical phenomenon).
Absorption: Applied in the blood bank; it implies the removal of specic antibodies present
in the serum with their specic antigen present on red cells.
ACD: The abbreviated form of acid-citrate-dextrose, an anticoagulant used in the blood bank.
Accuracy: A measure of how close a determined value is to the true value.
Acetone: An organic metabolite coming from incomplete degradation of fat; found in
the blood and urine in diabetic patients; bears a characteristic fruity smell; one of the
components of ketone bodies.
Acquired immunodeciency syndrome (AIDS): A form of severe immunodeciency caused
by infection with the human immunodeciency virus (HIV).
Acid: A sour substance like lemon juice (citric acid); it neutralizes bases (alkali), turns litmus
paper red; carries hydrogen ions (H+) and the pH is below 7.0. Common laboratory acids
are hydrochloric acid, sulphuric acid and nitric acid. These are highly corrosive.
Acid fast: Not decolorized easily by acids aer staining. It pertains to acid fast bacteria like
Mycobacterium spp. that retain the red dye aer acid-alcohol treatment. Other bacteria
lose the colour and picks up the blue colour of the counterstain (methylene blue).
Acidophilic: Stains readily with acid dyes, for example, methylene blue.
Acidosis: When the pH of blood tends to fall below 7.4; related to respiratory problem
(respiratory acidosis), or metabolic or kidney disorders (metabolic acidosis).
Actinomycete: A bacterium of the order Actinomycetales.
Acute: Having severe symptoms and a short course.
Acute phase proteins: Proteins that increase rapidly in serum during acute infection,
inammation, or following tissue injury.
Adhesion: The act of two parts of surfaces sticking together.
Adsorption: It is a loose adherence on the surface as distinct from absorption which penetrates
deeper.
Aerobe: A microorganism that lives and grows in the presence of free oxygen.
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Glossary of Technical Terms
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Aerobic: Requiring oxygen.
Aerosol: A colloidal system in which solid or liquid particles are suspended in a gas, especially
a suspension of a drug or other substances to be dispensed in a ne spray or mist.
Agammaglobulinemia: A pathological condition in which the body forms few or no gamma
globulins or antibodies.
Agar: A gelatinous colloidal extraction of a sea alga, used especially in culture media for
growing microorganisms.
Agglutination: The clumping or aggregation of particulate antigens due to reaction with a
specic antibody.
Agglutination inhibition: Interference with, or prevention of, agglutination.
Agglutinin: An antibody in serum that brings about agglutination of cells (red cells or bacteria).
Example: anti-A and anti-B.
Agglutinogen: An antigen which will react with a specic antiserum and will show
agglutination. Example: A and B antigens.
Aggregate: The total substances making up a mass; a cluster or clump of particles.
Aggregation: The collecting of separate objects into one mass.
Alanine aminotransferase (ALT): An enzyme present in high concentration in liver tissue and
that is measured to assess liver function; also called SGPT.
Albumin: A water soluble protein found in blood plasma and serum.
Alimentary tract: The digestive tube from the mouth to the anus.
Alkali: A substance with caustic characters; when in solution it has OH ions; pH more than 7.0;
reacts with acid and forms salt; also called base. Example: sodium hydroxide.
Alkaline phosphatase (ALP or AP): An enzyme widely distributed in the body, especially in
liver and bone.
Alkalosis: When the pH of blood tends to rise above 7.4 due to respiratory or metabolic
(or kidney) problems.
Alkaptonuria: Presence of alkaptone bodies (homogentisic acid) in urine, which causes the
urine to turn dark on standing or with addition of alkali.
Allele: An allele is one of a number of alternative forms of the same gene or same genetic
locus. For example, the genes for blood types A, B and O are at the same position on alleles.
Allergy: A condition resulting from an exaggerated immune response; hypersensitivity.
Amoeba: A minute unicellular protozoon, for example, Entamoeba histolytica causes amoebic
dysentery.
Amorphous: Without visible dierentiation of structure.
Amperometry: The technology that uses electrodes and electrode potential to measure electron
generation.
Ampoule: Small glass container capable of being sealed to preserve the contents in a sterile
condition.
Amyloid disease: A pathologic condition in which liver spleen and kidney tissue is replaced
by an amorphous (without shape) wax-like material.
Amylopsin: Enzyme of pancreas which hydrolyses complex carbohydrates into soluble
sugars.
Anaemia: It is a pathological condition caused by reduction in circulating red cells.
Anaerobe: An organism that lives and grows in the absence of molecular oxygen.
Anaerobic: Growing in the absence of oxygen.
Analyte: A chemical substance that is the subject of chemical analysis.
Analytical grade reagents: Pure chemicals of known composition.
Anaemia: A condition in which the red blood cell count or haemoglobin level is below normal;
a condition resulting in decreased oxygen-carrying capacity of the blood.
Anamnestic response: Rapid increase in blood immunoglobulins following a second exposure
to an antigen; booster response or secondary response.
Anhydride: A form of a substance where the water molecule is chemically removed.