Dimethyl sulfoxide inhibits histamine release induced by various chemicals

Methylsulfonylmethane: Applications and Safety of a Novel Dietary Supplement

Methylsulfonylmethane (MSM) has become a popular dietary supplement used for a variety of purposes, including its most common use as an anti-inflammatory agent. It has been well-investigated in animal models, as well as in human clinical trials and experiments. A variety of health-specific outcome measures are improved with MSM supplementation, including inflammation, joint/muscle pain, oxidative stress, and antioxidant capacity. Initial evidence is available regarding the dose of MSM needed to provide benefit, although additional work is underway to determine the precise dose and time course of treatment needed to provide optimal benefits. As a Generally Recognized As Safe (GRAS) approved substance, MSM is well-tolerated by most individuals at dosages of up to four grams daily, with few known and mild side effects. This review provides an overview of MSM, with details regarding its common uses and applications as a dietary supplement, as well as its safety for consumption.

Analysis of histamine release assays using the Bootstrap

The data from several types of bioassays is usually presented as a quotient as an intuitive parameter and a means of comparing results between experiments. For the example we considered here, we look at experiments with an experiment-wide negative control used to generate percent activity quotients from each experimental group. We asked if there was a valid means to statistically evaluate the transformed rather than the raw data. The experimental system chosen was a dose response of the agonist compound 48/80, which causes release of histamine from mast cells, thus providing test data from replicates of n=24. Descriptive statistics, the Ryan-Joiner test for normality of distribution of data, and normal probability plots confirm the normality of the distribution of data at each dose level. In parametric analysis, when the control group was treated as an errorless constant, there was a distinct consistent bias in the standard error of the data of 10% or less, which was not present if the control group's mean was treated as a variable with experimental error. This would be of minor interest in qualitative studies and might be safely ignored, but might be of considerable importance in quantitative assessments of activity using confidence intervals. When using Bootstrap estimates of standard error and probability plots of the bootstrap samples, the transformed data does not deviate significantly from normality. The standard, bias-corrected percentile limits (BCa), and empirical percentile methods gave very similar results when using resampling statistics to generate the transformed data from groups of n=6. Sample size can be as low as n=4 and still provide useful results. Thus, we have shown that resampling (i.e., bootstrap, Monte Carlo method, computer-intensive methods) can produce the data transform as well as provide confidence intervals using this type of raw data in small groups (n=4 to 6), giving improved statistical analysis of the transformed data (ratio estimates) without accepting a bias from methodology ignoring variation in the control group.

Activation of bladder mast cells in interstitial cystitis: a light and electron microscopic study

Interstitial cystitis, a sterile bladder condition, is characterized by urinary frequency, urgency, burning and suprapubic pain. Increasing evidence indicates that interstitial cystitis is a heterogeneous syndrome that reflects an immune response to a variety of triggers. More than 50% of the patients have allergies, 30% have the irritable bowel syndrome and almost 20% suffer from migraine headaches. Increased numbers of mast cells have been reported in interstitial cystitis. Mast cell activation, which is critical if these cells were to be implicated in this syndrome, has been investigated by electron microscopy, which definitively shows mast cell secretion. Recently, methylhistamine, the major metabolite of histamine, and the specific mast cell marker, tryptase, were shown to be significantly elevated in urine of interstitial cystitis patients. Bladder biopsies from 53 patients were analyzed blindly for the number and degree of activation of mast cells using 4 different stains for light microscopy, as well as electron microscopy. Controls included 16 patients with incontinence and chronic bacterial cystitis. Mast cells in controls were less than 10/mm.2 and were all nearly intact. Surprisingly, mast cells from 11 cancer patients averaged 50/mm.2 but almost all were intact. In contrast, mast cells from 26 interstitial cystitis patients averaged 40/mm.2 and more than 90% were activated to various degrees. Therefore, bladder mast cell activation is a characteristic pathological finding in at least a subset of patients with interstitial cystitis.

Unusual effects of the ionophore A23187 at suboptimal concentrations in mast cell histamine release

Certain peculiarities are observed in connection with histamine release induced by suboptimal concentrations of the ionophore A23187. The potency of the ionophore can increase by a factor of 3 when added to the incubation medium from solutions in either DMSO or buffer without added calcium as compared with addition from standard buffer. The effect was not due to the solvent per se but may relate to physicochemical conditions facilitating the ionophore's access to cellular domains.

Oxidation of dimethylsulphoxide to formaldehyde by oxyhaemoglobin and oxyleghaemoglobin in the presence of hydrogen peroxide is not mediated by "free" hydroxyl radicals

In the presence of excess hydrogen peroxide, human oxyhaemoglobin and oxyleghaemoglobin from soybean root nodules cause oxidation of dimethylsulphoxide to formaldehyde. This reaction is inhibited by thiourea but not by phenylalanine, HEPES, mannitol or arginine. It is concluded that dimethylsulphoxide oxidation is not mediated by "free" hydroxyl radicals, consistent with previous conclusions that intact haemoglobin, leghaemoglobin or myoglobin molecules do not react with H2O2 to form hydroxyl radicals detectable outside the protein.

Dimethyl sulfoxide decreases the fluorescence yield of the reaction between histamine and ortho-phthalaldehyde and may influence histamine release

A sensitive method for quantifying histamine is the assay based on the fluorescence of the product obtained after reacting the amine with ortho-phthalaldehyde. The presence of dimethyl sulfoxide (DMSO) even in concentrations as low as 1% decreases the yield of fluorescence. Neglecting this quenching leads to the erroneous conclusion that DMSO in a concentration dependent manner inhibits the thapsigargin induced histamine release from peritoneal rat mast cells. Apart from the release induced by the selective calcium ion mobilizers thapsigargin and ionophore A23147, DMSO potently inhibits the response to other secretagogues.

Loratadine, an antihistamine, blocks antigen-and ionophore-induced leukotriene release from human lung in vitro

Some H1-antihistamines possess anti-allergic properties, and inhibit the immunological release of mediators including histamine and sulfiopeptide-leukotrienes (slow reacting substance of anaphylaxis) from lung. The effects of the antihistiamine loratadine, SCH29851, on the release of leukotrienes and histamine from human lung fragments were measured, using the calcium ionophore A23187 and an extract of antigen from Dermatophagoides pteronyssinus, house dust mite, (with passively sensitized lung) as releasing agents. Loratadine (1-20 microM) inhibited the release of leukotrienes in a concentration-dependent manner when release was induced by calcium ionophore from lung specimens from 8 subjects, and also when release was induced by antigen from lung specimens from 7 subjects. Histamine release was unaffected by these concentrations of loratadine in both types of experiment.