Concomitant Reactions Research Articles

Occupational contact allergy to cocamidopropyl betaine and its impurities

Contact allergy to cocamidopropyl betaine has been attributed to its impurities dimethylaminopropylamine and cocamidopropyl dimethylamine. To describe patients with positive patch test reactions to cocamidopropyl betaine-related compounds in an occupational dermatology clinic. We reviewed the 2002-2009 patch test records at the Finnish Institute of Occupational Health for allergic reactions to cocamidopropyl betaine, dimethylaminopropylamine, cocamidopropyl dimethylamine, and oleamidopropyl dimethylamine. Results. Irritant reactions to at least one of the test substances were seen in 39% of the 1092 patients tested. Fifteen (1.3%) patients showed allergic reactions: 13 to cocamidopropyl dimethylamine, 11 to dimethylaminopropylamine, 8 to oleamidopropyl dimethylamine, and 2 to cocamidopropyl betaine. Concomitant reactions to cocamidopropyl dimethylamine, dimethylaminopropylamine and oleamidopropyl dimethylamine were common. Ten of the 15 patients were diagnosed with occupational allergic contact dermatitis caused by cocamidopropyl betaine-related compounds. The sources of occupational exposure included hair care products, hair colours, perm wave solutions, and liquid soaps. Multiple contact allergies and exposure to several irritant factors were common, and all patients had hand eczema. Patch test reactions to cocamidopropyl betaine-related compounds are difficult to interpret, owing to extremely common irritant reactions. Cocamidopropyl betaine itself is probably not an allergen. Occupational allergic contact dermatitis caused by cocamidopropyl betaine-related compounds is relatively rare and, unlike non-occupational cocamidopropyl betaine-related allergy, typically manifests as hand dermatitis.

Immediate and delayed allergic hypersensitivity to corticosteroids: practical guidelines

Corticosteroids (CS), anti-inflammatory drugs also widely used to treat various allergic diseases, may themselves give rise to immediate and delayed allergic hypersensitivity reactions. To realise an appropriate diagnostic work-up in order to determine the CS-allergic patient's sensitization/tolerance profile and define the potential replacement agents that can still be tolerated. Analysis of the patch test results and concomitant (cross-) reaction patterns obtained with 315 corticosteroid-allergic patients, as well as molecular modelling of molecules. Proposal of a simplified classification of corticosteroids as to their allergenic properties into 3 groups, determination of two patient profiles according to steric and electrostatic properties of the molecules. Conclusion. Practical information to the medical profession in order to detect and manage such reactions is provided.

Contact allergy to preservatives. Analysis of IVDK data 1996-2009

Preservatives are well-known and important contact allergens. To examine the frequency of sensitization to preservatives, including time trends. Retrospective analysis of data on patch testing of preservatives contained in the standard series and special series collected by the IVDK during 1996-2009. Some 120,000 and 80,000 patients were tested with the baseline and the preservative series, respectively. Sensitization frequencies of the standard series allergens all ranged above 1%: methyldibromoglutaronitrile (MDBGN) 2·36-4·5%, methy(chloro)isothiazolinone (MCI/MI) 2·22%, formaldehyde 1·54%, paraben mix 1·33% and Bronopol® 1·25%. Regarding the special preservative series, 1·54% reacted positive to methylisothiazolinone (MI), and < 1% to the other preservatives. Concomitant reactions to formaldehyde in formaldehyde releasers ranged from 15% to almost 50%, and 67% of MI positives reacted to MCI/MI. As indicated by the MOAHLFA index, sensitization to MI, iodopropynylbutyl carbamate (IPBC) and quaternium 15 was associated more often with occupational dermatitis, whereas sensitization to imidazolidinyl urea and diazolidinyl urea was associated with face dermatitis, indicating cosmetic exposure. Epidemiologically relevant decreases (> 10%) were seen in chloroacetamide, benzyl alcohol and MDBGN. Epidemiologically relevant increases were noted in IPBC, sodium benzoate and MI. Preservatives are still important contact allergens. The introduction of new preservatives should consider the specific characteristics of occupational and of nonoccupational (cosmetic, household) exposure, and preventive measures should aim equally at both areas.

Polymorphic and Morphological Transformation during the Transition from a Propagating Band to Static Bands in the Nickel Hydroxide/Ammonia Liesegang System

We present an experimental study of the Ni+2/Ni(OH)2/NH3 reaction-diffusion system in a gel (agar). The system, which consists of a gel containing an inner electrolyte Ni+2 and a diffusing outer electrolyte (NH3/OH-), exhibits pulse propagation due to the concomitant precipitation reaction between Ni+2 and hydroxide ions and re-dissolution due to ammonia. During the propagation of the pulse, a transition to Liesegang banding is shown to take place. The bands are characterized by IR and XRD and are shown to consist of the polymorph -Ni(OH)2 whereas the pulse contains the other polymorph -Ni(OH)2. SEM measurements also reveal a morphological change accompanying the polymorphic transition between the pulse and the bands and uncovering an Ostwald ripening mechanism.

The prevalence and natural course of food protein–induced enterocolitis syndrome to cow’s milk: A large-scale, prospective population-based study

The prevalence and natural history for food protein-induced enterocolitis syndrome (FPIES) have not been determined. We sought to determine the prevalence, clinical manifestations, and rate of recovery for FPIES in a large-scale, population-based prospective study. In a prospective study the feeding history of 13,019 infants was obtained. Infants with probable adverse reactions to cow's milk protein (CMP) were clinically examined, skin prick tested, and challenged orally. Diagnostic criteria for CMP-induced FPIES included age less than 9 months, delayed recurrent vomiting (usually with nausea), and lethargy after exposure to CMP in the absence of other IgE-mediated symptoms, such as rash, urticaria, and respiratory symptoms. In addition, a positive challenge response to milk resulted in the above-mentioned gastrointestinal symptoms, removal of milk from the diet resulted in the resolution of those symptoms, or both. Ninety-eight percent of the cohort participated in the study. The cumulative incidence for FPIES was 0.34% (44/13,019 patients). The most common symptoms were recurrent vomiting (100%), lethargy (77%) diarrhea (25%), pallor (14%), and bloody diarrhea (4.5%). All patients had FPIES within the first 6 months of life. By the age of 3 years, 90% of the patients had recovered. We did not detect any concomitant reaction to soy. Eight patients with FPIES had IgE-mediated cow's milk allergy (IgE-CMA). The prevalence of FPIES is significant, and its clinical presentation is distinct from that of IgE-CMA. Most patients with FPIES recover, although a proportion might convert to IgE-CMA. The likelihood for a cross-reactivity to soy in this population was less than previously estimated.

Oxygen non-stoichiometry, high-temperature properties, and phase diagram of CaMnO3–δ

The oxygen content in CaMnO3–δ is studied by a coulometric titration technique depending on temperature and oxygen partial pressure variations in the ambient atmosphere. The δ–T phase diagram is derived from the obtained data where single-phase fields are outlined for orthorhombic, tetragonal, and cubic structures. The thermal expansion coefficient considerably larger in the cubic phase than in the tetragonal one is related with formation of large Mn3+ cations at depletion of oxygen from the crystalline lattice. Negative thermopower is explained by concomitant reactions of oxygen loss and charge disproportionation, \( {\hbox{2M}}{{\hbox{n}}^{{{4 + }}}}{\hbox{ = M}}{{\hbox{n}}^{{{3 + }}}}{\hbox{ + M}}{{\hbox{n}}^{{{5 + }}}}{ } \). The forbidden energy gap in CaMnO3–δ is evaluated to be about 0.5 eV.

Textile allergy - the Melbourne experience

Textile allergy is a well-established entity, but there are relatively few Australian reports in this area. To report the combined experience of textile contact dermatitis from the general and occupational contact dermatitis clinics at the Skin and Cancer Foundation, Melbourne, Victoria, Australia. On the basis of the clinical suspicion of textile allergy, 2069 patients were tested with a textile series. One hundred and fifty-seven (7.6%) patients reacted to any of the textile-related allergens. The most common allergen was Basic Red 46 (20.2% of the positive reactions), followed by Disperse Blue 106 and Disperse Blue 124 (11.8% and 11.2%, respectively). Reactions to formaldehyde and formaldehyde-releasing chemicals accounted for 30.6% of the concomitant reactions, and reactions to p-phenylenediamine accounted for 12.6% of the concomitant reactions. The use of Disperse Blue mix yielded only 12.2% of patients sensitive to either of these two allergens, and it is not endorsed as a screening agent for textile dye allergy. Textile allergy is not uncommon. In Melbourne, Basic Red 46 in inexpensive, dark-coloured, acrylic-blend, men's work socks is the most important cause. It is important to test with samples of patients' clothing.

Formation of hybrid N2O in a suspended soil due to co‐denitrification of NH2OH

AbstractA few studies have shown that amine compounds (e.g., hydroxylamine) can be co‐metabolically introduced into the reaction pathway of denitrification. During this microbial process, the N atom of the amine species is bound to a N atom of nitrite. In case of hydroxylamine, this concomitant reaction ultimately results in the formation of hybrid N2O. Due to its co‐metabolic character the process has been termed co‐denitrification. Hybrid N2O production during co‐denitrification has been proven to occur in prokaryotic (e.g., Pseudomonas sp.) as well as eukaryotic (e.g., Fusarium sp.) species. Many of them are already well‐known as common denitrifiers. However, until now no clear evidence has been provided to show that N2O production by co‐denitrification really takes place in a soil. In the present study, a formation of hybrid N2O was revealed by an adapted 15N‐tracer model, when both hydroxylamine and 15N‐nitrate were applied (mol ratio 10:1) to an anaerobically incubated soil suspension from a Haplic Chernozem. The presence of hybrid N2O was also indicated by a novel characteristic factor (Rbinom) developed for a hybrid‐N‐N‐gas detection. By contrast, no hybrid N2O was found when either an autoclaved soil suspension, only nitrate or only hydroxylamine was used. Thus, it appears that hybrid‐N2O formation occurred due to co‐denitrification of hydroxylamine. Hence, this is the first study which demonstrates hybrid‐N2O production by co‐denitrification beyond a microbial species level. The 15N‐tracer model revealed that under the given experimental conditions N2O production by co‐denitrification prevailed against N2O from denitrification and abiotic hydroxylamine decomposition. In addition, a formation of hybrid N2 was also calculated by the model. However, the experimental results lead to the conclusion that it was most likely caused by a reduction of hybrid N2O due to conventional denitrification.

The Information Content of Marketing Investments: The Case of Sales Force Resizing Announcements

This paper is concerned with the ability of marketing investments to convey information from the “black box” of the firm to participants in the financial markets. We focus on the context of sales force resizing announcements in the pharmaceutical industry because the sales force comprises the main marketing instrument for firms in this industry. We hypothesize that sales force resizing announcements will generate a concomitant market reaction because they provide information about future demand. Moreover, we predict stronger absolute effects for “increase” announcements than for “decrease” announcements. This is because the mean-shifting and uncertainty reducing aspects of new information work in concert for increase announcements, but in opposing ways for decrease announcements. Our theory also predicts a more pronounced market reaction when investors are more uncertain about the firm’s future performance and the announcement contradicts the direction of investors’ prior beliefs. Employing an event-study analysis, we find an unusually strong two-day market reaction of 3.2% for increase announcements and no significant market reaction for decrease announcements. The hypothesized effects with respect to uncertainty and direction of investors’ prior beliefs are also supported. We conclude by discussing implications for managing the investor relations function.

Occupational methacrylate and acrylate allergy – cross‐reactions and possible screening allergens

Acrylic resin monomers, especially acrylates and methacrylates, are important occupational allergens. To analyse patterns of concomitant patch test reactions to acrylic monomers in relation to exposure, and to suggest possible screening allergens. We reviewed the patch test files for the years 1994-2009 at the Finnish Institute of Occupational Health for allergic reactions to acrylic monomers, and analysed the clinical records of sensitized patients. In a group of 66 patients allergic to an acrylic monomer, the most commonly positive allergens were three methacrylates, namely ethyleneglycol dimethacrylate (EGDMA), 2-hydroxyethyl methacrylate (2-HEMA) and 2-hydroxypropyl methacrylate (2-HPMA), and an acrylate, namely diethyleneglycol diacrylate (DEGDA). The patterns of concomitant reactions imply that exposure to methacrylates may induce cross-reactivity to acrylates, whereas exposure to acrylates usually does not lead to cross-allergy to methacrylates. Screening for triethyleneglycol diacrylate (TREGDA) in the baseline series was found to be useful, as 3 of 8 patients with diagnosed occupational acrylate allergy might have been missed without the screening. A short screening series of four allergens, EGDMA, DEGDA, 2-HPMA and pentaerythritol triacrylate (PETA), would have screened 93% of our 66 patients; each of the remaining 5 patients reacted to different acrylic monomer(s).

Patch testing with fragrance mix II: results of the IVDK 2005–2008

The fragrance mix (FM I), established in 1977, detects the majority, but not all cases of contact allergy to fragrances. Based on European research 2002/2003, fragrance mix II (FM II) was developed to supplement FM I. In 2005, the German Contact Dermatitis Research Group (DKG) added FM II to their baseline series. To evaluate reactions to FM II and its constituents in routine patch testing. Retrospective data analysis of the Information Network of Departments of Dermatology (IVDK), 2005-2008, of patch test results with FM II and its constituents. A total of 35 633 patients were patch tested with FM II as part of the DKG baseline series. Of these, 1742 (4.9%) reacted positively. Concomitant reactions to FM I were observed in 41.9% of the patients reacting to FM II. In 367 FM II-positive patients, a full breakdown test of the mix was performed. Of these, 47.7% reacted to hydroxyisohexyl 3-cyclohexene carboxaldehyde, 16.1% to citral, 11.4% to farnesol, 3.8% to hexyl cinnamal, 2.7% to coumarin, and 2.5% to citronellol. FM II is an important screening and diagnostic tool to detect fragrance allergy. Hydroxyisohexyl 3-cyclohexene carboxaldehyde is the most important fragrance allergen in FM II.

Pattern of Corticosteroid Allergy in Thailand

Corticosteroid allergy is a complication of topical therapy detected by patch-testing with corticosteroid allergens. Ten-year retrospective review to study the prevalence and patterns of corticosteroid allergy in Thai patients. Of 882 patients who were patch-tested, 29 (3.29%) had allergic reactions to corticosteroids. Of these 29 patients, 17 (58.62%) had positive reactions to one corticosteroid, and 12 (41.38%) reacted to multiple corticosteroids. Rates of reaction to corticosteroid groups ranged from 31.03 to 80.95%. Concomitant reactions between groups were noted. The prevalence of topical corticosteroid allergy (using two screening allergens, tixocortol pivalate and budesonide) was 2.27% (20 of 882). Testing with additional steroid allergens in suspected cases increased the prevalence to 3.29%. Tixocortol pivalate detected 51.72% of corticosteroid-allergic cases, and budesonide detected 24.14%. Combining both tixocortol and budesonide detected 68.97% of cases. Corticosteroid allergy is found to multiple corticosteroids, and concomitant reactions occur across groups. Group D1 corticosteroid esters produced a higher positive reaction rate (61.9%) than groups D2 (52.38%) and A (51.72%). This may be due to different prescribing habits or the easy access to D1 corticosteroids sold over the counter by pharmacies in Thailand.

Biological reduction of chlorinated solvents: Batch-scale geochemical modeling

Simulation of biodegradation of chlorinated solvents in dense non-aqueous phase liquid (DNAPL) source zones requires a model that accounts for the complexity of processes involved and that is consistent with available laboratory studies. This paper describes such a comprehensive modeling framework that includes microbially mediated degradation processes, microbial population growth and decay, geochemical reactions, as well as interphase mass transfer processes such as DNAPL dissolution, gas formation and mineral precipitation/dissolution. All these processes can be in equilibrium or kinetically controlled. A batch modeling example was presented where the degradation of trichloroethene (TCE) and its byproducts and concomitant reactions (e.g., electron donor fermentation, sulfate reduction, pH buffering by calcite dissolution) were simulated. Local and global sensitivity analysis techniques were applied to delineate the dominant model parameters and processes. Sensitivity analysis indicated that accurate values for parameters related to dichloroethene (DCE) and vinyl chloride (VC) degradation (i.e., DCE and VC maximum utilization rates, yield due to DCE utilization, decay rate for DCE/VC dechlorinators) are important for prediction of the overall dechlorination time. These parameters influence the maximum growth rate of the DCE and VC dechlorinating microorganisms and, thus, the time required for a small initial population to reach a sufficient concentration to significantly affect the overall rate of dechlorination. Self-inhibition of chlorinated ethenes at high concentrations and natural buffering provided by the sediment were also shown to significantly influence the dechlorination time. Furthermore, the analysis indicated that the rates of the competing, nonchlorinated electron-accepting processes relative to the dechlorination kinetics also affect the overall dechlorination time. Results demonstrated that the model developed is a flexible research tool that is able to provide valuable insight into the fundamental processes and their complex interactions during bioremediation of chlorinated ethenes in DNAPL source zones.

Allergic contact dermatitis from tincture of benzoin with multiple concomitant reactions

Contact DermatitisVolume 61, Issue 6 p. 358-360 Allergic contact dermatitis from tincture of benzoin with multiple concomitant reactions Denis Sasseville, Corresponding Author Denis Sasseville Division of Dermatology, McGill University Health Centre, Montréal, QC H3A 1A1, CanadaDr Denis Sasseville, MD, FRCPC Director, Division of DermatologyMcGill University Health CentreRoyal Victoria Hospital, Room A4.17687 Pine Avenue WestMontréal, QC H3A 1A1CanadaTel: 514 934 1934 ext. 34648Fax: 514 843 1570e-mail: [email protected]Search for more papers by this authorMélissa Saber, Mélissa Saber Service de Dermatologie, Centre Hospitalier Universitaire de Montréal, QC H2X 3J4, CanadaSearch for more papers by this authorLucie Lessard, Lucie Lessard Division of Plastic Surgery, McGill University Health Centre, Montréal, QC H3A 1A1, CanadaSearch for more papers by this author Denis Sasseville, Corresponding Author Denis Sasseville Division of Dermatology, McGill University Health Centre, Montréal, QC H3A 1A1, CanadaDr Denis Sasseville, MD, FRCPC Director, Division of DermatologyMcGill University Health CentreRoyal Victoria Hospital, Room A4.17687 Pine Avenue WestMontréal, QC H3A 1A1CanadaTel: 514 934 1934 ext. 34648Fax: 514 843 1570e-mail: [email protected]Search for more papers by this authorMélissa Saber, Mélissa Saber Service de Dermatologie, Centre Hospitalier Universitaire de Montréal, QC H2X 3J4, CanadaSearch for more papers by this authorLucie Lessard, Lucie Lessard Division of Plastic Surgery, McGill University Health Centre, Montréal, QC H3A 1A1, CanadaSearch for more papers by this author First published: 09 December 2009 https://doi.org/10.1111/j.1600-0536.2009.01645.xCitations: 14Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume61, Issue6December 2009Pages 358-360 RelatedInformation

Effect of natural seasonal pollen exposure and repeated nasal allergen provocations on elevation of exhaled nitric oxide

Exhaled nitric oxide (FENO) is a marker for allergic airway inflammation. We wondered whether in patients with intermittent allergic rhinitis only (i) natural pollen exposure and (ii) artificial pollen exposure by repeated nasal allergen provocations may lead to an elevation of FENO. In two prospective studies, we compared the FENO of nonatopic controls with the FENO of nonasthmatic individuals with mild intermittent rhinitis to tree and/or grass pollen. Study I: 13 atopic individuals and seven controls had measurements of FENO, blood eosinophils and eosinophilic cationic protein (ECP) before, during and after pollen season. Study II: 16 atopic individuals and 12 controls had nasal allergen provocations on four following days out of pollen season, with daily measurements of FENO before, 2 and 6 h after provocation, and determination of blood eosinophils, ECP and FEV1 at baseline, on days 5 and 10-12. Natural pollen exposure (study I) caused a significant elevation of FENO in allergic individuals. Nasal allergen provocations (study II) did not elicit a statistically significant rise neither of FENO nor of blood eosinophils between baseline and day 5. However, a subgroup of four individuals with a rise of blood eosinophils during nasal allergen provocations showed also a rise of FENO. We suppose that in allergic rhinitis a concomitant reaction of the bronchial system is dependent on a strong local inflammation leading to a generalized immune stimulation.

Positive Patch Test Reactions to Lanolin: Cross-Sectional Data from the North American Contact Dermatitis Group, 1994 to 2006

The prevalence of lanolin sensitivity in referred patients is less than 4%. To (1) describe patients with positive patch-test reactions to lanolin, (2) determine clinical and occupational relevance associated with reactions to lanolin and common sources, and (3) examine the frequency of co-reacting allergens. A retrospective analysis of 26,479 patients patch-tested by the North American Contact Dermatitis Group (NACDG), 1994 to 2006. Overall, 2.5% of patients (643 of 25,811) tested to lanolin alcohol 30% in petrolatum had positive reactions. Prevalence decreased from 3.7% in 1996 to 1998 to 1.8% in 2005 to 2006 (p <.0001); 83.4% of all positive reactions were currently relevant, but only 2.5% were occupationally relevant. Lanolin-positive patients were 1.2 times more likely to be male and 1.4 times more likely to have a history of atopic dermatitis when compared to allergic, but lanolin-negative, patients (p < .0002 and p < .0001, respectively). Cosmetics were the most common source. Lanolin-positive patients were significantly more likely to be co-sensitized to another NACDG standard screening allergen (p <.0001). The prevalence of allergic patch-test reactions to lanolin in North America patch-test populations is decreasing. Current relevance of reactions was high, but occupational relevance was low. Concomitant reactions were more common in lanolin-positive patients.

Cross-reactions among hair dye allergens

Background: p-Phenylenediamine (PPD) is an important hair dye allergen, but there remains a reasonable suspicion that other hair dye chemicals may also be responsible for a proportion of the clinical burden of hair dye allergy. Objective: To assess to what extent presently assessed additional patch test agents contribute to the diagnosis of non-PPD hair dye allergy. Methods: A retrospective analysis was conducted of patch test results with hair dye allergens, focusing on the extent to which patients who were positive for allergic reactions to other hair dye allergens also had a concomitant positive reaction to PPD. Results: For the hair dye allergens other than p-toluenediamine (PTD), reactions in the absence of a concomitant positive reaction to PPD were very rare. Positive reactors to PTD were also positive for reactions to PPD in 5 of every 6 cases. Pyrogallol positives often occurred in the absence of a PPD positive, but were never judged to be of clinical relevance. Conclusions: Hair dye chemicals other than PPD may be of importance, but the presently tested materials, with the possible exception of PTD, are normally positive only when a PPD-positive reaction is also present, suggesting that their use in patch testing in hair dye allergy is likely to be of limited value.

Positive Patch-Test Reactions to Propylene Glycol: A Retrospective Cross-Sectional Analysis from the North American Contact Dermatitis Group, 1996 to 2006

Propylene glycol (PG) may cause allergic or irritant contact dermatitis. It primarily functions as a vehicle, solvent, or emulsifier in cosmetics and topical medications. To characterize the prevalence of positive patch-test reactions to PG and the epidemiology of affected patients. Retrospective analysis of cross-sectional data compiled by the North American Contact Dermatitis Group (NACDG) from 1996 to 2006. Of 23,359 patients, 810 (3.5%) had allergic patch-test reactions to 30% PG; 12.8% of the reactions were of definite clinical relevance (positive reaction to a personal product containing PG), 88.3% were considered to be currently relevant (definite, probable, or possible relevance), and 4.2% of reactions were occupation related, most commonly to mechanical and motor vehicle occupations. Common sources of PG were personal care products (creams, lotions, and cosmetics, 53.8%), topical corticosteroids (18.3%), and other topical medicaments (10.1%). In patients positive only to PG (n = 135), the face was most commonly affected (25.9%), followed by a scattered or generalized pattern (23.7%). The most common concomitant reactions included reactions to Myroxilon pereirae, fragrance mix, formaldehyde, bacitracin, methyldibromoglutaronitrile/phenoxyethanol, carba mix, and tixocortol pivalate. In this select population of patients referred for patch testing, allergic reactions to PG were often currently clinically relevant but were rarely related to occupation. The most common sources were personal care products and topical corticosteroids.

Recent synthetic approaches toward non-anomeric spiroketals in natural products.

Many natural products of biological interest contain [6,5]- and [6,6]-spiroketal moieties that can adopt various configurations, benefiting or not from anomeric conformation stabilizing effects. The spiroketal fragments are often important for the biological activity of the compounds containing them. Most stable spiroketal stereoisomers, including those benefiting from conformational anomeric effects (gauche conformers can be more stable than anti conformers because of a contra-steric stabilizing effect), are obtained easily under acidic conditions that permit acetal heterolysis (formation of tertiary oxycarbenium ion intermediates). The synthesis of less stable stereoisomers requires stereoselective acetal forming reactions that do not permit their equilibration with their most stable stereoisomers or, in the case of suitably substituted derivatives, concomitant reactions generating tricyclic products that quench the less stable spiroketal conformers. Ingenuous approaches have been recently developed for the synthesis of naturally occurring [6,6]- and [5,6]-nonanomeric spiroketals and analogues. The identification of several parameters that can influence the stereochemical outcome of spirocyclization processes has led to seminal improvements in the selective preparation of the non-anomeric isomers that are discussed herein. This review also gives an up-dated view of conformational anomeric effect which represents a small fraction of the enthalpic anomeric effect that makes gem-dioxy substituted compounds much more stable that their 1,n-dioxy substituted isomers (n > 1). Although models assuming sp3-hybridized oxygen atoms have been very popular (rabbit ears for the two non-bonding electron pairs of oxygen atom), sp2-hybridized oxygen atoms are used to describe the conformational anomeric effect.

Dermite de contact systémique au nickel induite par un cathéter veineux

Systemic contact dermatitis is a form of delayed hypersensitivity reaction seen after systemic administration of a hapten in a subject previously sensitised via the cutaneous route. There have been few reports of this condition with nickel. In this paper, we describe four cases ascribable to the presence of nickel in a peripheral venous catheter. We reviewed the dossiers of four women developing pruriginous exanthema several hours after infusion. The same type of catheter (Optiva) was used in all cases. Epicutaneous tests were performed in all four patients, as well as a challenge test comprising a serum glucose infusion given via the incriminated catheter. Testing for the presence of nickel in the catheter was performed by means of a spot-test. Quantitative nickel assays were performed in vitro using inductively coupled plasma mass spectrometry on the glucose solution infusion kits with eight sample catheters and a negative control kit. The eruptions comprised maculopapular lesions, in some cases vesicular or bullous, arranged symmetrically around the tops of the limbs, the trunk and skin folds, with involvement of the infused forearm in most cases. Two of the four patients had previously presented a number of similar episodes. All four patients exhibited frankly positive test results for nickel and the role of the Optiva) catheter was demonstrated in all four patients by means of a challenge test. The presence of nickel in the catheter was demonstrated by a positive spot-test and was confirmed by quantitative assay demonstrating variations in nickel release for the different samples of the same Optiva) catheter model. As with the few reported cases published in the literature, our four cases of systemic contact dermatitis induced by nickel in a catheter all incriminated the same type of catheter and the tests performed clearly demonstrated the causative role of the device. The cases of systemic contact dermatitis were seen chiefly in women in the immediate postoperative period; they could be confused with adverse drug reactions and subsequently lead to inappropriate withdrawal of treatment. The diagnosis, which was suggested by the appearance of the lesions (symmetry, involvement of skinfolds and buttocks, concomitant reaction at the injection site), history of prior episodes and a frankly positive epicutaneous nickel test, may be readily confirmed using a challenge test.