Use of optical biosensor technology to study immunological cross-reactivity between different sulfonamide drugs

Four nephrology myths debunked

There are many controversial topics relating to renal disease in hospitalized patients. The aim of this review is to shed light on some important and often debated issues. Hypothyroidism, unlike myxedema, is not a cause of hyponatremia (although it can be sometimes seen in conjunction with the latter) and additional investigations should be done to determine its etiology. Sodium bicarbonate is effective for treatment of hyperkalemia primarily by enhancing renal potassium elimination rather than by translocating potassium into cells. Acetaminophen can be a cause of metabolic acidosis by causing 5-oxoprolinuria. Furosemide (and sulfa containing diuretics) can safely be used in patients with an allergy to sulfa-containing antibiotics (SCA).

Severe allergic reaction to hydrochlorothiazide mimicking septic shock

Hydrochlorothiazide (HCTZ) is a sulfonamide-containing drug with commonly reported adverse effects that include electrolyte abnormalities, orthostatic hypotension, hyperglycemia, and photosensitivity. A few reports have described rare but serious drug complications such as interstitial pneumonitis, angioedema, and aplastic anemia. We describe a patient who experienced a serious HCTZ-induced adverse event that, to our knowledge, has not yet been reported in the literature. A 78-year-old woman came to the emergency department with dyspnea and severe fatigue; her signs and symptoms were suggestive of septic shock from pneumonia. She was treated accordingly, her condition improved, and she was discharged home. During the next 2 months, the patient returned to the emergency department 2 more times and was hospitalized each time with the same diagnosis. During her third admission, it was discovered that the patient's primary care physician had restarted her HCTZ for hypertension after it had been discontinued during each of the first two hospitalizations. The patient's symptoms began within hours of the first and second hospitalizations and almost immediately after taking a dose of HCTZ on the day of the third hospitalization. Her medical history revealed documented allergic reactions to sulfonamide drugs and penicillin; thus a hypersensitivity reaction to HCTZ was suspected. Use of the Naranjo adverse drug reaction probability scale indicated a probable relationship between the patient's hypersensitivity reactions and HCTZ therapy. Because of a lack of evidence showing cross-reactivity among the different classes of sulfonamides, the mechanism of the allergic reaction to HCTZ was unlikely to be cross-sensitivity between sulfonamide antibiotics and sulfonamide nonantibiotic drugs. Although the mechanism is not clear, evidence shows that the allergy to the HCTZ (sulfonamide nonantibiotic) may be due to a predisposition to drug allergies rather than sulfonamide cross-sensitivity. Clinicians should be aware of the potential for these types of allergic reactions.

Advantages and limitations of on-line solid phase extraction coupled to liquid chromatography–mass spectrometry technologies versus biosensors for monitoring of emerging contaminants in water

On-line solid phase extraction (SPE) coupled to liquid chromatography-mass spectrometry (LC-MS) and biosensors are advanced technologies that have found increasing application in the analysis of environmental contaminants although their application to the determination of emerging contaminants (previously unknown or unrecognized pollutants) has been still limited. This review covers the most recent advances occurred in the areas of on-line SPE-LC-MS and biosensors, discusses and compares the main strengths and limitations of the two approaches, and examines their most relevant applications to the analysis of emerging contaminants in environmental waters. So far, the on-line configuration most frequently used has been SPE coupled to liquid chromatography-(tandem) mass spectrometry. Sorbents used for on-line SPE have included both traditional (alkyl-bonded silicas and polymers) and novel (restricted access materials (RAMs), molecularly imprinted synthetic polymers (MIPs), and immobilized receptors or antibodies (immunosorbents) materials. The biosensor technologies most frequently applied have been based on the use of antibodies and, to a lesser extent, enzymes, bacteria, receptors and DNA as recognition elements, and the use of optical and electrochemical transducing elements. Emerging contaminants investigated by means of these two techniques have included pharmaceuticals, endocrine disrupting compounds such as estrogens, alkylphenols and bisphenol A, pesticides transformation products, disinfection by-products, and bacterial toxins and mycotoxins, among others. Both techniques offer advantageous, and frequently comparable, features such as high sensitivity and selectivity, minimum sample manipulation, and automation. Biosensors are, in addition, relatively cheap and fast, which make them ideally suited for routine testing and screening of samples; however, in most cases, they can not compete yet with on-line SPE procedures in terms of accuracy, reproducibility, reliability (confirmation) of results, and capacity for multi-analyte determination.

Biosensors as useful tools for environmental analysis and monitoring

Recent advances in the development and application of biosensors for environmental analysis and monitoring are reviewed in this article. Several examples of biosensors developed for relevant environmental pollutants and parameters are briefly overviewed. Special attention is paid to the application of biosensors to real environmental samples, taking into consideration aspects such as sample pretreatment, matrix effects and validation of biosensor measurements. Current trends in biosensor development are also considered and commented on in this work. In this context, nanotechnology, miniaturisation, multi-sensor array development and, especially, biotechnology arise as fast-growing areas that will have a marked influence on the development of new biosensing strategies in the near future.

Cross-reactivity among drugs: clinical problems

Cross-reactivity among drugs is either mediated by immunologic mechanisms or not. The former kind is usually explained by the presence of common antigenic determinants in the cross-reacting drugs. In the case of compounds provoking non-allergic hypersensitivity reactions, cross-reactivity is explained by a common pharmacological characteristic, such as the inhibitory effect of non-steroidal anti-inflammatory drugs on cyclooxygenase-1 and the capability of muscle relaxants or contrast media to release histamine through a non-immunologic mechanism. The main clinical problem deriving from cross-reactivity among drugs is the compelling need to choose a potentially cross-reactive compound and, therefore, to assess cross-reactivity by diagnostic tests. In choosing alternative compounds, skin testing has been used in evaluating IgE-mediated cross-reactivity between penicillins and cephalosporins, as well as among muscle relaxants. In assessing T cell-mediated cross-reactivity among contrast media, corticosteroids, anticonvulsants and heparins, delayed-reading intradermal tests and patch tests, together with lymphocyte transformation tests, can be performed. Because of the limited sensitivity of in vivo and in vitro testing, the most prudent way of establishing the tolerability of a compound of the same group in patients who especially require one is a graded challenge when other allergologic tests are negative.

A survey of the year 2002 commercial optical biosensor literature

We have compiled 819 articles published in the year 2002 that involved commercial optical biosensor technology. The literature demonstrates that the technology's application continues to increase as biosensors are contributing to diverse scientific fields and are used to examine interactions ranging in size from small molecules to whole cells. Also, the variety of available commercial biosensor platforms is increasing and the expertise of users is improving. In this review, we use the literature to focus on the basic types of biosensor experiments, including kinetics, equilibrium analysis, solution competition, active concentration determination and screening. In addition, using examples of particularly well-performed analyses, we illustrate the high information content available in the primary response data and emphasize the impact of including figures in publications to support the results of biosensor analyses.

Likelihood and Mechanisms of Cross-Allergenicity Between Sulfonamide Antibiotics and Other Drugs Containing a Sulfonamide Functional Group

Concerns about cross-allergenicity between sulfonamide antibiotics and nonantibiotic, sulfonamide-containing drugs persist and can complicate patients' drug therapy unnecessarily. No interaction between the human immune system and the sulfonamide functional group has been demonstrated. The immunologic determinant of type I, immediate hypersensitivity responses to sulfonamide antibiotics is the N1 heterocyclic ring. Nonantibiotic sulfonamides do not contain this structural feature. Non-type I hypersensitivity responses to sulfonamide antibiotics are largely attributable to reactive metabolites that may cause either direct cytotoxicity or immunologic response. Formation of these metabolites is a stereospecific process that occurs at the N4 amino nitrogen of the sulfonamide antibiotics, a structure also not found on any nonantibiotic sulfonamide drugs. The stereospecificity of these reactions implies that cross-reactivity with nonantibiotic sulfonamide-containing drugs is highly unlikely; this assertion is supported by recent literature. However, T-cell recognition of unmetabolized, nonhaptenated parent sulfonamide antibiotic appears to occur in a small subset of hypersensitive patients. Several of the severe cutaneous reactions associated with sulfonamide antibiotics are mediated by T cells. It is not known whether T-cell recognition of antibiotic is related to the sulfonamide functional group. Until the mechanism of this recognition is elucidated, cross-reactivity with nonantibiotic sulfonamides appears to remain at least theoretically possible.

The use of the resonant mirror biosensor to detect point mutations, as demonstrated with synthetic oligonucleotides

The possibility of using the resonant mirror biosensor to detect point substitutions in oligonucleotides was demonstrated with a fragment of the Helicobacter pylori 23S rRNA gene, point mutations in which are responsible for clarythromycin resistance. Conditions were optimized for the interaction of a probe immobilized on the sensing surface with targets containing various nucleotide substitutions. A probe allowing reliable discrimination of mutant targets was selected. The mismatch position in the probe was shown to affect the kinetic parameters (response) of hybridization with mutant targets, reporting not only the position, but also the character (G or C) of a substitution.