Hypersensitivity reactions (HR) are immune responses that are exaggerated or inappropriate against an antigen or allergen. Coombs and Gell classified hypersensitivity reactions into four forms. Type I, type II, and type III hypersensitivity reactions are known as immediate hypersensitivity reactions (IHR) because occur within 24 hours. Antibodies including IgE, IgM, and IgG mediate them. Type I or Anaphylactic Response Anaphylactic Responseis mediated by IgE antibodies that are produced by the immune system in response to environmental proteins (allergens) such as pollens, animal danders or dust mites. These antibodies (IgE) bind to mast cells and basophils, which contain histamine granules that are released in the reaction and cause inflammation. Type I hypersensitivity reactions can be seen in bronchial asthma, allergic rhinitis, allergic dermatitis, food allergy, allergic conjunctivitis, and anaphylactic shock. Anaphylaxis Anaphylaxis is a medical emergency because can lead to an acute, life-threatening respiratory failure. It is an IgE-mediated process. It is the most severe form of an allergic reaction, where mast cells suddenly release a large amount of histamine and later on leukotrienes. In severe cases intense bronchospasm, laryngeal edema, cyanosis, hypotension, and shock are present.  Allergic bronchial asthma Allergic bronchial asthma is an atopic disease, characterized by bronchospasm. It may also be a chronic inflammatory disease. In its etiology, and environmental factors along with a genetic background play an important role. The diagnosis is dependent on history and examination. In allergic bronchial asthma, IgE is elevated, and sputum eosinophilia is common. Epidemiologically, a positive skin prick test or specific IgE are risk factors for asthma. Allergic rhinitis Allergic rhinitis is another atopic disease where histamine and leukotrienes are responsible for rhinorrhea, sneezing and nasal obstruction. Allergens are similar to those found in bronchial asthma. Nasal polyps may be seen in chronic rhinitis. Allergic conjunctivitis Allergic conjunctivitis presents with rhinitis and is IgE-mediated. Itching and eye problems including watering, redness, and swelling always occur. Food allergy One must differentiate food allergy (IgE-mediated) from food intolerance that can be cause for a variety of etiology including malabsorption and celiac disease. It is more frequent in children as seen in cow's milk allergy. Food allergy symptoms mostly affect the respiratory tract, the skin, and the gut. Skin prick tests are helpful to test for food allergens that can trigger severe reactions, e.g., peanuts, eggs, fish, and milk. Atopic eczema Atopic eczema is an IgE-mediated disease that affects the skin and has an immunopathogenesis very similar to that of allergic asthma and allergic rhinitis, which are present in more than half of the diseased. Radioallergosorbent (RAST) may reveal the specificity of the IgE antibody involved but has little help in management. Drug allergy Drugs may cause allergic reactions by any mechanism of hypersensitivity. For example, penicillin may cause anaphylaxis, which is IgE-mediated but must responses be trivial. Penicillin cross-reacts with other semisynthetic penicillins including monobactams and carbapenems and may also cross-react with other antibiotics such as cephalosporins.   Type II or Cytotoxic-Mediated Response IgG and IgM mediate cytotoxic-mediated response against cell surface and extracellular matrix proteins. The immunoglobulins involved in this type of reaction damages cells by activating the complement system or by phagocytosis. Type II hypersensitivity reactions can be seen in immune thrombocytopenia, autoimmune hemolytic anemia, and autoimmune neutropenia. Immune thrombocytopenia (ITP) ITP is an autoimmune disorder that occurs at any age. Phagocytes destroy sensitized platelets in the peripheral blood. Clinically, it manifests by thrombocytopenia with shortened platelet survival and increased marrow megakaryocytes. Sudden onset of petechiae and bleeding from the gums, nose, bowel, and urinary tract occurs. Bleeding can accompany infections, drug reactions, malignancy and other autoimmune disorders such as thyroid disease and SLE. Autoimmune hemolytic anemia (AIHA) There are two types of immune hemolytic anemia: IgG-mediated (warm AIHA) and IgM-mediated (cold AIHA). The warm type may be idiopathic autoimmune or secondary to other diseases such as malignancy affecting the lymphoid tissues. The cold type may be idiopathic or secondary to infections such as Epstein-Barr virus. The primary clinical sign of the two is jaundice. The laboratory diagnosis is made by a positive Coombs test, which identifies immunoglobulins and C3 on red blood cells.  Autoimmune neutropenia Autoimmune neutropenia may be present with bacterial and fungal infections, or it may occur alone or with autoimmune diseases (SLE, RA, autoimmune hepatitis), infections and lymphoma. Bone marrow examination is needed if neutropenia is severe. For associated autoimmune disorders, an autoimmune antibody panel is necessary (ANA, ENA, and dsDNA). Hemolytic disease of the fetus and the newborn (erythroblastosis fetalis) The maternal immune system suffers an initial sensitization to the fetal Rh+ red blood cells during birth, when the placenta tears away. The first child escapes disease but the mother, now sensitized, will be capable of causing a hemolytic reaction against a second Rh+ fetus, which develops anemia and jaundice once the maternal IgG crosses the placenta. Myasthenia gravis Myasthenia gravis is an autoimmune disorder caused by antibodies to post-synaptic acetylcholine receptors that interfere with the neuromuscular transmission. It is characterized by extreme muscular fatigue, double vision, bilateral ptosis, deconjugate eye movements, difficulty swallowing, and weakness in upper arms. Babies born to myasthenic mothers can have transient muscle weakness due to pathogenic IgG antibodies that cross the placenta. Goodpasture syndrome  Goodpasture syndrome is a type II hypersensitivity reaction characterized by the presence of nephritis in association with lung hemorrhage. In most patients, it is caused by cross-reactive autoantigens that are present in the basement membranes of the lung and kidney. A number of patients with this problem exhibit antibodies to collagen type IV, which is an important component of basement membranes.  Pemphigus Pemphigus causes a severe blistering disease that affects the skin and mucous membranes. The sera of patients with pemphigus have antibodies against desmoglein-1 and desmoglein-3, which are components of desmosomes, which form junctions between epidermal cells. Pemphigus is strongly linked to HLA-DR4 (DRB1*0402), which is a molecule that presents one of the autoantigens involved in the immunopathogenesis of this disease (desmoglein-3). Type III or Immunocomplex Reactions These are also mediated by IgM and IgG antibodies that react with soluble antigens forming antigen-antibody complexes. The complement system becomes activated and releases chemotactic agents that attract neutrophils and cause inflammation and tissue damage as seen in vasculitis and glomerulonephritis. Type III hypersensitivity reactions can classically be seen in serum sickness and Arthus reaction. Serum sickness Serum sickness can be induced with massive injections of foreign antigen. Circulating immune complexes infiltrate the blood vessel walls and tissues, causing an increased vascular permeability and leading to inflammatory processes such as vasculitis and arthritis. It was a complication of anti-serum prepared in animals to which some individuals produced antibodies to the foreign protein. It was also experienced in the treatment with antibiotics such as penicillin. Arthus reaction Arthus reaction is a local reaction seen when a small quantity of antigens is injected into the skin repeatedly until detectable levels of antibodies (IgG) are present. If the same antigen is inoculated, immune complexes develop at the mentioned local site and in the endothelium of small vessels. This reaction is characterized by the presence of marked edema and hemorrhage, depending on the administered dose of the foreign antigen.

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are two related mucocutaneous disorders with different severities. Although the incidence is low, SJS and TEN are life-threatening and predominantly drug-induced conditions. There is a strong relationship between the HLA-B*1502 allele and carbamazepine-induced SJS and TEN in different Southeast Asian populations. Here, we report a case of Filipino with SJS/TEN overlap probably induced by carbamazepine. The condition was treated with hydrocortisone followed by prednisone. The HLA-B*1502 allele was not found in this case. The patient tested positive for the HLA-B75 serotype, suggesting that carbamazepine-induced SJS/TEN may be serotype specific. Establishing the genotype before initiation of the drug may be advantageous for some patients and will aid physicians in determining the optimal drug therapy. Prevention of adverse drug reactions (ADR) may be done if pharmacists and other healthcare professionals work as a multidisciplinary ADR team to ensure that safe medication practices are realised.

At the onset of the 2013-2016 epidemic of Ebola virus disease (EVD), no vaccine or antiviral medication was approved for treatment. Therefore, considerable efforts were directed towards the concept of drug repurposing or repositioning. Amiodarone, an approved multi-ion channel blocker for the treatment of cardiac arrhythmia, was reported to inhibit filovirus entry in vitro. Compassionate use of amiodarone in EVD patients indicated a possible survival benefit. In support of further clinical testing, we confirmed anti-Ebola virus activity of amiodarone in different cell types. Despite promising in vitro results, amiodarone failed to protect guinea pigs from a lethal dose of Ebola virus.

Objective Unexplained chronic cough (UCC) is a perplexing condition treated with neuromodulators. Although previous literature describes the effectiveness of neuromodulators, there is little on the development of tachyphylaxis or dependence to neuromodulators over time. Our objective is to capture the experience of a large cohort of patients with UCC over an extended period, looking for these 2 phenomena. Study Design Case series with chart review. Setting Tertiary care hospital. Subjects and Methods We performed a retrospective review of patients diagnosed with UCC from 2010 to 2014. Patient outcomes were measured through percentage improvement scores. Treatment failures were attributed to no benefit, intolerable side effects, or tachyphylaxis. Tachyphylaxis was defined as the need for higher doses of medication following diminishing therapeutic benefit, while dependence was defined as a failure to stop therapy following attempted de-escalation or resurgence following drug cessation. Results Sixty-eight patients were included in the study. Tachyphylaxis was observed among 35% of patients while dependence was observed among 27% of successfully treated patients, together effecting >50% of the cohort. Sixty-eight percent of patients ultimately experienced successful treatment with neuromodulators, demonstrating strikingly distinct responses to different neuromodulator drug classes. Conclusion Tachyphylaxis and dependence occur frequently during UCC treatment and have a major impact on treatment outcomes. Patients sometimes demonstrate distinct responses to different neuromodulator classes. The majority of patients will experience successful treatment for their cough, although several trials may be required.

Small-conductance Ca2+-activated K+ (SK) channels mediate medium afterhyperpolarization in the neurons and play a key role in the regulation of neuronal excitability. SK channels are potential drug targets for ataxia and Amyotrophic Lateral Sclerosis (ALS). SK channels are activated exclusively by the Ca2+-bound calmodulin. Previously, we identified an intrinsically disordered fragment that is essential for the mechanical coupling between Ca2+/calmodulin binding and channel opening. Here, we report that substitution of a valine to phenylalanine (V407F) in the intrinsically disordered fragment caused a ~6 fold increase in the Ca2+ sensitivity of SK2-a channels. This substitution resulted in a novel interaction between the ectopic phenylalanine and M411, which stabilized PIP2-interacting residue K405, and subsequently enhanced Ca2+ sensitivity. Also, equivalent valine to phenylalanine substitutions in SK1 or SK3 channels conferred Ca2+ hypersensitivity. An equivalent phenylalanine substitution in the Caenorhabditis elegans (C. elegans) SK2 ortholog kcnl-2 partially rescued locomotion defects in an existing C. elegans ALS model, in which human SOD1G85R is expressed at high levels in neurons, confirming that this phenylalanine substitution impacts channel function in vivo. This work for the first time provides a critical reagent for future studies: an SK channel that is hypersensitive to Ca2+ with increased activity in vivo.

For strain improvement of Aspergillus oryzae, development of the transformation system is essential, wherein dominant selectable markers, including drug-resistant genes, are available. However, A. oryzae generally has a relatively high resistance to many antifungal drugs effective against yeasts and other filamentous fungi. In the course of the study, while investigating azole drug resistance in A. oryzae, we isolated a spontaneous mutant that exhibited high resistance to azole fungicides and found that pleiotropic drug resistance (PDR)-type ATP-binding cassette (ABC) transporter genes were upregulated in the mutant; their overexpression in the wild-type strain increased azole drug resistance. While deletion of the gene designated atrG resulted in increased azole susceptibility, double deletion of atrG and another gene (atrA) resulted in further azole hypersensitivity. Overall, these results indicate that the ABC transporters AtrA and AtrG are involved in azole drug resistance in A. oryzae.