Development of a model to mimic pleural space mechanics.

BACKGROUND: A simulator of the respiratory system which includes the pleural space is currently lacking. However, such mechanical models are essential to develop and test new medical devices regulating the pressure in the pleural space. OBJECTIVE: It was the aim of this study to develop a model which mimics the pleural space. The device should be able to represent biomechanical functions of the respiratory system and it is intended for applications in research and development to study pleural space mechanics. The system should allow adjusting parameters to simulate different kinds of breathing. Output parameters such as the pressure in pleural cavity or the breathing volume should be measured. METHODS: A mechanical lung simulator was developed. The chest wall is represented by an elastic shell in which silicone balloons were implemented to mimic the lung tissue. These two components establish a pleural cavity. Pressure sensors were installed to measure pressure in the pleural space and an aeroplethysmograph was positioned above the two lungs to measure flow. The system was assembled and tested under various conditions. RESULTS: Different tests demonstrated that the device is currently capable of simulating breathing volumes up to approx. 1700 ml. Different breathing characteristics including coughing can be simulated. Higher negative pressures especially during deep breathing were observed at the top of the lung because of higher balloon wall (lung) thickness in this area. It was possible to demonstrate the effect of certain changes of the lung tissue such as fibrosis with corresponding pressure recordings confirming known effects of such pathologies. CONCLUSIONS: The device allows simulating pressures in the pleural space during breathing at an advanced level and will be of use to develop and validate medical devices under laboratory conditions that control and regulate the pleural space. This represents a significant benefit to improve the development process for devices in this area.

A lectin-mediated resistance of higher fungi against predators and parasites.

Fruiting body lectins are ubiquitous in higher fungi and characterized by being synthesized in the cytoplasm and up-regulated during sexual development. The function of these lectins is unclear. A lack of phenotype in sexual development upon inactivation of the respective genes argues against a function in this process. We tested a series of characterized fruiting body lectins from different fungi for toxicity towards the nematode Caenorhabditis elegans, the mosquito Aedes aegypti and the amoeba Acanthamoeba castellanii. Most of the fungal lectins were found to be toxic towards at least one of the three target organisms. By altering either the fungal lectin or the glycans of the target organisms, or by including soluble carbohydrate ligands as competitors, we demonstrate that the observed toxicity is dependent on the interaction between the fungal lectins and specific glycans in the target organisms. The toxicity was found to be dose-dependent such that low levels of lectin were no longer toxic but still led to food avoidance by C. elegans. Finally, we show, in an ecologically more relevant scenario, that challenging the vegetative mycelium of Coprinopsis cinerea with the fungal-feeding nematode Aphelenchus avenae induces the expression of the nematotoxic fruiting body lectins CGL1 and CGL2. Based on these findings, we propose that filamentous fungi possess an inducible resistance against predators and parasites mediated by lectins that are specific for glycans of these antagonists.

Misalignment of total ankle components can induce high joint contact pressures.

BACKGROUND: A major cause of the limited longevity of total ankle replacements is premature polyethylene component wear, which can be induced by high joint contact pressures. We implemented a computational model to parametrically explore the hypothesis that intercomponent positioning deviating from the manufacturer's recommendations can result in pressure distributions that may predispose to wear of the polyethylene insert. We also investigated the hypothesis that a modern mobile-bearing design may be able to better compensate for imposed misalignments compared with an early two-component design. METHODS: Two finite element models of total ankle replacement prostheses were built to quantify peak and average contact pressures on the polyethylene insert surfaces. Models were validated by biomechanical testing of the two implant designs with use of pressure-sensitive film. The validated models were configured to replicate three potential misalignments with the most CLINICAL RELEVANCE: version of the tibial component, version of the talar component, and relative component rotation of the two-component design. The misalignments were simulated with use of the computer model with physiologically relevant boundary loads. RESULTS: With use of the manufacturer's guidelines for positioning of the two-component design, the predicted average joint contact pressures exceeded the yield stress of polyethylene (18 to 20 MPa). Pressure magnitudes increased as implant alignment was systematically deviated from this reference position. The three-component design showed lower-magnitude contact pressures in the standard position (<10 MPa) and was generally less sensitive to misalignment. Both implant systems were sensitive to version misalignment. CONCLUSIONS: In the tested implants, a highly congruent mobile-bearing total ankle replacement design yields more evenly distributed and lower-magnitude joint contact pressures than a less congruent design. Although the mobile-bearing implant reduced susceptibility to aberrant joint contact characteristics that were induced by misalignment, predicted average contact stresses reached the yield stress of polyethylene for imposed version misalignments of >5 degrees.

Urinary excretion of an intravenous 26Mg dose as an indicator of marginal magnesium deficiency in adults.

BACKGROUND: Measurement of magnesium (Mg) status is problematic because tissue Mg deficiency can be present without low serum Mg concentrations. OBJECTIVE: To evaluate a modified version of the Mg retention test using stable isotopes for the assessment of Mg status in general, and the detection of marginal Mg deficiency in particular. DESIGN: A modified version of the Mg retention test using a small dose of (26)Mg was evaluated for assessment of Mg status in 22 healthy subjects. Muscle Mg concentration was used as reference for Mg status. A muscle biopsy was taken from the lateral portion of the quadriceps muscle from each subject. After 2 to 4 weeks, 11 mg of (26)Mg (as MgCl(2) in 14 ml water) were injected i.v. over a period of 10 min and all urine was collected for the following 24 h. Excretion of the isotopic label was expressed as percentage of the administered dose excreted in urine within 24 h. RESULTS: Mean +/- s.d. Mg concentration in muscle was 3.85 +/- 0.17 mmol/100 g fat-free dried solids. Mean +/- s.d. excretion of the injected dose within 24 h was 7.9 +/- 2.1%. No correlation was found between muscle Mg concentration and excretion of the isotopic label (r (2 ) = 0.061, P = 0.27). CONCLUSIONS: In this study, urinary excretion of an intravenous Mg tracer was not influenced by muscle Mg concentration and its usefulness for the detection of marginal Mg deficiency could therefore not be demonstrated. SPONSORSHIP: Swiss Foundation for Nutrition Research and Swiss Federal Institute of Technology, Zurich, Switzerland.

Dietary magnesium intake in type 2 diabetes.

BACKGROUND: Magnesium deficiency is common in type 2 diabetes and may have a negative impact on glucose homeostasis and insulin resistance, as well as on the evolution of complications such as retinopathy, thrombosis and hypertension. OBJECTIVE: To assess the dietary magnesium intake of patients with type 2 diabetes in Zurich, Switzerland and to compare the magnesium intake of diabetic and non-diabetic subjects. DESIGN: The magnesium intake of 97 randomly selected patients with type 2 diabetes and 100 healthy, non-diabetic controls matched for age and sex was estimated using a diet history method. During winter and summer periods, mean daily magnesium intakes were calculated from detailed information given by the test subjects about their eating habits over the previous 2 months. The calculations were performed using EBIS, a computer program based on a German nutrient data base (BLS 2.3), with food items specific to Switzerland added or directly analysed when necessary. RESULTS: The mean+/-s.d. daily magnesium intake of the male diabetic and male control subjects was 423.2+/-103.1 and 421.1+/-111.0 mg, respectively. The mean daily magnesium intake of the female diabetic and female control subjects was 419.1+/-109.7 and 383.5+/-109.7 mg, respectively. There were no significant differences in daily magnesium intake between the diabetic and the non-diabetic subjects and mean intakes in both groups exceeded Swiss recommended dietary intakes. CONCLUSIONS: Dietary intake of magnesium appears sufficient in Swiss adults with type 2 diabetes and is unlikely to contribute to the aetiology of magnesium deficiency. SPONSORSHIP: The Swiss Federal Institute of Technology, Zurich, Switzerland.

The discovery of thiamethoxam: a second-generation neonicotinoid.

Neonicotinoids represent a novel and distinct chemical class of insecticides with remarkable chemical and biological properties. In 1985, a research programme was started in this field, in which novel nitroimino heterocycles were designed, prepared and assayed for insecticidal activity. The methodology for the synthesis of 2-nitroimino-hexahydro-1,3,5-triazines, 4-nitroimino-1,3,5-oxadiazinanes and 4-nitroimino-1,3,5-thiadiazinanes is outlined. Bioassays demonstrated that 3-(6-chloropyridin-3-ylmethyl)-4-nitroimino-1,3,5-oxadiazinane exhibited better insecticidal activity than the corresponding 2-nitroimino-hexahydro-1,3,5-triazine and 4-nitroimino-1,3,5-thiadiazinane. In most tests, this compound was equally or only slightly less active than imidacloprid. A series of structural modifications on this lead structure revealed that replacement of the 6-chloro-3-pyridyl group by a 2-chloro-5-thiazolyl moiety resulted in a strong increase of activity against chewing insects, whereas the introduction of a methyl group as pharmacophore substituent increased activity against sucking pests. The combination of these two favourable modifications led to thiamethoxam (CGA 293 343). Thiamethoxam is the first commercially available second-generation neonicotinoid and belongs to the thianicotinyl sub-class. It is marketed under the trademarks Actara for foliar and soil treatment and Cruiser for seed treatment. The compound has broad-spectrum insecticidal activity and offers excellent control of a wide variety of commercially important pests in many crops. Low use rates, flexible application methods, excellent efficacy and the favourable safety profile make this new insecticide well-suited for modern integrated pest management programmes in many cropping systems.

[Acetylsalicylic acid and pyrazole allergy or pseudo-allergy?]. / Acetylsalicylsäure- und Pyrazol-Allergie oder Pseudo-Allergie?

In a multicentric study by the European Study Group of Drug Allergy, 69 patients suffering from immediate type reaction after the intake of non-steroidal antiphlogistica were examined with regard to allergy or pseudo-allergy. Apart from the scratch test on the original substance, we performed cutaneous tests with salicyloyl and pyrazol conjugates, and determined IgE and IgG by means of a modified RAST method. There were 3 groups to be distinguished: (1) "intolerance" reaction of the aspirin type as a pseudo-allergic reaction (15 cases); (2) true IgE-mediated allergy (16 cases); (3) pyrazol "idiosyncrasy" (33 cases). 5 patients showed a combination of the three pathomechanisms.

Dot-immunobinding assay with monoclonal anti-IgE antibodies for the detection and quantitation of human IgE.

This paper describes a dot immunobinding assay for determining total human IgE with a tandem of monoclonal anti-IgE antibodies. Minute quantities of monoclonal anti-IgE antibodies were adsorbed on nitrocellulose discs. IgE bound to this solid phase monoclonal anti-IgE antibody was detected by a second monoclonal antibody conjugated with horseradish peroxidase. Using 4-chloro-1-naphthol as a chromogen results in a stable colour reaction that can be semiquantitatively analysed by the naked eye. The colour intensities of the reaction were also analysed by densitometry, yielding a very reproducible quantitation of human serum IgE. Using a serum dilution of 1:50, IgE could be detected in the range of 12.5-2500 U/ml. Using non-diluted serum samples IgE levels between 0.05-50 U/ml were reproducibly measured. Total serum IgE as determined by this dot assay correlated very well with IgE determinations performed by the commercial PRIST assay.

[Radioimmunologic detection of IgE and IgG antibodies against drugs. Conclusions after experience with over 1200 patients]. / Radioimmunologische Erfassung von IgEund IgG-Antikörpern gegen Medikamente. Standortbestimmung nach Erfahrungen mit über 1200 Patienten.

Based on the radioallergosorbent test (RAST), the authors have developed a series of assays to detect IgE and IgG antibodies against a number of frequently used drugs. In this system drugs bound covalently to cellulose paper are incubated with serum and washed; the hapten-specific IgE and IgG antibodies are then qualified and quantified by means of 125I-labelled anti-human IgE and IgG respectively. Thus far the sera of 1,228 patients have been analyzed following therapy with betalactam antibiotics, co-trimoxazole, salicylates, pyrazolones, flavonoids and tetrahydroisoquinoline. The induction of IgG antibodies is a frequent occurrence and that of IgE rare. Isolated high titers of IgE are associated mainly with anaphylactic reactions; in the presence of simultaneously raised IgG titers such side reactions are often absent. Highest IgG titers were found in patients with immune hemolysis after betalactam antibiotics, flavonoids and tetrahydroisoquinoline. In the other types of side reaction specific IgG titers were not significantly higher than in patients without side reactions. The estimation of circulating antibodies against drugs cannot yet be utilized diagnostically except in the rare cases of anaphylactic side reactions. However, the method described permits specific and sensitive detection of sensitization and is suited for scientific purposes.

[Immediate-type reactions to pyrazole derivatives: results of skin tests and antibody determinations]. / "Soforttyp"-Reaktionen auf Pyrazol-Derivate: Ergebnisse von Hauttesten und Antikörperbestimmungen.

In a multicentric study by the European Study Group for Drug Allergy 58 patients suffering from an immediate type reaction after intake of pyrazol analgetics were examined with regard to allergy or pseudoallergy. Besides the scratch tests with the original substance we performed cutaneous tests with pyrazol conjugates and determined IgE and IgG antibodies by means of modified radioallergosorbent (RAST) method. Three groups could be distinguished: pseudoallergic reactions to nonsteroidal analgetics of the aspirin type (15 cases); IgE-mediated pyrazolone allergy verified by skin tests and/or IgE-RAST (21 cases), and pyrazolone idiosyncrasy (26 cases).

[IE and IgG antibodies against flavonoids following therapy with flavonoid-containing drugs]. / IgE- und IgG-Antikörper gegen Flavonoide nach Therapie mit flavonoidhaltigen Medikamenten.

During treatment with flavonoid drugs a number of patients developed adverse reactions such as fever, various skin eruptions and intravascular hemolysis. The appearance of flavonoid-specific IgE and IgG antibodies and its possible relation to the observed side effects was studied on a total of 168 individuals treated with flavonoid drugs: 71 patients received troxerutin (Venoruton) parenterally to improve tolerance of radiation therapy, 12 patients were treated intravenously with silymarin (Legalon) for amanita intoxication and 77 patients received various flavonoid drugs for other indications. Flavonoid treatment often induced specific IgG antibodies and less frequently IgE antibodies. After short treatment IgE antibodies were more frequently detected than after treatment of longer duration which nearly always induced IgG antibodies. Patients with hemolysis had the highest IgG titers. In cases with fever and skin eruptions no correlation with antibody titers became evident. Antibody production in patients undergoing radiation therapy appeared to be lower than in non-irradiated patients. Both the IgE and IgG antibody test show a remarkable cross-reactivity between four different flavonoids. Prospective studies will be necessary to decide whether or not this method for the detection of anti-flavonoid antibodies will be suitable for recognizing increased risk of side reactions upon reexposure to flavonoid drugs.

Measurement of specific IgG antibody levels in serum of patients on regimes comprising high total dose beta-lactam therapy.

Sera from 125 patients receiving mean total doses of beta-lactam therapy of 215 g over a mean of 14 days were assayed by radioimmunoassay. Titres of anti-penicilloyl antibodies, expressed in arbitrary units of specific IgG per microliter of serum (u/microliter), ranged from undetectable (less than 3 u/microliter) to 1,650 u/microliter. There was a higher prevalence of elevated IgG levels in patients who developed haemolytic anaemia or neutropenia compared with patients with no adverse reactions but only in those patients who developed haemolytic anaemia were the antibody titres significantly higher. A subsidiary finding was that a correlation was established between mean total dose and prevalence of positive IgG titres, on a patient group basis (r = 0.87).

Bullous esophageal lesions due to cotrimoxazole: an immune-mediated process?

A 78-yr-old man experienced a generalized bullous eruption of the skin (a Stevens-Johnson variant of erythema multiforme) with simultaneous involvement of the esophagus due to co-trimoxazole. Immunologic tests revealed specific antibodies of the immunoglobulin G class but not of the immunoglobulin E class against sulfamethoxazole, and in particular against trimethoprim. Lymphocyte transformation tests demonstrated sensitized lymphocytes against trimethoprim but not sulfamethoxazole. The esophageal mucosa showed intraepithelial vesicle formation with diffuse cytoplasmic deposits of immunoglobulin G. This adverse drug reaction involving both the skin and the esophagus appears to be immune-mediated.

Amoxicillin-induced immune hemolysis.

Severe hemolysis occurred in a 51-year-old female after a 17-day course of intravenous amoxicillin. A strongly positive direct antiglobulin test (anti-IgG titer 1:2,000) ensued which disappeared after withdrawal of the drug. Both the patient's serum and eluate obtained from the patient's red cells contained an IgG antibody which reacted with red blood cells coated in vitro with amoxicillin, but not with uncoated cells. In addition, high-titer antipenicillin, antiampicillin and antiamoxicillin IgG antibodies could be demonstrated in her serum by a RAST-based solid-phase radioimmunoassay. The patient's hemolysis gradually subsided within 1 week after discontinuing the drug. This is the first report of amoxicillin-induced immune hemolytic anemia.

Adverse reactions following intravenous penicillin-G relate to degradation of the drug in vitro.

We have recently shown that high-dose intravenous therapy with penicillin-G always results in both sensitised lymphocytes and rise of anti-penicilloyl IgG antibodies. If penicillin-G is strictly given as freshly prepared bolus doses this sensitisation is prevented. In 193 patients, intravenous treatment with penicillin-G without special precautions (bolus doses stored up to 36 h at 4 degrees C or continuous infusions) led to 8.3% definite, 6.7% probable and 14.0% possible adverse reactions. In 116 patients treated exclusively with freshly dissolved doses, 0.9% definite, 1.7% probable and 4.3% possible reactions occurred. Whereas haemolytic anaemia (7) and neutropenia (12) were observed in 19 cases of the first group no such reactions were seen in the second group. Strict application of freshly prepared single doses prevents the majority of adverse reactions following highdose intravenous penicillin-G therapy. Degradation and transformation products formed in vitro are therefore the causative agents rather than the penicillin molecule itself.

[Demonstration of drug-specific IgE and IgG antibodies using RIA: clinical importance as shown with nomifensin (Alival)]. / Nachweis von arzneimittel-spezifischen IgE- und IgG-Antikörpern mittels RIA: klinische Bedeutung am Beispiel Nomifensin (Alival).

Serum samples from 41 patients who developed adverse reactions during therapy with nomifensine were screened by RAST-based immunoassay for specific IgE and IgG antibodies against nomifensine and three of its metabolites. The results were compared with those of 10 patients without side effects and with 8 non-treated controls. Nomifensine-specific IgE antibodies were found in none of the subjects. However, all patients treated with nomifensine (with and without side effects) had specific IgG antibodies. The antibody cross-reacted in all cases with the metabolites. The titers did not discriminate clearly between the different side reactions and only partially between the presence or absence of a side reaction. The finding of specific anti-drug IgG antibodies warrants more detailed investigation of immunological mechanisms, to determine the clinical relevance of these antibodies and identify patients at risk for serious side effects.