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Biomedical subjects

R Moser

Publications and source records attributed to R Moser.

At least 19 recordsLinked to original sources
PubMed1992

IL-4 controls the selective endothelium-driven transmigration of eosinophils from allergic individuals.

The mechanism leading to selective accumulation of eosinophils in allergic inflamed tissue is still unknown. In this article, transendothelial migration of circulating eosinophils from normal and allergic individuals is characterized by means of human umbilical vein endothelial cells cultivated on extracellular matrix from human fibroblasts. IL-4 pretreatment of these vascular constructs induced adherence and impressive layer penetration of eosinophils but not of neutrophils. For layer penetration, blood eosinophils from nonallergic donors needed in vitro priming by granulocyte/macrophage-CSF, IL-3, or IL-5. In contrast, freshly isolated blood eosinophils from a group of patients with atopic dermatitis spontaneously penetrated IL-4-activated vascular constructs. The here described selective pathway of eosinophil transmigration was 1) specifically induced by IL-4; 2) inhibited by the IL-4 specific, neutralizing mAb 8F12; and 3) dependent upon endothelial mRNA synthesis. Both eosinophil adherence and transmigration were present at an IL-4 concentration of 1 U/ml. The effect of endothelial preincubation with IL-4 culminated at 16 h and persisted up to 48 h. A linear increase of subendothelial accumulating eosinophils was observed within 2 h, reaching almost 100% after 4 h of coincubation. From inhibition experiments using different mAb, we conclude that the integrins CD11a/CD18, CD11b/CD18, and very late Ag-4 (CDw49d/CD29) are involved in this selective pathway of eosinophil transmigration. Taken together, this study demonstrates a novel mechanism which allows in vitro or in vivo primed eosinophils to leave the vascular compartment without influencing emigration of neutrophils.

Adult↗
PubMed1992

Migration of primed human eosinophils across cytokine-activated endothelial cell monolayers.

Eosinophils are known to adhere to cytokine-activated endothelium. Whereas transendothelial migration for neutrophils is an inevitable consequence of this endothelial-dependent adherence, this has not yet been shown for eosinophils. By means of human umbilical vein endothelial cells (HUVE) grown to confluence on microporous filters as an in vitro model of leukocytic migration across postcapillary venules, we have characterized the conditions leading to endothelium-driven transmigration of blood eosinophils from normals and from patients with allergic asthma. Freshly isolated eosinophils from nonallergic donors adhered to interleukin-1 (IL-1) and tumor necrosis factor-activated HUVE, but did not penetrate these monolayers. In contrast, eosinophils from allergic asthma patients showed an increased adherence and transmigration capacity. This increased functional competence was not caused by a difference in density phenotype, because the eosinophils from both groups showed a comparable density distribution over discontinuous Percoll gradients. Moreover, no difference existed within one group among eosinophils harvested from the Percoll density bands 1.080, 1.085, and 1.090 g/mL in terms of transendothelial migration. In vitro cultivation of freshly isolated eosinophils from nonallergic individuals in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-3 induced a stepwise decrease of the density distribution over such gradients. In contrast, eosinophils from patients with allergic asthma directly shifted to a final density of 1.075 g/mL within 24 hours of culture. Notwithstanding the kinetics of density changes, eosinophils from nonallergic donors already expressed the capacity to transmigrate IL-1-activated HUVE monolayers 20 hours after cultivation with different combinations of GM-CSF, IL-3, and IL-5. Inhibition studies with monoclonal antibodies showed that endothelium-driven transmigration of eosinophils predominantly implicates CD11/CD18 structures on the eosinophil surface, whereas no significant inhibition was found with the anti-VLA-4 monoclonal antibody HP2/1. From cytofluorometric studies, we conclude that spontaneous transmigration of eosinophils from allergic asthma patients is not accompanied by quantitative upregulation of these antigens. Taken together, these results allow the conclusion that blood eosinophils from allergic asthma patients have undergone in vivo priming, mimicked in vitro by cytokines such as GM-CSF, IL-3, and IL-5, leading to induction of the capacity to migrate across cytokine-activated HUVE monolayers.

Asthma↗
PubMed1992

Early activation or "priming" of eosinophils in asthma.

Increased numbers of blood and tissue eosinophils are regularly observed in subjects suffering from bronchial asthma. The eosinophil number in the diseased organ is normally closely associated with the presence of clinical symptoms. Not only the cell number, but also the concentration of eosinophil-granule derived mediators is increased in the diseased organ. In particular toxic proteins released by the eosinophil may be responsible for the allergic inflammatory reaction and the concomitant tissue damage. Our recent investigations have shown that eosinophilic granulocytes from asthmatic individuals have the same phenotype as eosinophils from normal individuals (i.e. with respect to their density distribution pattern and surface receptor expression). In contrast, eosinophils from asthmatic individuals do possess increased metabolic activity (i.e. increased leukotriene C4 (LTC4) generating capacity and migration capacity). This increased metabolic activity is due to the presence of circulating factors, i.e. the cytokines interleukin 3 (IL-3), interleukin 5 (IL-5) and granulocyte-macrophage colony stimulating factor (GM-CSF). These cytokines are demonstrable in the circulation of asthmatic, but not normal individuals; they are synthetized by activated T-lymphocytes. This early activation, called "priming", should be the goal of future pharmacological endeavours in order to achieve more efficient treatment of asthma.

Asthma↗
PubMed1992

Design, synthesis and structure of an amphipathic peptide with pH-inducible haemolytic activity.

A synthetic, 26-residue peptide having a strong helix forming potential in the protonated state was designed to interact with lipid bilayers in a pH-dependent way. On the basis of this concept a cluster of four glutamic acid residues was inserted in the central region of the amphipathic peptide to promote helix destabilization by mutual charge repulsion at neutral pH. Protonation of these residues might then bring about both a pH-mediated change in hydrophobicity and conformation forming a membrane-active amphiphilic helix. The sequence GLGTLLTLLEFLLEELLEFLKRKRQQamide produced by the design strategy induced pH-triggered lysis of human erythrocytes. A molecular model correlating the lytic activity to the formation of transmembrane pores which were detected by electron microscopy in erythrocyte membranes is discussed. Circular dichroism studies indicated a self-association of the monomeric random coil form with increasing peptide concentration leading to the apparent induction of strong alpha-helix formation (approximately 100% helicity) in the fully aggregated state. However, no pH-dependent helix-random coil transition was observed, implying that interhelical hydrophobic and ionic interactions not only govern the self-association but also decisively influence the conformational stability of the peptide.

Amino Acid Sequence↗
PubMed1992

Nuclear magnetic resonance studies and molecular dynamics simulations of the solution conformation of a 'designed', alpha-helical peptide.

The complete three-dimensional structure in methanol of an amphipathic alpha-helical peptide, that has been designed by taking into account the three-dimensional structures of small haemolytic peptides, secondary structure prediction algorithms and the well documented literature on alpha-helix stabilizing factors, has been elucidated by two-dimensional NMR spectroscopy. Initially various two-dimensional spectra (COSY, TOCSY, and NOESY) allowed the complete sequence specific assignment of all signals in the 1H spectrum. Consequently trial structures were generated which were then subjected to molecular dynamics simulations using 121 NOE-derived distances and 25 vicinal coupling constant values as structural restraints to give a final set of calculated structures. These structures are in complete agreement with the results of a circular dichroism study and reveal that the peptide adopted a highly ordered alpha-helical conformation. Details of the structure which throw light on future peptide/protein design are discussed.

Amino Acid Sequence↗
PubMed1992

Coffee consumption and the risk of cancer of the exocrine pancreas: a case-control study in a low-risk population.

Data from a population-based, case-control study of 149 cases of cancer of the exocrine pancreas (excluding insulinomas) and 363 controls were used to test the hypothesis that coffee consumption increased the risk of cancer of the exocrine pancreas. Because of the high mortality from cancer of the pancreas, all information was obtained from proxy respondents for cases and controls. Increased risk was present for coffee drinkers [odds ratio (OR) = 2.38], cigarette smokers (OR = 2.27), and alcohol users (OR = 1.60), but the effect for alcohol disappeared after adjustment for cigarette use. Risk increased with the amount of coffee drunk with an OR of 2.38 in the those having at least 50,000 lifetime cups. This gradient was present in both men and women, and in cigarette smokers and nonsmokers. Increased risk was present for users of regular and decaffeinated coffee, but the risk was higher for users of decaffeinated coffee than users of regular coffee. Cigarette smoking, after controlling for coffee consumption, was an independent risk factor for pancreatic cancer, with odds ratios in the heaviest smokers of 2.71 (95% confidence interval = 1.41-5.21.

Adult↗
PubMed1991

Apolipoprotein E gene expression in mouse 3T3-L1 adipocytes and human adipose tissue and its regulation by differentiation and lipid content.

Apolipoprotein E (apoE) is an important constituent of plasma lipoproteins and a ligand for several lipoprotein receptors. It is produced mainly in the liver but also in several peripheral tissues like brain, adrenal glands, kidney, and macrophages. Some of these tissues also coexpress lipoprotein lipase (LPL), an important enzyme in the metabolism of lipids and lipoproteins. This suggested a possible coordinate expression of these genes and led us to analyze whether adipocytes, a major source of LPL, could also synthesize apoE. Northern blotting experiments showed that apoE mRNA is found in differentiated mouse 3T3-L1 adipocytes as well as biopsies of human adipose tissue maintained in organ culture but not in undifferentiated 3T3-L1 preadipocytes. [35S]Methionine pulse-labeling experiments revealed that apoE protein is produced in human adipose tissue and differentiated mouse 3T3-L1 adipocytes but not in preadipocytes. In biosynthetic labeling experiments, most apoE was found to be cell associated even after prolonged chase periods. Heparin treatment of the cultured cells did not enhance apoE secretion. During differentiation of 3T3-L1 cells, the onset of apoE gene expression was later than that of LPL. The apoE mRNA and intracellular apoE protein concentrations increased linearly with time of differentiation, at least through day 11, whereas LPL showed highest expression at day 7 and then declined. The increase in apoE mRNA correlated with the cellular lipid content. Inhibition of lipid accumulation in differentiated cells by biotin deprivation decreased apoE expression. Cholesterol-loading experiments suggested that apoE mRNA expression is regulated by the intracellular free cholesterol content of 3T3-L1 adipocytes. In contrast, the LPL mRNA level was not influenced by biotin deprivation or cholesterol loading. Human recombinant tumor necrosis factor, a potent inhibitor of LPL gene transcription, had no effect on adipocyte apoE mRNA levels. Therefore, although apoE and LPL are both expressed in adipocytes in a differentiation-dependent manner, the time course of their expression differs as do their responses to cellular lipid content and tumor necrosis factor. We conclude that these genes are not coordinately regulated in adipocytes.

Adipose Tissue↗
PubMed1990

Fulminant group A streptococcal infections. Report of two cases.

We describe two female patients presenting with spontaneous peritonitis and fulminant Streptococcus pyogenes (Strep. pyogenes) septicemia and shock. Both patients recovered completely upon immediate antibiotic therapy, initially with broad range combination therapy effective against Strep. pyogenes, which was switched to penicillin G when culture results became available. This isolated strain in case 1 was M-type 28, which is the M-type most often isolated from vaginal swabs (as commensal) and from blood from patients with puerperal sepsis. Patient 1 had signs and symptoms of a toxic shock-like syndrome, including rapid onset of fever and shock, skin rash, desquamation of palms and soles, and multisystem involvement with vomiting, diarrhea, myalgia, renal failure, and severe disorientation without focal neurological deficits.

Anti-Bacterial Agents↗
PubMed1990

Pediatric HIV-1 disease in a Kampala Hospital.

Data of pediatric patients screened for HIV-1 infection between 1985 and 1989 were studied retrospectively in one of the major mission hospitals of Kampala (Uganda). Symptomatic HIV-1 infection was mainly acquired perinatally and was diagnosed in 87 per cent in children under 2 years of age. The mortality rate was 40 per cent in pediatric in-patients with symptomatic HIV-1 infection as compared to 12 per cent in overall pediatric inpatients. Symptoms included in the WHO clinical case definition for pediatric AIDS were mainly insensitive, unspecific and demonstrated a low positive predictive value. There was no difference in the prevalence of malaria and measles between HIV-1 positive and HIV-1 negative children.

Child↗
PubMed1990

Promotion of transendothelial neutrophil passage by human thrombin.

Thrombin has been reported to elicit two temporally different effects on neutrophil-endothelial interaction, categorically described as 'neutrophil adhesion': one expressed within a few minutes, the other after several hours of endothelial preincubation. Prolonged activation resulted in often elongated, tightly interacting neutrophils in contact with human umbilical vein endothelial cells (HUVE) mainly at the intercellular region. In contrast, the neutrophil-endothelial interaction due to short-time priming with thrombin was dominated by round, randomly distributed neutrophils, loosely adhering on the endothelial surface. Sheer stress, introduced to characterize these morphological entities in a quantitative manner, clearly defined the neutrophil response due to short time priming as sheer stresslabile compared to the sheer stress-resistant interaction expressed after prolonged preincubation of HUVE with thrombin. Quantitative determination of neutrophil transendothelial migration served to demonstrate the relevance of such differences in neutrophil binding with respect to subsequent layer penetration. Dependent upon endothelial protein synthesis and inhibited by antithrombin-III-heparin and hirudin, neutrophil layer penetration only occurred after prolonged activation of HUVE whereas the neutrophil-endothelial interaction due to short time priming with thrombin was limited to superficial neutrophil adhesion. We conclude that thrombin can be added to the list of activators capable of inducing the neutrophil passage-guiding principle, an effect that has recently been detected as closely related to neutrophil adhesion to endothelial ligands expressed upon activation with interleukin-1 and tumor necrosis factor. This biological activity, which can be separated from superficial attachment of polymorphonuclear leukocytes (PMN) to endothelial cells, is a catalytic site-dependent and late phase-specific effect of thrombin on HUVE.

Cell Movement↗
PubMed1990

Malaria incidence and prevention among European and North American travellers to Kenya.

A longitudinal survey was conducted among travellers departing from Nairobi airport to determine the use of malaria prevention measures and assess the risk for malaria while travelling in Kenya. Among 5489 European and North American travellers, 68 different drug regimens were used for prophylaxis, and 48% of travellers used both regular chemoprophylaxis and more than 1 antimosquito measure during travel; 52% of 3469 travellers who used chemoprophylaxis did so without interruption during their travel and for 4 weeks after departure. Compliance was lowest among travellers who visited friends and relatives, who were young, or who stayed more than 3 weeks. Sixty-seven (1%) travellers experienced symptoms of malaria, but the diagnosis could be verified for only 16 of these. Long-stay travellers appeared to be at higher risk for malaria than short-stay travellers, and health information needs to be targeted especially to the former. Similar investigations are needed among international travellers to other malaria-endemic countries. With comparable data available, consistent and effective malaria prevention guidelines can be developed.

Adult↗
PubMed1989

The cell surface glycoprotein Mac-1 (CD11b/CD18) mediates neutrophil adhesion and modulates degranulation independently of its quantitative cell surface expression.

It has previously been shown that during degranulation Mac-1 (CD11b/CD18)--a glycoprotein that plays a central role in neutrophil adhesion-is up-regulated on PMN surfaces. It has been assumed that this quantitative change in adhesion Ag expression on the cell surface would in turn lead to increased cellular adhesiveness. In contrast, we found that at an incubation temperature of 16 degrees C, stimulated neutrophil adhesion to plastic tissue culture dishes in the presence of FMLP (2.5 x 10(-6) M), TNF (10 ng/ml), or PAF (1 x 10(-4) M) occurred without cellular degranulation or Mac-1 surface up-regulation as measured cytofluorometrically. As shown by functional inhibition studies employing monoclonal antibodies 60.3 (anti-CD18) and 60.1 (anti-CD11b), adhesion at 16 degrees C, where no CD11b/CD18 up-regulation was seen, is mediated by CD11b/CD18 just as it is at 37 degrees C, where degranulation and CD11b/CD18 up-regulation could be demonstrated. The physiologic importance of these findings was underscored by experiments done on endothelial monolayers, which showed that PMN association with endothelial cells is absolutely independent from the quantitative up-regulation of Mac-1 on PMN surfaces. When neutrophils were stimulated at 37 degrees C by endotoxin, an agent that does not induce aggregation (a form of intercellular adhesion), Mac-1 surface expression increased only after cells had become adherent, whereas cells held in suspension to prevent cell-substrate adhesion neither degranulated nor up-regulated their Mac-1 surface expression. Thus, not only is adherence independent of degranulation and Mac-1 cell surface up-regulation, but both degranulation and Mac-1 surface up-regulation appear to depend on the process of adhesion. Correspondingly, incubation of neutrophils with antibodies 60.1 and 60.3 inhibited not only adhesion of cells stimulated with FMLP at 37 degrees C but degranulation as well. These results indicate that Mac-1 influences degranulation as well as it controls adhesion not by its mere quantity on the cell surface, but rather by an yet undefined molecular modulation.

Antibodies, Monoclonal↗
PubMed1989

Uncertainty in the diagnosis of histologically confirmed pancreatic cancer cases.

In doing a case-control study of cancer of the exocrine pancreas, a set of criteria was developed to classify cancer of the exocrine pancreas by pathological and diagnostic data as to the probability that the tumor arose in the pancreas. We applied these criteria to the records of 125 consecutive patients between the ages of 40-79 years who were identified as having adenocarcinomas of the exocrine pancreas from a population-based cancer registry. We found that histological confirmation by a cancer registry does not guarantee the site of origin is the pancreas. Of the histologically confirmed cases meeting our study criteria, 28.7% may not have arisen in the pancreas. Forty-seven per cent of non-histologically confirmed cases, which most studies exclude, were almost certainly of pancreatic origin based on computerized tomogram (CT) scan and/or surgical palpation and subsequent clinical course. These figures may underestimate the full extent of diagnostic misclassification, especially in older age groups. We conclude that epidemiological studies of cancer of the exocrine pancreas need more uniform criteria for defining cases, and these criteria should take into account uncertainty as to site of origin. Sufficient detail of our scheme is presented so it can be applied in other studies.

Adult↗
PubMed1989

Interleukin 1 and tumor necrosis factor stimulate human vascular endothelial cells to promote transendothelial neutrophil passage.

In an attempt to understand the regulatory mechanisms governing passage of neutrophils from the vascular bed to the interstitial tissue, we analyzed the effect of the pleiotropic monokines interleukin 1 (IL-1) and tumor necrosis factor (TNF) on transendothelial neutrophil traffic. Short-time preincubation of human umbilical vein endothelial cell (HUVE) monolayers with IL-1 and TNF led to an impressive time- and dose-dependent increase of endothelial cell-associated neutrophils when working in a full plasma system on petri dishes. Electron microscopic analysis revealed junctional penetration of monolayers by neutrophils. More quantitatively, when using a monolayer-on-filter-system, priming led to a severalfold increase in complete layer passage occurring in the absence of an external chemotactic gradient. Direct comparison with an upside-down modification of the system together with data demonstrating the vectorial behavior of such migration revealed that IL-1-stimulated transendothelial neutrophil traffic is polarized. The described enhancement of neutrophil transendothelial passage was found to be a unique feature of IL-1/TNF-activated HUVE since HUVE-dependent transmigration potentiation was not observed as a consequence of mere neutrophil attachment to endothelial cells (e.g., induced by Fc-mediated adherence of PMN to HUVE). IL-1 acts selectively on endothelial cells as demonstrated by total inhibition of its effect by actinomycin D. Moreover, IL-1 does not induce HUVE monolayers to secrete a chemotaxin, and the neutrophil passage guiding principle is removable from the HUVE surface by short trypsin exposure. Congruent results were obtained with human adult arterial as well as saphenous vein endothelial cells. As shown by blockade of neutrophil migration with pertussis toxin, IL-1- and TNF-inducible transendothelial migration can be dissected into an initial anchoring step, which is succeeded by active neutrophil migration, possibly along a putative endothelial membrane-bound gradient.

Cell Adhesion↗