Modern Medical Laboratory Journal

A positron emission tomography (PET) scan is an imaging test that can help reveal the metabolic or biochemical function of your tissues and organs. The PET scan uses a radioactive drug (tracer) to show both normal and abnormal metabolic activity. A PET scan can often detect the abnormal metabolism of the tracer in diseases before the disease shows up on other imaging tests, such as computerized tomography (CT) and magnetic resonance imaging (MRI).
The tracer is most often injected into a vein within your hand or arm. The tracer will then collect into areas of your body that have higher levels of metabolic or biochemical activity, which often pinpoints the location of the disease. The PET images are typically combined with CT or MRI and are called PET-CT or PET-MRI scans.

A PET scan is an effective way to help identify a variety of conditions, including cancer, heart disease and brain disorders. Your doctor can use this information to help diagnose, monitor or treat your condition.
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X-ray fluorescence (XRF), which has been applied during the 1970s to 1990s, is based on the observation of (X-ray) photon emissions of atoms, which are induced into an excited state by irradiation with X-rays causing the removal of a core electron from the atom. The resulting inner shell vacancies are filled by electrons from outer shells of the same atom. The difference in energy between the two electron orbitals appears as an emitted X-ray photon, which can be measured with an X-ray spectrometer.
The technology used for the separation (dispersion), identification and intensity measurement of a sample's X-ray fluorescence spectrum gives rise to two main types of spectrometer: wavelength dispersive (WDXRF) and energy dispersive (EDXRF) systems.
In WDXRF spectrometers, the X-ray tube acting as a source irradiates a sample directly, and the fluorescence coming from the sample is measured with a wavelength dispersive detection system. The characteristic radiation coming from each individual element can be identified using analyzing crystals which separate the X-rays based on their wavelength, or conversely their energies.
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Magnetic resonance imaging (MRI) is a non-destructive imaging technique that works on the basis of nuclear magnetic resonance (NMR). This noninvasive imaging method is used for the observation of anatomic structures, physiological functions, and molecular composition of tissues. Raymond Vahan Damadian (an American physician) performed a full-body scan of a human being for the first time, in 1977. The basis of MRI is that certain atomic nuclei, typically those of hydrogen, in the tissue, become magnetized when placed in an external magnetic field. This produces, in the tissue, a net magnetization, M, that is initially aligned with the direction of the main magnetic field, B₀. This imaging technique is remarkable because of high spatial resolution, strong soft tissue contrast and specificity, and good depth penetration. However, MR imaging of hard tissues, such as bone and teeth, remains challenging due to low proton content in such tissues as well as to very short transverse relaxation times.
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Nuclear Magnetic Resonance (NMR) is a spectroscopic technique that allows the analysis of three-dimensional structures and dynamics of macromolecules, as well as their complexes in solution, at atomic resolution. This non-destructive analytical technique which was discovered in 1945, consists of a superconducting magnet, a spectrometer, a control system, and a detector (probe). During NMR measurements, a sample solution is placed in the magnetic field and is irradiated with radio waves from a spectrometer that includes observation and irradiation systems. The bounced analog signal, called free induced decay, is amplified and digitized to obtain the corresponding NMR signals and spectrum.
NMR spectroscopic technique is one of the more sophisticated and authenticated techniques used to elucidate the structural characteristics of nanomaterials, polymers, and their nanocomposites. Multinuclear NMR spectral analyses, especially by solid state NMR studies, provide the conformation of different chemical environments for protons, carbons, nitrogen, silicon, etc.
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Scientists at the University of Virginia Health System developed a tiny mouse embryo with a beating heart which its muscles, blood vessels, gut and nervous system are beginning to develop. This investigation which was published by Nature communications in June 2021 shows that instruction of aggregates of mouse embryonic stem cells with an experimentally engineered morphogen signalling centre, that functions as an organizer, results in the development of embryo-like entities (embryoids). In situ hybridization, immunolabelling, cell tracking and transcriptomic analyses show that these embryoids form the three germ layers through a gastrulation process and that they exhibit a wide range of developmental structures, highly similar to neurula-stage mouse embryos.
This in vitro model is not a complete mouse yet and cannot develop into one due to the fact that Key parts are still missing, such as the anterior part of the brain. However, this embryoid will help scientists understand mammalian development, battle diseases, create new drugs and, eventually, grow tissues and organs for people in need of transplants.
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Mass spectrometry (MS) is known as a useful analytical detection technique. Various types of information about the molecular weights and chemical structures of the peptides, proteins, carbohydrates, oligonucleotides, natural products, and drug metabolites could be achieved by the use of MS. This technique which was invented in 1898, is widely used for various molecular biology analysis purposes either alone or combined with other structural proteomics techniques because of its advantages. The principle of MS is to generate ions from either inorganic or organic compounds by any suitable method, to separate these ions by their mass-to-charge ratio (m/z) and to detect them qualitatively and quantitatively by their respective m/z and abundance. The analyte may be ionized thermally, by electric fields or by impacting energetic electrons, ions or photons. The first step in the mass spectrometric analysis of compounds is the production of gas-phase ions of the compound, basically by electron ionization. This molecular ion undergoes fragmentation.
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Diabetic nephropathy is the most common cause of end-stage renal disease, accounting for 29% in Europe in 2018. As the prevalence of type 2 diabetes increases, the number of people with diabetes and end-stage renal disease requiring renal replacement therapy is also rising. End-stage renal disease and dialysis itself increase the risk of hypoglycemia and hyperglycemia, which are associated with adverse outcomes
Scientists from Cambridge University successfully tested an artificial pancreas on humans. The new technology could help people living with type 2 diabetes and who require kidney dialysis. A recent trial showed that the device can help patients safely manage their blood sugar levels. The new version of the artificial pancreas can function automatically. Unlike the artificial pancreas being used for type 1 diabetes, this version is a fully closed-loop system. In this study, they hypothesized that fully closed-loop insulin delivery may improve glycemic control compared to standard insulin therapy without increasing the risk of hypoglycemia in people with type 2 diabetes and end-stage renal disease undergoing maintenance dialysis in the outpatient setting.
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Hemocytometer, the first cell counting method, was invented in the late nineteenth century by Louis-Charles Malassez. A hemocytometer consists of a thick glass microscope slide with a grid of perpendicular lines etched in the middle. The grid has specified dimensions so that the area covered by the lines is known, which makes it possible to count the number of cells in a specific volume of solution. Preparing samples for total nucleated cell count begins with sample staining with 3% Acetic Acid with Methylene Blue.
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Brain organoids derived from human pluripotent stem cells provide a highly valuable in vitro model to recapitulate human brain development and neurological diseases. However, the current systems for brain organoid culture require further improvement for the reliable production of high-quality organoids. In the latest Nature publication, researchers demonstrate two engineering elements to improve human brain organoid culture, (1) a human brain extracellular matrix to provide brain-specific cues and (2) a microfluidic device with periodic flow to improve the survival and reduce the variability of organoids. A three-dimensional culture modified with brain extracellular matrix significantly enhanced neurogenesis in developing brain organoids from human induced pluripotent stem cells. Cortical layer development, volumetric augmentation, and electrophysiological function of human brain organoids were further improved in a reproducible manner by dynamic culture in microfluidic chamber devices. This engineering concept of reconstituting brain-mimetic microenvironments facilitates the development of a reliable culture platform for brain organoids, enabling effective modeling and drug development for human brain diseases.
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The MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay is the first widely accepted colorimetric assay to measure cell proliferation and viability. The use of MTT tetrazolium was first developed by Mossman in 1983. The mechanism of this assay based on the reduction of MTT, a yellow water-soluble tetrazolium dye, primarily by the mitochondrial dehydrogenases (nicotinamide adenine dinucleotide phosphate (NADPH)-dependent cellular oxidoreductase enzymes), to insoluble formazan crystals with purple color. Then, a solubilization solution should be added to dissolve the insoluble purple formazan into a colored solution. The absorbance of this colored solution can be quantified by measuring between 500 and 600 nm wavelength by a spectrophotometer.

Polymerase chain reaction (PCR) is a revolutionary method developed by Kary Mullis in the 1980s. PCR is based on using the ability of DNA polymerase to synthesize new strand of DNA complementary to the offered template strand. Because DNA polymerase can add a nucleotide only onto a preexisting 3'-OH group, it needs a primer to which it can add the first nucleotide. This requirement makes it possible to delineate a specific region of template sequence that the researcher wants to amplify. At the end of the PCR reaction, the specific sequence will be accumulated in billions of copies (amplicons).
PCR consist of three main stages: Denaturing – when the double-stranded template DNA is heated to separate it into two single strands. Annealing – when the temperature is lowered to enable the DNA primers to attach to the template DNA. Extending – when the temperature is raised and the new strand of DNA is made by the Taq polymerase enzyme.
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Enzyme-linked immunosorbent assay (ELISA) as a method that revolutionized medicine discovered by Eva Engvall and Peter Perlman in 1971. 
ELISA is a labeled immunoassay that is considered the gold standard of immunoassays. This immunological test is very sensitive and is commonly used to measure antibodies, antigens, proteins, glycoproteins, and hormones in biological samples. Some examples include diagnosis of HIV infection, pregnancy tests, and measurement of cytokines or soluble receptors in cell supernatant or serum. The detection of these products is accomplished by complexing antibodies and antigens to produce a measurable result. ELISA assays are generally carried out in 96 well plates, allowing multiple samples to be measured in a single experiment.
The four main types of ELISAs are indirect, direct, sandwich, and competitive.
The most straightforward version of these assays is the direct ELISA, a test capable of identifying antigens in a sample by optimizing the formation of antigen-antibody complexes. In a direct ELISA, the primary detection antibody binds directly to the protein of interest. Next, the plate is rewashed to remove any unbound antibody and followed by the addition of a substrate.

Read more about the other types of ELISA

Messenger RNA (mRNA) vaccines are some of the first COVID-19 vaccines authorized for use in the United States. mRNA vaccines are a new type of vaccine to protect against infectious diseases. To trigger an immune response, many vaccines put a weakened or inactivated germ into our bodies. Not mRNA vaccines. Instead, they teach our cells how to make a protein—or even just a piece of a protein—that triggers an immune response inside our bodies. That immune response, which produces antibodies, is what protects us from getting infected if the real virus enters our bodies.COVID-19 mRNA vaccines give instructions for our cells to make a harmless piece of what is called the “spike protein.” The spike protein is found on the surface of the virus that causes COVID-19.
Facts about COVID-19 mRNA Vaccines

1. mRNA vaccines cannot give someone COVID-19.
2. mRNA never enters the nucleus of the cell and they can not affect or interact with our DNA.
3. the cell gets rid of the mRNA soon after it is finished using the instructions.
4. The benefit of mRNA vaccines, like all vaccines, is those vaccinated gain protection without ever having to risk the serious consequences of getting sick with COVID-19.
5. mRNA vaccines have been held to the same rigorous safety and effectiveness standards external icon as all other types of vaccines in the United States.

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Most of us know about vaccines given to healthy people to help prevent infections, such as measles and chicken pox. These vaccines use weakened or killed germs like viruses or bacteria to start an immune response in the body. Getting the immune system ready to defend against these germs helps keep people from getting infections. Most vaccines used to treat cancer work the same way, but they make the person’s immune system attack cancer cells. The goal is to help treat cancer or to help keep it from coming back after other treatments. But there are also some vaccines that may actually help prevent certain cancers.
Cancer immunotherapy has branched into various categories, and one of the most promising and also frustrating approaches is cancer vaccination. Vaccination has saved a million lives in the world. However, Cancer Vaccine technology has gone a long and challenging way to reach today’s place. A lot of failures in this therapy, galvanized scientists to find more efficient methods for better targeting and precise antigen and adjuvant selection. Divergent platforms and various vaccine types have been tested during the last thirty years.
Dendritic Cells, Long/Short peptides, whole tumor cell lysate, viral-based, and Genetic-based vaccines are the most common vaccine types. Novel approaches in cancer vaccination are mainly based on personalized vaccination, Nano-carrier usage, and combination therapy.
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A novel variant of concern (VOC) named CAL.20C (B.1.427/B.1.429), originally detected in California, carries spike glycoprotein mutations S13I in the signal peptide, W152C in the N-terminal domain (NTD), and L452R in the receptor-binding domain (RBD).
An international project which was done in the Department of Biochemistry at the University of Washington in Seattle indicates that the Epsilon variant is one of the most resistant SARS-CoV-2 variants to vaccines relying on an indirect and unusual neutralization-escape strategy. To learn more about the characteristics of this variant the researchers examined plasma from individuals vaccinated with a Wuhan-1 isolate-based mRNA vaccine or convalescent individuals. The results of this evaluation exhibited neutralizing titers, which were reduced 2-3.5 fold against the B.1.427/B.1.429 variant relative to wildtype pseudoviruses. The L452R mutation reduced neutralizing activity of 14 out of 34 RBD-specific monoclonal antibodies (mAbs). The S13I and W152C mutations resulted in total loss of neutralization for 10 out of 10 NTD-specific mAbs since the NTD antigenic supersite was remodeled by a shift of the signal peptide cleavage site and formation of a new disulphide bond, as revealed by mass spectrometry and structural studies.
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Human umbilical cord-derived mesenchymal stem cells (UC-MSCs) have been proposed that are effective in the regeneration of damaged lungs in severe COVID-19 patients. In this regard, In a randomized, double-blind, placebo-controlled phase 2 trial, Shi et al. illustrated that UC-MSCs treatment is a safe and potentially effective therapeutic approach for COVID-19 patients with lung damage. 
Mesenchymal stem cells (MSCs) are non-hematopoietic cells with immune-modulatory, regenerative, and differentiation properties. And their efficacy as a therapeutic method against pathological changes of the lung induced by the influenza virus. moreover, The safety and potential efficacy of MSC have also been evaluated in patients with acute respiratory distress syndrome (ARDS). The immunomodulatory and regenerative properties of MSCs offer a potential cellular therapeutic option for lung damage in patients with COVID-19.
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The first evidence for cellular reprogramming was provided in 1958 by John Gurdon. In his famous experiment, the somatic nuclei of an adult Xenopus (African frog) were transplanted into an oocyte, which was then able to develop into a sexually mature adult.
The reprogramming of somatic cells with defined factors, which converts cells from one lineage into cells of another, has greatly reshaped our traditional views on cell identity and cell fate determination. Cells can be reprogrammed into induced pluripotent stem cells (iPSCs), embryonic-like stem cells that can turn into any cell type and have extensive potential medical uses. Ectopic expression of Oct4, Sox2, Klf4 and c-Myc can reprogram somatic cells into induced pluripotent stem cells (iPSCs). Attempts to identify genes or chemicals that can functionally replace each of these four reprogramming factors have revealed that exogenous Oct4 is not necessary for reprogramming under certain conditions or in the presence of alternative factors that can regulate endogenous Oct4 expression.
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