Home About us Contact
|
Home About us Contact | ||
|
|
||
Increased Reactivity (increased + reactivity)
Selected AbstractsSusceptibility and reactivity in polysensitized individuals following controlled inductionCONTACT DERMATITIS, Issue 1 2010Nannie Bangsgaard Background: It is uncertain whether polysensitized patients acquire multiple allergies only because of a high degree of exposure to environmental allergens, or because of being highly susceptible to developing contact allergy. Objectives: The aim of this study was to investigate and compare susceptibility and reactivity in polysensitized and monosensitized individuals, and in healthy controls. Patients/methods: We sensitized 66 adult individuals (21 polysensitized, 22 monosensitized, and 23 healthy controls) with diphenylcyclopropenone and assessed challenge responses with visual scoring and ultrasound. We compared sensitization rates using a chi-square test and logistic regression analyses, and calculated linear regression lines of the elicitation responses for each individual. The mean values of the slopes and the intercepts for each group were used to measure the strength of the elicitation response, and were compared using the Mann,Whitney test. Results: Sensitization ratio was equal in the three groups: 57% for the polysensitized, 59% for the monosensitized, and 65% for the healthy control group. There was a lowered elicitation threshold in the polysensitized group compared with that in the monosensitized and healthy control groups and, although not statistically significant, a stronger elicitation response was observed in the polysensitized group. Conclusion: Increased reactivity was found in the polysensitized group, demonstrated by a lowered elicitation threshold, compared with that in the monosensitized and healthy control groups. [source] Response to soy: T-cell-like reactivity in the intestine of Atlantic salmon, Salmo salar L.JOURNAL OF FISH DISEASES, Issue 1 2007A M Bakke-McKellep Abstract T-cell-mediated hypersensitivity could be central in soybean meal (SBM)-induced intestinal changes in salmon. However, tools for immunohistochemical detection of T cells have been lacking in teleosts, including Atlantic salmon. Application of a specific histochemical protocol allowed demonstration of T-cell-like reactivities in formalin-fixed, paraffin-embedded tissues using an antibody reacting to a conserved region of human CD3, (Dako A0452). Characteristic staining was observed in cells of the thymus as well as distal intestine, skin, gills and spleen. These cells were negative for immunoglobulin M (IgM). Intestinal intraepithelial leucocytes were CD3, positive. During the SBM-induced enteropathy, the mixed inflammatory infiltrate in the lamina propria of the distal intestine included many lymphocytes with a T-cell-like reactivity. Real-time polymerase chain reaction revealed significantly increased expression of a complex polypeptide (CD3pp), CD4 and CD8, (P < 0.05) in the distal intestine of SBM-fed fish compared to fish meal-fed reference fish. Increased reactivity for extracellular IgM in the lamina propria and a positive material between the epithelial cells at the tips of the folds was observed, possibly due to leakage of IgM through an abrogated epithelial barrier. In conclusion, a T-cell-like response appears to be involved in this example of a food-sensitive enteropathy. [source] Evidence for a familial correlation between increased reactivity to stress and positive psychotic symptomsACTA PSYCHIATRICA SCANDINAVICA, Issue 5 2010T. Lataster Lataster T, Collip D, Lardinois M, van Os J, Myin-Germeys I. Evidence for a familial correlation between increased reactivity to stress and positive psychotic symptoms. Objective:, This study tested the hypothesis that stress-reactivity may represent an intermediary phenotype underlying positive psychotic symptoms. It was examined whether: (i) stress-reactivity clusters within families of psychotic patients and (ii) stress-reactivity in relatives cosegregates with positive symptoms in patients. Method:, The sample consisted of 40 patients and 47 siblings of these patients. The Experience Sampling Method (ESM , a structured diary technique) was used to measure stress-reactivity. Positive symptoms in patients were measured with the Comprehensive Assessment of Symptoms and History. Results:, Within-trait, cross-sib associations showed a significant association between stress-reactivity in the patient and stress-reactivity in their siblings. Significant cross-trait, cross-sib associations were established showing a significant association between positive psychotic symptoms in the patient and stress-reactivity in the sibling. Conclusion:, The findings show familial clustering of increased stress-reactivity, suggesting common aetiological influences, probably both genetic and environmental, underlying stress-reactivity in the siblings and patients. In addition, the results underscore the hypothesis that increased stress-reactivity is an unconfounded mechanism of risk underlying the positive symptoms of psychotic disorders. [source] The T-cell receptor repertoire of regulatory T cellsIMMUNOLOGY, Issue 4 2008Rafal Pacholczyk Summary The CD4+ CD25+ regulatory population of T cells (Treg cells), which expresses the forkhead family transcription factor (Foxp3), is the key component of the peripheral tolerance mechanism that protects us from a variety of autoimmune diseases. Experimental evidence shows that Treg cells recognize a wide range of antigenic specificities with increased reactivity to self antigens, although the affinity of these interactions remains to be further defined. The Treg repertoire is highly diverse with a distinct set of T-cell receptors (TCRs), and yet is overlapping to some extent with the repertoire of conventional T cells (Tconv cells). The majority of Treg cells are generated in the thymus. However, the role of the TCR specificity in directing thymic precursors to become Treg or Tconv cells remains unclear. On the one hand, the higher self reactivity of Treg cells and utilization of different TCRs in Treg and Tconv repertoires suggest that in TCR interactions an initial decision is made about the ,suitability' of a developing thymocyte to become a Treg cell. On the other hand, as Treg cells can recognize a wide range of foreign antigens, have a diverse TCR repertoire, and show some degree of overlap with Tconv cells, the signals through the TCR may be complementary to the TCR-independent process that generates precursors of Treg cells. In this review, we discuss how different features of the Treg repertoire influence our understanding of Treg specificities and the role of self reactivity in the generation of this population. [source] POTASSIUM HYDROXIDE REPLACEMENT FOR LYE (SODIUM HYDROXIDE) IN TOMATO PEELINGJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 1 2006D.J. DAS ABSTRACT Lye (sodium hydroxide [NaOH]) peeling is the most common method for peeling tomatoes in the Midwest U.S. With the rise in the cost of NaOH and the associated disposal problems, alternative methods for peeling need to be examined. Solutions of NaOH, potassium hydoxide (KOH) and calcium hydroxide (Ca[OH]2) at different concentrations were compared to determine their efficacy as peeling agents. Ca(OH)2 was ineffective as a peeling agent because of its low solubility. KOH produced peeling equivalent to NaOH, but at half the normality. A lower normality is needed because of the increased reactivity of KOH compared to NaOH. This is further demonstrated by the addition of salts to the solution. The use of KOH instead of NaOH may result in cost savings and decreased waste disposal problems. [source] Does Bipolar Pacemaker Current Activate Blood Platelets?PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 5 2009GRUNDE GJESDAL M.D. Objective: The aim of this study was to investigate whether bipolar pacemaker current lead can activate blood platelets. The null hypothesis was that 1 minute of electrical stimulation of platelets would not influence their subsequent reactivity to adenosine diphosphate (ADP). Background: Both platelets and muscle cells contain actin and myosin filaments, and both cells are activated following calcium influx. Muscle cells open their calcium channels and contract when exposed to an electric current. Current through a bipolar pacemaker lead will expose a small volume of blood, including platelets, to the depolarizing current. Platelet activation may ensue, resulting in aggregation, release reaction, and contraction. In contrast, a unipolar pacemaker system will not depolarize blood, but transmit current directly into the myocardium, and the current afterward passes through other tissues before returning to the pacemaker can. Methods: Platelet-rich plasma was prepared from two healthy subjects. Platelet reactivity to the agonist ADP was tested in paired samples in an aggregometer in a case/control setup. Results: Eighteen of 46 tested pairs of platelet-rich plasma showed increased reactivity in the paced sample; 26 were unchanged while two showed decreased reactivity in the paced sample. Using a two-sided sign test, the null hypothesis was rejected (P = 0.0004). Conclusions: The study demonstrates increased reactivity to ADP in platelets exposed in vitro to stimulation by pacemaker current. The clinical relevance of these findings remains to be investigated. [source] Acid-Base Interactions in Energetic Materials: I. The Hard and Soft Acids and Bases (HSAB) Principle,Insights to Reactivity and Sensitivity of Energetic MaterialsPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 1 2005Ernst-Christian Koch Abstract The chemistry of energetic materials can be described applying acid-base reaction formalism. Addressing the HSAB concept, the number of electrons transferred, ,N, in an acid-base reaction, allows for description and prediction of properties of composite and homogeneous materials. At first ,N helps in estimating the rate of reaction of binary systems with either given fuel or oxidizer. Nevertheless ,N is only a relative number thus the range of comparability remains narrow. At second ,N can be used as a measure for the sensitivity of homogeneous explosives. The increased reactivity of hypothetical fragments to recombine in a reaction such as R3C.+.NO2=R3C,NO2 given by ,N correlates very well with experimentally determined reduced impact sensitivity of 1,3,5-trinitrobenzene compounds. On the contrary the rising impact sensitivity of metal azides correlates with rising values of ,N of Mn+/N3, reaction because increased reactivity, that is increased electron transfer from the azide anion to the metal cation triggers formation of the azide radical (.N3). The latter then decomposes rapidly to give dinitrogen. This increased reactivity/sensitivity of metral azides coincides with covalent bonding whereas ionic azides are relatively insensitive. [source] Physiological stress responses in defensive individuals: Age and sex matterPSYCHOPHYSIOLOGY, Issue 2 2010Karine Lévesque Abstract The association between defensiveness and physiological responses to stress were evaluated in 81 healthy working men and 118 women, aged 20 to 64 years (M=41; SD=11.45). Participants underwent laboratory testing during which they were exposed to interpersonal stressors. Heart rate (HR), heart rate variability (HRV), blood pressure (BP), and salivary cortisol were measured. Defensiveness was evaluated using the Marlowe-Crowne Social Desirability Scale. In women, higher defensiveness was associated with greater BP and HR reactivity to stress (p<.05). In older men, lower defensiveness was associated with increased systolic BP reactivity to stress (p<.02), delayed HRV recovery (p<.02), and greater salivary cortisol levels (p<.02). In conclusion, greater defensiveness was associated with increased reactivity to stress in women whereas in older men, lower defensiveness was associated with elevated cardiovascular, autonomic, and endocrine responses to stress. [source] Tail arteries from chronically spinalized rats have potentiated responses to nerve stimulation in vitroTHE JOURNAL OF PHYSIOLOGY, Issue 2 2004Melanie Yeoh Patients with severe spinal cord lesions that damage descending autonomic pathways generally have low resting arterial pressure but bladder or colon distension or unheeded injuries may elicit a life-threatening hypertensive episode. Such episodes (known as autonomic dysreflexia) are thought to result from the loss of descending baroreflex inhibition and/or plasticity within the spinal cord. However, it is not clear whether changes in the periphery contribute to the exaggerated reflex vasoconstriction. The effects of spinal transection at T7,8 on nerve- and agonist-evoked contractions of the rat tail artery were investigated in vitro. Isometric contractions of arterial segments were recorded and responses of arteries from spinalized animals (,spinalized arteries') and age-matched and sham-operated controls were compared. Two and eight weeks after transection, nerve stimulation at 0.1,10 Hz produced contractions of greater force and duration in spinalized arteries. At both stages, the ,-adrenoceptor antagonists prazosin (10 nm) and idazoxan (0.1 ,m) produced less blockade of nerve-evoked contraction in spinalized arteries. Two weeks after transection, spinalized arteries were supersensitive to the ,1 -adrenoceptor agonist phenylephrine, and the ,2 -adrenoceptor agonist, clonidine, but 8 weeks after transection, spinalized arteries were supersensitive only to clonidine. Contractions of spinalized arteries elicited by 60 mm K+ were larger and decayed more slowly at both stages. These findings demonstrate that spinal transection markedly increases nerve-evoked contractions and this can, in part, be accounted for by increased reactivity of the vascular smooth muscle to vasoconstrictor agents. This hyper-reactivity may contribute to the genesis of autonomic dysreflexia in patients. [source] Evaluation of binding selectivities and affinities of platinum-based quadruplex interactive complexes by electrospray ionization mass spectrometryBIOPOLYMERS, Issue 4 2009Sarah E. Pierce Abstract The quadruplex binding affinities and selectivities of two large ,-surface PtII phenanthroimidazole complexes, as well as a smaller ,-surface platinum bipyridine complex and a larger RuII complex, were evaluated by electrospray ionization mass spectrometry. Circular dichroism (CD) spectroscopy was used to determine the structures of various quadruplexes and to study the thermal denaturation of the quadruplexes in the absence and presence of the metal complexes. In addition, chemical probe reactions with glyoxal were used to monitor the changes in the quadruplex conformation because of association with the complexes. The platinum phenanthroimidazole complexes show increased affinity for several of the quadruplexes with elongated loops between guanine repeats. Quadruplexes with shorter loops exhibited insubstantial binding to the transition metal complexes. Similarly binding to duplex and single strand oligonucleotides was low overall. Although the ruthenium-based metal complex showed somewhat enhanced quadruplex binding, the PtII complexes had higher quadruplex affinities and selectivities that are attributed to their square planar geometries. The chemical probe reactions using glyoxal indicated increased reactivity when the platinum phenanthroimidazole complexes were bound to the quadruplexes, thus suggesting a conformational change that alters guanine accessibility. © 2008 Wiley Periodicals, Inc. Biopolymers 91: 233,243, 2009. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Migraine: a review and future directions for treatmentACTA NEUROLOGICA SCANDINAVICA, Issue 2 2006M. Linde Migraine is a chronic, neurological disorder generally manifesting itself in attacks with severe headache, nausea and an increased reactivity to sensory stimuli. A low migraine threshold is set by genetic factors, although the phenotype also modulates the manifestations. The 1-year prevalence is approximately 13% and is higher among women. Patients usually experience neuropsychological dysfunction, and sometimes also reversible focal neurological symptoms. The trajectories of the characteristic symptoms of acute migraine usually follow a similar time course, indicating a reciprocal underlying mechanism. A central nervous system hyperexcitability has been demonstrated in neurophysiological studies. The dibilitating effects of migraine are not confined to the attacks per se. Many individuals do not recover completely between the attacks and most report a negative impact on the most important life domains, and an interest in testing other treatments. Young persons have a higher frequency of attacks. Acute treatment should routinely be initiated with an analgesic plus a prokinetic anti-emetic. Triptans must not be provided early during the attack to ensure their efficacy. The natural course of attacks is commonly only temporarily altered by acute treatment. Non-pharmacological treatment and drugs may be equally viable in prophylaxis for migraine. In more complicated cases, conjoint therapy should be considered. New strategies to improve adherence with existing therapeutic regimens might yield greater benefits than will new pharmacological agents. [source] Role of protein kinases in mediating diabetes-induced augmented vasoconstriction to endothelin-1 in the renal arteries of STZ-diabetic ratsCELL BIOCHEMISTRY AND FUNCTION, Issue 5 2006Mariam H. M. Yousif Abstract Diabetes is associated with increased reactivity of the renal vascular bed to endothelin-1 (ET-1). It has been observed that diabetes is associated with over-expression of ETA - and ETB -receptors in the rat renal cortex. However it is not known if these receptors are over-expressed in the renal artery. The objectives of this study were to determine changes in ET-1 receptors and signalling pathways in diabetic renal arteries, to determine the relative roles of protein kinase C and tyrosine kinase activation in mediating these responses and to investigate the role of Rho-kinase activity in mediating the vasoconstrictor responses to ET-1. This study was performed on isolated renal artery segments obtained from STZ-diabetic rats. Results from this study showed that the vasoconstrictor response to ET-1 was potentiated in the diabetic renal artery segments compared to the control animals. Using selective ET-1 receptor antagonists, BQ123 and BQ788, the enhanced ET-1-induced vasoconstriction was shown in this study not to be related to changes in receptor affiinity or receptor subtype distribution. However, the augmented vasoconstrictor response to ET-1 in the diabetic renal artery preparations may be related to increased influx of Ca2+ through L-type channels and also to increased tyrosine kinase activity. Copyright © 2005 John Wiley & Sons, Ltd. [source] | ||||||||||||||||