"Hands off hand hygiene training": Implementation of a COVID safe auditor training program

Optimal hand hygiene practices reduce the risk of healthcare-associated infections, especially in high-risk settings of immunocompromised patients. In 2020, face-to-face learning was disallowed in the environment of coronavirus disease 2019 transmission. We developed a revised learning program for hand hygiene auditors for our cancer care facility. The learning package resulted in a 2-fold increase in the number of participants, with effective promotion by managers, due in part to reduced time and resources for training, and flexibility for staff.

Adenosine triphosphate bioluminescence to validate decontamination of endoscopes

The reports of outbreaks involving carbapenemase-resistant Enterobacteriaceae (CRE) associated with gastrointestinal endoscopy prompted a review and study of a novel method of assessing cleaning. This study assessed adenosine triphosphate (ATP) bioluminescence to demonstrate cleanliness prior to endoscopy. ATP testing was compared with microbiological monitoring for 127 endoscopes. Samples were taken after cleaning, reprocessing and storage, but immediately before the endoscopy procedure. We recommend implementing ATP testing prior to endoscopy procedures as an alternative to microbiological testing at periodic intervals. ATP testing provides a convenient assessment of endoscopy hygiene to demonstrate safety and quality assurance.

Adverse events related to medications identified by a Canadian poison centre

BACKGROUND

Poison centres are an underutilized source of information on adverse events related to medications, including therapeutic errors and adverse drug reactions.

OBJECTIVE

To demonstrate the feasibility of using a poison centres' electronic data to identify and describe adverse events related to medications.

METHODS

This one-year, retrospective cross-sectional pilot study was conducted at one Canadian Poison Centre. All records from the IWK Regional Poison Centre database in Nova Scotia between November 1, 2007 and October 31, 2008 for unintentional exposures were abstracted for a descriptive data analysis.

RESULTS

An issue related to use of a medication was the main reason for 1,525 (32.5%) of 4,697 eligible calls. Of the 1,525 calls, 970 (63.6%) were coded as 'unintentional-general.' There were 470 (30.8%) calls for unintentional therapeutic errors and 61 (4.0%) for adverse drug reactions. The majority of calls involving medications were judged to have resulted in minimal or no toxic effect (78.4%). However, 3.3% of calls involving adverse drug reactions resulted in admission to a critical care unit (n=2). Approximately 1% of calls involving unintentional therapeutic errors resulted in admission to hospital (n=6).

CONCLUSIONS

Calls to poison centres provide a potentially valuable source of information on adverse events related to medications that are likely not reported elsewhere. Establishment of a mechanism to routinely share information from all Canadian poison centres with relevant national drug safety programs (e.g., MedEffect™ Canada) will provide a supplementary source of information and contribute to building capacity for detection of sentinel events and pharmacosurveillance.

Obesity and Angiolymphatic Invasion in Primary Breast Cancer

Background and Objectives: Obesity is associated both with higher rates of breast cancer and with unfavorable breast cancer outcomes. Small studies have suggested that obesity may be associated with unfavorable tumor biologic characteristics, such as angiolymphatic invasion. The purpose of this study was to characterize the independent association of obesity with the presence of angiolymphatic invasion, stage at presentation, estrogen receptor (ER) status, the triple-negative phenotype, and tumor grade after controlling for clinical factors.Methods: Detailed clinical and pathologic data were abstracted from the medical records of all 1361 patients with 1398 Stage I, II, or III primary breast cancers who had breast surgery at the University of Michigan Comprehensive Cancer Center between January 1, 2000 and December 31, 2006. A second abstractor, who did not have access to the clinical and pathologic tumor characteristics, collected patient height and weight. Bivariate and multivariate analyses were conducted to investigate the relationships between body mass index (BMI) and tumor biologic features controlling for menopausal status, comorbid diabetes and hypertension, use of hormone replacement therapy before the diagnosis of breast cancer, race, and ethnicity. Results: In bivariate analyses, obesity was not associated with hormone receptor status, HER2 status, triple-negative phenotype, or histologic grade. There was a borderline significant association between obesity category and the presence of angiolymphatic invasion (p = 0.06) in the sample of 1398 tumors, severely obese women being the most likely to have angiolymphatic invasion. Among pre- and perimenopausal women, the likelihood of angiolymphatic invasion in the tumors varied by obesity category (p = 0.02) with angiolymphatic invasion more likely in obese (20.0%) compared with the tumors of healthy weight (14.4%) women. In multivariate analyses, obesity status was independently associated with the presence of angiolymphatic invasion (joint test of significance, p = 0.04) after controlling for menopausal status, use of hormone replacement therapy at the time of diagnosis, diabetes and hypertension, and tumor features, including grade, stage, estrogen receptor status, and HER2 status. Obesity was associated with lower odds of triple-negative disease (odds ratio, OR, among severely obese women 0.37, 95% C.I. 0.15 – 0.92). There were significant associations between diabetes and tumor biology in multivariate analyses restricted to tumors in pre- and perimenopausal women. Diabetes was associated with ER-negative tumor status (OR 5.66, 95% C.I. 1.05 to 30.55) and with the triple-negative phenotype (OR 13.73, 95% C.I. 2.23 to 84.50).Discussion: In this large sample of invasive breast cancers, obesity was independently associated with the presence of angiolymphatic invasion. Furthermore, diabetes was found to be associated with ER-negative and triple-negative breast cancer among premenopausal women. Higher rates of angiolymphatic invasion among obese women may account in part for the poorer outcomes among obese women with breast cancer, and higher rates of triple-negative breast cancer may account for poorer outcomes among women with diabetes.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5151.

Inhibitors of cholesterol biosynthesis. 2. Hypocholesterolemic and antioxidant activities of benzopyran and tetrahydronaphthalene analogues of the tocotrienols

Tocotrienols exhibit antioxidant and cholesterol-biosynthesis-inhibitory activities and may be of value as antiatherosclerotic agents. The mechanism of their hypolipidemic action involves posttranscriptional suppression of HMG-CoA reductase (HMGR) in a manner mimicking the action of putative non-sterol feedback inhibitors. The in vitro cholesterol-biosynthesis-inhibitory and HMGR-suppressive activities in HepG2 cells of an expanded series of benzopyran and tetrahydronaphthalene isosteres and the hypocholesterolemic activity of selected compounds assessed in orally dosed chickens are presented. Preliminary antioxidant data of these compounds have been obtained using cyclic voltammetry and Cu-induced LDL oxidation assays. The farnesyl side chain and the methyl/hydroxy substitution pattern of gamma-tocotrienol deliver a high level of HMGR suppression, unsurpassed by synthetic analogues of the present study. In orally dosed chickens, 8-bromotocotrienol (4o), 2-desmethyltocotrienol (4t), and the tetrahydronaphthalene derivative 35 exhibit a greater degree of LDL cholesterol lowering than the natural tocotrienols.

Inhibitors of blood platelet cAMP phosphodiesterase. 2. Structure-activity relationships associated with 1,3-dihydro-2H-imidazo[4,5-b]quinolin-2-ones substituted with functionalized side chains

A series of 1,3-dihydro-2H-imidazo[4,5-b]quinolin-2-one derivatives, substituted at the 7-position with functionalized side chains, was synthesized and evaluated as inhibitors of human blood platelet cAMP phosphodiesterase (PDE) as well as ADP- and collagen-induced platelet aggregation, in vitro. Structural modifications focused on variation of the side-chain terminus, side-chain length, and side-chain connecting atom. Functionality incorporated at the side-chain terminus included carboxylic acid, ester and amide, alcohol, acetate, nitrile, tetrazole, and phenyl sulfone moieties. cAMP PDE inhibitory potency varied and was dependent upon the side-chain terminus and its relationship with the heterocyclic nucleus. Methylation at N-1 or N-3 of the heterocycle diminished cAMP PDE inhibitory potency. Several representatives of this structural class demonstrated potent inhibition of ADP- and collagen-induced blood platelet aggregation and were half-maximally effective at low nanomolar concentrations. Amides 13d, 13f, 13h, 13k, 13m, and 13w are substantially more potent than relatively simply substituted compounds. However, platelet inhibitory properties did not always correlate with cAMP PDE inhibition across the series, probably due to variations in membrane permeability. Several compounds inhibited platelet aggregation measured ex vivo following oral administration to rats. Ester 11b, acid 12b, amide 13d, and sulfone 29c protected against thrombus formation in two different animal models following oral dosing and were found to be superior to anagrelide (2) and BMY 20844 (5). However, ester 11b and acid 12b demonstrated a unique pharmacological profile since they did not significantly affect hemodynamic parameters in dogs at doses 100-fold higher than that required for complete prevention of experimentally induced vessel occlusion in a dog model of thrombosis.

Inhibitors of blood platelet cAMP phosphodiesterase. 3. 1,3-Dihydro-2H-imidazo[4,5-b]quinolin-2-one derivatives with enhanced aqueous solubility

Two series of 1,3-dihydro-2H-imidazo[4,5-b]quinolin-2-one derivatives incorporating an additional site for acid salt formation were synthesized and evaluated as inhibitors of human blood platelet cAMP phosphodiesterase (PDE) and ADP-induced platelet aggregation. The objective of this study was to identify compounds that blended potent biological activity with a satisfactory level of aqueous solubility. From a series of 7-aminoimidazo[4,5-b]quinolin-2-ones, biological and physical properties were optimally combined in the 1-piperidinyl derivative 11c. However, this compound offered no significant advantage over earlier studied compounds as an antithrombotic agent in an animal model of small vessel thrombosis. A series of 7-alkoxy alkanoic piperazinamide derivatives, in which the additional basic nitrogen atom was remote from the heterocyclic nucleus and accommodated in a secondary binding region of the cAMP PDE enzyme, demonstrated greater intrinsic cAMP PDE inhibitory activity. Structural modifications of this series focused on variation of the piperazine substituent and side-chain length. The lipophilicity of the N-substituent influenced biological potency and aqueous solubility, with substituents of seven carbon atoms or less generally providing acceptable solubility properties. The N-(cyclohexylmethyl)piperazinamide 21h was identified from this series of compounds as a potent inhibitor of platelet cAMP PDE, IC50 = 0.4 nM, and ADP-induced platelet aggregation, IC50 = 0.51 microM after a 3-min exposure and 0.1 microM after a 15-min exposure of platelet-rich plasma to the drug. Evaluation of 21h and representative analogues in vivo using a rabbit model of small vessel thrombosis revealed significantly greater antithrombotic efficacy compared to that of previously studied compounds with similar intrinsic biological activity measured in vitro but inferior aqueous solubility.

1,3-Dihydro-2H-imidazo[4,5-b]quinolin-2-ones--inhibitors of blood platelet cAMP phosphodiesterase and induced aggregation

A series of 1,3-dihydro-2H-imidazo[4,5-b]quinolin-2-one derivatives was synthesized and evaluated as inhibitors of cAMP hydrolysis by a crude human platelet phosphodiesterase preparation and as inhibitors of ADP- and collagen-induced aggregation of rabbit blood platelets. The parent structure 7a, demonstrated potent inhibitory activity that was enhanced by the introduction of alkyl, alkoxy, or halogen substituents at the 5-, 6-, 7-, and 8-positions. Methylation at N-1 or N-3 produced weaker inhibitors of cAMP PDE and platelet aggregation. 1,3,9,9a-Tetrahydro-2H-imidazo[4,5-b]quinolin-2-ones (6) were found to be equipotent with their fully oxidized congeners (7). On the basis of platelet inhibitory properties in vitro, efficacy at preventing thrombus formation in animal models of thrombosis, and a favorable hemodynamic profile, 1,3-dihydro-7,8-dimethyl-2H- imidazo[4,5-b]quinolin-2-one (7o, BMY 20844) was selected for advancement into toxicological evaluation and clinical trial. An efficient synthesis of 7o is described.

Imidazoquinoline derivatives: potent inhibitors of platelet cAMP phosphodiesterase which elevate cAMP levels and activate protein kinase in platelets

Compounds containing the imidazoquinoline nucleus are a new class of potent, broad-spectrum inhibitors of platelet aggregation. This report describes studies with a simply-substituted imidazoquinoline (BMY 20844) and several new ether-linked side chain derivatives (BMY 21638 and BMY 43351). These compounds are potent inhibitors of platelet cAMP phosphodiesterase (IC50 values: BMY 20844, 1.3 X 10(-8); BMY 21638, 2 X 10(-10); and BMY 43351, 1 X 10(-10) M, measured using 0.15 microM cAMP) but have little effect on platelet homogenate cGMP phosphodiesterase (IC50 greater than 10(-5) M). Inhibition of different cAMP phosphodiesterase isozymes was tested to determine if the compounds inhibited similar isozymes in other tissues. Rabbit heart cAMP phosphodiesterase isozymes were resolved by ion-exchange chromatography and three peaks of activity were obtained. BMY 20844 inhibited only fraction III (a "cGMP-inhibitable, low Km" cAMP-specific phosphodiesterase) with an IC50 value of 5 X 10(-8) M. These compounds also inhibited canine cardiac sarcoplasmic reticulum membrane-bound "cGMP-inhibitable, low Km" cAMP-specific phosphodiesterase with virtually the same potency as inhibition of cAMP phosphodiesterase in platelet homogenate. In washed platelets these compounds elevated cAMP levels and activated the platelet cAMP dependent protein kinase. Activation of cAMP-dependent protein kinase was determined by cAMP-dependent protein kinase ratio measurements and phosphorylation of intracellular proteins. These studies suggest that this potent new class of agents inhibits platelet phosphodiesterase activity in intact platelets causing an elevation in cAMP levels sufficient to activate the cAMP-dependent protein kinase and stimulate protein phosphorylation. This mechanism is, at least in part, responsible for the ability of these compounds to prevent platelet aggregation and thrombosis in experimental animal models.

Pharmacology of a potent, new antithrombotic agent, 1,3-dihydro-7,8-dimethyl-2H-imidazo[4,5-b]quinolin-2-one (BMY-20844)

The effects of 1,3-dihydro-7,8-dimethyl-2H-imidazo[4,5-b]quinolin-2-one (BMY-20844) on platelet function and experimental thrombosis were evaluated in a series of in vitro, ex vivo and in vivo experiments. The compound inhibited platelet aggregation in vitro in platelet rich plasma obtained from humans, rats and rabbits with EC50s of less than 1 microgram/ml when aggregation was induced by ADP, collagen or thrombin. Supra-additive interaction against ADP aggregation was also observed when BMY-20844 was combined with prostacyclin. BMY-20844 was orally active with an ex vivo ED50 in the rat of 3.2 mg/kg vs ADP. Significant antithrombotic activity was observed in two animal models (laser induced thrombosis in the microcirculation of the rabbit ear and coronary artery thrombosis in the dog). Inhibitions of 52% at 3 mg/kg p.o. in the laser model and 100% at 1 mg/kg i.d. in the coronary artery thrombosis model were obtained. Modest inotropic and hemodynamic effects were observed in ferrets and dogs. BMY-20844 was found to be a potent, specific inhibitor of platelet low Km cyclic AMP phosphodiesterase.

Enhancement of the horseradish peroxidase-catalyzed chemiluminescent oxidation of cyclic diacyl hydrazides by 6-hydroxybenzothiazoles

6-Hydroxybenzothiazole, 2-cyano-6-hydroxybenzothiazole, and 2-(6-hydroxy-2-benzothiazolyl)thiazole-4-carboxylic acid (dehydroluciferin) dramatically enhance light emission from the horseradish peroxidase conjugate catalyzed oxidation of luminol, isoluminol, N-(6-aminobutyl)-N-ethyl isoluminol, and 7-dimethylaminonaphthalene-1,2-dicarboxylic acid hydrazide by either peroxide or perborate. Light emission is enhanced by up to 1000-fold, which is an improvement over the enhancement previously observed using firefly luciferin (4,5-dihydro-2-(6-hydroxy-2-benzothiazolyl)thiazole-4-carboxylic acid). Enhancement is influenced by enhancer concentration and pH. Spectral scans of light emitted in enhanced and unenhanced reactions are similar, suggesting that aminophthalate products, and not the enhancers, are the emitters.

Selected immunologic properties of tiprinast, a non-steroidal antiallergy agent

Tiprinast [(3,4-dihydro-5-methyl-6-(2-methylpropyl)-4-oxothieno[2,3-d]- pyrimidine-2-carboxylic acid] is a new antiallergy compound which shares many of the pharmacological actions of disodium cromoglycate (DSCG). Both compounds inhibit passive cutaneous anaphylaxis in the rat, histamine release from rat peritoneal mast cells and nasal constriction due to antigen in the rat. In all cases tiprinast is more potent than DSCG and also longer acting.

The role of cyclic AMP in modulating cytotoxic T lymphocytes. II. Sequential changes during culture in responsiveness of cytotoxic lymphocytes to cyclic AMP-active agents

Agents that increase cyclic AMP (cAMP) levels inhibited the activity of cytotoxic T lymphocytes (CTL) obtained from spleens of mice immunized with allogeneic cells. Cultured CTL, however, were desensitized to cAMP-active agents, in that the capacity of these agents to inhibit the activity of cultured CTL was markedly reduced. The capacity to inhibit CTL activity was reduced more rapidly for some agents than for others; the percent inhibition by histamine and PGE2 was reduced after 4 hr and was reduced more than 20% after 24 hr, whereas the percent inhibition by dibutyryl cAMP, theophylline, and cholera enterotoxin was reduced less than 6% after 24 hr, and was reduced significantly only after 48 hr. Culture in the presence of antigen accelerated desensitization to the latter three agents. CTL populations were also tested for their capacity to increase cAMP levels in response to agonists. The capacity of histamine to increase cAMP levels of the CTL was lost within 4 hr (i.e., as rapidly as its capacity to inhibit CTL activity) and was never restored, whereas the capacity of PGE2 to increase cAMP levels persisted throughout culture. These results suggest that culture induces multiple alterations in cAMP metabolism of CTL. These alterations, which result in dissociation of CTL activity from cAMP-mediated regulatory steps, may include loss of histamine receptors and/or histamine receptor-adenylate cyclase coupling, and also loss of one or more biochemical reactions that link elevated cAMP levels to inhibition of lysis.

The role of cyclic AMP in modulating cytotoxic T lymphocytes. II. Sequential changes during culture in responsiveness of cytotoxic lymphocytes to cyclic AMP-active agents

Agents that increase cyclic AMP (cAMP) levels inhibited the activity of cytotoxic T lymphocytes (CTL) obtained from spleens of mice immunized with allogeneic cells. Cultured CTL, however, were desensitized to cAMP-active agents, in that the capacity of these agents to inhibit the activity of cultured CTL was markedly reduced. The capacity to inhibit CTL activity was reduced more rapidly for some agents than for others; the percent inhibition by histamine and PGE2 was reduced after 4 hr and was reduced more than 20% after 24 hr, whereas the percent inhibition by dibutyryl cAMP, theophylline, and cholera enterotoxin was reduced less than 6% after 24 hr, and was reduced significantly only after 48 hr. Culture in the presence of antigen accelerated desensitization to the latter three agents. CTL populations were also tested for their capacity to increase cAMP levels in response to agonists. The capacity of histamine to increase cAMP levels of the CTL was lost within 4 hr (i.e., as rapidly as its capacity to inhibit CTL activity) and was never restored, whereas the capacity of PGE2 to increase cAMP levels persisted throughout culture. These results suggest that culture induces multiple alterations in cAMP metabolism of CTL. These alterations, which result in dissociation of CTL activity from cAMP-mediated regulatory steps, may include loss of histamine receptors and/or histamine receptor-adenylate cyclase coupling, and also loss of one or more biochemical reactions that link elevated cAMP levels to inhibition of lysis.

Inhibition of basophil histamine release by anti-inflammatory steroids. II. Studies on the mechanism of action

The glucocorticosteroids inhibit the IgE-dependent release of histamine by human basophils with an order of potency that very closely parallels that found in vivo (i.e., triamcinolone acetonide greater than dexamethasone greater than beta-methasone greater than prednisolone greater than hydrocortisone much greater than progesterone approximately tetrahydrocortisone approximately 0). The effect is seen after a 24-hr preincubation with nanomolar to micromolar concentrations of glucocorticoid. In contrast, release of histamine stimulated by the formyl methionine containing peptide f-met-leu-phe, the calcium ionophore A23187, and the tumor-promoting phorbol diester 12-O-tetradecanoylphorbol-13-acetate was not inhibited by 24-hr incubation with the potent glucocorticoid dexamethasone. Dexamethasone inhibited anti-IgE-induced histamine release without altering its rate, suggesting that the glucocorticoids do not inhibit histamine release by elevating the intracellular level of cAMP. Dexamethasone did not consistently alter either the total or occupied basophil IgE Fc receptor number, and therefore the glucocorticoid effect does not appear to be due to the modulation of cell surface Fc epsilon receptor content. These data indicate that steroid hormones inhibit basophil IgE-dependent activation through a specific glucocorticoid receptor. The mechanism by which they do so appears not to involve an elevation of cAMP or a shedding of cell surface Fc epsilon receptors. Further, because the glucocorticoids did not inhibit release initiated by the PLA2-dependent stimuli f-met-leu-phe, A23187 and TPA, the inactivation of IgE-dependent histamine release by glucocorticoids may not be the result of PLA2 inhibition.

Inhibition of basophil histamine release by anti-inflammatory steroids. II. Studies on the mechanism of action

The glucocorticosteroids inhibit the IgE-dependent release of histamine by human basophils with an order of potency that very closely parallels that found in vivo (i.e., triamcinolone acetonide greater than dexamethasone greater than beta-methasone greater than prednisolone greater than hydrocortisone much greater than progesterone approximately tetrahydrocortisone approximately 0). The effect is seen after a 24-hr preincubation with nanomolar to micromolar concentrations of glucocorticoid. In contrast, release of histamine stimulated by the formyl methionine containing peptide f-met-leu-phe, the calcium ionophore A23187, and the tumor-promoting phorbol diester 12-O-tetradecanoylphorbol-13-acetate was not inhibited by 24-hr incubation with the potent glucocorticoid dexamethasone. Dexamethasone inhibited anti-IgE-induced histamine release without altering its rate, suggesting that the glucocorticoids do not inhibit histamine release by elevating the intracellular level of cAMP. Dexamethasone did not consistently alter either the total or occupied basophil IgE Fc receptor number, and therefore the glucocorticoid effect does not appear to be due to the modulation of cell surface Fc epsilon receptor content. These data indicate that steroid hormones inhibit basophil IgE-dependent activation through a specific glucocorticoid receptor. The mechanism by which they do so appears not to involve an elevation of cAMP or a shedding of cell surface Fc epsilon receptors. Further, because the glucocorticoids did not inhibit release initiated by the PLA2-dependent stimuli f-met-leu-phe, A23187 and TPA, the inactivation of IgE-dependent histamine release by glucocorticoids may not be the result of PLA2 inhibition.

Release of histamine from human leukocytes stimulated with the tumor-promoting phorbol diesters. II. Interaction with other stimuli

The tumor promoter and irritant, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), previously shown to be a potent histamine releaser, has been used to further probe the mechanism of histamine release from human basophils. TPA and the calcium ionophore, A23187, produced a synergistic response in which subeffective concentrations of each stimulus (which alone produced less than 3% release) together produced over 70% histamine release. TPA also synergized with the IgE cross-linking stimulus anti-IgE. Desensitization of cells by incubation with anti-IgE in the absence of calcium rendered the cells unresponsive to anti-IgE and super-responsive to TPA. This marked increase in the TPA response was the result of an increase in the rate of TPA-induced histamine release, and occurred in the absence of extracellular calcium. The ability of various concentrations of anti-IgE to "sensitize" cells to TPA paralleled their ability to produce histamine release in untreated cells rather than their ability to desensitize the cells. These results suggest that in the absence of calcium, anti-IgE induces desensitization of some activation of other elements of the histamine-release process. The anti-IgE dose-response pattern of this activation event further suggests that it is an integral part of the anti-IgE-induced release process itself.

Release of histamine from human leukocytes stimulated with the tumor-promoting phorbol diesters. II. Interaction with other stimuli

The tumor promoter and irritant, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), previously shown to be a potent histamine releaser, has been used to further probe the mechanism of histamine release from human basophils. TPA and the calcium ionophore, A23187, produced a synergistic response in which subeffective concentrations of each stimulus (which alone produced less than 3% release) together produced over 70% histamine release. TPA also synergized with the IgE cross-linking stimulus anti-IgE. Desensitization of cells by incubation with anti-IgE in the absence of calcium rendered the cells unresponsive to anti-IgE and super-responsive to TPA. This marked increase in the TPA response was the result of an increase in the rate of TPA-induced histamine release, and occurred in the absence of extracellular calcium. The ability of various concentrations of anti-IgE to "sensitize" cells to TPA paralleled their ability to produce histamine release in untreated cells rather than their ability to desensitize the cells. These results suggest that in the absence of calcium, anti-IgE induces desensitization of some activation of other elements of the histamine-release process. The anti-IgE dose-response pattern of this activation event further suggests that it is an integral part of the anti-IgE-induced release process itself.

13-Hydroperoxylinoleic acid inhibits rat liver glyoxalase II

13-Hydroperoxylinoleic acid (13-HPLA) inhibited glyoxalase II in rat liver supernatants with half the maximum inhibition occurring at a 13-HPLA concentration below 0.1 microgram/ml. The extent of inhibition was increased by EDTA and decreased by Mn2+ and Co2+. Zn2+ and Cu2+ inhibited control enzyme activity. Glyoxalase II catalyzes the destruction of S-lactoylglutathione. Both 13-HPLA and S-lactoylglutathione have been shown to potentiate histamine secretion. It is suggested that 13-HPLA does so, in part at least, by inhibiting glyoxalase II and thereby causing a concomitant increase in S-lactoylglutathione level. It is also possible that S-lactoylglutathione mediates other of the effects of 13-HPLA and fatty acid hydroperoxides in general.

Effects of colchicine, vinblastine, griseofulvin and deuterium oxide upon phospholipid metabolism in concanavalin A-stimulated lymphocytes

Colchicine has previously been shown to inhibit the incorporation of [3H]-inositol into phosphatidylinositol in lymphocytes stimulated with concanavalin A. In the present study other agents known to interact with tubulin or affect microtubule assembly/disassembly were examined for effects on 32PO4 incorporation into phospholipids and [3H]inositol incorporation into phosphatidylinositol. Vinblastine inhibited the enhanced incorporation caused by concanavalin A of either [3H]inositol or 32PO4 into phosphatidylinositol and phosphatidic acid. It had no effect on basal incorporation of 32PO4 and enhanced basal incorporation of [3H]inositol into nonstimulated lymphocytes. Griseofulvin at concentrations up to 10(-3) M had no effect on uptake of either label. Deuterium oxide had effects similar to vinblastine in that basal incorporation of both labels was enhanced while inhibition of the concanavalin A stimulated incorporation was observed. These results suggest an action of these various compounds other than or in addition to their known effects on cytoplasmic microtubules.

Concanavalin A increases glyoxalase enzyme activities in polymorphonuclear leukocytes and lymphocytes

Glyoxalase I converts methylglyoxal and glutathione to S-lactoylglutathione and glyoxalase II converts this compound to D-lactic acid, regenerating glutathione in the process. A recent study from my laboratory has provided evidence that S-lactoylglutathione modulates microtubule assembly in vitro whereas concanavalin A (Con A) has been shown to increase microtubule occurrence in polymorphonuclear leukocytes (PMN). The present report describes the dose-dependent activation by Con A of both glyoxalase I and II in PMN and lymphocytes. In nine experiments with PMN, Con A (100 microgram/ml) increased glyoxalase I and II activities by 19 +/- 8% and 12 +/- 10% (mean +/- S.D.). In 17 experiments with lymphocytes, activation of the two enzymes by 10 microgram/ml Con A was 30 +/- 14% and 28 +/- 8%. Changes occurred after a 1-min incubation with Con A and persisted for at least 60 min. Since both enzyme activities are increased it is not clear if S-lactoylglutathione levels are increased or decreased but presumably they change. The present findings are compatible with the hypothesis that Con A increases microtubule occurrence in PMN by affecting the glyoxalase enzymes. They also represent a newly described early biochemical change caused by Con A in lymphocytes.

IgE-induced changes in human basophil cyclic AMP levels

We studied a unique patient with 77% basophils, not different from normal by a number of criteria, in order to measure the changes in cyclic AMP level associated with IgE-mediated histamine release. In accordance with previous hypothesis and circumstantial evidence, anti-IgE challenge led to a significant fall in the cyclic AMP level which preceded histamine release.

Histamine release from human leukocytes: relationships between cyclic nucleotide, calcium, and antigen concentrations

The antigen-induced IgE-mediated release of histamine from human basophils has previously been shown to require calcium, to be inhibited by agents which raise cyclic AMP levels and by high antigen levels, and to be unaffected by cyclic GMP. The interrelationship between these phenomena has been studied. The major findings are: 1) in the region of antigen-excess inhibition dibutyryl cyclic AMP potentiates release; 2) antigen-excess inhibition is seen at lower antigen concentrations when the calcium concentration is reduced from 0.6 to 0.1 mM; and 3) cyclic GMP modestly potentiates release when the calcium concentration is 0.1 mM.

The effects of the H1 and H2 antihistamines on "allergic" histamine release and its inhibition by histamine

Antigen-induced, IgE-mediated release of histamine from human basophiles is an in vitro model of allergic reacttions; it is blocked by extracellular histamine, presumably as a result of its ability to increase adenosine 3',5'-monophosphate (cyclic AMP) levels. The H1 antihistamines do not antagonize these effects of histamine but at approximately equal to 1 mM cause histamine release and at approximately equal to 0.1mM inhibit antigen-induced histamine release. The phenothiazine antihistamines are 10-30 fold more potent inhibitors than the rest; other tricyclic antidepressant drugs share this activity. The mechanism of this inhibition, which occurs in both the 1 degree and 2 degree stages of histamine release, is not known but it is not due to partial agonist activity since the anti-H1 drugs cause a significant fall in cyclic AMP levels. The anti-anaphylactic effects of the H1 antagonists probably play no therapeutic role but we suggest that drugs structurally similar to the phenothiazine antihistamines should be developed for clinical testing. The H2 antihistamines block histamine-induced inhibition of histamine release and the increase in cyclic AMP levels, but neither cause nor inhibit histamine release. The K-B values for the anti-H2 drugs (burimamide approximately equal to 5 muM); metiamide approximately equal to 0.5muM); are similar to those described for other H2 receptors.

In vivo suppression of the immune response to alloantigen by cholera enterotoxin

The immune response of C57BL/6 mice to allogeneic (DBA/2) mastocytoma cell suspensions was profoundly suppressed by intraperitoneal administration of 1 mug cholera enterotoxin 4 days after antigenic stimulation. The immune response assayed 11 days after antigen showed decreased cytolytically active thymusderived (T) lymphocytes and markedly depressed serumagglutinating titers. A comparable suppression of the immune response to skin allografts (DBA/2-->C57BL/6) was also effected by cholera toxin administration, although there was no prolongation of allograft survival. The mechanism of the immune suppression is apparently related to the known adenylate cyclase stimulatory activities of choleragen.