Epstein-Barr virus: increased the risk of multiple sclerosis!

 | Post date: 2022/01/21 | 
Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system of unknown etiology. The demyelination in the brain and spinal cord is an immune-mediated process possibly triggered by a viral infection . Among the putative causal agents, the top candidate is Epstein-Barr virus (EBV). EBV is a human herpesvirus that after infection persists in latent form in B lymphocytes throughout the life of the host. According to a study led by Harvard T.H. Chan School of Public Health researchers, MS, a progressive disease that affects 2.8 million people worldwide and for which there is no definitive cure, is likely caused by infection with the EBV. To determine the connection between EBV and MS, the researchers conducted a study among more than 10 million young adults on active duty in the U.S. military and identified 955 who were diagnosed with MS during their period of service.
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First pig-to-human heart transplant: how many of the modifications are necessary?

 | Post date: 2022/01/17 | 
Physicians and scientists worldwide have for decades been pursuing the goal of transplanting animal organs into people, known as xenotransplantation. Xenotransplantation has seen significant advances in recent years with the advent of CRISPR–Cas9 genome editing, which made it easier to create pig organs that are less likely to be attacked by human immune systems. The latest transplant, performed at the University of Maryland Medical Center (UMMC), used organs from pigs with ten genetic modifications. The heart used in the transplant came from a pig with several genetic modifications, including some to knock out genes that trigger the human immune system. 

The researchers had applied to the US Food and Drug Administration (FDA) to do a clinical trial of the pig hearts in people but were turned down. According to Muhammad Mohiuddin, the University of Maryland surgeon who leads the research team behind the transplant, the agency was concerned about ensuring that the pigs came from a medical-grade facility and wanted the researchers to transplant the hearts into ten baboons before moving on to people. But 57-year-old David Bennett gave Mohiuddin’s team a chance to jump straight to a human transplant.
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Polarized Light Microscopy

 | Post date: 2022/01/14 | 
Polarized light microscopy provides unique opportunities for analyzing the molecular order in heterogeneous systems, such as living cells and tissues, without using exogenous dyes or labels. The polarizing microscope is essentially a light microscope equipped with a linear polarizer located below the condenser and an additional polarizer mounted on top of the eyepiece. The polarizing microscope has the ability to detect anisotropic objects, such as Oriented bonds (anisotropic phase objects), Oriented chromophores (anisotropic amplitude objects), Oriented micelles (cellulose, actin fibrils, plasma membrane), etc. 

Materials fall into one of two categories. The first are materials that demonstrate the same optical properties in all directions, such as gases, liquids, and certain glasses and crystals. These are isotropic materials. Because they are optically the same in all directions, they have only one RI. Light, therefore, passes through them at the same speed with no directional restrictions.

The second category is anisotropic materials, which have optical properties that vary with the orientation of the incoming light and the optical structure of the material. About 90% of all solid materials are anisotropic. The RIs vary in anisotropic materials depending both on the direction of the incident light and on the optical structure. 


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Caspase Activity Assay

 | Post date: 2022/01/7 | 
Many assays are available to discern whether dead and dying cells are undergoing apoptosis or necrosis. Because caspases are the central executioners involved in apoptosis, their activity is a hallmark of this form of cell death. Detection of caspase activity is conveniently done with chromogenic substrates such as DEVD-pNA or its more sensitive fluorogenic counterpart, DEVD-AFC. Because of the high caspase concentrations in crude extracts or cytosol preparations, it is possible to perform activity assays in a conveniently small sample volume. Caspase activation is a central biochemical process in apoptosis. Caspase activity assays in multi-well plate formats represent powerful tools for understanding experimental modulation of the apoptotic response.
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Agar Diffusion Test: the primary method to determine the antimicrobial activity

 | Post date: 2022/01/3 | 
The agar diffusion method was developed as a practical alternative to the agar and broth tube dilution procedures. The most popular agar diffusion method is the Kirby-Bauer disk diffusion method. In this method, the test agar plate is swabbed with a standardized concentration of the test organism, and then paper disks containing a defined antibiotic concentration are placed on the lawn of bacteria. After overnight incubation, the diameter of the zone of inhibited growth around the disk is measured. This zone is influenced by a number of variables, including the susceptibility test medium (Mueller-Hinton agar is the standard for bacterial tests), the concentration of the test organism, the rate of growth of the test organism, the concentration of antibiotic in the disk, the diffusion of the antibiotic in the agar, and the susceptibility of the organism to the antibiotic. The method was originally devised by Ouchterlony. 
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Liquid Chromatography Mass Spectrometry (LCMS)

 | Post date: 2021/12/27 | 
Liquid chromatography-mass spectrometry (LC–MS) is a powerful analytical technique used for separation, identification, and quantification of both unknown and known compounds as well as to elucidate the structure and chemical properties of different molecules. It is very useful for analyzing small molecules and offers higher sensitivity and selectivity in the trace analysis of multicomponent containing substances.  LC-MS combines the physical separation capabilities of liquid chromatography (or HPLC) with the mass analysis capabilities of MS. Multiple different LC-MS platforms including, LC-MS, liquid chromatography tandem mass spectrometry (LC-MS/MS), liquid chromatography/time-of-flight mass spectrometry (LC-TOF), Liquid Chromatography-quadrupole Time-of-flight Mass Spectrometry (LC-QTOF), and liquid chromatography-Orbitrap mass spectrometry (LC-Orbitrap) have been used for toxicology testing. In addition, multiple different data acquisition modes have been described; including, targeted and untargeted data acquisition methods with and without data dependent acquisition of product ion spectra (DDA or DIA).
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Magnetic-Activated Cell Sorting (MACS)

 | Post date: 2021/12/23 | 
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Fluorescence-activated Cell Sorting (FACS): a Specialized Type of Flow Cytometry!

 | Post date: 2021/12/20 | 
Fluorescence-activated cell sorting (FACS) is a specialized type of flow cytometry. It provides a method for sorting a heterogeneous mixture of biological cells into two or more containers, one cell at a time, based upon the specific light scattering and fluorescent characteristics of each cell. It is a useful scientific instrument, as it provides fast, objective and quantitative recording of fluorescent signals from individual cells as well as physical separation of cells of particular interest.
This method enables researchers to better understand the characteristics of a single cell population without the influence of other cells. Compared to other methods of cell enrichment, such as magnetic-activated cell sorting (MCS), FACS is more flexible and accurate for cell separation due to the ability of phenotype detection by flow cytometry. In addition, FACS is usually capable of separating multiple cell populations simultaneously, which improves the efficiency and diversity of experiments. Although FACS has some limitations, it has been broadly used to purify cells for functional studies in both in vitro and in vivo settings. Different cell types usually express unique molecules, or a unique combination of several molecules, on the plasma membrane that can distinguish one cell population from another. Upon binding of these cell surface molecules by specific fluorescence-conjugated antibodies, a detecting machine called flow cytometer/sorter is able to excite and detect the light signals of different fluorescent dyes that represent different molecule markers on the cells at the single cell level. The combined information consisting of either the presence of a light signal (representing positive expression of the corresponding surface molecule) or the absence of a light signal (representing negative expression of a molecule) defines the phenotype of the cell. After passing through the detector, cells with the same phenotype of interest are diverted towards a designated collecting tube based on electrical charge.

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Mesenchymal stromal cells: Prevention of post-surgery liver failure after extended partial hepatectomies!

 | Post date: 2021/12/10 | 
Post-surgery liver failure is a serious complication for patients after extended partial hepatectomies (ePHx). mesenchymal stromal cells (MSC) have been reported that improve circulatory maintenance and support multi-organ functions after 70% liver resection. Mechanisms behind the beneficial MSC effects remained unknown. In the latest Nature publication, scientists performed 70% liver resection in pigs with and without MSC treatment, and animals were monitored for 24 h post surgery. Gene expression profiles were determined in the lung and liver. Bioinformatics analysis predicted organ-independent MSC targets, importantly a role for thrombospondin-1 linked to transforming growth factor-β (TGF-β) and downstream signaling towards providing epithelial plasticity and epithelial-mesenchymal transition (EMT). This prediction was supported histologically and mechanistically, the latter with primary hepatocyte cell cultures. MSC attenuated the surgery-induced increase of tissue damage, of thrombospondin-1 and TGF-β, as well as of epithelial plasticity in both the liver and lung. This suggests that MSC ameliorated surgery-induced hepatocellular stress and EMT, thus supporting epithelial integrity and facilitating regeneration. MSC-derived soluble factor(s) did not directly interfere with intracellular TGF-β signaling, but inhibited thrombospondin-1 secretion from thrombocytes and non-parenchymal liver cells, therewith obviously reducing the availability of active TGF-β.
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Human immunodeficiency virus (HIV):Diagnosing, Concepts and Tests |

 | Post date: 2021/12/6 | 

HIV stands for human immunodeficiency virus. It weakens a person’s immune system by destroying important cells that fight disease and infection. There is currently no effective cure for HIV. But with proper medical care, HIV can be controlled. Some groups of people in the United States are more likely to get HIV than others because of many factors, including their sex partners and risk behaviors.
Newer, Improved HIV Tests Allow for Earlier HIV Detection

HIV tests have improved substantially over the years, and are now easier and less expensive, with a more rapid turnaround time for results.

Three types of HIV tests are available:

  • Nucleic acid tests (NATs) — detects HIV ribonucleic acid (RNA)
  • Antigen/antibody combination tests — detects HIV p24 antigen as well as HIV immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies
  • Antibody tests — detects HIV IgM and/or IgG antibodies

Following an exposure that leads to HIV infection, the amount of time during which no existing diagnostic test is capable of detecting HIV is called the eclipse period.
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Injectable, Pore-Forming, Perfusable Double-Network Hydrogels

 | Post date: 2021/12/3 | 
Scientists from McGill University developed an injectable hydrogel that possessed both high porosity and toughness at the same time which could be suitable for heart, muscles, and vocal cords regeneration. 
Biological tissues hinge on blood perfusion and mechanical toughness to function. Injectable hydrogels that possess both high permeability and toughness have profound impacts on regenerative medicine but remain a long-standing challenge. To address this issue, injectable, pore-forming double-network hydrogels are fabricated by orchestrating stepwise gelation and phase separation processes. The interconnected pores of the resulting hydrogels enable direct medium perfusion through organ-sized matrices. The hydrogels are amenable to cell encapsulation and delivery while promoting cell proliferation and spreading. They are also pore insensitive, tough, and fatigue resistant. When tested in biomimetic perfusion bioreactors, the hydrogels maintain physical integrity under prolonged, high-frequency biomechanical stimulations (>6000 000 cycles at 120 Hz). The excellent biomechanical performance suggests the great potential of the new injectable hydrogel technology for repairing mechanically dynamic tissues, such as vocal folds, and other applications, such as tissue engineering, biofabrication, organs-on-chips, drug delivery, and disease modeling.
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New approach in treating mental illness: Closed-loop enhancement and neural decoding of cognitive control in humans

 | Post date: 2021/11/26 | 
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Liver transplantation: history, outcomes and perspectives

 | Post date: 2021/11/22 | 

A liver transplant is a surgical procedure that removes a liver that no longer functions properly (liver failure) and replaces it with a healthy liver from a deceased donor or a portion of a healthy liver from a living donor. Liver transplant is usually reserved as a treatment option for people who have significant complications due to end-stage chronic liver disease. Liver transplant may also be a treatment option in rare cases of sudden failure of a previously healthy liver.
In 1963, Starzl et al. performed the first liver transplantation. In the first five liver transplantations no patient survived more than 23 days. In 1967, stimulated by Calne who used antilymphocytic serum, Starzl began a successful series of liver transplantation. Until 1977, 200 liver transplantations were performed in the world. In that period, technical problems were overcome. Roy Calne, in 1979, used the first time cyclosporine in two patients who had undergone liver transplantation. In 1989, Starzl et al. reported a series of 1,179 consecutives patients who underwent liver transplantation and reported a survival rate between one and five years of 73% and 64%, respectively.  Liver Transplantation Program was initiated at Hospital Israelita Albert Einstein in 1990 and so far according to the American Liver Foundation, around 8,000 liver transplant surgeries are performed in the United States every year.
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Bioactive scaffolds with enhanced supramolecular motion: promote recovery from spinal cord injury!

 | Post date: 2021/11/19 | 
The signaling of cells by scaffolds of synthetic molecules that mimic proteins is known to be effective in the regeneration of tissues. Álvarez et al. synthesized supramolecular peptide fibril scaffolds bearing two peptide sequences that promote nerve regeneration, one that reduces glial scarring and another that promotes blood vessel formation (see the Perspective by Wojciechowski and Stevens). In a mouse model of paralyzing human spinal cord injury, mutations in a tetrapeptide domain outside of the signaling regions improved recovery by promoting intense supramolecular motion within the fibrils. They describe peptide amphiphile supramolecular polymers containing two distinct signals and test them in a mouse model of severe spinal cord injury. One signal activates the transmembrane receptor β1-integrin and a second one activates the basic fibroblast growth factor 2 receptor. By mutating the peptide sequence of the amphiphilic monomers in nonbioactive domains, they intensified the motions of molecules within scaffold fibrils. This resulted in notable differences in vascular growth, axonal regeneration, myelination, survival of motor neurons, reduced gliosis, and functional recovery. 
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Diagnostic ultrasound: a valuable and safe procedure that uses low-power sound waves!

 | Post date: 2021/11/15 | 

The ultrasound image is produced based on the reflection of the waves off of the body structures. In an ultrasound exam, a transducer both sends the sound waves and records the echoing (returning) waves. When the transducer is pressed against the skin, it sends small pulses of inaudible, high-frequency sound waves into the body. As the sound waves bounce off internal organs, fluids and tissues, the sensitive receiver in the transducer records tiny changes in the sound's pitch and direction. A computer instantly measures these signature waves and displays them as real-time pictures on a monitor. The technologist typically captures one or more frames of the moving pictures as still images. They may also save short video loops of the images.
Ultrasound imaging is a medical tool that can help a physician evaluate, diagnose and treat medical conditions. Common ultrasound imaging procedures include:

  • Abdominal ultrasound (to visualize abdominal tissues and organs)
  • Bone sonometry (to assess bone fragility)
  • Breast ultrasound (to visualize breast tissue)
  • Doppler fetal heart rate monitors (to listen to the fetal heart beat)
  • Doppler ultrasound (to visualize blood flow through a blood vessel, organs, or other structures)
  • Echocardiogram (to view the heart)
  • Fetal ultrasound (to view the fetus in pregnancy)
  • Ultrasound-guided biopsies (to collect a sample of tissue)
  • Ophthalmic ultrasound (to visualize ocular structures
  • Ultrasound-guided needle placement (in blood vessels or other tissues of interest)

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Cord blood–derived mesenchymal stem cell: hope for recessive dystrophic epidermolysis bullosa patients!

 | Post date: 2021/11/11 | 
Recessive dystrophic epidermolysis bullosa (RDEB) is an incurable disease that causes severe mucocutaneous fragility due to mutations in COL7A1 (encoding type VII collagen [C7]). the results of the first phase I/II clinical trial of intravenous administrations of allogeneic human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) in patients with RDEB indicate that intravenous hUCB-MSC infusions were well tolerated, without serious adverse events. Improvements in the Birmingham Epidermolysis Bullosa Severity Score, body surface area involvement, blister counts, pain, pruritus, and quality of life were observed with maximal effects at 56–112 days after treatment. hUCB-MSC administration induced M2 macrophage polarization and reduced mast cell infiltration in RDEB skin. Serum levels of substance P were decreased after therapy.
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Neuro Embolization: a procedure used to treat an aneurysm!

 | Post date: 2021/11/9 | 
Embolization of brain aneurysms and arteriovenous malformations (AVM) uses imaging guidance to place small, soft metal coils into an aneurysm to block the flow of blood and prevent the aneurysm from rupturing. It also is used to fill AVMs – abnormal connections between arteries and veins – with liquid embolic agents (similar to fast-sealing glue). AVMs may prevent oxygenated blood from completely circulating throughout the brain and can cause a variety of problems, including headache, weakness, and other neurological symptoms. Embolization treats cerebral aneurysms and AVMs previously thought inoperable and is much less invasive than open surgery.
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Electroencephalography (EEG): the non-invasive brain imaging tools for assessing neurophysiological function!

 | Post date: 2021/11/5 | 
Electroencephalography (EEG) has been instrumental in making discoveries about cognition, brain function, and dysfunction. Hans Berger, a German psychiatrist, pioneered the EEG in humans in 1924. The EEG is an electrophysiological technique for the recording of electrical activity arising from the human brain.  EEG is particularly useful for evaluating patients with suspected seizures, epilepsy, and unusual spells. EEG uses the principle of differential amplification, or recording voltage differences between different points using a pair of electrodes that compares one active exploring electrode site with another neighboring or distant reference electrode.
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Hemodialysis: the most common type of dialysis!

 | Post date: 2021/11/2 | 

The renal functional capacity can be assessed by measuring serum creatinine/blood urea nitrogen (BUN) or by urea and creatinine clearance. There are two types of dialysis procedures; it may be hemodialysis (using a machine/artificial kidney-like apparatus) or peritoneal dialysis (using a peritoneal membrane as a filter). Peritoneal dialysis is recommended for younger patients because of its flexibility and can be performed at home. Hemodialysis is done for patients with no residual renal function. Dr. Willem Kolff is considered the father of dialysis. This young Dutch physician constructed the first dialyzer (artificial kidney) in 1943. 

The mechanism of hemodialysis:

In hemodialysis, the wastes and excess water are removed by using an external filter called a dialyzer, which contains a semipermeable membrane. The separation of wastes is done by creating a counter-current flow gradient, where blood flow is in one direction and the fluid of the dialyzer is in the opposite direction. Peritoneal dialysis uses the peritoneum as a natural semipermeable membrane and removes waste and water into the dialysate (the material or fluid that passes through the membrane of the dialysis).
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Gene therapy: providing hope for a way to restore visual function after ischemic injury!

 | Post date: 2021/10/28 | 
Neural circuits underlying brain functions are vulnerable to damage, including ischemic injury, leading to neuronal loss and gliosis. Neurons don't regenerate. The brain can sometimes remap its neural pathways enough to restore some visual function after a stroke, but that process is slow, it's inefficient, and for some patients, it never happens at all. A research team at Purdue University investigated the effect of NeuroD1-mediated in vivo direct reprogramming on visual cortical circuit integration and functional recovery in a mouse model of ischemic injury. After performing electrophysiological extracellular recordings and two-photon calcium imaging of reprogrammed cells in vivo and mapping the synaptic connections formed onto these cells ex vivo, they discovered that NeuroD1 reprogrammed neurons were integrated into the cortical microcircuit and acquired direct visual responses. Furthermore, following visual experience, the reprogrammed neurons demonstrated maturation of orientation selectivity and functional connectivity. their results show that NeuroD1-reprogrammed neurons can successfully develop and integrate into the visual cortical circuit leading to vision recovery after ischemic injury.
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