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Read up on technical terms frequently used in diagnostics.
The letters marked blue will lead you to the desired headwords, the white arrows will lead you back to the beginning. |
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| A |
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| Amplification Viral and bacterial nucleic acids sometimes being present in only
minute quantities, these small quantities are copied up to 40 times
using the PCR method, in which every new copy is copied again. Based on
a small piece of a DNA double strand, 40 polymerase copying procedures
will result in 2 to the power of 2 = 4, 4 to the power of 2 = 16,
up to 2 to the power of n copies (n = the number of copying
procedures). With these “vast” quantities, the obtained DNA, for
example of a virus, can then be detected using a number of techniques
(real time, ethidium bromide). |
| Annealing Binding of oligo nucleotides to DNA single strands. |
| Apoptosis is a highly regulated mechanism eliminating damaged, superfluous or
potentially hazardous cells by programmed cell death. It is important
in removing endogenous cells during the embryonic development, in
growth and differentiation, in the immuno response and in cellular
homeostasis. During the average human life span, every second several
million cells go into apoptosis, thus maintaining the cellular
balance between old and new cells. An imbalance between apoptosis
and proliferation may result in tumour formation. |
Aspiration biopsies are gained by organ or tissue aspiration using large needles or aspiration cannulae.
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Aspiration cytology The microscopic analysis of individual cells removed from cell
aggregates in order to determine diseases, especially tumours,
inflammations or storage diseases.
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| Atypia Non-typical cell morphology, deviating from its usual form; used as a synonyma for dysplasia. |
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| B |
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| Bacteria Compared to most viruses, these are giant micro organisms with DNA as
nucleic acid. This is located “naked” in the cell, meaning that it is
not organized in a cell nucleus. These are called prokaryotes (pro =
before / prior, karyo = kernel). Apart from a number of useful bacteria
which are processed in the food industry (such as lactobacillaceae in
yoghurt) there are many which may cause serious diseases in humans.
Some known examples are salmonella, legionella and various myco
bacteriae. If recognized early enough, some diseases can be treated
with antibiotics. However, as a result of the massive use of
antibiotics, a number of bacterial strains have become resistant,
making antibiotic therapy much more difficult. Then again, some
bacteria and the enzymes they produce (such as DNA polymerase) are very
important for the work of biologists and physicians. |
| Biopsy (in Greek: bios = life, opsy = look, appearance) Removal of tissue from
the living by aspiration or using special instruments for the purpose
of histological examination. |
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| C |
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Carbuncle Several confluent boils.
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Carcinoma A malignant tumour arising from epithelial cells. About 90 per cent of
all malignant tumours arise from epithelial cells, these lesions are
called cancer in its original meaning (examples: bronchial carcinoma,
gastric cancer, cancer of the prostate, carcinoma of the mammary gland).
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Cell cycle The cell cycle is a complex sequence of events of one single cell, ranging from its origin from the mother cell to its division. Being part of a sophisticated tissue system, a working cell cycle is mandatory for the development of an organism and its homeostasis (loss of cells and their replacement by the formation of new cells). In the development of a malignant tumour, the complex cell cycle control system is changed in many different ways, resulting in unregulated cell proliferation. Atypical cells (cancer cells) have the transmittable property to be able to multiply ignoring the usual restrictions of cell division. They can spread to tissue areas normally reserved for other cells (metastatic spread). It is supposed that most malignant tumours are descendend from just one single atypical cell. The speed of growth of a malignant tumour depends on its cell proliferation kinetics. To the pathologist, a number of techniques are available for determining the proliferation kinetics of malignant tumours (see table below):
| Marker |
determination in certain phases of the cell cycle |
| mitotic index |
M phase |
| uptake of h thymidine |
S phase |
| labeling with 5 bromodeoxyuridin |
S phase |
| flow cytometry |
S phase |
| Ki67 |
G1, S, G2 and M phase |
| PCNA |
G1, S and G2 phase |
| p105 |
G1, S, G2 and M phase |
| AgNOR |
S, G2 and M phase |
| Cyclin A |
S, G2 and phase |
| Cyclin B |
G2 and M phase |
| Cyclin C |
G1 phase |
| Cyclin D |
G1 and S phase |
In clinical pathology, proliferation activity is often determined by recording the mitotic index of the tumour cells, on the protein level of the tumour cells, the proliferation markers Ki67 and PCNA are established immunohistochemically. |
Central dogma It is not long ago that scientists believed proteins were always
produced in this way. The gene (DNA level) is copied in transcript (RNA
level). This in turn serves as a detailed blueprint for a protein
(amino acid level). The other way round seemed unlikely. However, some
viruses showed that they were able to copy their DNA into DNA. This
“new” DNA is then smuggled as a gene among the genes of the host
organism.
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CD52 (human) – protein name: CAMPATH-1 [synonyma: Cambridge pathology 1 antigen, epididymal secretory protein E5, CDw52]
CD52 is a glycosolphosphatidylinisotol-anchored antigen bound to
the outer surface of plasma membranes of lymphocytes, monocytes,
thymocytes, eosinophilic granulocytes, macrophages and epithelial cells
of the distal epididymis and ductus deferens. CD52 is localized on
chromosome 1 (1p36). The physiological role of CD52 is unclear. CD52 is
expressed in a number of malignant lymphatic diseases. Antibodies
directed against CD52 (CAMPATH-1) are used with success in the
therapeutical management of lympho-proliferative diseases. |
CUP-syndrome (Cancer of unknown primariy): In 2 – 10 per cent of patients with
malignant tumours (cancer), metastases are found but their . CUP
syndrome studies show that primary bronchogenic are at the top of the
list of lesions responsible for CUP syndrome, followed by malignant
tumours of the pancreas. CUP syndrome caused by tumours of the liver,
the gall bladder, large or small intestine, mammary gland, prostate or
ovaries are less frequent.
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| D |
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| Denaturation Often irreversible alteration of a protein shape through heat or
chemicals. DNA denaturation for PCR is achieved by applying heat,
however, this process is reversible, meaning that the DNA single
strands resume their native state. |
| Deparaffinization It is possible to isolate DNA from paraffin-embedded tissue. To do
this, the paraffin has to be removed. This may be done in several ways,
some of which are based on using xylene. |
Detection techniques There are a number of methods which can make the amplified DNA visible
to the human eye. One very common method is the separation of DNA
copies using a gel. On this gel, after gel electrophoresis, all DNA
segments will be sorted according to size. The DNA is then stained and
the gel is visualized with ultraviolet light. In this way, a segment
containing 560 base pairs (bp) can very easily be distinguished from a
fragment with 1,000 base bairs. The visible band does not really equal
just one single molecule, but at best 2 to the power of x copies of the
same segment.
See also -> amplification.
Real time PCR is one very sophisticated method for the detection of PCR fragments. |
| DNA-extraction There exists a large variety of techniques used for isolating DNA from
cells. Some cells, for example certain bacteriae, have to be treated
with an additional enzyme solution, because they have a very firm cell
wall. |
| DNA-polymerase This enzyme is used in PCR. Normally, enzymes are quickly destroyed by
heat, this process is called denaturation of an enzyme. For some time
now, extremely thermo stable polymerases whose blueprints originate
from micro organisms found in extremely hot environments (for example thermus aquaticus)
have been used in order to save having to add new enzyme to the
reaction vessel for every copy step in amplification. This also enables
the automation of PCR cycles. |
Dysplasia - "Atypical epithelium", melting pot of all atypically proliferating
cell alterations, especially alterations of the cell nucleus (cell
nucleus polymorphism, hyperchromatic nuclei).
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| E |
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| Elongation At 72 degree centigrade, DNA polymerase elongates the oligo nucleotide chain attached to the template DNA. |
Empyema (in Greek: en = within, pyon = pus) purulent inflammation in a
pre-existing cavity (for example pleural, pericardial or peritoneal
cavity).
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| Epithelium Specialized cells forming cell aggregations. |
| Ethidium bromide (EtBr) Because of its structure, it squeezes between two steps of the
rope-ladder-like double stranded DNA. This is called intercalation.
When stored in the DNA, it will fluoresce under ultraviolet light. This
way, DNA can be visualized on a gel and be photographed. This is what
happens in conventional PCR. In living cells, intercalation of the
material in the DNA causes mutations, therefore, EtBr is classified as
carcinogenic and adequate precautions have to be made when working with
it. |
Exfoliative cytology (in Latin: folium = leaf, exfoliatio = flaking off, peeling off) Taking
of cells which have spontaneously detached from the surface;
preparation of stained smear samples and microscopic analysis of cells
of
- spontaneously shed fluids (for example sputum, urine)
- lavages (for example bronchial lavage)
- direct smears taken from the surface of mucous membrane (for example upper digestive system, opening of uterus)
- body cavity fluids, of the neighboring surfaces (for example fluids in joint cavities, abdominal and pleural region).
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| Expression Summarizing term for the process by which a gene is converted into a protein. |
| Expression analysis Among other things, molecular methods are used in order to determine
which gene should be chosen for making particularly many or few
transcripts – RNA copies. This allows conclusions as to the “piece
numbers” of the respective protein. |
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| F |
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Frozen section analysis Tissue taken during surgery is examined within minutes in a frozen
section; the result is communicated immediately either by phone or in
writing and is crucial for the subsequent surgical procedure.
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Fungi As well as large fungi (such as mushrooms), there is a number of fungi
existing as micro organisms. Just like bacteriae, some of them are
useful, some are not. Some useful fungi can be found in the food
industry, for example the yeas saccharomyces cerevisiae and various
moulds used in the production of cheese. Cutaneous fungi
(athlete’s foot, onychomycosis) or of the Candida species (candidiasis
in infants) are some pathogen fungi. One special thing about them is
the fact that they keep their DNA in a cell nucleus and are therefore
eukaryotes (in Greek: eu = good, karyo = nucleus) just like humans.
Some anti-bacterial antibiotics are ineffective in the treatment of
funci, so specially designed antibiotics have to be used in the
therapeutical management of fungal diseases. However, fungi play a very
important role in medicine: they produce substances inhibiting or
killing many bacteriae or even other fungi – antibiotics (such as
penicillin and cephalosporin).
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| Furuncle (in Latin: furunculus = little thief) is a small abscess surrounding a hair follicle. |
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| G |
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| Genes “Blueprints” for proteins, every living subject is constructed on their
basis – the look and making of all that lives is determined by genes. |
| Genome The total of all genetic information of any organism. Humans have an estimated 30,000 genes. |
Germs See also pathogen: “bug” (bacteriae, fungi) or infectious particle (virus) causing a disease.
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Granulation tissue is a tissue comprising proliferating capillaries and fibroblasts and
some other cellular elements in changing numbers, demarking necrotic
tissue and repairing tissue defects.
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Granuloma Small, tumour-like nodules (thus the suffix –om), normally consisting
of macrophages, that are able to transform into various cell types;
they are very often surrounded by lympho-plasmic cell rims and often
contain multinuclear giant cells.
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| H |
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HER-2/neu(c-erbB2) Herceptin is a monoclonal antibody (active ingredient: trastuzumab),
specifically intervening in molecular biological proceedings in
breast carcinoma cells, thus inhibiting tumour growth. The active
ingredient Trastuzumab was constructed in such a way that it can attach
to the binding site of the signal receptor – human epidermal growth
factor receptor 2, in short: HER 2 -, in order to block the receptor.
However, in only 10 – 34 per cent of all breast cancer patients, the
number of HER-2 receptors on the cell surface is high enough to be able
to have a therapeutical impact.
Basis: The HER-2 / neu gene is localized on chromosome 17q, encoding
the transmembrane tyrosine kinase receptor protein, which is a member
of the so-called erbB2 or HER family. |
| Histology The science of tissues, including the science of cells. |
Hyperplasia Increase in the size of an organ or tissue caused by an increase in the number of cells.
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| Hypertrophy (in Greek: hyper = over) Increase in the size of an organ or tissue caused by an increase in the size of the individual cells. |
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| I |
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Infarction (infarcire, lat. = hineinstopfen) umschriebene Nekrose infolge eines
Verschlusses der versorgenden Gefäße. (Beispiel: Herzinfarkt,
Darminfarkt, Lungeninfarkt)
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Inflammation Complex response of the vascular connective tissue to cell or tissue
damage. Defence mechanism of the organism, removing hazardous influence
and assisting in the regeneration of lesions. Inflammations are
labelled with the suffix –itis, as in dermatitis, hepatitis, gastritis
and others.
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| M |
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| Metaplasia (in Greek: meta = after, plasso = to form) is a reversible alteration
of any differentiated tissue into another differentiated tissue of
similar architecture; often as a response to chronic irritation;
(example: the bronchial mucosa consists of cilitated epithelium, goblet
cells and basal cells, and are a kind of reserve cells responsible for
cell replenishment. The first step in metaplasia is the development of
basal cell hyperplasia. These basal cells then differentiate into
squamous cells. Squamous cell metaplasia of the bronchial mucosa, which
is very common, is reversible, in this process columnar epithelium
develops underneath the squamous epithelium. |
| Metastases (in Greek: methistemi = move something to another place) are filiae of
a primary tumour that have spread to another site by the misplacement
of tumour cells. |
| Microarray technology Using so-called microarrays it is possible to create a profile of
certain tissues or cells. This profile records which genes in the cells
are switched on or off. When comparing different profiles, differences
between a tumour cell and a healthy cell can be visualized. In order to
obtain such a profile, the RNA of different cells is compared. |
| Microorganisms (MO) This term summarizes bacterial and certain fungal forms of life. In
microbiology, virusses are also included, however, these have no
metabolism of their own and therefore their survival and reproduction
are dependent on host cells. Because of this, they are not really
microorganisms. Microbic disease-causing agents are often calles
pathogens. |
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| N |
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| Necrosis (in Greek: nekros = dead) is the morphological chance following the
death of a circumscribed tissue region or single cells in the living
organism. |
| Neoplasia Tissue growth caused by autonomic, progressive and overflowing
proliferation of endogenous cells. The term neoplasia itself does not
indicate the dignity, it does not differentiate between benign and
malignant lesions. |
| Nucleic acids Desoxyribonucleic acid – DNA and ribonucleic acid – RNA are found in
cells, where they are some kind of blueprint for proteins. The
sequences G, A, T and C (DNA) or G, A, U and C (RNA) determine the
shape of the three-dimensional protein consisting of amino acids. PCR
testing for pathogens tries to determine nucleic acids of viruses or
bacteriae. DNA is normally found in the shape of a double helix. |
| Nucleotides (dNTPs) Components used in DNA polymerase for elongation at 72 degrees centigrade. |
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| O |
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| Oligonucleotides Short DNA sequences which bind to suitable regions of a DNA single
strand, with A always binding to T and C always binding to G (for
example, ATGGGCCTAT will bind to TACCCGGATA). |
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| P |
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Pathogens A pathogen is a disease-causing germ. These germs may be bacteriae, fungi or viruses.
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| PCR Polymerase chain reaction, a method invented by Kary Mullis and since
then further developed and employed for numerous medical and scientific
purposes, used for the targeted demonstration of nucleic acid sequences. |
| Primer See oligonucleotides |
Protein Collagen und keratin (found in connective tissue, bone, skin, hair, and
finger nails) are just two samples of proteins. The shape and function
(for example elasticity of the skin by collagen) of every protein are
determined by a blueprint gene.
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| Pyoarthros Empyema of the joint cavity. |
| Pyometra Empyema of the uterus. |
| Pyosalpinx Empyema of the tuba uterina. |
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| R |
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| Real-Time-PCR Amongst other purposes, this special PCR method is used to determine
very quickly whether or not a certain gene (DNA level) is present in a
sample (for example testing for pathogens). It is also used for
recording the number of genes or their RNA copies. This makes real time
PCR a highly valued tool in expression analysis. |
| Recurrence The recurrence of the same disease after a symptom-free interval; for example tumour recurrence. |
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| S |
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| Sample taking This is the surgical removal of tissue for histological analyses, all organs and tissues can be reached using this method. |
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| T |
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Target DNA (see also template) Sequence of the pathogen DNA which is to be copied and detected by PCR.
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| Template Starting material for PCR, the DNA. Oligonucleotides attach to the
“template”, the target DNA which is to be amplified or detected (for
example mycobacterium tuberculosis), offering the enzyme DNA polymerase
a starting point for its work. |
| Transcript The transcript is a connection between gene (DNA) and protein (amino
acids). Every protein originates from a gene. The transcript conists of
RNA and is some kind of gene copy (DNA). The RNA reaches the cellular
protein synthesis where it is used as a blueprint. |
| Transcription The process during which the transcript of a gene (DNA) – a copy of the
RNA – is produced. During transcription, several hundred to thousands
of transcripts of one single gene are produces within a short time. In
this way a cell is able to produce many many numbers of a protein |
Tumour = growth = neoplasia (in Greek: new growth)
A tumour is an abnormal tissue mass resulting from a continuous,
overflowing proliferation of endogenous cells; it is an increase in
tissue uncoordinated with normal tissue, the increase will remain even
after the triggering stimulus has gone down;
benign tumours: generally, these are not life-threatening;
malignant tumours will, if untreated, result in death after a short time, ranging from a couple of months to some years.
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| Tumour markers are various proteins which can be demonstrated in the blood or other
body fluids of cancer patients, on the surface of tumour cells or
within tumour cells. Tumour markers are produced by cancer cells or
their production is triggered by tumour cells. Most tumour markers are
not tumour-specific. Some tumour markers may be increased in various
malignant tumours. |
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| V |
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| Viruses Minute, microscopic particles, consisting of a protein coat (capsid), a
little RNA or DNA (only one of the two) and a small number of enzymes,
needed for smuggling in their “genotype” into the cells and the genome
of the host. One of these enzymes, which is used in many different ways
in medicine and research, is the reverse transcriptase of retroviruses
(RNA as nucleic acid). Viruses have no metabolism of their own, their
“survival” depending on host cells. Some known examples are the
influenza virus and viruses causing rabies, herpes simplex, glandular
fever and mumps. |
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