bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of platelet‐activating factor in aggregation of leukocytes and platelets in cerebral ischemia
Authors: Uchiyama S. , Yamazaki M. , Maruyama S. 
Published: February 2007

AbstractLeukocyte and platelet aggregation stimulated with formyl‐methionyl‐leucyl‐phenylalanine (FMLP) was measured in 32 patients with cerebral ischemia and in 15 controls, using a whole blood aggregometer. The increases in impedance and the reductions in leukocyte and platelet counts were significantly greater in stroke patients than in controls. Aggregation was inhibited by oral ticlopidine, but not by oral aspirin. The effects were clearly counteracted by platelet‐activating factor (PAF) antagonists, and counteracted in part by a 5‐lipoxygenase inhibitor. The results suggest that platelets tend to be activated by PAF and leukotrienes liberated from hyperaggregable leukocytes in patients with ischemic stroke.
Platelet‐activating factor in cardiovascular stress situations
Authors: Rabinovici Reuven , Yue Tian‐Li , Feuerstein Giora 
Published: February 2007

AbstractSince the elucidation of its chemical structure two decades ago, platelet‐activating factor (PAF) has emerged as an important mediator of various cardiovascular stress situations. Most notably, PAF was implicated as a key factor in the septic shock syndrome, based on the similarities between endotoxin and PAF biological effects, the elevation of circulating and tissue levels of PAF during endotoxemia, and the protective effect of PAF antagonists in the septic state. In addition, accumulating data suggest the involvement of PAF in the pathophysiological processes associated with ischemia, hemorrhage and trauma, where PAF exerts its effects directly on cells and blood elements or indirectly through interactions with other mediators such as cytokines and prostaglandins. Nevertheless, the relative contribution of PAF to the pathophysiological processes in endotoxemia is still unknown and should await further investigations. The primary aims of this chapter are: to delineate the effects of PAF on the cardiovascular system, to summarize the data which suggest the involvement of PAF in stress situations of the cardiovascular system, and to identify areas where future experimental efforts should be focused.
Intravascular release of a platelet‐activating factor‐like lipid (PAF‐LL) induced by cigarette smoking
Authors: Imaizumi Tada‐atsu 
Published: February 2007

AbstractTo assess the role of platelet‐activating factor (PAF) in smoking‐induced vascular injury, the effect of cigarette smoking on PAF‐like lipid (PAF‐LL) in plasma was studied. The subjects were 12 young smokers (22±1.3 years old), 13 young non‐smokers (22±2.1 years old), 14 older smokers (59±9.6 years old), and 11 older non‐smokers (60±8.7 years old). Lipids were extracted from 5 mL of plasma and then were separated by thin‐layer chromatography. The fraction with the same migration as authentic PAF was recovered and tested for the ability to aggregate human polymorphonuclear neutrophils (PMN). The activity was identified as PAF‐LL because it was inactivated by phospholipase A2, and because the effects on PMN were blocked by CV‐3988, a competitive antagonist of the PAF receptor. PAF‐LL was detected in plasma from 3 young non‐smokers (23%), 5 young smokers (42%), 3 older non‐smokers (27%) and 11 older smokers (79%). The incidence of the detection of plasma PAF‐LL in older smokers was significantly higher than those in young non‐smokers (p<0.01) or in older non‐smokers (p<0.05). In young smokers, the acute effect of smoking was also studied. Plasma PAF‐LL was detected in all of the 12 subjects immediately after smoking a cigarette, in sharp contrast to the incidence of 42% before smoking. Plasma β‐thromboglobulin was highest in older smokers, and it increased significantly after smoking a cigarette in young smokers. Smoking is associated with increased production of PAF or a similar lipid, which may play an important role in the pathogenesis of smoking‐induced vascular diseases.
Platelet‐activating factor (PAF) induces contraction of saponin‐skinned smooth muscle of coronary artery
Authors: Soloviev A. I. , Braquet P. 
Published: February 2007

AbstractThe effect of platelet‐activating factor (PAF) on the development of isometric tension by saponin‐skinned coronary artery was studied. PAF caused two types of contractions of coronary smooth muscle cells (SMC):(i) rapid, transient (phasic) contractions of SMC were induced by inositol 1,4,5‐trisphosphate dependent Ca2+ release from sarcoplasmic reticulum (SR); (ii) slow sustained (tonic) contractions were induced by increase in Ca2+‐ensitivity of the contractile apparatus of SMC by protein kinase C activation. The present results support the hypothesis that, in SMC of coronary artery, PAF receptors are located not only on the plasma membrane, but also on the SR membranes.
The contribution of platelet‐activating factor to allergen‐induced eosinophil infiltration and bronchial hyperresponsiveness
Authors: Page C. P. 
Published: February 2007

AbstractPlatelet‐activating factor (PAF) is an ether‐linked phospholipid having a range of biological properties of relevance to our understanding of the pathogenesis of bronchial asthma and related allergic diseases. In particular the ability of PAF to induce eosinophil activation and recruitment has received considerable attention. Since in experimental animals PAF and allergen‐induced eosinophil infiltration are dependent upon platelet activation, it is suggested that platelet activation may be an important component of the allergic process. The ability of PAF antagonists to inhibit various aspects of the allergic response has been demonstrated in a number of animal models but not all of them have been extended into man.
Effect of the selective PAF antagonist SM‐10661 on an asthmatic model. 2. Effect on antigen‐induced dual asthmatic response and infiltration of leukocytes into airways in actively sensitized conscious guinea pigs
Authors: Sugasawa Toshinari , Imanishi Noriaki , Morooka Shigeaki 
Published: February 2007

AbstractThe effect of a selective platelet‐activating factor (PAF) receptor antagonist, SM‐10661, on antigen‐induced dual asthmatic response and leukocyte infiltration into the airways of actively sensitized conscious guinea pigs was investigated. The animals were pretreated with mepyramine maleate (10 mg/kg i.p.) and then challenged with ovalbumin. The inhalation of ovalbumin caused an immediate decline in specific airway conductance (sGaw) which peaked at 5 min after the challenge. sGaw gradually returned to the baseline 6 hr after the challenge. After the early asthmatic response (EAR), a second phase change, a late asthmatic response (LAR) in sGaw peaking at 17–20 hr was observed. When 1% w/v disodium cromoglycate was inhaled for 2 min on two occasions, EAR was not affected, but LAR was significantly inhibited. Oral administration of 50 mg/kg fenoterol (30 min before challenge) significantly inhibited EAR, but had no significant effect on LAR. SM‐10661 administered orally 1 hr before the challenge inhibited EAR dose‐dependently (50% inhibitory dose (ID50); 59 mg/kg, but was even more effective against the LAR (ID50); 13–16 mg/kg). When 30 mg/kg of SM‐10661 was administered orally 6 hr after ovalbumin challenge, LAR was completely inhibited. The number of total cells, macrophages and eosinophils in bronchoalveolar lavage fluids rose significantly 17 hr after antigen challenge compared to that observed after saline challenge. The number of neutrophils and lymphocytes also increased in response to the ovalbumin challenge, but not significantly. SM‐10661 (30 mg/kg) administered orally 1 hr before the challenge significantly inhibited the increase in total cells, macrophages and eosinophils. By comparison, when 30 mg/kg SM‐10661 was administered orally 6 hr after the challenge, these increases were not significantly inhibited. These results suggest that PAF is involved in EAR and LAR, and that SM‐10661 may be a useful therapeutic agent for the treatment of allergic asthma.
The role of platelet‐activating factor (PAF) in experimental glomerular injury
Authors: Artiz A. , Gomez‐Chiarri M. , Lerma J. L. , Gonzalez E. , Egido J. 
Published: February 2007

AbstractPlatelet‐activating factor (PAF) is a potent autacoid that participates in inflammation and other pathophysiological processes. In this review we deal with recent evidence suggesting that PAF is a mediator that is released early during glomerular injury. PAF can be synthesized in the glomerulus by infiltrating intrinsic glomerular cells. Normal glomeruli produce PAF upon stimulation, and glomerular PAF synthesis is increased in a variety of experimental glomerulopathies. The local infusion of PAF into the renal artery of isolated blood‐free kidneys induces proteinuria. PAF attracts and activates inflammatory cells. Glomerular mesangial, endothelial and epithelial cells are also targets for PAF. Therapy with specific PAF receptor antagonists has prevented or reduced proteinuria and improved glomerular inflammation in several experimental models of proliferative glomerulonephritis and minimal change nephrosis. However, the beneficial effect of administration of PAF antagonists once proteinuria is fully developed has been minimal. PAF may also play a role in the recruitment of inflammatory interstitial cells.
Nephrotoxicity of cyclosporine: The role of platelet‐activating factor and thromboxane
Authors: Pavão dos Santos Oscar F. , Boim Mirian A. , Barros Elvino J. G. , Pirotzky Eduardo , Braquet Pierre , Schor Nestor 
Published: February 2007

AbstractCyclosporine (CsA), an immunosuppressive agent, is potentially nephrotoxic. We had previously observed that acute administration of CsA to Munich‐Wistar rats induced a decrease in single nephron glomerular filtration rate, due to a decline in glomerular plasma flow, and in the glomerular ultrafiltration coefficient. Moreover, these alterations were prevented when an antagonist of platelet‐activating factor (PAF) was administered. In the present study we examined whether the protective effect of the PAF blocker in CsA nephrotoxicity could have been mediated by thromboxane (TxA2). Our data show that the PAF effects were not mediated by TxA2, since administration of dazmegrel, a thromboxane synthetase inhibitor, did not ameliorate the acute renal failure caused by CsA. Thus, PAF appears to be a direct mediator of acute CsA nephrotoxicity, while TxA2 is not significantly involved in this process.
Presence of platelet‐activating factor in pyuria in humans
Authors: Ikeda Ichiro , Oda Makoto , Sakakura Muneki , Yasunaga Kojiro 
Published: February 2007

AbstractThe relationship between the occurrence of platelet‐activating factor (PAF) and neutrophils in urine from patients with urinary tract infection was examined. PAF was detected in human pyuria, when leukocyte levels reached at least 300 cells/μL (n=45), but not in normal urine (n=12). The amount of PAF found in pyuria, measured by platelet aggregation assay, was 0.01 to 13.3 pmol/mL. A close correlation was seen between the amount of PAF present and the number of urinary leukocytes (p<0.01, r=0.70). The leukocytes in pyuria consisted almost entirely of neutrophils (96±4%, mean ±S.D.). Our findings suggest that the occurrence of PAF is associated with the accumulation of neutrophils in urine.
The effect of CV‐3988 and CV‐6209 on the acute gastric erosions of rats due to water‐immersion and restraint stress
Authors: Nogami Makoto , Hoshihara Yoshio , Tsubura Kunihiko , Yamamoto Takashi , Tabuchi Masafumi , Miyamoto Terumasa , Shiga Junji 
Published: February 2007

AbstractCV‐3988 and CV‐6209 inhibited gastric erosions in rats due to water‐immersion and restraint stress in a dose‐dependent manner. The above inhibitory effects of CV‐3988 were observed in the presence of indomethacin, which may indicate that the inhibition is not prostaglandin dependent. The studies indicate that platelet‐activating factor may be involved in the formation of erosions in rats under water‐immersion and restraint stress.
Myoelectric intestinal disturbances inEscherichia coli endotoxic shock in rats. Involvement of platelet‐activating factor
Authors: Pons Laurent , Droy‐Lefaix Marié‐Thèrese , Braquet Pierre , Buéno Lionel 
Published: February 2007

AbstractAdministration of BN 52021 (50 mg/kgi.v.), a specific antagonist of platelet‐activating factor (PAF), significantly reduced the intestinal myoelectric disturbances induced byE. coli endotoxin injection (50 μg/kgi.v.) by 62%. Thus, PAF may be involved in the intestinal motor alterations observed in endotoxic shock. When given in combination with indomethacin (10 mg/kgi.p.), BN 52021 inhibited endotoxic shock intestinal disturbances. Indomethacin alone also reduced PAF induced (25 μg/kgi.p.) disruption of migrating myoelectric complexes. Endotoxins may act on intestinal motilityvia release of endogenous PAF and prostaglandins, the effects of PAF being mediated through the release of prostaglandins.
Platelet‐activating factor type activity in plasma from patients with septicemia and other diseases
Authors: Heuer Hubert O. , Darius Harald , Lohmann Helmut F. , Meyer Juergen , Schierenberg Manuela , Treese Norbert 
Published: February 2007

AbstractThe purpose of the present study was to determine whether increased levels of platelet‐activating factor (PAF) type activity can be detected in plasma from patients with septicemia and other diseases. A level of PAF below 0.5 ng/mL of plasma was considered normal. We found that plasma from a patient with adverse anaphylactoidic reaction to intravenous analgetics contained 2.1 ng PAF/mL. In seven patients with septicemia, including urosepsis, endocarditis and peritonitis, and with positive blood culture, increased plasma PAF levels (1–20 ng PAF/mL) were observed. Other patients with clinical indications of septicemia had negative blood cultures and/or increased levels of C‐reactive protein (CRP). Yet, in the plasma from these patients, no increased PAF levels were detected under the assay conditions used. Two patients with allergic asthma, requiring treatment with steroids, had no measurable plasma PAF. In the plasma from a patient with idiopathic thrombocytopenic purpura (ITP) only an “endogenous” inhibitor of PAF induced platelet aggregation was initially observed. In spite of this, the patient responded to treatment with the PAF antagonist WEB 2086 with a dramatic increase in platelet count (Lohmannet al., Lancet ii, 1147, 1988). Thereafter, also increased PAF levels (3.3 ng PAF/mL) were detected in plasma, although some “endogenous” inhibitor of PAF was still present. In conclusion, increased PAF levels in plasma from patients support a role of PAF in certain human disease states, such as in anaphylactoid reaction, sepsis and septic shock. The type, relevance and specificity of endogenous inhibitors of PAF deserve further study.
Involvement of platelet‐activating factor in zymosan‐induced rat pleurisy
Authors: Imai Yohsuke , Hayashi Masahiko , Oh‐ishi Sachiko 
Published: February 2007

AbstractThe role of platelet‐activating factor (PAF) in inflammatory reactions was studied in zymosan‐induced rat pleurisy. Pleurisy was induced by injection of a 2% zymosan suspension into the pleural cavity of rats. The time course of pleural exudate accumulation, the exudation rate, and exudate leukocyte numbers were followed then for 96 hr. Peak pleural exudate accumulation was about 3 mL at 24 hr, whereas the exudation rate increased biphasically with peaks at 0.5 hr and 5 hr. The migration of leukocytes into the pleural cavity increased with time up to 48 hr. The polymorphonuclear leukocytes were the dominant white cells in the exudate between 5 and 16 hr, but mononuclear leukocytes started to outnumber them around 24 hr. Pretreatment with cyproheptadine (5 mg/kg), an inhibitor of both histamine and seotonin, significantly suppressed pleural fluid accumulation and the exudation rate at 0.5 hr. The PAF antagonist CV‐6209 (1 mg/kg) significantly suppressed pleural fluid accumulation and the exudation rate at both 0.5 and 5 hr. At either time point, the parameters were not suppressed by indomethacin. We detected PAF activity in the high‐performance liquid chromatography (HPLC) fraction (with a retention time corresponding to that of authentic PAF) of the exudates at 0.5 hr, 5 hr, and 16 hr using an aggregation bioassay with washed rabbit platelets. The results suggest that in zymosan‐induced rat pleurisy, histamine and/or serotonin are the main mediators of exudation at 0.5 hr and that PAF may be partly responsible for exudation at 0.5 hr and later at 5 hr to 16 hr.
Antitumor activity of ilmofosine (BM 41.440) in the3Lewis‐lung carcinoma model
Authors: Herrmann Dieter B. J. , Opitz Hans‐George , Munder Paul G. 
Published: February 2007

AbstractIlmofosine (1‐hexadecylthio‐2‐methoxymethyl‐1,3‐propanediol‐phosphocholine, BM 41.440) is a thioether phospholipid with cytostatic/cytotoxic properties. The antineoplastic activity of this compound was investigatedin vivo in the3Lewis‐lung carcinoma system.3Lewis lung tumor‐bearing C57Bl/6 mice were treated with 0.625 to 40 mg Il‐mofosine/kg per dayp.o. either from days 1 to 9 or from days 11 to 28 after intrafoot‐pad tumor cell inoculation. Ilmofosine caused a significant dose‐related response on tumor growth and metastases, expressed in terms of tumor diameter, tumor weight, survival time and number of metastases‐free animals as compared to sham‐treated and positive (cyclophosphamide) controls. The results suggest that direct cytostatic/cytotoxic effects, rather than immune‐modulatory mechanisms, preferentially contribute to the antitumor activity of Ilmofosinein vivo.
1‐β‐D‐arabinofuranosylcytosine conjugates of ether and thioether phospholipids. A new class of ara‐C prodrug with improved antitumor activity
Authors: Hong Chung Il , West Charles R. , Bernacki Ralph J. , Tebbi Cameron K. , Berdel Wolfgang E. 
Published: February 2007

AbstractThe 1‐β‐D‐arabinofuranosylcytosine (ara‐C) conjugates 1‐O‐alkyl (ether) and 1‐S‐alkyl (thioether) phospholipids, being analogues of ara‐CDP‐sn‐1,2‐O‐dipalmitoylglycerol (1), showed significant antitumor activity against L1210 and P388 leukemiain vivo. The more active conjugates include the 1‐O‐alkyl analogues, ara‐CDP‐rac‐1‐O‐hexadecyl‐2‐O‐palmitoylglycerol (2) and ara‐CDP‐rac‐1‐O‐octadecyl‐2‐O‐palmitoylglycerol (3), and the corresponding 1‐S‐alkyl analogues, ara‐CDP‐rac‐1‐S‐hexadecyl‐2‐O‐palmitoyl‐1‐thioglycerol (4) and ara‐CDP‐rac‐1‐S‐octadecyl‐2‐O‐palmitoyl‐1‐thioglycerol (5, Cytoros). The conjugates were formulated by sonication, in which the conjugates existed as discs (size 0.01–0.04 μ).. Among the conjugates of the three different phospholipids, the 1‐S‐alkyl analogues 4 and 5 displayed the strongest antitumor activity against L1210 leukemia in mice, followed by the 1‐O‐alkyl (2 and 3) and the 1‐O‐acyl (1) analogues. The 1‐S‐alkyl analogue 5 was considerably more effective than the 1‐O‐acyl analogue 1 against myelomonocytic WEHI‐3B leukemia in mice. Conjugate 5 (Cytoros) showed a significant therapeutic activity in mice with colon 26 carcinoma, M5076 sarcoma, and C‐1300 neuroblastoma. Furthermore, this agent inhibited liver metastases of M5076 sarcoma. Conjugates 3 and 5 also inhibited the metastasis of 3‐Lewis lung carcinoma to the lungs of mice. Cytoros (5) and its analogues, with other ether and thioether phospholipids, appear to offer increased therapeutic benefit to mice with tumors.
Induction of differentiation of human myeloid leukemia HL‐60 cells by novel nonphosphorus alkyl ether lipids
Authors: Honma Yoshio , Kasukabe Takashi , Hozumi Motoo , Akimoto Hiroshi , Nomura Hiroaki 
Published: February 2007

AbstractWe synthesized a new series of nonphosphorus alkyl ether glycerolipids, in which the 2‐acetyl group of platelet‐activating factor was replaced by a pyrimidin‐2‐yl group and the 3‐phosphocholine portion by anω‐(substituted ammonio)ethoxyethyl side‐chain including ω‐thiazolio‐, imidazolio‐and pyridinio groups with or without a carboxyl substituent, respectively (compound I–XI). Their effects on cell proliferation and differentiation of human myeloid leukemia HL‐60 cells were examined. Incubation of HL‐60 cells with these cationic and zwitterionic alkyl ether lipids inhibited proliferation of HL‐60 cells with IC50 values ranging from 10 to 500 ng/mL. The cells were induced by the lipids to differentiate into morphologically and functionally mature granulocytes. Among the compounds we tested, 1‐octadecyl‐2‐pyrimidinyl‐3‐[3‐(5‐carboxylatepenty)imidazolioethoxyethyl]glycerol (compound I) was the most effective in inducing differentiation of HL‐60 cells. Compound I showed on a molar basis, an inhibitory effect on the leukemic cells over 50 times greater than did 2‐(2‐dodecyloxyethoxy)ethyl 2‐pyridinioethyl phosphate, the antileukemic alkyl ether phospholipid.
Search for new industrial oils. XII. Fifty‐eight euphorbiaceae oils, including one rich in vernolic acid
Authors: Kleiman R. , Smith C. R. , Yates S. G. , Jones Quentin 
Published: February 2007

AbstractSeed oil ofEuphorbia lagascae Spreng. contains 57% ofcis‐12,13‐epoxy‐cis‐9‐octadecenoic (vernolic) acid. The amt of trivernolin in the glycerides of this species indicates random or restricted random distribution of the vernolic acid.Seed from 57 additional species in the Euphorbiaceae were analyzed for oil and protein contents and also for fatty acid composition of the oils. Iodine values (I.V.) of the oils ranged from 87舑221. Among these oils, samples were encountered with as much as 76% linolenic, 77% linoleic or 84% oleic acid.
The effect of temperature upon foam fractionation
Authors: Grieves R. B. , Bhattacharyya D. 
Published: February 2007

AbstractAn experimental investigation is presented of the effect of temp on the foam fractionation of the ethylhexadecyldimethylammonium bromide‐water system. Two feed concn, two foam heights, and a temp range of 14舑54C are included. For each fixed set of values of feed concn and of foam height, the greater and lesser coefficients of fractionation are both increasing functions of temp. The effect of a variation in temp on the greater coefficient is more pronounced for more dilute feed solutions, and at greater foam heights. The effect of a temp change on the lesser coefficient is more pronounced for more concd feed solutions and is not related to foam height. At any fixed temp, an increase in feed concn at constant foam height generally decreases the greater coefficient and decreases the lesser coefficient. An increase in foam height at constant feed concn increases both coefficients. The greater and lesser coefficients may be related to temp by power equations with 5% accuracy. The above results may be explained qualitatively on the basis of the response of foam stability and drainage to temp.
A colorimetric method for the determination of parts/million of nonionic surfactants
Authors: Greff R. A. , Setzkorn E. A. , Leslie W. D. 
Published: February 2007

AbstractA method for the determination of nonionics in low concn (0舑20 ppm) has been developed. This method is based on the formation of a blue complex between ammonium cobaltothiocyanate reagent and a polyethoxylated compound. This complex is extracted into benzene from a saturated salt solution and measured with a spectrophotometer at 320 mƁ. The absorbance reading is compared to a standard.The method requires only a single extraction and no preliminary concn step is necessary. It is sensitive to polyethoxylated compounds containing three or more moles of ethylene oxide. We have used this method to detect as little as 0.01 mg of nonionic in 100 ml of sample (0.1 ppm). Reaction conditions, sensitivity differences between compounds, interferences and suitability for use in biodegradation studies have been investigated. The accuracy and repeatability of this method is ŷ3% relative at 20 ppm concn.