98 resultados para Retro-Diels-Alder reactions

em BORIS: Bern Open Repository and Information System - Berna - Suiça


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OBJECTIVES: There is increasing research on posttraumatic stress (PS) 4-6 weeks and 3 months postpartum, but, there are no data on acute stress reactions (ASR) in the first 3 weeks postpartum, i.e. the potential precursors of PS. However, ASR may have long-term effects, e.g., on a subsequent pregnancy without having manifested as PS in the meantime. We propose: (i) to describe the patterns of ASR after childbirth, (ii) to explore differences between women with normal and traumatogenic ASR, and (iii) to provide data on the early detection of traumatogenic ASR 2 and 3 weeks postpartum. STUDY DESIGN: Intra-event variables (relationship with caregivers, overall birth experience, and dissociative experiences, as well as obstetric variables) were assessed 48-96h. postpartum, as were ASR (by means of the Impact-of-Event Scale IES) in weeks 1, 2, and 3 postpartum. According to research on PS the upper 33%-range of ASR in weeks 2 and 3 was defined as 'traumatogenic'. RESULTS: Normal ASR in week 1 are at a level which in non-obstetric trauma-situations is considered as the upper range of low stress or lower range of medium distress. ASR decline constantly from week 1 to week 3. However, high ASR in week 1 do not drop faster than do low ones, thus indicating a prolonged stress reaction in women with high ASR in week 1. Low ASR (IES-scores <10) and high ASR (IES-scores >20) in week 1 are highly predictive for normal ASR, and traumatogenic ASR in weeks 2 and 3, respectively. Medium ASR (IES-scores 10-20) in week 1 are of uncertain predictive value for stress reactions in weeks 2 and 3 and have to be re-assessed at that time. CONCLUSIONS: Clinical screening for ASR appears to be helpful in detecting women with a compromised ability to process childbirth-related stress. The association between ASR and long-term development should be further explored.

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Immune reactions to drugs can cause a variety of diseases involving the skin, liver, kidney, lungs, and other organs. Beside immediate, IgE-mediated reactions of varying degrees (urticaria to anaphylactic shock), many drug hypersensitivity reactions appear delayed, namely hours to days after starting drug treatment, showing a variety of clinical manifestations from solely skin involvement to fulminant systemic diseases which may be fatal. Immunohistochemical and functional studies of drug-specific T cells in patients with delayed reactions confirmed a predominant role for T cells in the onset and maintenance of immune-mediated delayed drug hypersensitivity reactions (type IV reactions). In these reactions, drug-specific CD4+ and CD8+ T cells are stimulated by drugs through their T cell receptors (TCR). Drugs can stimulate T cells in two ways: they can act as haptens and bind covalently to larger protein structures (hapten-carrier model), inducing a specific immune response. In addition, they may accidentally bind in a labile, noncovalent way to a particular TCR of the whole TCR repertoire and possibly also major histocompatibility complex (MHC)-molecules - similar to their pharmacologic action. This seems to be sufficient to reactivate certain, probably in vivo preactivated T cells, if an additional interaction of the drug-stimulated TCR with MHC molecules occurs. The mechanism was named pharmacological interaction of a drug with (immune) receptor and thus termed the p-i concept. This new concept may explain the frequent skin symptoms in drug hypersensitivity to oral or parenteral drugs. Furthermore, the various clinical manifestations of T cell-mediated drug hypersensitivity may be explained by distinct T cell functions leading to different clinical phenotypes. These data allowed a subclassification of the delayed hypersensitivity reactions (type IV) into T cell reactions which, by releasing certain cytokines and chemokines, preferentially activate and recruit monocytes (type IVa), eosinophils (type IVb), or neutrophils (type IVd).

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To compare the haemostatic effect and tissue reactions of different agents and methods used for haemorrhage control in apical surgery.

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The aim of this study was to analyze the influence of total serum IgE and other potential risk factors on severity of systemic allergic Hymenoptera sting reactions.

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Sulfonamides are generally classified into 2 groups: antibiotics and non-antibiotics. Recent studies showed that patients allergic to sulfonamide antibiotics do not have a specific risk for an allergy to sulfonamide non-antibiotic. However, the anti-inflammatory drug sulfasalazine represents an important exception. Used in rheumatic diseases, it is classified as a non-antibiotic sulfonamide, but is structurally related to antibiotic sulfonamides. Therefore, we aimed to analyze in vitro the cross-reactivity between the antimicrobial sulfamethoxazole and the anti-inflammatory drug sulfasalazine.

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Cross reactions are an often observed phenomenon in patients with allergy. Sensitization against some allergens may cause reactions against other seemingly unrelated allergens. Today, cross reactions are being investigated on a per-case basis, analyzing blood serum specific IgE (sIgE) levels and clinical features of patients suffering from cross reactions. In this study, we evaluated the level of sIgE compared to patients' total IgE assuming epitope specificity is a consequence of sequence similarity.

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Aggregation of the high-affinity IgE receptor (FcεRI) with the low-affinity IgG receptor (FcγRIIb) on basophils or mast cells has been shown to inhibit allergen-induced cell degranulation. Molecules cross-linking these two receptors might therefore be of interest for the treatment of allergic disorders. Here, we demonstrate the generation of a novel bispecific fusion protein efficiently aggregating FcεRI-bound IgE with FcγRIIb on the surface of basophils to prevent pro-inflammatory mediator release.

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Using an in silico allergen clustering method, we have recently shown that allergen extracts are highly cross-reactive. Here we used serological data from a multi-array IgE test based on recombinant or highly purified natural allergens to evaluate whether co-reactions are true cross-reactions or co-sensitizations by allergens with the same motifs.

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The spectrum of cutaneous adverse drug reactions (cADRs) ranges from benign presentations to severe life-threatening forms such as toxic epidermal necrolysis (TEN). In TEN, granulysin has been shown to be the key cytotoxic molecule. Still, little is known about the expression of granulysin in other cADRs. As an important source of granulysin, natural killer (NK) cells are of major interest in cADRs. Recently, NKp46 has been identified as the most selective NK-cell marker. However, the role of NKp46(+) cells in cADRs and their contribution to granulysin expression remain to be elucidated.

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The antithyroid drugs mainly include thioimidazole (carbimazole, methimazole=thiamazole) and propylthiouracil. After absorption, carbimazole is rapidly metabolized to methimazole and thus switching between these two drugs should not be considered in case of side effects. Furthermore, in case of side effects, sometimes even cross reactions between thioimidazoles and propylthiouracil occur. Common and typical adverse reactions of antithyroid drugs include dose dependent hypothyroidism and thus thyroid function should be repeatedly checked while the patient is on antithyroid drugs. Furthermore, pruritus and rash may develop. In this case, one might try to switch from thioimidazoles to propylthiouracil or vice versa. Antithyroid drugs may cause mild dose dependent neutropenia or severe allergy-mediated agranulocytosis, which typically occurs during the first three months of treatment, has an incidence of 3 per 10,000 patients and cross reactivity between thioimidazoles to propylthiouracil may occur. Rarely, antithyroid drugs can cause aplastic anemia. Mainly propylthiouracil, but sometimes also methimazole may lead to an asymptomatic transient increase in liver enzymes or to severe, even lethal liver injury of cholestatic or hepatocellular pattern. Since propylthiouracil associated liver injury was observed increasingly among children and adolescent, it has been suggested to prefer thioimidazoles for these patients. Because of these potential serious adverse effects, physicians should advise patients to immediately seek medical help if they get a fever or sore throat or malaise, abdominal complaints or jaundice, respectively. Furthermore, arthralgias may develop in 1-5% of patients under both antithyroid drugs. Since arthralgias may be the first symptom of more serious immunologic side effects, it is recommended to stop the antithyroid drug in this case. Drug induced polyarthritis mainly develops during the first month of therapy, whereas ANCA-positive vasculitis is generally observed only after long term exposure to propylthiouracil or very rarely with the thioimidazoles. The teratogenic risk of the thioimidazoles is somewhat higher (Aplasia cutis congenita), that is why one generally recommends preferring propylthiouracil during pregnancy. During breast feeding both, thioimidazoles or propylthiouracil, may be administered. Nowadays, perchlorate is only used short term in case of latent hyperthyroidism before administering iodine-containing contrast agents. Therefore, the known side effects, which usually are only observed after long term treatment, are not an issue any more.

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In drug hypersensitivity, change of drug treatment and continuation with a new drug may result in reappearance of drug hypersensitivity symptoms. This is not uncommon in patients with chronic infections requiring continued and long-lasting antibiotic treatments. For the clinician, the question arises whether these symptoms are due to cross-reactivity, are due to a new sensitization or are a reflection of a multiple drug hypersensitivity syndrome. Based on the p-i concept (pharmacological interaction with immune receptors), we propose that the efficient stimulation of T cells by a drug is the sum of drug-T-cell receptor affinity and readiness of the T cell to react, and therefore not constant. It heavily depends on the state of underlying immune activation. Consequently, drug hypersensitivity diseases, which go along with massive immune stimulations and often high serum cytokine values, are themselves risk factors for further drug hypersensitivity. The immune stimulation during drug hypersensitivity may, similar to generalized virus infections, lower the threshold of T-cell reactivity to drugs and cause rapid appearance of drug hypersensitivity symptoms to the second drug. We call the second hypersensitivity reaction a "flare-up" reaction; this is clinically important, as in most cases the second drug may be tolerated again, if the cofactors are missing. Moreover, the second treatment is often too short to cause a relevant sensitization.