"Immunoelectron microscopy" defines a group of techniques developed for visualizing where components of cells or tissues are localized, by means of a transmission electron microscope (TEM) at a ...subcellular resolution. The method is based on antigen recognition by primary antibodies and subsequent visualization of recognized structures by means of electron-opaque gold granules, which are easily visible in TEM images. The potentially high resolution of this method relies on the very small size of the colloidal gold label, which consists of granules ranging from 1 to 60 nm in diameter, mostly used in the 5-15 nm sizes.
Controls for Immunohistochemistry Hewitt, Stephen M.; Baskin, Denis G.; Frevert, Charles W. ...
The journal of histochemistry and cytochemistry,
10/2014, Letnik:
62, Številka:
10
Journal Article
Recenzirano
Odprti dostop
Immunohistochemistry is widely used in biomedical research to localize specific epitopes of molecules in cells and tissues. The validity of interpretations based on immunohistochemistry requires ...appropriate positive and negative controls that are often not reported in publications. This omission may lead to incorrect interpretations and irreproducible results in the literature and contribute to wasted time, effort, and resources as well as erosion of confidence in scientific investigation by the general public, legislative bodies and funding agencies. The present article summarizes essential controls required for validation of immunohistochemical findings and represents a standard of practice for the use of immunohistochemistry in research and diagnostic investigations. Adherence to the guidelines described in the present article can be cited by authors as support for the validity of interpretations of the immunohistochemistry reported in their publications.
A 67-year-old man was admitted to our hospital for massive pleural effusion. He had a history of mandibular gingival carcinoma treated with radiation therapy (RT). Based on the cytology findings of ...pleural effusion and a thoracoscopic pleural biopsy, we finally diagnosed him with radiation-associated angiosarcoma. Retrospective cell-block immunocytochemistry with pleural effusion also showed potential utility for the diagnosis. This case highlights the importance of considering the possibility of radiation-associated secondary cancer in patients with pleural effusion who have a history of RT.
The ability to culture and maintain postnatal mouse hippocampal and cortical neurons is highly advantageous, particularly for studies on genetically engineered mouse models. Here we present a ...protocol to isolate and culture pyramidal neurons from the early postnatal (P0-P1) mouse hippocampus and cortex. These low-density dissociated cultures are grown on poly-L-lysine-coated glass substrates without feeder layers. Cultured neurons survive well, develop extensive axonal and dendritic arbors, express neuronal and synaptic markers, and form functional synaptic connections. Further, they are highly amenable to low- and high-efficiency transfection and time-lapse imaging. This optimized cell culture technique can be used to culture and maintain neurons for a variety of applications including immunocytochemistry, biochemical studies, shRNA-mediated knockdown and live imaging studies. The preparation of the glass substrate must begin 5 d before the culture. The dissection and plating out of neurons takes 3-4 h and neurons can be maintained in culture for up to 4 weeks.
Glutamate is the most abundant free amino acid in the brain and is at the crossroad between multiple metabolic pathways. Considering this, it was a surprise to discover that glutamate has excitatory ...effects on nerve cells, and that it can excite cells to their death in a process now referred to as “excitotoxicity”. This effect is due to glutamate receptors present on the surface of brain cells. Powerful uptake systems (glutamate transporters) prevent excessive activation of these receptors by continuously removing glutamate from the extracellular fluid in the brain. Further, the blood–brain barrier shields the brain from glutamate in the blood. The highest concentrations of glutamate are found in synaptic vesicles in nerve terminals from where it can be released by exocytosis. In fact, glutamate is the major excitatory neurotransmitter in the mammalian central nervous system. It took, however, a long time to realize that. The present review provides a brief historical description, gives a short overview of glutamate as a transmitter in the healthy brain, and comments on the so-called glutamate–glutamine cycle. The glutamate transporters responsible for the glutamate removal are described in some detail.
Background
Mas‐related G protein‐coupled receptor X2 (MRGPRX2) is regarded as a mast cell‐specific receptor mediating non–IgE‐dependent activation. We aimed to investigate whether human basophils and ...eosinophils express functional MRGPRX2.
Methods
Flow cytometry, immunocytochemistry, immunofluorescence, Western blot, and RT‐PCR were performed in highly purified peripheral blood basophils and eosinophils of atopic and nonatopic donors. To assess functional activity, fluorescent avidin‐based degranulation assay, calcium mobilization, cytokine production in supernatants, assessment of viability/apoptosis, and tricolor granulocyte activation test were used.
Results
MRGPRX2 was significantly expressed by basophils and eosinophils but not neutrophils. Functional capacity was shown by anti‐MRGPRX2 mAb‐induced calcium influx and concentration‐dependent induction of degranulation. Sequential stimulation in the calcium mobilization assay gave no evidence for desensitization or receptor internalization. Anti‐MRGPRX2 mAb significantly promoted survival. Inhibition of apoptosis could be due to released IL‐3, IL‐5, and GM‐CSF found in supernatants. Short‐term incubation with IL‐3 dose‐dependently upregulated MRGPRX2 expression in both, stimulation for 24 hours with anti‐IgE, C5a, fMLP, and IL‐3 in basophils and by IL‐3, IL‐5, and IL‐33 in eosinophils. Among known mast cell MRGPRX2 agonists ciprofloxacin but not PMX‐53 was functional on basophils and eosinophils. In basophils of allergic subjects, tricolor granulocyte activation test using grass pollen demonstrated MRGPRX2 upregulation associated with degranulation and CD63 expression.
Conclusion
Unraveling the regulation and signaling mechanisms of MRGPRX2 on basophils and eosinophils might enable the development of new therapeutic strategies to prevent or inhibit allergic and nonallergic hypersensitivity. Moreover, addressing MRGPRX2 might have potential for diagnostic purposes in (drug) hypersensitivity.
MRGPRX2 is not mast cell specific, as it is expressed on comparable levels on peripheral blood basophils and eosinophils, but not neutrophils, from atopic and non‐atopic donors. Engagement of MRGPRX2 by monoclonal antibodies results in calcium influx, enhanced survival, and degranulation with release of cytokines. Mast cell MRGPRX2 ligand ciprofloxacin, but not PMX‐53, shows similar effects.# Granulocyte activation test with grass pollen in allergic subjects results in basophil and eosinophil MRGPRX2 upregulation similar to CD63 upregulation.
# survival not assessed with ciprofloxacin, cytokine release not assessed with PMX‐53;
Abbreviations: MRGPRX2, mas‐related G‐protein coupled receptor X2; PMX‐53, C5a receptor antagonist
The detection of cancer biomarkers in histological samples and blood is of paramount importance for clinical diagnosis. Current methods are limited in terms of sensitivity, hindering early detection ...of disease. We have overcome the shortcomings of currently available staining and fluorescence labeling methods by taking an integrative approach to establish photon-upconversion nanoparticles (UCNP) as a powerful platform for cancer detection. These nanoparticles are readily synthesized in different sizes to yield efficient and tunable short-wavelength light emission under near-infrared excitation, which eliminates optical background interference of the specimen. Here we present a protocol for the synthesis of UCNPs by high-temperature co-precipitation or seed-mediated growth by thermal decomposition, surface modification by silica or poly(ethylene glycol) that renders the particles resistant to nonspecific binding, and the conjugation of streptavidin or antibodies for biological detection. To detect blood-based biomarkers, we present an upconversion-linked immunosorbent assay for the analog and digital detection of the cancer marker prostate-specific antigen. When applied to immunocytochemistry analysis, UCNPs enable the detection of the breast cancer marker human epidermal growth factor receptor 2 with a signal-to-background ratio 50-fold higher than conventional fluorescent labels. UCNP synthesis takes 4.5 d, the preparation of the antibody-silica-UCNP conjugate takes 3 d, the streptavidin-poly(ethylene glycol)-UCNP conjugate takes 2-3 weeks, upconversion-linked immunosorbent assay takes 2-4 d and immunocytochemistry takes 8-10 h. The procedures can be performed after standard laboratory training in nanomaterials research.
Objective
Pathogenic variants in KCNB1, encoding the voltage‐gated potassium channel KV2.1, are associated with developmental and epileptic encephalopathy (DEE). Previous functional studies on a ...limited number of KCNB1 variants indicated a range of molecular mechanisms by which variants affect channel function, including loss of voltage sensitivity, loss of ion selectivity, and reduced cell‐surface expression.
Methods
We evaluated a series of 17 KCNB1 variants associated with DEE or other neurodevelopmental disorders (NDDs) to rapidly ascertain channel dysfunction using high‐throughput functional assays. Specifically, we investigated the biophysical properties and cell‐surface expression of variant KV2.1 channels expressed in heterologous cells using high‐throughput automated electrophysiology and immunocytochemistry–flow cytometry.
Results
Pathogenic variants exhibited diverse functional defects, including altered current density and shifts in the voltage dependence of activation and/or inactivation, as homotetramers or when coexpressed with wild‐type KV2.1. Quantification of protein expression also identified variants with reduced total KV2.1 expression or deficient cell‐surface expression.
Interpretation
Our study establishes a platform for rapid screening of KV2.1 functional defects caused by KCNB1 variants associated with DEE and other NDDs. This will aid in establishing KCNB1 variant pathogenicity and the mechanism of dysfunction, which will enable targeted strategies for therapeutic intervention based on molecular phenotype. ANN NEUROL 2019;86:899–912
The recent outbreak of 2019 coronavirus disease (COVID-19), caused by a novel coronavirus, has now spread quickly worldwide. Like the severe acute respiratory syndrome coronavirus (SARS-CoV), this ...novel type of coronavirus, SARS-CoV-2, has been demonstrated to utilize angiotensin-converting enzyme 2 (ACE2) as an entry point to the cells. There is a growing body of reports indicating that COVID-19 patients, especially those in severe condition, exhibit neurological symptoms, thus supporting the possibility that SARS-CoV-2 could infect and damage neurons within the central nervous system in humans. Using human pluripotent stem cells-derived neurons, here we show the expression of ACE2 in human neurons via immunocytochemistry. From this perspective, we elaborate on the idea that the neuro-invasive potential of SARS-CoV-2 should be considered as a possible contributory factor, as well as a therapeutic target, for the severe respiratory symptoms in critical COVID-19 cases.
Pilocytic astrocytomas (PAs) were recognized as a discrete clinical entity over 70 years ago. They are relatively benign (WHO grade I) and have, as a group, a 10-year survival of over 90 %. Many ...require merely surgical removal and only very infrequently do they progress to more malignant gliomas. While most show classical morphology, they may present a spectrum of morphological patterns, and there are difficult cases that show similarities to other gliomas, some of which are malignant and require aggressive treatment. Until recently, almost nothing was known about the molecular mechanisms involved in their development. The use of high-throughput sequencing techniques interrogating the whole genome has shown that single abnormalities of the mitogen-activating protein kinase (MAPK) pathway are exclusively found in almost all cases, indicating that PA represents a one-pathway disease. The most common mechanism is a tandem duplication of a ≈2 Mb-fragment of #7q, giving rise to a fusion between two genes, resulting in a transforming fusion protein, consisting of the N-terminus of KIAA1549 and the kinase domain of BRAF. Additional infrequent fusion partners have been identified, along with other abnormalities of the MAP-K pathway, affecting tyrosine kinase growth factor receptors at the cell surface (e.g., FGFR1) as well as BRAF V600E, KRAS, and NF1 mutations among others. However, while the KIAA1549-BRAF fusion occurs in all areas, the incidence of the various other mutations identified differs in PAs that develop in different regions of the brain. Unfortunately, from a diagnostic standpoint, almost all mutations found have been reported in other brain tumor types, although some retain considerable utility. These molecular abnormalities will be reviewed, and the difficulties in their potential use in supporting a diagnosis of PA, when the histopathological findings are equivocal or in the choice of individualized therapy, will be discussed.
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