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Biomedical subjects

L M McManus

Publications and source records attributed to L M McManus.

At least 19 recordsLinked to original sources
PubMed1995

Molecular heterogeneity of PAF in normal human mixed saliva: quantitative mass spectral analysis after direct derivatization of PAF with pentafluorobenzoic anhydride.

Platelet-activating factor (PAF), a family of phospholipid autacoids with potent pro-inflammatory activities, is present in saliva. The current study has quantitated various species of PAF isolated from normal human mixed saliva. Choline-containing, sn-2 acetylated phospholipids with sn-1 ether- or ester-linked fatty alcohol/acid moieties (alkyl-PAF or acyl-PAF, respectively) were evaluated after direct derivatization with pentafluorobenzoic (PFB) anhydride. Individual species of PFB-derivatized PAF were separated by gas chromatography prior to mass spectral analysis; quantitative estimates of six different species of PAF in saliva were made by comparison to corresponding authentic, synthetic PAF standards. In each saliva sample, all six species of PAF were readily detected by this facile procedure. The predominant PAF was 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine or 16:0-alkyl-PAF (0.75 +/- 0.09 pmol/ml saliva; mean +/- S.E.; n = 5) which represented only 30.4 +/- 1.5% of the total PAF. Substantial amounts of 18:1- and 18:0-alkyl-PAF and 16:0-acyl-PAF were also identified (0.52 +/- 0.07, 0.35 +/- 0.06, and 0.35 +/- 0.02 pmol/ml saliva, respectively). In summary, mass spectrometric analysis of PAF after direct derivatization with PFB anhydride has revealed that at least six different species of PAF are present in normal human mixed saliva. This structural diversity may represent an important aspect of homeostasis in the healthy oral cavity.

Anhydrides↗
PubMed1995

Lipid inhibitors of platelet-activating factor (PAF) in normal human plasma.

Endogenous, human plasma-derived lipids that inhibit the platelet stimulating activity of platelet-activating factor (PAF) have been identified. Chromatographic fractionation of neutral lipid PAF inhibitors revealed a majority of PAF inhibitory activity comigrating with cholesterol and a second peak localized with free fatty acids. Plasma phospholipids demonstrated three distinct PAF inhibitory fractions in TLC regions corresponding to those of sphingomyelin, phosphatidylcholine and phosphatidylethanolamine. Three fractions (one neutral lipid and two phospholipid) specifically inhibited PAF-induced platelet activation. Thus, there are both specific and non-specific lipid inhibitors of PAF in normal human plasma. These plasma lipids may be important in the specific regulation of the diverse, potent biological activities of PAF in various physiological states.

Acetone↗
PubMed1995

Salivary PAF levels correlate with the severity of periodontal inflammation.

Platelet-activating factor (PAF), a potent phospholipid mediator of inflammation, has been previously identified in inflamed gingival tissues and gingival crevicular fluid. However, the role of PAF in oral pathobiology remains unknown. The purpose of the present study was to evaluate the relationship between salivary PAF levels and the severity of periodontal inflammation. PAF activity in lipid extracts of whole (mixed) saliva collected from 69 untreated subjects immediately prior to routine oral evaluation was determined by platelet bioassay. Significant positive correlations were observed between the level of PAF in saliva and measures of periodontal inflammation, i.e., the percentage of periodontal probing depths greater than 4 mm, the number of periodontal bleeding sites, and the number of histologically identified polymorphonuclear neutrophilic leukocytes (PMN) in saliva. Moreover, when subjects were subdivided into groups on the basis of periodontal probing depths, a significant correlation was observed between salivary PAF levels and the extent of periodontal disease, i.e., PAF levels in saliva progressively increased from the healthiest group to the most severely affected group. Thus, salivary PAF levels correlate with the severity of periodontal inflammation. These results support the hypothesis that this pro-inflammatory phospholipid autacoid may participate in the pathogenesis of periodontal tissue injury and disease.

Adolescent↗
PubMed1995

The effect of initial periodontal therapy on salivary platelet-activating factor levels in chronic adult periodontitis.

Platelet-activating factor (PAF), a potent phospholipid inflammatory mediator, is increased in the mixed saliva of subjects with periodontal disease and correlates with the extent of oral inflammation. The present study was designed to provide a longitudinal evaluation of the effect of initial periodontal therapy (home care instruction, prophylaxis, and scaling/root planing) on salivary PAF levels in chronic adult periodontitis patients (n = 15). Mixed saliva was collected prior to, during, and after initial therapy and was utilized to assess PAF levels after lipid extraction and fractionation as well as to histologically assess the number of polymorphonuclear leukocytes (PMN). PAF activity was determined in bioassay relative to authentic PAF (1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine; 16:0-alkyl-PAF). Initial salivary PAF levels (12.1 +/- 2.8 pmole equivalents of 16:0-alkyl-PAF/ml saliva; mean +/- SE) decreased following supragingival plaque control (9.6 +/- 2.4) and were further reduced following scaling and root planing (5.7 +/- 1.4). In parallel, salivary PMN levels were significantly reduced and clinical estimates of periodontal disease were significantly improved; i.e., there was a decrease in the percentage of sites with both bleeding on probing (from 46.1 +/- 4.6% of sites at pretreatment to 25.9 +/- 2.6% after scaling and root planing) and probing depths > or = 4 mm (from 16.7 +/- 1.9% of sites to 10.3 +/- 1.2%). Thus, initial periodontal therapy reduced salivary PAF levels in concert with improvements in clinical estimates of marginal and submarginal periodontal inflammation suggesting that PAF may participate in inflammatory events during periodontal tissue injury and disease.

Adult↗
PubMed1993

PAF molecular heterogeneity: pathobiological implications.

The existence and potential (patho)physiologic significance of PAF molecular heterogeneity can no longer be summarily dismissed or ignored. While significant advances in the chemistry of PAF have been made, the (patho)physiologic behaviors of most of the PAF molecular species of biologic origin await further study. This is because to date, investigators have studied the biologic activities of what was previously thought to be PAF, i.e., only 16:0- and 18:0-AGEPC. In view of the evidence presented in this review, a comprehensive investigation of the possible biologic relevance and significance of PAF molecular heterogeneity is warranted. Hopefully, such studies will be designed to elucidate the extent to which the various molecular species of PAF differ in their intrinsic in vitro and in vivo (patho)physiologic behaviors (agonistic, synergistic, and possibly antagonistic) and modes of action. Once this additional information has been derived, the pathobiologic relevance of this class of phospholipid autacoid may be better understood.

Animals↗
PubMed1992

Differential responsiveness of human neutrophils to the autocrine actions of 1-O-alkyl-homologs and 1-acyl analogs of platelet-activating factor.

The phlogistic actions of six molecular species of platelet-activating factor (PAF) (1-O-alkyl-PAF homologs, 16:0-, 18:0- and 18:1-alkyl-PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (AGEPC) and their respective 1-acyl-PAF analog counterparts, 16:0-, 18:0- and 18:1-acyl-PAF, 1-acyl-2-acetyl-sn-glycero-3-phosphocholine (AGPC)) were assessed relative to five human neutrophilic polymorphonuclear leukocyte (PMN) functional responses: 1) lysosomal enzyme secretion; 2) specific desensitization to 16:0-AGEPC-induced lysosomal enzyme secretion; 3) O2- production; 4) chemotaxis; and 5) priming for enhanced O2- production. With respect to inducing lysozyme secretion, 18:0-AGEPC was 30- and 75-fold less potent than 16:0-AGEPC and 18:1-AGEPC, respectively, and was 25- and 40-fold less potent for inducing beta-glucuronidase secretion. 18:0-AGEPC was also 10-fold less active than 18:1- and 16:0-AGEPC for inducing O2- production. Thus, the rank order of potency of the alkyl-PAF homologs for inducing both lysosomal enzyme secretion and O2- production was 18:1- greater than or equal to 16:0- much greater than 18:0-AGEPC. In contrast, these three alkyl-PAF homologs had the same potency for desensitizing PMN to subsequent 16:0-AGEPC-induced lysosomal enzyme secretion and for priming PMN for augmented O2- production in response to FMLP or human recombinant C5a. Paradoxically, however, the rank order of potency of the alkyl-PAF homologs for effecting PMN chemotaxis was 18:0- greater than 18:1- much greater than 16:0-AGEPC. At concentrations as high as 1.0 microM, the acyl-PAF analogs did not initiate PMN lysosomal enzyme secretion, O2- production, or chemotaxis. However, the acyl-PAF analogs induced partial PMN desensitization to 16:0-AGEPC. A novel finding of potential (patho)-physiologic significance was the ability of acyl-PAF at nM concentrations to prime PMN for significantly enhanced O2- production after stimulation with FMLP or human recombinant C5a. The priming action of acyl-PAF was due to an increase in the rate as opposed to a prolongation of O2- production. The differing rank orders of potency of the alkyl-PAF homologs and acyl-PAF analogs for stimulating several physiologic responses of the same target cell, the human PMN, support the premise that there may be more than one PAF receptor subtype on the PMN and/or that differences in the biophysical properties of the various molecular species of PAF modulate their interaction with PAF receptor(s) linked to stimulus-response coupling.

Acylation↗
PubMed1990

Deficiency of salivary PAF in edentulous individuals.

PAF, a potent phospholipid mediator of inflammation, is present in normal human, mixed saliva. However, the anatomic origin of PAF is not known. In this study, PAF levels in mixed saliva of edentulous subjects were estimated in comparison to that of dentate individuals. PAF activity was assessed in bioassay and expressed relative to the activity of known amounts of authentic PAF, 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine (AGEPC). PAF was not detected in the saliva of 60% of the edentulous subjects; moreover, when present, the PAF levels were significantly less (635 +/- 82 AGEPC fmole equivalents/ml saliva, mean +/- SEM, n = 6) than in dentate subjects (5568 +/- 1135 AGEPC fmole equivalents/ml saliva, n = 27). Of relevance, the numbers of polymorphonuclear leukocytes in the mixed saliva samples of edentulous subjects were markedly reduced when compared to those of normal subjects. These findings suggest that salivary PAF most likely originates from the crevicular space, and derives from inflammatory cells within the gingival and/or periodontal tissues.

Adult↗
PubMed1990

Anatomic basis for species differences in peripheral lung strip contraction to PAF.

Platelet-activating factor (PAF) is a very potent contractile agonist in guinea pig peripheral lung strips but is without effect on rabbit peripheral lung strips. Histological examination of guinea pig peripheral lung strips revealed a layer of smooth muscle cells in the visceral pleura that is not present in rabbit peripheral lung strips. Removal of the pleural surface of the guinea pig peripheral lung strips eliminated the ability of these tissues to contract to PAF, and the (removed) thin pleural strip contracted to PAF in a manner similar to that of intact strips. Removal of the pleural surface did not prevent these tissues from contracting to histamine or leukotriene D4 (LTD4), although potency of these agonists was somewhat reduced. The pleural smooth muscle cell layer is present throughout the pleural lining of the guinea pig lung but is thicker in lower than in upper lobes. PAF contractility is also reduced in upper compared with lower lung lobes. Thus we suggest that the pleural smooth muscle is the critical contractile element for PAF contraction of guinea pig peripheral lung strips, whereas other agonists such as histamine and LTD4 contract additional elements in these tissues.

Animals↗
PubMed1990

Atypical multinucleated cells form in long-term marrow cultures from patients with Paget's disease.

Although Paget's disease is the most flagrant example of a primary osteoclast disorder, little is known of osteoclast biology in this disease. In this report we have studied the formation of cells with the osteoclast phenotype in long-term cultures of marrow mononuclear cells derived from patients with Paget's disease, and compared these with similar cells formed in long-term marrow cultures from normal individuals, and with osteoclasts present in pagetic bone. Osteoclasts formed in pagetic marrow cultures resembled osteoclasts present in pagetic bone, but were distinctly different from osteoclasts formed in normal marrow cultures. Osteoclast formation was 10-20-fold greater in pagetic marrow cultures than in normal cultures. The multinucleated cells formed in cultures of pagetic marrow were much larger in size, were hyperresponsive to 1,25(OH)2 vitamin D, had more nuclei per cell, had increased levels of tartrate-resistant acid phosphatase activity and had ultrastructural features which were not seen in multinucleated cells formed from normal marrow mononuclear cells. These pagetic marrow-derived multinucleated cells formed large resorption lacunae on calcified matrices and cross-reacted with monoclonal antibodies which preferentially bind to osteoclasts. The multinucleated cells formed from marrow obtained from uninvolved sites in Paget's patients also displayed these abnormal features.

Bone Marrow↗
PubMed1989

Osteoclast-like cells form in long-term human bone marrow but not in peripheral blood cultures.

Transplantation studies have suggested that peripheral blood mononuclear cells contain precursors for osteoclasts. Thus we tested the capacity of peripheral blood monocytes to form osteoclasts in long-term culture. We have reported previously that mononuclear cells from feline, baboon, and human marrow form osteoclast-like cells in long term cultures. Further, the formation of these cells is increased in response to bone resorption stimulatory agents such as PTH, interleukin 1, and transforming growth factor alpha. We now report that these cells show characteristic cytoplasmic contraction with calcitonin and form resorption lacunae when cultured on sperm whale dentine. Thus, these bone marrow-derived multinucleated cells fulfill the functional criteria for osteoclasts. Although cultured peripheral blood monocytes can be induced to form multinucleated cells with 1,25-dihydroxyvitamin D3, these cells did not show similar responses to the osteotropic factors as multinucleated cells formed in the bone marrow cultures multinucleated cells. These results indicate that osteoclasts or cells closely related to osteoclasts form in long-term human bone marrow cultures. In contrast, few mononuclear cells in the peripheral blood appear capable of forming osteoclasts under the culture conditions used in these experiments.

Bone Marrow↗
PubMed1989

Osteoclast-like cells formed in long-term human bone marrow cultures express a similar surface phenotype as authentic osteoclasts.

Long-term cultures of human bone marrow form multinucleated cells (MNC) with many functional characteristics of osteoclasts including: expression of tartrate-resistant acid phosphatase, appropriate responses to osteotropic hormones, calcitonin-induced contraction and formation of resorption lacunae on calcified matrices. However, it is unclear if these cells express similar surface antigens as expressed by authentic osteoclasts, since they form on plastic surfaces in the absence of bone. Bone may be required to complete the differentiation process for osteoclasts. Therefore, we have examined the surface phenotype of MNC and compared it with that of osteoclasts freshly isolated from bone, to determine if MNC express similar surface antigens, and if MNC express antigens which identify their cellular origin. Similar to bone-derived osteoclasts, MNC formed in long-term human bone marrow culture expressed osteoclast-specific antigens (detected by monoclonal antibodies 13c2 and 23c6) and did not express Fc receptors, T cell specific antigens, most myeloid antigens or mature macrophage antigens. In contrast to authentic osteoclasts, MNC reacted with a monoclonal antibody (Mol) which identifies an antigen present on myeloblasts, monocytes, granulocytes, and null cells from human peripheral blood and bone marrow. MNC also reacted with the monoclonal antibody My11, which is present on CFU-GM, the granulocyte-macrophage colony-forming cell, the probable precursor for MNC. These data demonstrate that MNC formed in long-term human marrow cultures express a similar surface phenotype to osteoclasts. This phenotype is different from that expressed by macrophage polykaryons. In addition, MNC also expressed monocyte-related antigens (My11, Mol), suggesting that are derived from or related to the monocytic lineage.

Animals↗
PubMed1989

Platelet activating factor in pulmonary pathobiology.

Platelet activating factor (PAF) is a potent phospholipid mediator of inflammation that has been gaining increasing attention because of its pathophysiologic effects upon the lung. In particular, PAF stimulates pulmonary hypertension, ventilatory alterations, bronchoconstriction, airway hyperreactivity, and pulmonary inflammatory cell accumulation and edema in a variety of experimental animals and in humans. These observations promote the speculation that this unique phospholipid likely is involved in similar tissue responses during the course of human lung disease. The use of specific PAF antagonists should expand our understanding of these processes and may be useful in treating or preventing PAF-mediated pulmonary disorders in the future.

Animals↗
PubMed1988

Complement and neutrophil activation in the pathogenesis of ischemic myocardial injury.

Complement depletion with cobra venom factor (CVF) before coronary artery ligation has been previously shown to reduce subsequent ischemic myocardial tissue injury in the baboon; however, whether complement depletion after the initiation of acute myocardial ischemia affords similar myocardial preservation is not known. Both complement depletion with CVF or the administration of certain nonsteroidal anti-inflammatory drugs, including ibuprofen, are thought to decrease myocardial infarct size by reducing polymorphonuclear leukocytic (PMN) infiltration; nevertheless, complement activation also could alter tissue injury by PMN-independent actions. Thus, the relative effects of CVF administered after coronary artery ligation on the subsequent development of myocardial tissue injury were assessed in a baboon myocardial infarction model. The animals were randomized into three treatment groups (n = 6): either CVF (125 units/kg) or saline was given 30 minutes after coronary artery ligation, and ibuprofen (12.5 mg/kg) was administered 30 minutes and 4 hours after ligation. The extent of ischemic myocardial injury was assessed 24 hours later. Relative to saline-treated baboons, both CVF and ibuprofen reduced PMN infiltration (36 +/- 4 vs. 24 +/- 4 and 24 +/- 4 PMN/mm2, respectively; mean +/- SEM) and histological evidence of transmural myocardial infarction (100% vs. 47% and 53%, respectively) in electrocardiographically designated, expected infarct sites. In both saline- and ibuprofen-treated animals, there was extensive localization of C4, C3, and C5 in all infarct sites; in contrast, there was only C4 localization in the CVF-treated baboons. When expected infarct sites were assessed for creatine kinase content as an indicator of tissue injury, there was significantly less epicardial and endocardial creatine kinase depletion in the CVF-treated animals (31.7 +/- 5.6% and 39.3 +/- 4.8%) than in the saline-treated animals (54.1 +/- 5.4% and 59.0 +/- 4.7%; p = 0.012 and 0.011, respectively). The percent creatine kinase depletion in the ibuprofen-treated animals was intermediate between the two other groups. These results suggest that depletion of complement after coronary ligation has beneficial effects in reducing tissue injury that cannot be explained solely on the basis of reducing PMN infiltration into the ischemic myocardium.

Animals↗
PubMed1988

Platelet-activating factor in the rabbit uterus during early pregnancy.

Platelet-activating factor (PAF) concentrations were low in the non-pregnant, oestrous uterus (mean +/- s.e.m.: 2.2 +/- 1.2 pmol/g, n = 3). However, uterine PAF increased dramatically during pregnancy to a maximum of 37.8 +/- 4.90 pmol/g (n = 7) on Day 5. By Day 7, PAF concentrations in the uteri of pregnant rabbits had returned to levels similar to those found at oestrus. In contrast, uterine PAF in pseudopregnant rabbits peaked at 30.6 +/- 2.8 pmol/g (n = 8) on Day 4, declined to 20.5 +/- 2.4 pmol/g (n = 8) on Day 5 and then remained at that concentration through Day 7. Uterine PAF co-migrated with synthetic PAF (1-O-hexadecyl-2-acetyl-sn-glycero-phosphocholine) in both thin-layer and normal-phase high-performance liquid chromatography. PAF activity in the uterus during pregnancy and pseudopregnancy was found almost exclusively in the endometrium; little or no PAF was found in myometrium, uterine flushings or blastocysts. While no PAF was detected in blastocysts on Days 5 and 6 of pregnancy, the presence of the embryo appears to modulate biosynthesis and/or degradation of PAF by the uterus, since PAF decreased significantly in uterine tissue apposed to the implanting embryo (but not in similar areas between such attachment sites). Increased concentrations of PAF in the preimplantation rabbit uterus followed by a dramatic decrease on the day of blastocyst attachment suggest that this potent inflammatory autacoid may play a vital role in implantation.

Animals↗
PubMed1987

Formation of multinucleated cells that respond to osteotropic hormones in long term human bone marrow cultures.

Studies of osteoclasts and their precursors in normal and pathological states have been severely hampered by the lack of an in vitro system for forming osteoclasts. We developed a human marrow culture system in which multinucleated cells with several characteristics of osteoclasts form. Multinucleated cells began to form during the first week of culture, with maximum numbers formed after 3 weeks. PTH (25-50 ng/ml) and 1,25-dihydroxyvitamin D3 (10(-10)-10(-8) M) increased formation of these cells, and these effects were inhibited by calcitonin. These multinucleated cells contained nonspecific esterase and tartrate-resistant acid phosphatase, a marker enzyme of osteoclasts, and had several ultrastructural features of osteoclasts. We used this marrow cell culture technique to study a patient with hyperparathyroidism and markedly increased osteoclasts on bone marrow biopsy. The marrow from this patient formed increased numbers of multinucleated cells in vitro. After parathyroidectomy both multinucleated cell formation in vitro and osteoclast numbers on bone biopsy decreased significantly. This long term marrow culture system represents the first demonstration of human osteoclast-like cell formation in vitro. This system should permit studies to evaluate factors controlling formation of cells with certain osteoclast characteristics in vitro and their precursors as well as to evaluate abnormalities in osteoclast formation in patients with metabolic bone disease.

Bone Marrow Cells↗
PubMed1987

Ontogeny of the responsiveness to intravenous platelet-activating factor.

Neonatal and young animals fail to develop antigen-induced, lethal, systemic anaphylactic reactions. Recent evidence has documented that, in the adult rabbit, an unusual phospholipid autacoid, platelet-activating factor, induces almost all of the physiologic events associated with IgE-induced anaphylaxis. Thus, in the present study, the intravascular alterations after intravenous infusion of synthetic platelet-activating factor (1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine; AGEPC) into young rabbits were examined. In comparison to 13-week-old, adult rabbits, the intravascular infusion of greater than 1.0 micrograms/kg AGEPC was not lethal in rabbits of 8 weeks of age or less. In dose-response studies, the amount of AGEPC required to induce a lethal response in 50% of the animals tested (LD50) was found to inversely correlate with age. In contrast, AGEPC-induced platelet aggregation in vitro was not affected by the age of the donor animal. Consistent with age-independent platelet responsiveness in vitro, AGEPC-induced thrombocytopenia and intravascular accumulation of platelet factor 4 and thromboxane B2 were also unaffected by animal age. Neutropenia and basopenia, as well as platelet and neutrophil sequestration in the pulmonary microvasculature after intravenous AGEPC infusion also were similarly unaffected by animal age. Although the mechanisms which modulate the profound and lethal physiologic responses following AGEPC infusion in the adult rabbit remain to be established, the current study clearly documents an age-dependent acquisition of systemic physiologic sensitivity to AGEPC and/or other mediators released as a result of intravascular AGEPC administration.

Aging↗
PubMed1986

Pathobiology of platelet-activating factors.

Throughout the evolution of knowledge about inflammation, a primary goal has been to understand this important biological response in sufficient depth to prevent the unwanted tissue injury that may spontaneously occur or that may coevolve to produce disease. That is, although the host defense systems normally function in a protective manner, excessive activation or alterations of the homeostatic regulation of the inflammatory responses often results in overt tissue injury and organ dysfunction. Thus, significant attention has been focused upon precise definition of the interactions of the myriad of involved cells and mediators so that interventions may be developed to block these events to prevent and control inflammatory tissue injury. PAF, as a relative newcomer to the investigative eye of experimental pathologists, is a potent proinflammatory mediator of many aspects of the complex host defense system. No doubt, its role in the initiation and maintenance of tissue injury or disease will be conclusively documented with additional research and forthcoming advances in biomedical technology. At present, however, we must be content to accept the conclusion that, while it is tempting to speculate that this unique phospholipid is involved in many different disease processes, unequivocal details to this end are lacking. Nonetheless, the spectrum of antagonists of PAF action which are currently evolving [cf. 95-100] will undoubtedly permit assessment of the putative contributions of PAF to many biological conditions associated with disease. At that time, meaningful conclusions as to the biological role of PAF in human tissue injury and disease may be provided.

Animals↗