Levels of complement factor H-related 4 protein do not influence susceptibility to age-related macular degeneration or its course of progression

Dysregulation of the alternative pathway (AP) of the complement system is a significant contributor to age-related macular degeneration (AMD), a primary cause of irreversible vision loss worldwide. Here, we assess the contribution of the liver-produced complement factor H-related 4 protein (FHR-4) to AMD initiation and course of progression. We show that FHR-4 variation in plasma and at the primary location of AMD-associated pathology, the retinal pigment epithelium/Bruch's membrane/choroid interface, is entirely explained by three independent quantitative trait loci (QTL). Using two distinct cohorts composed of a combined 14,965 controls and 20,741 cases, we ascertain that independent QTLs for FHR-4 are distinct from variants causally associated with AMD, and that FHR-4 variation is not independently associated with disease. Additionally, FHR-4 does not appear to influence AMD progression course among patients with disease driven predominantly by AP dysregulation. Modulation of FHR-4 is therefore unlikely to be an effective therapeutic strategy for AMD.

3Alpha,5beta-tetrahydrocortisol effect on outflow facility

3Alpha,5beta-Tetrahydrocortisol (THF) was administered topically and intracamerally to ocular normotensive cynomolgus monkeys to determine whether it affects outflow facility. Monkeys received THF either topically at a dose of 2 x 5 microl drops of 300 microg/10 microl twice daily for 4 days (n = 4) or 3 times daily for 10 days (n = 4) with 10% DMSO as vehicle to the control eye, or intracamerally via 2 ml anterior chamber (AC) exchange of 30 microg/ml THF with vehicle, 0.1% DMSO, to the control eye followed by a second AC exchange using 300 microg/ml THF with vehicle to the control eye. Outflow facility was measured by a two-level constant pressure AC perfusion after administration of eye drops or after baseline outflow facility measurement and AC exchange with THF solution. The results showed no effect on outflow facility in normotensive cynomolgus monkeys.

Effects of prednisone on the cellular responses and release of cytokines and mediators after segmental allergen challenge of asthmatic subjects

BACKGROUND

Systemic glucocorticoids are a major therapy for the management of allergic inflammation and asthma; however, information about their effects in vivo are limited.

OBJECTIVE

This study was performed to examine the effects of prednisone on inflammatory mediators, cytokines, and cellular responses in the model of segmental allergen challenge (SAC) of allergic asthmatic subjects.

METHODS

The effects of a 3-day pretreatment with oral prednisone (30 mg twice daily) on the physiologic and inflammatory responses to SAC were studied in 10 allergic asthmatic subjects in a double-blind, placebo-controlled, crossover protocol.

RESULTS

Prednisone improved baseline FEV(1) by 10% and modestly inhibited the SAC-induced fall in FEV(1) at 30 minutes and at 6 to 8 hours. Five minutes after challenge, levels of histamine, PGD(2), 9alpha,11beta-PGF(2), and thromboxane B(2) increased in bronchoalveolar lavage fluid (median increase, 5- to 14-fold); prednisone did not inhibit these responses. Prednisone inhibited (median decrease, 66%-97%) the total influx of inflammatory cells, specifically eosinophils, basophils, and some subsets of T lymphocytes (CD4, CD45RA, and CD45RO cells) assessed 19 hours after SAC, but it did not inhibit the influx of neutrophils. Increases in soluble E-selectin, kinins, and albumin were also inhibited by the glucocorticoid (median decrease, 36%-74%). Prednisone treatment inhibited the appearance of mRNA, protein, or both for T(H)2 cytokines (IL-4 and IL-5), as well as for IL-2 and transforming growth factor alpha, but did not inhibit increases of immunoreactive GM-CSF in bronchoalveolar lavage fluid.

CONCLUSION

These studies indicate that prednisone suppresses multiple components of allergic airway inflammation, including cell recruitment, adhesion molecule expression or release, airway permeability, and production of cytokines potentially involved in airway immunity or remodeling.

Measurement of low picomolar levels of triamcinolone acetonide in human bronchoalveolar lavage fluid by gas chromatography-electron-capture negative-ion mass spectrometry

The intense inherent electron-capture properties of the C21 acetate derivative of triamcinolone acetonide (TAA) under methane chemical ionization mass spectrometric conditions were exploited for the development of a highly sensitive and selective gas chromatography-mass spectrometric (GC-MS) technique for measurement of levels of TAA in human bronchoalveolar lavage (BAL) fluid. After the addition of 3.0 ng of a heptadeuterated analog of TAA and varying concentrations of TAA to 2-ml aliquots of BAL fluid, the deuterium and protium forms of the steroid were extracted with diethyl ether, converted to the C21 acetate derivative, and purified via adsorptive chromatography prior to GC-MS analysis. Standard curves obtained from 2-ml aliquots of BAL fluid were linear over a wide range of concentrations of TAA from 0.0 to 24,600 pg/2-ml aliquots of BAL fluid. Levels as low as 6.0 pg/ml (13.8 pmol x L(-1)) in BAL fluid can be reliably determined in 2-ml aliquots of the biological fluid with <10% error. These findings suggest that the assay method exploiting the intense electron-capture properties of TAA is highly suitable for determination of the deposition pattern and in vivo kinetics of TAA in human airways following inhalation of the steroid.

Acute effects of H-7 on ciliary epithelium and corneal endothelium in monkey eyes

PURPOSE

Topical or intracameral administration of H-7 doubles outflow facility and reduces intraocular pressure in cynomolgus monkeys, by relaxing and expanding the trabecular meshwork (TM) and Schlemm's canal (SC). Since H-7 may have anti-glaucoma potential, we determined its effects on the corneal endothelium and ciliary epithelium for safety considerations.

METHODS

Following topical H-7, aqueous humor flow (AHF), corneal endothelial transfer coefficient (k(a)) and anterior chamber (AC) entry of i.v. fluorescein were measured by fluorophotometry; AC aqueous protein concentration ([Protein](AC)) was determined by Lowry assay; and corneal thickness and endothelial cell density and morphology were measured by ultrasonic pachymetry and specular microscopy respectively. Following intracameral H-7, specular and/or light and electron microscopy of the corneal endothelium or ciliary epithelium were performed.

RESULTS

Following unilateral topical H-7: (1) AHF and k(a) were essentially unchanged at 0.5--3.0, 3.5--6.0, and 0.5--6.0 hr, with an insignificant increase from 0.5--1.5 hr; (2) [Protein]( AC) was insignificantly increased at 1-1.5 hr but had returned to baseline by 2.5 hr; (3) entry of i.v. fluorescein into aqueous or cornea was modestly and transiently increased; (4) the central cornea thickened significantly at 1--2.5 hr, gradually returning to baseline 2.5 hr after H-7, while peripheral corneal thickness was less affected; (5) corneal endothelial cell borders became indistinct by 1 hr, but cell morphology was recovering by 3--5 hr and had completely returned to normal by 24 hr; (6) corneal endothelial cell density was unchanged at 5--24 hr. Following intracameral H-7, no significant changes were observed in corneal endothelial cell density or morphology by specular microscopy, nor in corneal endothelial or ciliary epithelial morphology by light and electron microscopy.

CONCLUSIONS

A facility-effective intracameral dose of H-7 had no discernible structural effect on the corneal endothelium or ciliary epithelium. It is not yet clear whether carefully chosen topical doses of H-7 or analogues can enhance outflow facility without meaningfully affecting the cornea and ciliary processes.

Endogenous glucocorticoids and antigen-induced acute and late phase pulmonary responses

BACKGROUND

Several studies suggest that endogenous glucocorticoids can dampen the severity of experimental allergic reactions in animals.

OBJECTIVE

To investigate the influence that endogenous glucocorticoids have on the course of IgE-mediated pulmonary early and late phase reactions.

METHODS

Twenty-one allergic asthmatic and six healthy control subjects underwent inhaled antigen challenge with measurements of plasma cortisol and cortisone by gas chromatography-mass spectrometry.

RESULTS

There were no differences between the asthmatic and control groups in the baseline levels of cortisol or cortisone. However, the asthmatic subjects had significantly higher cortisol levels (67.2 +/- 8.6 vs 35.1 +/- 4.5 ng/mL; P = 0.04) and had higher cortisol/cortisone ratios (4.8 +/- 0. 6 vs 3.0 +/- 0.2; P = 0.01) 8 h after challenge compared to the control subjects. Among the asthmatic subjects, those whose FEV1 recovered rapidly had higher baseline levels of cortisol and those who displayed a late phase reaction had lower levels of cortisol during the late phase period.

CONCLUSION

The results suggest that endogenous glucocorticoids may play a significant role in the modulation of airway responses to antigen challenge, and that antigen challenge may induce cortisol production in allergic subjects.

Latrunculins' effects on intraocular pressure, aqueous humor flow, and corneal endothelium

PURPOSE

To determine the effects of latrunculin (LAT)-A or -B on intraocular pressure (IOP), aqueous humor flow (AHF), anterior chamber (AC) protein concentration ([protein]AC), corneal endothelial permeability and morphology, and corneal thickness in living cynomolgus monkeys.

METHODS

Topical LAT-A or LAT-B was administered to one eye, and vehicle to the other. IOP was measured by Goldmann tonometry, AHF and corneal endothelium transfer coefficient (ka) by fluorophotometry, [protein]Ac by Lowry assay, corneal endothelial cell morphology by specular microphotography, and corneal thickness by ultrasound pachymetry.

RESULTS

LAT-A began to lower IOP at 6 hours and maximally reduced IOP by 4.6 mm Hg at 9 hours. LAT-B lowered IOP within 1 hour and maximally reduced IOP by 3.1 mm Hg at 6 hours. LAT-A increased AHF by 87% for 3 hours and increased ka by 94% over 6 hours; LAT-B increased ka by 39% over 6 hours without affecting AHF. LAT-A increased IV fluorescein entry into the cornea approximately 10 fold, but did not affect IV fluorescein entry into the AC. LAT-A increased [protein]AC by 25% at 2 hours but not 5.5 hours. LAT-B variably and insignificantly increased [protein]AC: at 1 hour but not at 6.5 hours. LAT-A induced extensive corneal endothelial pseudoguttata within 1 hour, with normal cell counts by 7 days. LAT-B increased central corneal thickness maximally by 47 microm at 3.5 hours.

CONCLUSIONS

LAT-A and -B significantly reduced IOP and were consistent in their facility-increasing effect, indicating that pharmacologic disorganization of the actin cytoskeleton in the trabecular meshwork by latrunculins may be a useful antiglaucoma strategy. However, effects on corneal endothelium or ciliary epithelium are a potential safety issue.

Low doses of pilocarpine do not significantly increase outflow facility in the cynomolgus monkey

Low doses (10(-9)-10(-6) M) of pilocarpine reportedly increase outflow facility in the organ-cultured human eye, suggesting a direct action on the trabecular meshwork. M3 muscarinic receptors have been found in both cultured human trabecular meshwork cells and tissue. We determined whether low pilo doses would increase outflow facility in the living monkey. The anterior chambers of both eyes of 17 pentobarbital anesthetized cynomolgus monkeys were cannulated and outflow facility measured bilaterally by 2-level constant pressure perfusion after an initial 2 ml exchange with Bárány's perfusand containing 24.5 microM phenylephrine (PE). Two subsequent exchanges were performed with one eye receiving Bárány's + PE + 10(-10)-10(-4) M pilocarpine and the contralateral eye receiving only Bárány's + PE. Outflow facility was measured for 35-40 min following each exchange. Accommodation and pupil diameter were measured before each exchange and approximately every 10 min during facility measurements. Outflow facility was significantly increased by 154 and 313% in eyes treated with 10(-5) M and 10(-4) M pilocarpine, respectively, related to contralateral controls. Accommodation and miosis also were induced only at 10(-5) M (accommodation, 3.3 +/- 1.6 diopters, NS; miosis, -4.1 +/- 0.5 mm, P < or = 0.001) and 10(-4) M (accommodation, 10.6 +/- 0.0 diopters, P < or = 0.02; miosis, -3.4 +/- 1.0 mm, P < or = 0.025) pilocarpine. We conclude that low anterior chamber doses of pilocarpine do not increase outflow facility in the living monkey as reported in the organ-cultured human eye, nor do they induce miosis or accommodation. All three parameters respond to pilocarpine at similar doses, and there is no functional evidence of a meaningful outflow facility-relevant pilocarpine effect on the trabecular meshwork at doses lower than those which affect the ciliary muscle.

Experimental glaucoma and cell size, density, and number in the primate lateral geniculate nucleus

PURPOSE

To examine the effects that elevated intraocular pressure (IOP), a glaucoma risk factor, has on the size, density, and number of neurons in the primate lateral geniculate nucleus (LGN).

METHODS

The monkey model of experimental glaucoma was combined with standard histologic staining and analysis techniques. Fourteen animals were examined.

RESULTS

Mean IOPs higher than 40 mm Hg for 2.5, 4, 8, and 24 weeks resulted in reductions of 10% to 58% in the cross-sectional areas of LGN neurons receiving input from the glaucomatous eye. Reductions for animals with lower mean IOPs (37 and 28 mm Hg) for 16 and 27 weeks were 16% and 30%, respectively. Neurons receiving input from the normal eye also were reduced in size (4 -26%). No differential effect in cell size was seen for magnocellular versus parvocellular neurons. Elevation of IOP resulted in an increase in cell density in all layers of the LGN. The increase was approximately two times greater in parvocellular (59%) than magnocellular (31%) layers. When corrected for volumetric shrinkage of the LGN, the estimated loss of neurons was approximately four times greater in the magnocellular than parvocellular layers (38% versus 10%).

CONCLUSIONS

Elevation of IOP affects the size, density, and number of neurons in the LGN, and the volume of the nucleus itself. Although higher mean pressures (more than 40 mm Hg) reduce the period during which these changes occur, comparable damage can be achieved by even moderate (28 -37 mm Hg) levels of elevated IOP. On the basis of cell loss, elevation of IOP appears to have a more profound degenerative effect on the magnocellular than on the parvocellular regions of the LGN.

Tissue prostanoids as biomarkers for chemoprevention of colorectal neoplasia: correlation between prostanoid synthesis and clinical response in familial adenomatous polyposis

Recent studies indicate that sulindac, a nonsteroidal anti-inflammatory drug (NSAID), lowers mucosal prostanoid levels and regresses colorectal adenomas in patients with familial adenomatous polyposis (FAP). To determine whether they are biomarkers for sulindac-mediated chemoprevention of colorectal adenomas, levels of 5 prostanoids [prostaglandin (PG) D2, PGE2, PGF2alpha, thromboxane B2, and 6-keto-PGF1alpha] in the normal-appearing rectal mucosa from 7 FAP patients with a history of subtotal colectomy and ileorectal anastomosis and 4 FAP patients without surgery, were measured in the absence or presence of exogenously added arachidonic acid before the initiation and at the end of 3 months of sulindac treatment. The addition of arachidonic acid resulted in a uniform increase in the levels of all 5 prostanoids although this increase was selectively attenuated in patients with ileorectal anastomosis who took sulindac. In the latter patients, arachidonic acid also augmented the inhibition of prostanoid synthesis by sulindac. In contrast, sulindac failed to attenuate the increase in prostanoid levels resulting from arachidonic acid in patients without previous surgery. Importantly, when measured in the presence of arachidonic acid, the reduction in the levels of all 5 prostanoids due to sulindac was statistically correlated with a reduction in the size and number of adenomas in the two groups of patients combined. These results suggest that tissue prostanoids measured in the presence of arachidonic acid may serve as sensitive and reliable biomarkers in monitoring the clinical responsiveness of FAP patients undergoing chemoprevention for colorectal neoplasia with NSAIDs.

Extracellular signal-regulated kinases regulate leukotriene C4 generation, but not histamine release or IL-4 production from human basophils

Human basophils secrete histamine and leukotriene C4 (LTC4) in response to various stimuli, such as Ag and the bacterial product, FMLP. IgE-mediated stimulation also results in IL-4 secretion. However, the mechanisms of these three classes of secretion are unknown in human basophils. The activation of extracellular signal-regulated kinases (ERKs; ERK-1 and ERK-2) during IgE- and FMLP-mediated stimulation of human basophils was examined. Following FMLP stimulation, histamine release preceded phosphorylation of ERKs, whereas phosphorylation of cytosolic phospholipase A2 (cPLA2), and arachidonic acid (AA) and LTC4 release followed phosphorylation of ERKs. The phosphorylation of ERKs was transient, decreasing to baseline levels after 15 min. PD98059 (MEK inhibitor) inhibited the phosphorylation of ERKs and cPLA2 without inhibition of several other tyrosine phosphorylation events, including phosphorylation of p38 MAPK. PD98059 also inhibited LTC4 generation (IC50 = approximately 2 microM), but not histamine release. Stimulation with anti-IgE Ab resulted in the phosphorylation of ERKs, which was kinetically similar to both histamine and LTC4 release and decreased toward resting levels by 30 min. Similar to FMLP, PD98059 inhibited anti-IgE-mediated LTC4 release (IC50, approximately 2 microM), with only a modest effect on histamine release and IL-4 production at higher concentrations. Taken together, these results suggest that ERKs might selectively regulate the pathway leading to LTC4 generation by phosphorylating cPLA2, but not histamine release or IL-4 production, in human basophils.

Endothelin-1 effects on aqueous humor dynamics in monkeys

PURPOSE

To report data showing no effect of endothelin-1 on aqueous humor formation and total outflow facility in the cynomolgus monkey, in contrast to the enhancement of outflow facility in monkeys and the suppression of aqueous humor flow in rabbits previously reported by others.

METHODS

Living monkeys received, unilaterally: (i) intracameral endothelin-1 (10 microl bolus, or 2ml or 4ml exchange; final intracameral concentration 1 or 10 nM) with total outflow facility measured for up to 1 hr post-treatment by two-level constant pressure perfusion, and (ii) intravitreal endothelin-1 (20 microl, final intravitreal concentration 0.1 or 1 microM) with aqueous humor flow measured by scanning fluorophotometry for 5 hr starting 12 hr post-treatment. Contralateral eyes received vehicle.

RESULTS

Endothelin-1 had no effect on total outflow facility or aqueous humor flow with any of the methods described.

CONCLUSION

Endothelin-1 seems have a variable effect on aqueous humor dynamics within and between species.

Morphology of single ganglion cells in the glaucomatous primate retina

PURPOSE

To examine the degenerative effects that prolonged elevation of intraocular pressure (IOP), a risk factor commonly associated with glaucoma, has on the morphology of single ganglion cells in the primate retina.

METHODS

The monkey model of glaucoma was combined with intracellular staining techniques using an isolated retina preparation. Midget and parasol cells from normal and glaucomatous eyes were labeled intracellularly, and their axons, somas, and dendritic fields were compared using confocal microscopy.

RESULTS

In midget and parasol cells, the earliest signs of pressure-induced degeneration involved structural abnormalities associated with the dendritic arbor. Reductions in axon thickness appeared later, with changes in soma size occurring concomitantly or slightly later. Chronic elevation of IOP resulted in a significant decrease in the mean soma sizes of midget and parasol cells, but only parasol cells showed a significant reduction in dendritic field size and axon diameter. Comparisons of eyes with different levels of optic nerve damage, based on cup- disc ratio, showed that the axons and dendritic fields of parasol cells were significantly smaller at lower cup-disc ratios than were those of midget cells, suggesting a possible differential effect.

CONCLUSIONS

In glaucoma, retinal ganglion cells undergo a pattern of degeneration that originates with the dendritic arbor and ends with shrinkage of the cell soma. Although this pattern of degeneration implies early functional deficits and retinal ganglion cell atrophy that occurs earlier than previously thought, based on ganglion cell loss alone, it also suggests a window of opportunity for effective neuroprotection.

Factors associated with suicide attempts among patients with schizophrenia

This study explored the association between psychosocial variables and symptoms among patients with schizophrenia-spectrum disorders who have attempted suicide and those who have not attempted suicide. Of 336 patients with a DSM-III-R diagnosis of schizophrenia or schizoaffective disorder who were consecutively evaluated at a university-affiliated clinical research center, 98, or 29.2 percent, reported one or more suicide attempts. Compared with patients who had not attempted suicide, patients who had made an attempt had a greater number of lifetime depressive episodes, an earlier age of onset of their illness, and an earlier age at first hospitalization.

Phosphorylation of cytosolic phospholipase A2 by IL-3 is associated with increased free arachidonic acid generation and leukotriene C4 release in human basophils

BACKGROUND

Human basophils secrete leukotriene C4 (LTC4) in response to various stimuli, and a short treatment with IL-3 enhances LTC4 release, although IL-3 alone does not induce LTC4 release. However, the mechanism of this priming effect of IL-3 for LTC4 generation remains unknown in human basophils.

OBJECTIVE

This study was designed to explore the mechanisms by which short treatments with IL-3 enhance stimulated secretion of LTC4, with a focus on the activation of cytosolic phospholipase A2 (cPLA2).

METHODS

The phosphorylation state of cPLA2 in human basophils was examined by its shift in electrophoretic mobility as detected by Western blotting. Free arachidonic acid (AA) and LTC4 were measured by gas chromatography-negative ion chemical ionization mass spectrometry and LTC4-specific RIA, respectively.

RESULT

Human basophils expressed cPLA2. IL-3, as well as the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate, caused a shift in the electrophoretic mobility of cPLA2, which indicated phosphorylation of cPLA2 and therefore its activation. Ionomycin at a concentration of 0.1 microg/mL was used to induce a modest elevation of cytosolic calcium response ([Ca2+]I), no apparent cPLA2 phosphorylation, and little free AA and LTC4 generation. Pretreatment with IL-3 (1 to 10 ng/mL) markedly enhanced ionomycin (0.1 microg/mL)-mediated AA and LTC4 generation. The concentration dependence of cPLA2 phosphorylation by IL-3 and its effects on free AA and LTC4 generation were similar. The selective PKC inhibitors, bis-indolylmaleimide II and Ro-31-8220 inhibited the phorbol 12-myristate 13-acetate-mediated cPLA2 electrophoretic mobility shift, but not the IL-3-mediated shift, suggesting that the IL-3 effect is PKC independent. Both the anaphylatoxin split product of the C component C5 (C5a) and f-Met-Leu-Phe induced PKC-independent cPLA2 phosphorylation with a similar time course most notable for the absence of observable changes in cPLA2 phosphorylation before 30 seconds. These results suggested an explanation for the absence of free AA generation by C5a. When [Ca2+]I was elevated in response to C5a, there was no phosphorylation of cPLA2, and by the time cPLA2 became phosphorylated, [Ca2+]I had returned to resting levels. Treatment with IL-3 preconditioned the cPLA2 by causing its phosphorylation so that the transient [Ca2+]I response, which followed stimulation by C5a, could induce the generation of free AA and LTC4.

CONCLUSION

Taken together, these results suggest that the effect of IL-3 for free AA generation and LTC4 release might be due to induction of cPLA2 phosphorylation. The studies demonstrated a need for synchronous cPLA2 phosphorylation and elevations in [Ca2+]I.

The role of platelet activating factor and other lipid mediators in inflammatory angiogenesis

Chronic inflammatory diseases are often accompanied by intense angiogenesis. A model of inflammatory angiogenesis is the murine air pouch granuloma which has a hyperangiogenic component. Proinflammatory lipid mediator generation is also a hallmark of chronic inflammation and the role of endogenous production of these mediators in angiogenesis is not known. The 14 kDa phospholipase A2 (PLA2) deacylates phospholipid, liberating arachidonic acid, which is used for leukotriene production, and lysophospholipid, which can drive the production of platelet-activating factor (PAF). Therefore, SB 203347, an inhibitor of the 14 kDa PLA2, zileuton, an inhibitor of 5-lipoxygenase, and Ro 24-4736 a PAF receptor antagonist were evaluated for their effects in the murine air pouch granuloma. SB 203347 reduced both LTB4 and PAF, but not PGD2 levels measured in the day 6 granuloma. This correlated with a significant reduction in angiogenesis. Zileuton reduced LTB4 levels as expected, but did not significantly inhibit angiogenesis, whereas Ro 24-4736 potently reduced angiogenesis. These data support the hypothesis that PAF, and to a lesser extent leukotrienes contribute to the angiogenic phenotype in chronic inflammation.

Size-dependent increase in prostanoid levels in adenomas of patients with familial adenomatous polyposis

Recent studies indicate that nonsteroidal anti-inflammatory drugs have a chemopreventive effect against colorectal neoplasia. Nonsteroidal anti-inflammatory drugs inhibit cyclooxygenases, principal enzymes that mediate the formation of prostanoids. To determine whether prostanoids are involved in the pathogenesis of colorectal adenomas, we compared the levels of five major stable metabolic products of the cyclooxygenase pathway in the normal-appearing mucosa and in adenomas of patients with familial adenomatosis polyposis. Of 12 patients tested, 6 had elevated levels of at least one prostanoid in the adenomas. More importantly, the relative levels of three prostanoids [prostaglandin (PG)D2, PGE2, and 6-keto-PGF1alpha] were elevated in adenomas compared to normal-appearing mucosa from the same patients, and the resulting ratios were correlated with the size of the adenoma. These results suggest a role for prostanoids in progression of colorectal polyposis in familial adenomatosis polyposis patients.

Characteristics of arachidonic acid generation in human basophils: relationship between the effects of inhibitors of secretory phospholipase A2 activity and leukotriene C4 release

In human basophils, degranulation stimulated by receptor activation or Ca++ ionophores is accompanied by an increase in free arachidonic acid (AA) as determined by gas chromatography negative ion chemical ionization mass spectrometry. Previous studies suggested that there was more than one pool of AA generated during stimulation and indirectly suggested that the leukotriene (LTC4) generated in these reactions was dependent on only one of these pools of AA. Our studies further examined these issues. Preliminary studies demonstrated discordance in the generation of free AA and LTC4 release. Treatment of basophils with triacsin C, a reacylation inhibitor, led to a marked increase in N-formyl-L-methionyl-L-leucyl-L-phenylalanine-(fMLP) stimulated free AA generation with no effect on LTC4 release. Similarly, incubation of basophils with recombinant human secretory phospholipase A2 (sPLA2), before and during fMLP stimulation, led to the generation of extremely high levels of free AA with no effect on LTC4 release. Pretreatment of basophils with anti-14 kDa phospholipase A2 monoclonal antibody (mAb 3F10) inhibited fMLP-induced synthesis of LTC4 but did not attenuate the mass of AA measured nor histamine release. Treating human basophils with zileuton (an inhibitor of 5-lipoxygenase) inhibited the stimulated synthesis of LTC4 and in combination with triacsin C increased the amount of observable AA by an amount approximately equal to the loss in LTC4 mass. Monoclonal antibody 3F10 blocked only the enhanced AA production caused by the combination of zileuton and triacsin C. Monoclonal antibody 3F10 did not inhibit the increases in free AA produced by pretreatment with triacsin C alone. These findings were supported by experiments using another relatively specific inhibitor of sPLA2, SB 203347. In all respects, SB 203347 mimicked the addition of mAb 3F10. Taken together, these data indicate that not all pools of AA are well used for LTC4 synthesis. These experiments also suggest that LTC4 synthesis in human basophils stimulated with fMLP depends on a SB 203347- and monoclonal antibody 3F10-inhibitable deacylation activity, presumably a sPLA2 acting at or near the cell surface. Furthermore, under normal conditions, this pool of AA is not observable because it is efficiently coupled to 5-lipoxygenase. Other deacylating enzymes, which do not supply AA for 5-lipoxygenase metabolism, also appear to be activated by fMLP and these other enzymes appear responsible for the net free AA normally observed after stimulation.

Prostaglandin levels in human colorectal mucosa: effects of sulindac in patients with familial adenomatous polyposis

Recent evidence suggests that nonsteroidal antiinflammatory drugs (NSAIDs) may prevent colorectal cancer. The mechanism of action of NSAIDs in chemoprevention is unknown but may be linked to their effect on mucosal prostaglandin levels. Levels of five major prostaglandin metabolites were measured by gas chromatography-mass spectrometry in biopsy specimens of flat rectal mucosa from four patients with familial adenomatous polyposis (FAP) before and after sulindac therapy and from five healthy individuals. The prostaglandin present at highest concentration in rectal mucosa from FAP and control subjects was prostaglandin E2. The concentration of thromboxane B2 alone was significantly elevated in FAP patients compared to controls (P = 0.016). In FAP patients treated with sulindac, all prostaglandin metabolite levels were significantly reduced compared to pretreatment levels (P < 0.05) except prostaglandin D2 (P = 0.07). Prostaglandins D2, E2, F2alpha, and 6-keto-F1alpha levels also were significantly reduced in FAP patients on sulindac compared to healthy controls (P < 0.05). However, interpatient heterogeneity of response to sulindac was evident with changes ranging from +19% to -89%, and the patient with the greatest reductions after sulindac developed colorectal cancer after 35 months of therapy. Sulindac treatment, at drug doses shown to regress colorectal adenomas in FAP patients, has heterogeneous effects on the level of major prostaglandins in their rectal mucosa and may not prevent colorectal cancer due to uncoupling of prostaglandin levels and carcinogenesis.

Intraocular pressure and outflow facility are unchanged following acute and chronic intracameral chondroitinase ABC and hyaluronidase in monkeys

We determined the effect of chronic and acute loss of glycosaminoglycans from the aqueous outflow pathway on intraocular pressure (IOP) and outflow facility in the subhuman primate eye. For the study of the chronic effects of the GAGases, cynomolgus monkeys received intracameral injections of hyaluronidase (Streptomyces, 5 or 50 units, n=2) or chondroitinase ABC (0.05 or 0.25 units, n=2) biweekly for 8 months (4 months for each dose). IOP was measured at 3, 7, 10 and 14 days after each injection. Outflow facility (2-level constant pressure) was determined at 2, 4, 6, and 8 months. Monkeys were killed 6 days after the last injection. The changes in the distribution of hyaluronic acid and sulfated proteoglycans in the outflow pathway were examined using substrate-specific histochemical techniques. The acute effects of these enzymes on outflow facilities (30 min or 2 hr after enzyme) were determined in another group of animals (n=4 for each time enzyme-1). IOP and outflow facility were unchanged compared to controls (heat inactivated enzyme) at any time in the chronically or acutely treated monkeys. Hyaluronic acid staining was absent in the outflow pathways of eyes treated chronically with hyaluronidase compared with control eyes, while collagen-associated sulfated proteoglycans were decreased but not completely removed by the chronic chondroitinase ABC treatment. Chronic loss of these glycosaminoglycans from the trabecular meshwork does not appear to contribute to the IOP elevation and decrease in outflow facility that accompanies open-angle glaucoma. Most importantly, no increase in outflow facility was found with acute hyaluronidase or chondroitinase treatment.

Preliminary characterization of diacylglycerol generation in human basophils: temporal relationship to histamine release and resolution of degranulation

Purified human basophils were examined for changes in diacylglycerol levels to determine whether the transient nature of a N-formyl-methionyl-leucyl-phenylalanine (fMLP) -stimulated elevation in membrane protein kinase C (PKC) activity could be explained by the transient production of diacylglycerol (DAG). In preliminary experiments total DAG levels were measured by the DAG kinase assay. Although elevations followed stimulation with 1 microM fMLP (basal levels of 15 pmol/10(6) basophils vs. 45 pmol/10(6) basophils at the 3-min time point), there were no detectable changes in the first 60 s of the reaction. Histamine release is typically complete by 30-45 s. Measurement of inositol trisphosphate indicated a rapid increase by 5 s of 2.5 pmol/10(6) basophils. If DAG were produced at similar levels, the DAG kinase assay would not have detected the elevation. Consequently, fMLP-stimulated basophils were examined for changes in 1-stearoyl, 2-arachidonoyl, 3-sn-glycerol (SA-DAG) and 1-oleoyl, 2-arachidonoyl, 3-sn-glycerol by GC-NICIMS (negative ion chemical ionization mass spectroscopy). A 5-s elevation in these two species averaged 2 pmol/10(6) basophils, consistent with the inositol trisphosphate levels and occurring during the period of histamine release. However, a much more pronounced second phase to the SA-DAG response also occurred, mirroring the total DAG levels. This second phase of the DAG response, either total or SA-DAG, was transient on a time scale temporally coincident with the appearance and resolution of degranulation sacs as measured by fluorescence microscopy. These data suggest that there is selective generation of DAG species in the early reaction and the later appearance of DAG may be related to the formation and resolution of granule structures that follow the secretion of histamine.

The Iowa Longitudinal Study of Recent Onset Psychosis: one-year follow-up of first episode patients

The natural history of schizophrenia remains unclear. One strategy to further inform this area is to prospectively evaluate individuals early in the course of the disorder, both in terms of symptomatic and psychosocial/occupational functioning. Subjects were recruited into the study if they were in the midst of their first psychiatric hospitalization for a non-'organic' psychotic disorder. Subjects were extensively evaluated at index with semi-structured interviews including the Comprehensive Assessment of Symptoms and History (CASH), and followed at 6-month intervals. Data are presented on 35 subjects who were followed through 1 year. There was a significant improvement in overall symptomatology during index hospitalization, but this was accounted for primarily by improvement of positive symptoms, with negative symptoms remaining prominent. No further improvement was noted between discharge and 1-year follow-up in any of the symptom measures. Employment, interpersonal relationships, and sexual activity remained markedly impaired throughout the follow-up period. These data demonstrate that; (1) negative symptoms are prominent and stable early in the course of the disorder; (2) symptom severity at discharge from index hospitalization is predictive of symptom severity at 1 year; and (3) despite substantial overall symptomatic improvement during the first hospitalization, psychosocial and occupational functioning were found to be markedly impaired at 1-year follow-up.

Mechanisms of prostanoid synthesis in human synovial cells: cytokine-peptide synergism

Bradykinin (BK)2 and interleukin-1 (IL-1) interact synergistically to stimulate prostaglandin synthesis in human synovial fibroblast-like cells. The effect of BK is rapid and correlates with its capacity to elevate cytosolic levels of calcium ([Ca2+]i), while IL-1's effect is slow and s dependent upon de novo protein synthesis. The mechanism of this synergistic interaction was investigated. In the basal state, high levels of arachidonic acid (AA) were spontaneously released from synovial cells but near absent levels of cyclooxygenase activity prevented metabolism of AA to prostanoid. BK was a potent stimulus for elevating AA, but not prostaglandins, above basal levels. IL-1, in contrast, increased prostaglandins but not AA, above basal levels. IL-1 treatment was not associated with a loss or redistribution of AA among phospholipid classes. These results are consistent with high basal phospholipase activity in synovial cells and demonstrate the ability of BK, presumably via its ability to raise [Ca2+]i, to further elevate this activity(ies). Metabolism of AA to prostanoid is minimal in resting and BK-stimulated synovial cells, however, without the concomitant induction of cyclooxygenase activity by IL-1. These studies clarify the different, but synergistic, mechanisms of action of a peptide and cytokine in stimulating prostanoid synthesis in synovial cells. In addition, these data extend the results of previous investigations in demonstrating that basal phospholipase activity provides sufficient AA substrate for IL-1 induced prostanoid synthesis without invoking the concomitant induction of phospholipase activity by IL-1.

Indomethacin and epinephrine effects on outflow facility and cyclic adenosine monophosphate formation in monkeys

PURPOSE

To investigate the effect of indomethacin inhibition of prostanoid production on the epinephrine-stimulated increase in outflow facility and cyclic adenosine monophosphate (cAMP) production in the anterior segment of the monkey eye.

METHODS

Topical indomethacin was given 1 hour before the intracameral administration of epinephrine to living cynomolgus monkeys. Outflow facility was measured for 45 to 60 minutes, beginning 3 hours after epinephrine administration, by two-level constant pressure perfusion of the anterior chamber. Cyclic adenosine monophosphate formation was measured in cell membranes isolated from rhesus monkey ciliary muscle, ciliary processes, trabecular meshwork, and iris in the presence of forskolin, indomethacin, epinephrine, or indomethacin and epinephrine combined.

RESULTS

Three hours after the intracameral administration of 5.5 micrograms epinephrine, facility increased by approximately 40%, a putatively maximal response, at which time the intracameral epinephrine concentration was approximately 15 microM. Pretreatment with topical indomethacin produced a dose-dependent inhibition of epinephrine's facility-increasing effect; the maximum inhibition of 50% to 70% occurred at an indomethacin dose of 50 to 125 micrograms. Doubling the indomethacin dose (250 micrograms) produced no further inhibition, whereas a fivefold larger epinephrine dose (27.5 micrograms) did not overcome the inhibition. Forskolin and epinephrine both stimulated cAMP production in vitro, whereas [indomethacin] > or = 10(-4) M partially inhibited both basal and epinephrine-stimulated cAMP production in all four tissues.

CONCLUSIONS

Approximately half of the epinephrine-induced facility increase is inhibited by indomethacin, but it is unclear whether the indomethacin-inhibitable fraction is mediated by epinephrine-stimulated prostanoid production or release.

Antigen-induced generation of lyso-phospholipids in human airways

The goal of the current study was to examine the formation of phospholipids, 1-radyl-2-lysosn-glycero-phospholipids (lyso-PL) and 2-acetylated phospholipids (such as PAF) as well as mechanisms responsible for generating these phospholipids in bronchoalveolar lavage fluid (BAI.F) from allergic subjects challenged with antigen. Bronchoalveolar lavage was performed in normal and allergic subjects before, 5-30 min, 6 h, and 20 h after segmental antigen challenge via a wedged bronchoscope. Levels of 1-hexadecyl-2-lyso-phospholipids and 1-hexadecyl-2-acetyl-phospholipids were initially determined by negative ion chemical ionization gas chromatography/mass spectrometry (NICI-GC/MS). Antigen dramatically elevated quantities of 1-hexadecyl-2-lyso-phospholipids in allergic subjects 20 h after challenge when compared to non-allergic controls. In contrast, there was not a significant increase in levels of 1-hexadecyl-2-acetyl-phospholipids after antigen challenge. Closer examination of 1-radyl-2-lyso-sn-glycero-3-phosphocholine (GPC) revealed that 1-palmitoyl-2-lyso-GPC, 1-myristoyl-2-lyso-GPC and 1-hexadecyl-2-lyso-GPC were three major molecular species produced after antigen challenge. 1-palmitoyl-2-lyso-GPC increased sevenfold to levels of 222 +/- 75 ng/ml of BALF 20 h after antigen challenge. The elevated levels of lyso-PL correlated with levels of albumin used to assess plasma exudation induced by allergen challenge. In contrast, the time course of prostaglandin D2 (PGD2) or 9 alpha, 11 beta PGF2 (11 beta PGF2) formation did not correlate with lyso-PL generation. To examine the mechanism leading to lyso-phospholipid formation in antigen-challenged allergic subjects, secretory phospholipase A2 (PI.A2) and acetyl hydrolase activities were measured. There was a significant increase in PLA2 activity found in BALF of allergic subjects challenged with antigen when compared to saline controls. This activity was neutralized by an antibody directed against low molecular mass, (14 kD) human synovial PLA2 and dithiothreitol. Acetyl hydrolase activity also markedly increased in BALF obtained after antigen challenge. This study indicates that high levels of lyso-PLs are present in airways of allergic subjects challenged with antigen and provides evidence for two distinct mechanisms that could induce lyso-PL formation. Future studies will be necessary to determine the ramifications of these high levels of lyso-phospholipids on airway function.

Quantitation of 1-stearoyl-2-arachidonoyl-sn-3-glycerol in human basophils via gas chromatography-negative ion chemical ionization mass spectrometry

Investigation of the role of diacylglycerol molecular species in signal transduction in human basophils has been impeded by the lack of an assay method with adequate sensitivity and selectivity. Conversion of 1-stearoyl-2-arachidonoyl-sn-3-glycerol to the pentafluorobenzoyl ester conveys electron-capture properties to the diacylglycerol. The electron-capture derivative of the diacylglycerol is amenable to gas chromatographic analysis and undergoes limited fragmentation under negative ion mass spectrometric conditions with generation of an intense molecular anion at m/z 838. Monitoring m/z 838 for detection of 1-stearoyl-2-arachidonoyl-sn-3-glycerol and m/z 841 for detection of 1-trideuterostearoyl-3-arachidonoyl-sn-2-glycerol employed as the internal standard provides the analytical basis for GC-MS quantitation of the endogenous diacylglycerol in human basophils. The assay displays excellent reproducibility over a wide range of concentrations with variations < or = 10%. The GC-MS assay is highly selective and exquisitely sensitive with a detection limit of < or = 0.20 pg (approximately 30 fmol) for endogenous 1-stearoyl-2-arachidonoyl-sn-3-glycerol per injection. Approximately 400 fmol of the diacylglycerol were extracted from 10(5) stimulated human basophils.

Unilateral nasal allergen challenge leads to bilateral release of prostaglandin D2

BACKGROUND

Multiple mediators including prostaglandin D2 and leukotriene B4 have been shown to increase in nasal secretions during the early response to nasal challenge with antigen.

OBJECTIVE

Our objective was to investigate the time course of prostanoid and leukotriene B4 release into nasal secretions on both the ipsilateral and contralateral side after a unilateral nasal allergen challenge.

METHODS

We performed a controlled, randomized trial. Six volunteers were challenged unilaterally with antigen or diluent in a randomized order and discs were used to collect nasal secretions from both nostrils at 2 min intervals for 20 min after the challenge. Prostanoids and leukotriene B4 (LTB4) in recovered nasal secretions were measured by combined capillary gas chromatography-negative ion chemical ionization mass spectrometry (GC/MS).

RESULTS

Nasal allergen challenge resulted in a significant and immediate increase in symptoms and sneezing. PGD2 was significantly elevated above diluent values (0.6 +/- 0.6 pg) 30 s after removal of the allergen disc (P < 0.05), reached its peak (423.2 +/- 182.4 pg) at 2 min and then slowly decreased. PGD2 also increased on the contralateral side after unilateral allergen challenge, reaching peak values about six times lower than on the ipsilateral side (70.8 +/- 21.7 pg at 6 min). Levels of 9a, 11b-PGF2 after antigen provocation became significantly higher than after diluent (0 +/- 0 pg) on the ipsilateral side at 2 min (17.2 +/- 5.9 pg), and reached peak levels at 4 min (25.1 +/- 8.0 pg). LTB4 also increased significantly on the side of challenge. For the other prostanoids measured (PGF2, PGF2 alpha, TxB2, 6kPGF1 alpha), no significant changes in either ipsilateral or contralateral secretions were observed after allergen challenge.

CONCLUSIONS

Our study described the kinetics of PGD2 and LTB4 release as well as the contralateral release of PGD2.

Aceclidine effects on outflow facility after ciliary muscle disinsertion

Aceclidine increases outflow facility with little accommodative effect. To determine whether this dissociation resides in the ciliary muscle (CM) or trabecular meshwork (TM), we measured aceclidine effects on perfusion outflow facility in both eyes of 8 rhesus monkeys after unilateral disinsertion of the CM from the TM. Facility in the control eyes increased by approximately 250% following intravenous pilocarpine and by an additional approximately 250% following intracameral pilocarpine, relative to baseline and uncorrected for washout. In CM-disinserted eyes, the facility response to intravenous and intracameral pilocarpine averaged approximately 25% of that in contralateral controls. Cytochalasin B, which acts directly on the TM to increase facility but is not additive to maximal pilocarpine doses in normal eyes, had no additional effect beyond that of pilocarpine in control eyes but induced an additional 100% facility increase relative to baseline in CM-disinserted eyes. The accommodative response to carbachol in CM-disinserted eyes was approximately 80% of that in contralateral controls, consistent with retention of CM contractility and the gonioscopic appearance of shallow CM disinsertion. Intracameral aceclidine HCl doses of 5 and 50 micrograms increased outflow facility by approximately 80 and 250%, respectively, in control eyes, and by approximately 0 and 80% in CM-disinserted eyes. Either the low aceclidine dose affected facility via the CM, while the high dose exerted an additional effect on the TM, or aceclidine acted only via the CM, with the low dose being ineffective and the high dose modestly effective in CM-disinserted eyes because only a few CM-TM attachments remained.

Neurological soft signs in neuroleptic-naive and neuroleptic-treated schizophrenic patients and in normal comparison subjects

OBJECTIVE

The goal of this study was to assess neurological soft signs and developmental reflexes in schizophrenic patients who had never received neuroleptic medication and those who were receiving neuroleptic medication.

METHOD

Neurological soft signs and developmental reflexes were examined in 26 schizophrenic patients who had never received a neuroleptic, 126 schizophrenic patients who were currently receiving neuroleptics, and 117 normal subjects.

RESULTS

Soft signs were present in 23% of the neuroleptic-naive and 46% of the medicated schizophrenic patients. Developmental reflexes were present in 19% of the neuroleptic-naive and 12% of the medicated patients. Both soft signs and developmental reflexes were absent in the normal subjects. There were significant differences between patients and normal subjects in neurological soft signs and developmental reflexes. The possibly confounding variables of age, age at onset, duration of illness, number of hospitalizations, Abnormal Involuntary Movement Scale (AIMS) scores, and Simpson-Angus Scale extrapyramidal symptom scores were assessed by using logistic regression in the patients who were receiving neuroleptics. AIMS scores and Simpson-Angus Scale scores correlated with soft signs in these patients.

CONCLUSIONS

The presence of neurological soft signs in schizophrenic patients who had never received neuroleptics indicates that these signs are present independent of medication effects, but it is possible that neuroleptics contribute to the prevalence of these abnormalities, as demonstrated by the patients who were receiving neuroleptics.

Apraclonidine and brimonidine effects on anterior ocular and cardiovascular physiology in normal and sympathectomized monkeys

Apraclonidine and brimonidine administered topically to one eye of ketamine-anesthetized normal cynomolgus monkeys each produced a dose-related bilateral reduction in intraocular pressure which was not dependent on intact sympathetic innervation. Brimonidine was more potent and efficacious (10-12 mmHg maximum intraocular pressure reduction 2 hr after 200 micrograms) but produced a shorter-lasting effect than apraclonidine (4 mmHg maximum intraocular pressure reduction 1-6 hr after 600-1000 micrograms). Apraclonidine had little effect on pupil diameter, but brimonidine produced a dose-related bilateral miosis which was dependent on intact sympathetic innervation. Neither drug significantly affected refractive error. Topical brimonidine, but not apraclonidine, produced a dose-dependent reduction in mean arterial blood pressure, while both drugs lowered heart rate. A dose-dependent bilateral reduction in aqueous humor flow rate calculated over a 6-hr period following drug administration was produced by both topical apraclonidine (maximum 30-35% reduction with 600 micrograms) and brimonidine (maximum 30-45% reduction with 50-250 micrograms), which was not dependent on intact sympathetic innervation. Maintenance of blood pressure by intravenous infusion of angiotensin II had no effect on the aqueous humor flow suppression produced by 100 micrograms of topical brimonidine, but pentobarbital anesthesia abolished it. Intracameral injection of 10 micrograms brimonidine in rhesus monkeys produced an ipsilateral approximately 15% reduction in aqueous humor flow calculated for the 1-3 hr post-injection period. The cardiovascular and contralateral ocular effects observed with both drugs are presumably related to the monkeys' small body weight, and the magnitude of IOP reduction for a given degree of flow suppression would be greater in hypertensive than in normotensive eyes. Caution must therefore be exercised in extrapolating from our data in ocular normotensive monkeys to the glaucomatous human.

Recombinant stem cell factor-induced mast cell activation and smooth muscle contraction in human bronchi

The effect of human recombinant stem cell factor (SCF) on inflammatory mediator release and smooth muscle contraction was evaluated in human isolated intralobar bronchi. Bronchi from 21 of 26 donors contracted in response to SCF. The threshold concentration was approximately 0.01 micrograms/ml. At 1 micrograms/ml, the tissues contracted to about 60% of the carbamylcholine-induced maximum contraction. The responses to SCF mimicked those obtained with anti-IgE. Thus, the contractions to SCF and anti-IgE were inhibited to a similar extent by a combination of a cysteinyl-leukotriene receptor antagonist and a histamine H1 receptor antagonist. SCF also mimicked the effect of anti-IgE in releasing histamine, i-LTD4, and PGD2 from the bronchi. At a threshold concentration for contraction (0.01 micrograms/ml), SCF had no effect on subsequent responses to anti-IgE in the bronchi. The data suggest that human recombinant SCF contracts airway smooth muscle by stimulating the release of contractile mediators from bronchial mast cells. The data fail to support the hypothesis that SCF primes bronchial mast cells to subsequent immunologic stimuli.

Obstruction of aqueous humor outflow by cross-linked polyacrylamide microgels in bovine, monkey, and human eyes

PURPOSE

Orcolon, a synthetic viscoelastic, may have contributed to refractory intraocular pressure (IOP) elevation after intracameral injection in some patients. Cross-linked polyacrylamide (microgels), an altered form of the polymer, was investigated as an etiologic candidate.

METHODS

Four adult rhesus monkeys underwent anterior chamber exchange with mock aqueous humor containing microgels in one eye and a vehicle in the other. Outflow facility (perfusion) and IOP (applanation) were determined before and at various times thereafter. Facility also was determined before and after microgel or vehicle infusion into organ-cultured individual human (n = 9) and paired calf (n = 6) anterior segments. Representative monkey and human eyes were examined by light and electron microscopy.

RESULTS

In the microgel-infused monkey eyes, IOP was consistently higher, by approximately 5 mmHg for approximately 1 month. In all three species, microgel infusion acutely decreased facility by approximately 50% to 80%. In the living monkeys where longer-term observation and retesting were possible, a facility reduction of approximately 40% to 50% persisted for at least 1 to 2 months, and rechallenge again produced an acute 80% facility decrease and subsequent 10-mmHg IOP rise. Results of electron microscopic examination in human and monkey eyes showed accumulation of microgels in the cribriform meshwork and beneath the inner wall of Schlemm's canal, with no cellular alterations or inflammatory infiltrate.

CONCLUSIONS

Cross-linked polyacrylamide microgels can produce an acute and longstanding obstruction of trabecular drainage experimentally, and might therefore do so clinically.

Release of inflammatory mediators from guinea pig trachea by electrical field stimulation: lack of neuronal involvement

Electrical field stimulation (EFS; 5-10 V, 1 ms, 20 Hz for 1 min) of isolated guinea pig trachea resulted in a rapid increase in tone that is blocked by either atropine or tetrodotoxin (TTX). EFS of tracheal spirals also caused large increases in the release of certain prostanoids with release of prostaglandin (PG)D2, PGE2 and PGF2 alpha (16.5-, 3.0- and 4.1-fold, respectively). In contrast to the smooth muscle response, however, EFS-induced release of prostanoids was not significantly altered in the presence of TTX. Removal of the epithelium reduced the amount of prostanoids released by EFS. Thus, EFS-induced production of PGD2, PGE2 and PGF2 alpha was significantly reduced by about 30%, 70% and 80% in epithelium-denuded tissues, respectively. Direct vagal stimulation caused a rapid contraction of the trachealis but failed to elicit increases in the release of histamine or arachidonic acid metabolites. Furthermore, the selective stimulant of C-type sensory fibers capsaicin (3 microM) or exogenously applied substance P (1 microM) or neurokinin A (1 microM) failed to induce histamine, leukotriene or prostanoid release from guinea pig tracheal rings. Although, the mechanism involved in stimulation of arachidonic acid metabolism by EFS is unclear, this effect in part involves the epithelium but apparently is not mediated by airway elements sensitive to TTX, direct vagal stimulation or tachykinins.

Ragweed antigen E and anti-IgE in human central versus peripheral isolated bronchi

The ability of antigen to contract passively sensitized tissues was examined in human central (5 to 12 mm) and peripheral (0.5 to 2 mm) bronchi. Both central and peripheral bronchi contracted to ragweed antigen E (RW AgE), and these contractions were virtually abolished by a combination of indomethacin, cysteinyl-leukotriene, and histamine antagonists. There were, however, quantitative differences in contractile responses and in mediator release to RW AgE between central and peripheral bronchi. RW AgE was approximately 20-fold more potent in contracting peripheral bronchi compared with central bronchi. On a per weight of tissue basis, RW AgE released six-fold more histamine, 15- to 20-fold more immunoreactive leukotriene D4 (i-LTD4) and two- to 10-fold more prostanoids in the peripheral bronchi compared with central bronchi. Anti-IgE mimicked the effect of RW AgE with respect to inflammatory mediator release and with respect to the magnitude of the contractile response in peripheral and central bronchi. Anti-IgE, however, was more potent in contracting central than peripheral bronchi. Moreover, in peripheral bronchi, contractile responses to anti-IgE were only partially inhibited by a combination of indomethacin, cysteinyl-leukotriene, and histamine antagonists. These results indicate that the qualitative characteristics of antigen-induced mediator release and muscle contraction are similar in central versus peripheral bronchi. However, RW AgE is much more potent in causing smooth muscle constriction, and is capable of releasing a greater quantity of inflammatory mediators in peripheral bronchi/bronchioles than in the more central bronchi.

Simultaneous quantitation of endogenous levels of cortisone and cortisol in human nasal and bronchoalveolar lavage fluids and plasma via gas chromatography-negative ion chemical ionization mass spectrometry

Investigation of the influence of pulmonary disease upon local catabolism of cortisol in vivo is limited by the lack of availability of a selective and sensitive assay for simultaneous quantitation of cortisol and cortisone in lung and nasal lavage fluids as well as in plasma. Synthesis of bispentafluorobenzylcarboxymethoxime derivatives of cortisone and cortisol followed by trimethylsilylation yields compounds with almost ideal gas chromatographic properties. The derivatized steroids generate intense M(-.)-181 fragment ions in negative ion chemical ionization mass spectrometry. Monitoring of ions at m/z 829 and m/z 903, respectively, for cortisone and cortisol and corresponding fragment ions generated from multideuterated internal standards provides the analytical basis for assessment of local in vivo conversion of cortisol to cortisone in the respiratory system of human subjects. The assay method displays excellent reproducibility with variations < or = 10%. Detection limits are < or = 1 pg of steroid analyte per injection (S/N > 3). Endogenous levels of cortisone and cortisol, respectively, measured in human samples were as follows: nasal lavage fluid, 47 and 25 pg/ml; bronchoalveolar lavage fluid, 380 and 153 pg/ml; plasma 12.8 and 61.6 ng/ml.

Dry air- and hypertonic aerosol-induced bronchoconstriction and cellular responses in the canine lung periphery

Dry air and hypertonic saline both create an osmotic stress to the airways, whilst dry air alone induces transient cooling of the airway mucosa. It is unclear whether these two stimuli lead to bronchoconstriction via the same mechanisms. We compared airflow- and hypertonic aerosol-induced bronchoconstriction (AIB and HIB, respectively) in the canine lung periphery, using a wedged bronchoscope to measure collateral system resistance (Rcs). Bronchoalveolar lavage (BAL) was used to examine changes in cells and mediators during AIB and HIB. We found that: 1) peripheral airways are not refractory to either dry air or hypertonic aerosols, and do not exhibit cross-refractoriness to these stimuli; 2) differences in strength of stimulus can alter the magnitude but not the time course of HIB; 3) within an individual, AIB and HIB are significantly correlated; 4) epithelial cells recovered in BAL fluid (BALF) are significantly elevated after AIB, and are similarly increased after HIB; 5) when compared to control, mediators recovered in BALF are significantly elevated after AIB but not HIB; 6) HIB is not altered by cyclo-oxygenase inhibition; and 7) lavage with hypertonic fluid does not affect the number of epithelial cells recovered, although the concentrations of some mediators are increased. We speculate that differences in cell and mediator profiles reflect differences in the time course of AIB and HIB that result from the modulation of temperature sensitive pathways that occurs during dry air, but not during hypertonic aerosol challenge.

Blood and bronchoalveolar eosinophils in allergic subjects after segmental antigen challenge: surface phenotype, density heterogeneity, and prostanoid production

Eosinophil infiltration into the airways has been implicated in the pathophysiology of asthma. To improve our understanding of the function of eosinophils in asthma, we have compared the phenotype and function of eosinophils obtained simultaneously from blood and bronchoalveolar lavage (BAL) of allergic subjects 19 hours after segmental lung allergen challenge. Eosinophils were purified by discontinuous density gradient centrifugation, and their distribution at various layers was quantitated. Eosinophils at the 1.080 to 1.085 gm/ml interfaces from blood and BAL (purity > 70%) were analyzed by immunofluorescence and flow cytometry for several surface markers including adhesion-activation antigens. Eosinophils in BAL from antigen-challenged sites were markedly increased compared with control diluent-challenged BAL sites (0.3% +/- 1% vs 28.1% +/- 9.7%, n = 12, p < 0.002), and a greater percentage were hypodense (specific gravity < 1.080 gm/ml) than in peripheral blood (51.3 +/- 5.3 vs 19.0 +/- 4.4, n = 15, p < 0.01). In vitro, resting and activated BAL eosinophils biosynthesized less thromboxane B2 than blood eosinophils. Although both BAL and blood eosinophils expressed similar levels of Fc gamma RII (CD32), CD11a, and CD45, resting levels of Mo-1 (CD11b) were upregulated on BAL eosinophils (mean fluorescence intensity, 316% +/- 48% of blood eosinophils, n = 5, p < 0.05). Blood eosinophils stimulated in vitro with 1 mumol/L platelet activating factor or N-formyl-methionyl-leucyl-phenylalanine achieved levels of CD11b expression similar to those of BAL eosinophils. In contrast, CD11b expression on BAL eosinophils could not be further increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Nasal allergen challenge generates 1-0-hexadecyl-2-lyso-sn-glycero-3-phosphocholine

We studied antigen-induced platelet activating factor and the 1-0-hexadecyl-2-lyso-sn-glycero-3-phosphocholine (lyso-PAF) in nasal lavage fluids (NLF) by combined gas chromatography/mass spectrometric analysis (GC/MS). During the early allergic reaction, there was a dramatic increase in the levels of lyso-PAF that peaked at 15 min (2.6 +/- 5.2 ng/ml, mean +/- SEM, n = 6). Increasing doses of antigen produced a dose-dependent increase in the levels of lyso-PAF that peaked at the highest dose. Levels of lyso-PAF correlated strongly with those of N-alpha-tosyl-L-arginine methyl ester (TAME)-esterase activity (rs = 0.82, p = 0.0001) and histamine (rs = 0.57, p = 0.002). There was a no significant increase in the quantity of lyso-PAF found in NLF from allergic individuals challenged with diluent or nonallergic individuals challenged with antigen. In subjects showing a late phase reaction, as indicated by symptoms and histamine release, we detected lyso-PAF along with TAME-esterase activity and histamine during the late phase reaction. In contrast to lyso-PAF, PAF levels were near or below the detection limit of the assay in NLF and remained unchanged after antigen challenge. We also investigated the potential pathways for lyso-PAF generation from 2-acetylated phospholipids. We found that the time required for deacetylation of 50% of [3H]PAF (t1/2) to lyso-PAF was 50 min in baseline secretions and 10 and 22 min in NLF obtained 10 min and 24 h after antigen challenge, respectively. These data suggested that catabolic pathways were present in NLF.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of ethacrynic acid on aqueous outflow dynamics in monkeys

PURPOSE

To determine the long-term effect of ethacrynic acid (ECA) on aqueous outflow dynamics in ocular normotensive monkeys.

METHODS

(1) Twelve cynomolgus monkeys received 10 microliters of 2.5 mM (= 7.5 micrograms) ECA intracamerally in one eye, vehicle in the other; outflow facility (perfusion) was determined at 1 hour, 24 hours, or 1 week, and intraocular pressure (IOP; applanation) at 24 hours, 1 week, and 6 to 7 weeks later. Six other cynomolgi received 10 microliters of 0.13 or 1.3 mM phalloidin in one eye 45 minutes before receiving ECA OU; facility was measured 1 hour after ECA. (2) Groups of five rhesus monkeys underwent intracameral injection of 2.5, 5.0, or 10 micrograms ECA in one eye, vehicle in the other, with IOP measured hours to weeks thereafter. (3) Five rhesus monkeys received 540 micrograms of ECA unilaterally as a 30-microliter topical drop once daily for 4 days. On the first and fourth treatment days, baseline IOP, pupil diameter, and refraction were measured immediately before and again at 2, 4, and 7 hours after topical treatment.

RESULTS

(1) ECA divided by vehicle facility averaged 1.83 +/- 0.23 (SEM) (P < 0.02, n = 6), 1.50 +/- 0.27 (P < 0.11, n = 7), and 1.05 +/- 0.10 (n = 7) at 1 hour, 24 hours, and 1 week, respectively. IOP was 1 to 2 mm Hg lower in ECA eyes 24 hours (P < 0.05, n = 5) and 6 to 7 weeks (P < 0.05, n = 7) after treatment. Phalloidin did not diminish the 1-hour ECA facility effect. (2) Five (but not 2.5 or 10) micrograms of ECA lowered IOP 1 to 3 mm Hg, starting at 2 hours and lasting up to 48 hours. The maximum ECA effect (-2.6 +/- 0.25 mm Hg; P < 0.001, n = 5) occurred at 4 hours. IOP, corneal thickness and endothelial cell count, and anterior chamber depth were not significantly different 8 weeks after 5 micrograms ECA or vehicle. (3) Once-daily unilateral topical application of 540 micrograms of ECA induced no change in IOP, refraction, or pupil diameter compared to contralateral vehicle-treated control eyes. There were no significant ECA-related ocular bio-microscopic abnormalities.

CONCLUSIONS

ECA may lower IOP and increase outflow facility longer than previously thought, but not by affecting meshwork actin filaments.

Comparison of clarithromycin and penicillin VK suspensions in the treatment of children with streptococcal pharyngitis and review of currently available alternative antibiotic therapies

In a randomized investigator-blinded study, 506 children ages 6 months to 12 years with positive rapid direct antigen tests for Group A beta-hemolytic Streptococcus (GABHS) received treatment with either clarithromycin suspension, 7.5 mg/kg twice daily, or penicillin VK suspension, 13.3 mg/kg three times per day for 10 days. Signs and symptoms of pharyngitis or tonsillitis were evaluated and throat cultures were obtained before treatment, once during treatment and 4 to 6 days and 19 to 25 days posttreatment. All GABHS isolates were susceptible in vitro to clarithromycin. Successful clinical responses at the end of treatment were demonstrated in 169 of 176 (96%) evaluable clarithromycin-treated patients and 179 of 191 (94%) evaluable penicillin-treated patients. GABHS was successfully eradicated at end of treatment in 168 of 183 (92%) evaluable clarithromycin-treated patients compared with 162 of 199 (81%) evaluable penicillin-treated patients (P = 0.004). There were no significant changes in hematologic or serum chemistry parameters in either group. Both drugs were well-tolerated. The incidence and nature of adverse events were similar in the clarithromycin and penicillin groups, except for gastrointestinal complaints reported in 35 of 250 (14%) clarithromycin recipients compared with 12 of 256 (5%) penicillin recipients (P < or = 0.001). The results indicate that twice daily clarithromycin was as safe and effective as three times daily penicillin VK in the treatment of children with streptococcal pharyngitis or tonsillitis. Clarithromycin was statistically superior to penicillin VK in the eradication of GABHS.

IL-3 alters free arachidonic acid generation in C5a-stimulated human basophils

IL-3 is known to enhance the secretion of several mediators from human basophils activated by receptor-mediated stimuli. IL-3 can cause a qualitative change in the mediator release pattern for C5a-mediated stimulation; without IL-3, C5a causes no leukotriene release whereas in the presence of IL-3, significant leukotriene occurs. This study examines the influence of a 15-min pretreatment of basophils with IL-3 (10 ng/ml) on several signal transduction events. Basophils stimulated with C5a typically displayed only a transient cytosolic Ca2+ response [Ca2+]i, attributed to the release of intracellular calcium stores. IL-3 had sporadic, statistically nonsignificant, effects on the peak of this initial response as well as inconsistent effects on the generation of a second phase in the [Ca2+]i response (i.e., that which is caused by the influx of extracellular Ca2+). IL-3 also had no effect on resting [Ca2+]i levels. Challenge of basophils in the presence of EGTA had little effect on the amount of leukotrienes generated. This maneuver did not influence the initial transient elevation of [Ca2+]i. Although basophil leukotriene release is usually slow, after exposure to IL-3 it was found that leukotriene release occurred rapidly, during the brief window of time (0 to 45 s) in which the [Ca2+]i transient occurred. These results suggested that the generation of AA was accelerated by pretreatment with IL-3. Subsequent mass measurements of free AA by gas chromatography-mass spectroscopy showed: 1) IL-3 itself caused no free AA generation; 2) without IL-3, C5a stimulated little or no free AA generation; and 3) in the presence of IL-3, C5a generated substantial levels of free AA at an accelerated rate. A similar acceleration in the rate of free AA generation, without any apparent increase in the amount, occurred in IL-3-primed basophils stimulated with FMLP. Additional studies showed that IL-3 had no effects on whole cell ATP levels and that the kinase inhibitor, staurosporine, did not inhibit the ability of IL-3 to cause enhanced responses to C5a. We conclude that the primary effect of a short period of pretreatment with IL-3 is to couple the generation of free AA to C5a-mediated stimulation in particular and to accelerate its generation after other stimuli. Enhancements of the [Ca2+]i response, while sporadic and at best modest, may have some influence on enhanced mediator release but did not clearly explain the functional effects of IL-3.

IL-3 alters free arachidonic acid generation in C5a-stimulated human basophils

IL-3 is known to enhance the secretion of several mediators from human basophils activated by receptor-mediated stimuli. IL-3 can cause a qualitative change in the mediator release pattern for C5a-mediated stimulation; without IL-3, C5a causes no leukotriene release whereas in the presence of IL-3, significant leukotriene occurs. This study examines the influence of a 15-min pretreatment of basophils with IL-3 (10 ng/ml) on several signal transduction events. Basophils stimulated with C5a typically displayed only a transient cytosolic Ca2+ response [Ca2+]i, attributed to the release of intracellular calcium stores. IL-3 had sporadic, statistically nonsignificant, effects on the peak of this initial response as well as inconsistent effects on the generation of a second phase in the [Ca2+]i response (i.e., that which is caused by the influx of extracellular Ca2+). IL-3 also had no effect on resting [Ca2+]i levels. Challenge of basophils in the presence of EGTA had little effect on the amount of leukotrienes generated. This maneuver did not influence the initial transient elevation of [Ca2+]i. Although basophil leukotriene release is usually slow, after exposure to IL-3 it was found that leukotriene release occurred rapidly, during the brief window of time (0 to 45 s) in which the [Ca2+]i transient occurred. These results suggested that the generation of AA was accelerated by pretreatment with IL-3. Subsequent mass measurements of free AA by gas chromatography-mass spectroscopy showed: 1) IL-3 itself caused no free AA generation; 2) without IL-3, C5a stimulated little or no free AA generation; and 3) in the presence of IL-3, C5a generated substantial levels of free AA at an accelerated rate. A similar acceleration in the rate of free AA generation, without any apparent increase in the amount, occurred in IL-3-primed basophils stimulated with FMLP. Additional studies showed that IL-3 had no effects on whole cell ATP levels and that the kinase inhibitor, staurosporine, did not inhibit the ability of IL-3 to cause enhanced responses to C5a. We conclude that the primary effect of a short period of pretreatment with IL-3 is to couple the generation of free AA to C5a-mediated stimulation in particular and to accelerate its generation after other stimuli. Enhancements of the [Ca2+]i response, while sporadic and at best modest, may have some influence on enhanced mediator release but did not clearly explain the functional effects of IL-3.

Relative contributions of direct and indirect mechanisms mediating endothelin-induced contraction of guinea-pig trachea

1. The present study was undertaken to determine the mechanism of action of endothelin-1 (ET-1)-induced contraction of the guinea-pig isolated trachea. 2. ET-1 (1 nM-0.3 microM) produces a concentration-dependent contraction of guinea-pig trachea with an EC50 of approximately 25 nM. The combination of the peptidoleukotriene receptor antagonist, SK&F 104353 (10 microM) and the H1-histamine receptor antagonist, mepyramine (10 microM), which abolishes antigen-induced contraction in guinea-pig trachea, was without effect on ET-1 concentration-response curves. Furthermore, the platelet-activating factor (PAF) receptor antagonist, WEB 2086, (1 or 10 microM) did not inhibit ET-induced contraction. 3. ET-1 (0.3 microM) did not stimulate histamine or immunoreactive peptidoleukotriene release from guinea-pig isolated trachea. 4. The release of various prostanoids from guinea-pig trachea was increased significantly by ET-1 (0.3 microM); the profile of release was prostaglandin D2 (PGD2) = PGE2 = 6-keto PGF1 alpha (PGI2 metabolite) > thromboxane B2 = PGF2 alpha >> 9 alpha, 11 beta PGF2 (PGD2 metabolite). ET-1-induced release of prostaglandins, which was about 30% of that elicited by antigen in sensitized tissues, was not affected by epithelium removal and was observed in tissues from which the smooth muscle had been removed. Previous studies in our laboratory indicated that indomethacin potentiated contraction produced by high concentrations of ET-1, whereas a thromboxane receptor antagonist was without appreciable effect on ET-1 concentration-response curves. 5. Pretreatment of tissues for 1 h with capsaicin (10 microM), which depletes different sensory neurones, produced a small, but significant, inhibitory effect on ET-1 concentration-response curves in the presence but not the absence of the epithelium. The combination of the NK1 tachykinin receptor antagonist,CP-96,345 (0.1 microM), and the NK2 tachykinin receptor antagonist, SR 48968 (0.1 microM), was without effect on ET-l concentration-response curves but substantially antagonized capsaicin-induced contraction.6. The present data suggest that in guinea-pig isolated trachea, ET- 1 produces contraction predominantly via a direct mechanism: there is no significant contribution of the release of histamine,leukotrienes, PAF, or tachykinins (acting on NK1 or NK2 receptors). Although ET-1 evokes the release of an array of prostanoids from the trachea they do not appear to have a major influence on the contractile response.

Endothelin receptor subtypes in human and guinea-pig pulmonary tissues

1. In this study the endothelin (ET) receptor subtypes mediating contractions produced by ET-1 in human and guinea-pig pulmonary tissues were investigated. In addition the receptor responsible for ET-1-induced prostanoid release in human bronchus was determined. 2. In human bronchus and human pulmonary artery ET-1 (0.1 nM-0.3 microM) was a potent and effective contractile agent (pD2 = 7.58 +/- 0.15, n = 6, and 8.48 +/- 0.11, n = 7, respectively). BQ-123 (1-10 microM), a potent and selective ETA receptor antagonist, potently antagonized ET-1-induced contraction in human pulmonary artery (pKB = 6.8 with 1 microM BQ-123, n = 7) but had no effect in human bronchus (n = 6). 3. Sarafotoxin S6c (0.1 nM-0.1 microM), the ETB-selective agonist, did not contract human pulmonary artery (n = 5), but potently and effectively contracted human bronchus: pD2 = 8.41 +/- 0.17, maximum response = 74.4 +/- 3.1% of 10 microM carbachol; n = 5. BQ-123 (1-10 microM) did not antagonize sarafotoxin S6c-induced contraction in human bronchus (n = 5). 4. ET-1 potently contracted guinea-pig trachea, bronchus, pulmonary artery and aorta (pD2 = 8.15 +/- 0.14, 7.72 +/- 0.12, 8.52 +/- 0.12, and 8.18 +/- 0.12, respectively, n = 6-14). BQ-123 (0.1-10 microM)antagonized ET-1-induced contractions in guinea-pig pulmonary artery (pKB = 6.7 with 1 microM BQ-123,n = 6), aorta (pKB = 7.1 with 1 microM BQ-123, n = 6) and trachea (pKB = 6.2 with 1 microM BQ-123, n = 6) butwas without marked effect in bronchus (n = 4). In contrast, sarafotoxin S6c (0.1 nM-0.l microM) did not contract guinea-pig aorta (n = 4) or guinea-pig pulmonary artery (n = 6) but potently and effectively contracted guinea-pig bronchus: pD2= 8.55 +/- 0. 1; maximum contraction = 63.6 +/0 3.1% of 10 microM carbachol,n = 4. Sarafotoxin S6c (0.1 nM-0. 1 microM) was a much less effective agonist in guinea-pig trachea:maximum contraction = 13.9 +/- 2.5% of 10 JM carbachol, n = 4; P< 0.0001, compared to bronchus.Contractions produced by sarafotoxin S6c in guinea-pig bronchus or trachea were unaffected by BQ-123(IO microM, n=4).5. Significant differences were observed in the efficacy, relative to carbachol, but not the potency of sarafotoxin S6c in guinea-pig airways, with a much greater maximum contractile response in bronchus(69.6 +/- 2.4% of 10 microM carbachol, n = 6) or lower region of the trachea (48.5 +/- 5.9% of 10 microM carbachol,n = 6) than in the middle region of the trachea (14.4 +/- 4.0% of 10 microM carbachol, n = 6) or the upper region of the trachea (19.3 +/- 2.7% of 10 microM carbachol, n = 6). There were minimal regional differences in either ET-1-induced contraction or the potency of BQ-123 (3 microM) for inhibition of responses to ET-1 in guinea-pig airways.6. Release of various prostanoids in human bronchus induced by ET-1 (0.3 microM) was essentially abolished with 10 IM BQ-123.7. These data provide evidence that distinct ET receptors mediate ET-1-induced contraction in human pulmonary artery, guinea-pig pulmonary artery and guinea-pig aorta (ETA subtype) compared with human bronchus and guinea-pig bronchus (non-ETA, perhaps ETB subtype). Contractions to ET-1 in guinea-pig trachea appear to involve both ETA and non-ETA (ETB?) receptor subtypes. Furthermore,regional differences appear to exist in the relative distribution of ET receptor subtypes in guinea-pig airways. In human bronchus ET-1-induced prostanoid release, unlike the contractile response, appears to be mediated via ETA receptor activation.

Endothelin-induced contraction and mediator release in human bronchus

1. To elucidate the role of acetylcholine and various autacoids in endothelin-1 (ET-1)-induced contraction in human bronchus, the effects of various receptor antagonists were examined. In addition, the ability of ET-1 to stimulate the release of histamine, peptidoleukotrienes and prostanoids was determined. 2. ET-1 was a potent and effective contractile agonist in human bronchus, possessing similar potency and efficacy to leukotriene D4 (LTD4); EC50 (-log M): ET-1 = 7.76 +/- 0.09, n = 7; LTD4 = 8.46 +/- 0.53, n = 7; P > 0.2; maximum response (% 10 microM pre-carbachol): ET-1 = 103.8 +/- 17.4, n = 7; LTD4 = 95.5 +/- 9.3, n = 7; P > 0.6. 3. The cyclo-oxygenase inhibitor, sodium meclofenamate (1 microM) or the potent and selective thromboxane receptor antagonist, SQ 29,548 (1 microM) were without significant effect on ET-1 concentration-response curves. 4. In the presence of sodium meclofenamate (1 microM), the muscarinic receptor antagonist, atropine (1 microM), the platelet activating factor (PAF) receptor antagonist, WEB 2086 (1 microM) or the combination of the H1-histamine receptor antagonist, mepyramine (10 microM) and the leukotriene receptor antagonist, SK&F 104353 (10 microM), were without marked effect on ET-1 concentration-response curves. In addition, the combination of all four receptor antagonists did not antagonize ET-1-induced contraction. 5. ET-1 (0.3 microM) did not stimulate the release of histamine or immunoreactive leukotrienes from human bronchus. 6. ET-1 (0.3 microM) significantly stimulated the release of prostaglandin D2 (PGD2), 9alpha, 11beta PGF2 (PGD2 metabolite), PGE2, 6-keto PGF1alpha (PGI2 metabolite), PGF2alpha, and thromboxane B2 (TxB2) a lower concentration, 10 nM, was without effect on prostanoid release. The production of PGD2 was increased 7.5 fold, whereas the release of the other prostanoids was stimulated only about 1.6 to 2.7 fold.7. These data provide evidence that ET-1 elicits contraction of human isolated bronchus predominantly via a direct mechanism with no significant involvement of the release of acetylcholine, leukotrienes,histamine or PAF. Although ET-1 increased the release of several prostanoids they did not have a significant modulatory effect on the smooth muscle contraction.

Importance of prostanoids in calcium chelator-induced airway constriction

To elucidate the mechanism of calcium chelator-induced airway constriction, we examined the relationship between prostanoids and histamine in bronchoalveolar lavage (BAL) fluid and the magnitude of airway constriction in peripheral airways of anesthetized Basenji-Greyhound dogs. A wedged bronchoscope technique was used to measure collateral system resistance (Rcs) before and after aerosol challenges. Sublobar segments were challenged either with acetylcholine or with Na2EDTA in the presence or absence of meclofenamate sodium (3 mg/kg iv) or methylprednisolone (2 mg.kg-1.day-1). After measurements of Rcs, BAL was performed, and the fluid was analyzed for prostanoids with the use of gas chromatography-mass spectrometry. Sublobar segments challenged with Na2EDTA showed increased concentrations of prostaglandin (PG) D2 but no increases in PGE2, PGF2 alpha, 9 alpha,11 beta-PGF2, 6-keto-PGF1 alpha, thromboxane B2, or histamine. There was a strong relationship (r = 0.84, P = 0.005) between changes in Rcs after Na2EDTA and concentrations of PGD2 in BAL fluid. Acetylcholine, which increased Rcs to a similar degree as Na2EDTA did, produced no significant increase in prostanoid concentrations. Changes in Rcs after Na2EDTA and concentrations of PGD2 were reduced in the presence of meclofenamate or methylprednisolone. These data support the idea that the mechanism of calcium chelator-induced bronchoconstriction involves the release of bronchoconstricting prostanoids.

Influence of arachidonic acid on indices of phospholipase A2 activity in the human neutrophil

The present studies were conducted to understand better the regulation of phospholipase A2 (PLA2)-dependent mobilization of lipid mediators by arachidonic acid (C20:4). After stimulation of human neutrophils, g.l.c./m.s. analysis of non-esterified fatty acids indicated that the quantity of C20:4 increased as a function of time after stimulation, from undetectable quantities to > 800 pmol/10(7) cells. In contrast with C20:4, the quantities of other free fatty acids such as oleic and linoleic were high in resting cells and did not change after stimulation. Some 15% of the C20:4 released from cellular lipids remained cell-associated. To examine the effect of C20:4 on its own release, neutrophils were exposed to [2H8]C20:4, to differentiate it by g.l.c./m.s. from naturally occurring C20:4. In A23187-stimulated neutrophils, low concentrations (5-10 microM) of [2H8]C20:4 added just before A23187 increased the quantity of C20:4 produced by the cell, whereas higher concentrations (30-50 microM) decreased the quantity of C20:4 released from phospholipids. As other measures of PLA2 activity, the effects of C20:4 on production of platelet-activity factor (PAF) and leukotriene B4 (LTB4) were assessed. C20:4 treatment just before stimulation of neutrophils blocked PAF and LTB4 production in a concentration-dependent manner (IC50 10-20 microM). The effect of C20:4 was not blocked by the cyclo-oxygenase inhibitor naproxine (10 microM), nor could it be mimicked by 1 microM LTB4, 5-hydroxyeicosa-6,8,11,14-tetraenoic acid (5HETE), 5-hydroperoxyeicosa-6,8,11,14-tetraenoic acid (5HPETE) or 15-hydroxyeicosa-5,8,11,13-tetraenoic acid (15HETE). The 5-lipoxygenase (5LO) inhibitor zileuton induced a concentration-dependent decrease in PAF, with a maximal effect of a 50% decrease at 10-50 microM. The decrease in PAF by the 5LO inhibitor could not be circumvented by addition of 1 microM 5HETE, 5HPETE and LTB4, and may be attributed to the capacity of zileuton to increase the quantity of C20:4 in A23187-treated neutrophils. The inhibitory effect of C20:4 (20-40 microM) on PAF production could be antagonized by the protein kinase C inhibitor staurosporine (30 nM), but not by inhibitors of protein kinase A, tyrosine kinase or calmodulin kinase II. Taken together, these data demonstrate that C20:4 is selectively released from membrane phospholipids of A23187-stimulated neutrophils, and this C20:4 may play an important role in regulating the mobilization of C20:4 by altering PLA2 activity.

Dietary n-3 fatty acid effects on neutrophil lipid composition and mediator production. Influence of duration and dosage

Healthy volunteers supplemented their usual Western diets with Promega fish oil supplement (eicosapentaenoic acid [EPA], 0.28 g; docosahexaenoic acid [DCHA], 0.12 g; other n-3 fatty acids 0.10 g per capsule) using three protocols. Initial experiments (protocol 1 and 2) investigated the kinetics of incorporation of n-3 fatty acids into serum and neutrophil lipids after 10 capsules/d of Promega. EPA was rapidly detected in both serum and neutrophil lipids; the arachidonic acid (AA) to EPA ratio in neutrophil phospholipids showed a maximal reduction of 49:1 to 8:1 within 1 wk of beginning supplementation. EPA was preferentially incorporated into phosphatidyl-ethanolamine and phosphatidylcholine but not phosphatidylinositol. Long-term supplementation for up to 7 wk did not influence the AA/EPA ratio or the distribution of EPA among neutrophil phospholipids in a manner that was not observed after the first week. Neutrophils produced similar quantities of platelet-activating factor and slightly lower quantities of leukotriene B4 during long-term supplementation when compared with presupplementation values. Experiments examining the influence of Promega dosage indicated that the AA/EPA ratio in neutrophil lipids decreased in a dose-dependent manner. Only when the dose was increased to 15 capsules/d was there a reduction in the AA/DCHA ratio in neutrophil lipids. The quantity of AA in neutrophil lipids remained relatively constant at all supplement doses. Taken together, the current study demonstrates the capacity of n-3 fatty acids provided with a Western diet to be rapidly incorporated into neutrophil lipids. However, dietary n-3 fatty acids appear not to significantly reduce arachidonate content within neutrophil phospholipids. Constant arachidonate levels may account for the lack of large reductions in the biosynthesis of lipid mediators by neutrophils after fish-oil supplementation.

Characterization of platelet-activating factor synthesized by normal and granulocyte-macrophage colony-stimulating factor-primed human eosinophils

Platelet-activating factor (PAF; 1-alkyl-2-acetyl-sn-glycero-3- phosphocholine) is a mediator involved in the pathogenesis of inflammatory diseases associated with tissue eosinophil infiltration. Previous studies utilizing bioassay or assaying enzymes associated with PAF biosynthesis have suggested that human eosinophils produce PAF. The present study has extended these initial studies by identifying and quantifying the different PAF molecular species and analogues synthesized by human eosinophils in response to A23187 and f-Met-Leu-Phe (FMLP). Gas chromatography-mass spectrometric analysis indicated that A23187-stimulated eosinophils produce at least three molecular species of PAF. The predominant species is 1-hexadecyl-2-acetyl-GPC (16:0) followed by 1-octadecyl-2-acetyl-GPC (18:0) and 1-octadecyl-2-acetyl-GPC (18:1). Eosinophils stimulated with FMLP produce approximately 100-fold smaller quantities of PAF relative to those produced in response to A23187 and only the 16:0 molecular species could be measured. A small percentage (comprising between 2 and 5%) of the 2-acetylated phospholipids produced by eosinophils was the 1-acyl analogue of PAF. Long-term (72 hr) incubation with granulocyte-macrophage colony-stimulating factor (GM-CSF) resulted in a three- to fourfold increase in PAF synthesis from eosinophils stimulated with FMLP, without changes in the profile of PAF molecular species or in the percentage of the 1-acyl analogue of PAF. These data indicate that human eosinophils can produce various molecular species of PAF and that this process can be quantitatively enhanced by GM-CSF.