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PubMed1978

Membrane-bound, pyridine nucleotide-independent L-lactate dehydrogenase of Rhodopseudomonas sphaeroides.

Rhodopseudomonas sphaeroides has a pyridine nucleotide-independent L-lactate dehydrogenase associated with the membrane fraction of cells grown either aerobically or phototrophically. The dehydrogenase is present in cells grown on a variety of carbon sources, but at levels less than 20% of that found in cells grown with DL-lactate. The dehydrogenase has been purified 45-fold from membranes of strain L-57, a non-photosynthetic mutant, by steps involving solubilization with lauryl dimethylamine oxide and three anion-exchange chromatography steps. The purified enzyme was specific for the L-isomer of lactate. The Km of the purified enzyme for L-lactate is 1.4 mM, whereas that of the membrane-associated enzyme is 0.5 mM. The enzyme activity was inhibited competitively by D-lactate and non-competitively by oxalate and oxamate. Quinacrine, a flavin analog, also inhibited the activity. The inducible enzyme may serve as a marker of membrane protein in studies of membrane development.

Cell Membrane↗
PubMed1982

Purification of pyruvate formate-lyase from Streptococcus mutans and its regulatory properties.

Pyruvate formate-lyase (EC 2.3.1.54) from Streptococcus mutans strain JC2 was purified in an anaerobic glove box, giving a single band on disk and sodium dodecyl sulfate electrophoresis. This enzyme was immediately inactivated by exposure to the air. Enzyme activity was unstable even when stored anaerobically, but the activity was restored by preincubating the inactivated crude enzyme with S-adenosyl-L-methionine, oxamate, and reduced for ferredoxin or methylviologen. On the other hand, the purified enzyme was not reactivated. Either D-glyceraldehyde 3-phosphate or dihydroxyacetone phosphate strongly inhibited this enzyme. The inhibitory effects of these compounds were largely influenced by enzyme concentration. The inhibition of these triose phosphates in cooperation with the reactivating effect of ferredoxin and the fluctuations of both the enzyme and the triose phosphate levels may efficiently regulate the pyruvate formate-lyase activity in S. mutans in vivo.

Acetyltransferases↗
PubMed1987

Transcriptional regulation of the DAL5 gene in Saccharomyces cerevisiae.

We demonstrate that the DAL5 gene, encoding a necessary component of the allantoate transport system, is constitutively expressed in Saccharomyces cerevisiae. Its relatively high basal level of expression did not increase further upon addition of allantoin pathway intermediates. However, steady-state DAL5 mRNA levels dropped precipitously when a repressive nitrogen source was provided. These control characteristics of DAL5 expression make this gene a good model with which to unravel the mechanism of nitrogen catabolite repression. Its particular advantage relative to other potentially useful genes derives from its lack of control by induction and hence the complicating effects of inducer exclusion.

Allantoin↗
PubMed1997

Effect of lodoxamide and disodium cromoglycate on tear eosinophil cationic protein in vernal keratoconjunctivitis.

AIM: To validate the use of tear eosinophil cationic protein (ECP) as a marker for eosinophil activation, and its pharmacological modulation, in addition to evaluating the efficacy of lodoxamide and sodium cromoglycate in the treatment of vernal keratoconjunctivitis (VKC). METHODS: Tears were collected from 30 patients affected by active mild to moderate VKC before and after therapy with disodium cromoglycate 4% (DSCG) (n = 15) or lodoxamide 0.1% (n = 15) for 10 days. Tear cytology and ECP measurement were performed, and ocular signs and symptoms evaluated. RESULTS: While statistically significant changes did not occur after DSCG therapy, mean tear ECP increased from 343 (SD 363) micrograms/l to 571 (777) micrograms/l due to marked elevation in six eyes. The clinical score in DSCG eyes did not improve. After lodoxamide therapy, both clinical signs and symptoms, and tear ECP levels (560 (756) micrograms/l to 241 (376) micrograms/l) decreased significantly (p < 0.0001 and p < 0.01, respectively). Compared with DSCG treatment, lodoxamide was more effective in reducing signs and symptoms (p < 0.005). ECP levels were significantly correlated with signs, symptoms, corneal involvement, and number of eosinophils in tears (p < 0.0001). CONCLUSIONS: In patients with VKC, lodoxamide significantly reduced ECP tear levels, and thus, eosinophil activation, and was more effective than DSCG in reducing clinical signs and symptoms.

Biomarkers↗
PubMed1996

Acute stress causes mucin release from rat colon: role of corticotropin releasing factor and mast cells.

We determined the effects of immobilization stress on rat colonic mucus release and mast cell degranulation and examined whether corticotropin releasing factor (CRF) was involved in these responses. After 30-min immobilization, rats were killed, colonic mucosal explants were cultured, and levels of rat mast cell protease II (RMCP II) and prostaglandin E2 (PGE2) were measured. Mucin release from explants was assayed by incorporation of [3H]glucosamine into colonic mucin and by histological evaluation of goblet cell depletion. Stress caused significant increases of colonic RMCP II, PGE2, and mucin release and fecal pellet output and caused an approximately 10-fold increase in colonic mucosal levels of cyclooxygenase-2 (COX-2) mRNA. These stress-associated changes were reproduced by intravenous or intracerebral injection of CRF in conscious, nonstressed rats. Pretreatment of rats with the CRF antagonist alpha-helical-CRF9-41, hexamethonium, atropine, or bretylium, or the mast cell stabilizer lodoxamide inhibited stress-induced release of RMCP II, PGE2, and mucin, whereas indomethacin prevented mucin release but not mast cell degranulation. Hexamethonium and CP-96,345, a substance P antagonist, inhibited fecal pellet output caused by stress. We conclude that CRF released during immobilization stress increases colonic transit via a neuronal pathway and stimulates colonic mucin secretion via activation of neurons and mast cells.

Animals↗
PubMed1993

Role of cardiac mast cells in complement C5a-induced myocardial ischemia.

Activated complement component C5a causes myocardial ischemia mediated by thromboxane (Tx) A2 and leukotrienes C4/D4. Blood cells are not involved in either the mediator release or the myocardial effects of C5a, suggesting that a C5a-sensitive, cardiac resident inflammatory cell is responsible. The goals of this study were to determine whether 1) cardiac mast cell activation accompanies the C5a response, 2) inhibition of mast cell degranulation inhibits the response, and 3) histamine release plays a role in the C5a-induced myocardial ischemia. The left anterior descending coronary artery (LAD) of open-chest pigs (n = 13) was perfused with arterial blood at constant pressure (95 mmHg). Coronary blood flow (CBF) was measured (in-line flowmeter) and regional function [percent segment shortening (%SS)] determined with sonomicrometry. A coronary vein was cannulated for measurement of plasma TxB2 and histamine (a marker of mast cell degranulation). Intracoronary C5a (500 ng) decreased coronary blood flow (45% of preinfusion levels) and LAD %SS (65% of preinfusion) and was accompanied by increases in coronary venous TxB2 (delta 63.3 ng/ml) and histamine (delta 200 nM). Mast cell inhibition with lodoxamide (2 mg/kg iv, n = 8) attenuated the C5a-induced fall in CBF (14 vs. 53% decrease, P < 0.01) and %SS (10 vs. 38% decrease, P < 0.01) and also reduced the C5a-induced increase in both coronary venous histamine (delta 26 vs. 278 nM, P < 0.05) and TxB2 (delta 0.34 vs. 63.3 ng/ml, P < 0.01). However, histamine H1 (pyrilamine) and H2 (ranitidine) receptor blockade had no effect on the C5a-induced fall in CBF or LAD %SS.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1996

Role of mast cells in oxidized low-density lipoprotein-induced microvascular dysfunction.

Previous studies demonstrated that human low-density lipoprotein (LDL) oxidized with Cu2+ promotes leukocyte-endothelial cell adhesion, mast cell degranulation, and albumin extravasation in rat mesentery. The objective of this study was to determine whether the mast cell degranulation elicited by oxidized LDL accounts for the accompanying microvascular responses. Leukocyte rolling, adherence, and emigration, fluorescein isothiocyanate-albumin leakage, and mast cell degranulation were monitored in rat mesentery before and during local intra-arterial infusion of either normal LDL (nLDL) or copper-oxidized LDL (CuLDL). Infusion of CuLDL, but not nLDL, elicited significant increases in leukocyte rolling, adherence and emigration, albumin leakage, and mast cell degranulation. Pretreatment with the mast cell-stabilizing agent ketotifen or superfusion of the mesenteric microcirculation with iodoxamide significantly reduced CuLDL-induced mast cell degranulation. The mast cell stabilization was accompanied by attenuated leukocyte-endothelial cell adhesion and albumin leakage responses to CuLDL. The results of this study indicate that 1) CuLDL-induced microvascular dysfunction (albumin leakage) involves the activation of mast cells, and 2) the protective action of mast cell stabilizers may be related to their ability to blunt CuLDL-induced leukocyte-endothelial cell interactions in postcapillary venules.

Animals↗
PubMed1998

Inhibitory effects of lodoxamide on eosinophil activation.

Recent reports describe the beneficial use of lodoxamide, an anti-allergic compound, for the treatment of asthma and allergic conjunctivitis. Lodoxamide is known as a mast cell stabilizer, however, the association of a significant clinical improvement with a specific decrease in eosinophil infiltrate suggested possible direct effects of lodoxamide on eosinophils. The chemotactic response of eosinophils to fMLP as well as to IL-5, in vitro, was very significantly and dose-dependently inhibited by Lodoxamide. Lodoxamide was also able to strongly inhibit the release of eosinophil peroxidase after IgA-dependent activation and, to a lesser extent, the release of eosinophil cationic protein and eosinophil-derived neurotoxin. Moreover, the release of cytotoxic mediators evaluated in an antibody-dependent cytotoxicity assay against parasitic targets was also significantly reduced, not only in the case of human eosinophils but also in a rat eosinophil-mast cell model of cytotoxicity. Taken together, these results indicate that lodoxamide can exert potent inhibitory effects on eosinophil activation in vitro combined with a strong inhibition of eosinophil attraction, leading therefore to a reduction in their pathological potential in vivo.

Animals↗
PubMed1998

Pharmacological mechanism of topical lodoxamide treatment in vernal keratoconjunctivitis: a flow-cytometric study.

The aim of this study was to investigate the possible effect of lodoxamide 0.1% ophthalmic solution (LOS) on tear T lymphocytes, especially Th2 (T helper 2 subgroup of helper T lymphocytes), in the tear specimens of patients with vernal keratoconjunctivitis (VKC) and to explore the mechanism of the anti-allergic effect of this drug. Twenty-eight active VKC patients were randomly divided into two groups each containing 14 patients. We obtained tear samples from all patients at the beginning of the study. LOS was prescribed to the study group (group A), but the controls (group B) received placebo over the course of 6 weeks. Tear samples were also collected from all patients following a 6-week course of treatment with either LOS or placebo. The percentages of Th1, Th2 and Th cells in the tear samples were measured by using a flow-cytometric technique and the results were compared to each other by using Wilcoxon matched-pairs signed-rank and Mann-Whitney U tests. We found that LOS treatment decreased the percentages of Th2 and Th cells in the tears of group A patients, while placebo had no effect on these values. Th1 cell count in the tears of both groups of patients did not show any significant change between the pre- and posttreatment stages. Our data suggest that LOS exerts, at least, some part of its anti-allergic effect via decreasing the Th2 cell number in the tears of VKC patients.

Administration, Topical↗
PubMed1991

Mobilization of renal carnosine and histidine to histamine during compound-48/80-induced shock.

Recently the presence of carnosine in the kidney has been established, and several potential roles for histamine have been proposed in renal metabolism. Histamine is known to occur in relatively high concentrations in renal tissue of several species and has been implicated in the autoregulation of renal blood flow and glomerular filtration. This study was designed to evaluate the effect of shock produced by compound 48/80 on the mobilization of renal carnosine to histamine and the effects of various blocking agents such as lodoxamide, diphenhydramine and cimetidine on this mobilization. Our results showed that compound-48/80-induced shock causes significant mobilization of renal carnosine and histidine to histamine and that this response can be blocked by administration of lodoxamide and diphenhydramine, but not cimetidine.

Animals↗
PubMed1984

Modulation of sulfur dioxide-induced airways hyperresponsiveness in the conscious dog.

Brief exposure of conscious dogs to 30 ppm SO2 directly into the lungs resulted in a transient bronchoconstriction followed by a period of hypersensitivity to aerosolized methacholine and 5-hydroxytryptamine. The hypersensitivity was maximal 4 h after exposure to SO2. Both Wy-41,195 and disodium cromoglycate, two antiallergic drugs, inhibited the hypersensitivity to methacholine when administered just prior to methacholine challenge. Neither drug significantly influenced SO2-induced bronchospasm nor influenced methacholine hypersensitivity when administered just prior to SO2 exposure. Furthermore, Wy-41,195 was ineffective against methacholine hypersensitivity when administered orally for 4 days. SO2-induced airway hypersensitivity in the dog may thus provide a useful model for exploring mechanisms and pharmacologic modulation of bronchial hyperreactivity, a common feature of asthma.

Administration, Oral↗
PubMed1990

Antiallergic and anti-inflammatory action of tioxamast in rats. II. Anti-inflammatory action in vivo.

Tioxamast is an antiallergic drug that inhibits anaphylaxis in various models in rats, and it inhibits the release and synthesis of certain mediators of inflammation [see Tarayre et al., this issue]. Here we report that the drug also has an anti-inflammatory effect in vivo in various nonimmunological models in rats. It reduces zymosan-induced inflammation in the paw and pleural cavity, starting at doses from 1.5625 to 3.125 mg/kg given intraperitoneally. In pleurisy, tioxamast lowers the concentration of leukotriene B4 (LTB4) in the exudate, at doses from 50 mg/kg i.p. Also, at doses from 12.5 mg/kg i.p., the compound reduced PAF-acether-induced pleurisy and the concentrations of LTB4 and peptidoleukotrienes in the exudate. An anti-inflammatory action against carrageenin-induced edema of the paw was seen only at doses of 50 mg/kg i.p. or more. The anti-inflammatory and antiallergic effect of tioxamast makes it a potentially useful drug in the treatment of allergies in humans.

Animals↗
PubMed1994

Lodoxamide treatment of allergic conjunctivitis.

Lodoxamide is an antiallergic compound. The present study evaluated the efficacy on clinical and cytological parameters and safety of topical lodoxamide compared to placebo in the treatment of allergic conjunctivitis. The trial, designed as double-blind, randomized, placebo-controlled and parallel group treatment, was carried out in 30 patients, suffering from seasonal allergic conjunctivitis due to grass pollen, during the pollen season. Patients received lodoxamide tromethamine 0.1% eye drops or placebo eye drops, one drop in each eye t.i.d. for 4 weeks. The clinical and cytological evidence was investigated by clinicians on admission and after 4 weeks' treatment. At the end of the trial, only the lodoxamide-treated group showed a significant clinical improvement, associated with a reduction of inflammatory cells. No serious side effects were observed. The results show the clinical efficacy of lodoxamide in the treatment of pollen-induced allergic conjunctivitis. In addition, lodoxamide exerts its antiallergic activity by reducing inflammatory infiltrate (mainly eosinophils).

Adult↗
PubMed1988

Acute reoxygenation injury in the isolated rat heart: role of resident cardiac mast cells.

Leukocyte-mediated myocardial reperfusion injury is characterized by the progressive migration and accumulation of polymorphonuclear leukocytes within the myocardium. In this study, we hypothesized that leukocytes normally resident to the myocardium also contribute to myocardial injury in the absence of migration and accumulation of peripheral polymorphonuclear leukocytes. In isolated crystalloid-perfused rat hearts, we found numerous resident cardiac leukocytes that were identified primarily as macrophages and mast cells, the latter staining avidly for peroxidase. When hypoxic perfused hearts (60 minutes, n = 16) were reoxygenated there was a prompt release of this peroxidase activity, the extent of which correlated closely with the degree of myocardial injury (total creatine kinase release, r = 0.96). When reoxygenation associated mast cell degranulation was prevented in six additional hypoxic hearts using 10 microM Lodoxamide Tromethamine, peroxidase release was reduced 7.8-fold (p less than 0.001) and creatine kinase release (injury) was reduced 5.9-fold (p less than 0.001). These results demonstrate that the isolated crystalloid-perfused rat heart is not a leukocyte-free preparation and suggest that mast cells resident to the heart play an important role in acute reoxygenation injury.

Acute Disease↗
PubMed1996

Lodoxamide in vernal keratoconjunctivitis.

Lodoxamide may be superior compared with cromolyn sodium for treatment of VKC. It is difficult, however, to conclusively determine the superiority of lodoxamide compared with cromolyn from the three studies reviewed in this article. Optimally, a triple-blind, randomized, placebo-controlled, multicenter trial involving the ophthalmic products cromolyn sodium 4%, lodoxamide 0.1%, and placebo (preferably NaCl 0.9%) with a treatment duration of at least 90 days and a similar sample size for each study group would lend the most credence to the determination of superiority of lodoxamide compared with cromolyn sodium for the treatment of VKC.

Anti-Asthmatic Agents↗
PubMedDate not supplied

Comparison of lodoxamide 0.1% ophthalmic solution and levocabastine 0.05% ophthalmic suspension in vernal keratoconjunctivitis.

PURPOSE: To compare the clinical efficacy and safety of lodoxamide 0.1% ophthalmic solution with levocabastine 0.05% ophthalmic suspension, each given four times daily (QID) for three months to patients with vernal keratoconjunctivitis (VKC). METHODS: The study was conducted multinationally according to a triple-masked parallel design in 95 VKC patients, with assessments at baseline then monthly during the three months of treatment. The primary efficacy variables were a Physician's Clinical Judgement Scale and a Patient's Overall Judgement Scale of improvements from baseline. Signs and symptoms of VKC were also assessed. RESULTS: Both primary efficacy variables showed significantly greater overall improvement of VKC from baseline with lodoxamide than levocabastine. The superiority of lodoxamide was demonstrated by the Physician's Clinical Judgement Scale at months 2 and 3, with a trend, at month 1, and by the Patient's Overall Judgement Scale at months 1, 2 and 3. All signs and symptoms of VKC improved significantly from baseline at all time points, regardless of treatment (p<0.001). However, relative to levocabastine, conjunctival discharge, photophobia and lacrimation were significantly reduced by lodoxamide at months 1, 2 and 3, itching at months 2 and 3, and bulbar conjunctiva at month 3. The temporal improvement of superior tarsal papillae did not differ significantly between treatments. Both were well tolerated. CONCLUSIONS: Lodoxamide 0.1% and levocabastine 0.05% eye drops, instilled four times daily for three months, were effective, safe and well tolerated by patients with VKC, but lodoxamide was significantly superior to levocabastine.

Adolescent↗
PubMed2003

Tear and serum eosinophil cationic protein levels in seasonal allergic conjunctivitis.

PURPOSE: Eosinophil cationic protein (ECP) levels in tear fluid and sera of patients with seasonal allergic conjunctivitis (SAC) were measured to assess local and systemic eosinophilic activity in SAC. The correlation between ECP levels and disease activity was evaluated. METHODS: Tears and sera were collected from 21 patients with SAC and 13 healthy control subjects. ECP levels in tears and sera were measured before and 4 weeks after treatment with 0.1% lodoxamide eyedrops. Clinical signs and symptoms of SAC were scored and the correlation of ECP levels with the clinical scores was evaluated. RESULTS: Tear and serum levels of ECP were significantly increased (p = 0.01, p = 0.02, respectively) in patients with SAC compared with the control subjects, but ECP levels were not correlated with the severity of the disease. Following treatment with topical 0.1% lodoxamide eyedrops, the mean level of ECP in tears decreased significantly (p = 0.02), whereas no significant change was observed in serum ECP levels. Furthermore, a significant decrease in clinical signs and symptoms scores was found after treatment (both p < 0.0001). CONCLUSIONS: Increased serum and tear ECP levels in patients with SAC confirms that both local and systemic eosinophil activation occurs in SAC. However, clinical signs and symptoms of SAC were not found to be correlated with the degree of eosinophilic activity. Thus ECP does not seem to have an important role in clinical manifestations of SAC.

Adult↗