Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 97
Filter
1.
Trials ; 22(1): 935, 2021 Dec 19.
Article in English | MEDLINE | ID: mdl-34924004

ABSTRACT

BACKGROUND: Trials involving adults who lack capacity to provide consent rely on proxy or surrogate decision-makers, usually a family member, to make decisions about participation. Interventions to enhance proxy decisions about trial participation are now being developed. However, a lack of standardised outcome measures limits evaluation of these interventions. The aim of this study was to establish an agreed standardised core outcome set (COS) for use when evaluating interventions to improve proxy decisions about trial participation. METHODS: We used established methods to develop the COS including a consensus study with key stakeholder groups comprising those who will use the COS in research (researchers and healthcare professionals) and patients or their representatives. Following a scoping review to identify candidate items, we used a modified two-round Delphi survey to achieve consensus on core outcomes, with equivocal items taken to a consensus meeting for discussion. The COS was finalised following an online consensus meeting in October 2020. RESULTS: A total of 28 UK stakeholders (5 researchers, 10 trialists, 3 patient/family representatives, 7 recruiters and 3 advisors/approvers) participated in the online Delphi survey to rank candidate items from the scoping review (n = 36) and additional items proposed by participants (n = 1). Items were broadly grouped into three categories: how family members make decisions, their experiences of making decisions, and the personal aspects that influence the decision. Following the Delphi survey, 27 items were included and ten items exhibited no consensus which required discussion at the consensus meeting. Sixteen participants attended the meeting, including additional patient/family representatives invited to increase representation from this key group (n = 2). We reached consensus for the inclusion of 28 outcome items, including one selected at the consensus meeting. CONCLUSIONS: The study identified outcomes that should be measured as a minimum in all evaluations of interventions to enhance proxy decisions about trials. These relate to the process of decision-making, proxies' experience of decision-making, and factors that influence decision-making such as understanding. Further work with people with impairing conditions and their families is needed to explore their views about the COS and to identify appropriate outcome measures and timing of measurement. TRIAL REGISTRATION: The study is registered on the COMET database ( https://www.comet-initiative.org/Studies/Details/1409 ).


Subject(s)
Health Personnel , Outcome Assessment, Health Care , Adult , Consensus , Humans , Informed Consent , Research Personnel
3.
Eur J Clin Nutr ; 67(11): 1182-7, 2013 Nov.
Article in English | MEDLINE | ID: mdl-24045793

ABSTRACT

BACKGROUND/OBJECTIVES: The emptying of the gall bladder in response to feeding is pivotal for the digestion of fat, but the role of various food ingredients in contracting the gall bladder postprandially is not well understood. We hypothesized that different food ingredients, when consumed, will have a different effect on stimulating gall bladder emptying. To investigate this we designed two randomized, investigator-blind, cross-over studies in healthy subjects using magnetic resonance imaging (MRI) to measure gall bladder volumes serially and non-invasively. SUBJECTS/METHODS: Study 1: exploratory study evaluating the effects of 10 different food ingredients on gall bladder emptying in eight healthy subjects. The choice of ingredients varied from common items like coffee, tea and milk to actives like curcumin and potato protease inhibitor. Study 2: mechanistic study investigating the cholecystokinin (CCK) dose response to the best performer ingredient from Study 1 in 21 healthy subjects four ways. RESULTS: The largest gall bladder volume change in Study 1 was observed with fat, which therefore became the dose-response ingredient in Study 2, where the maximum % gall bladder volume change correlated well with CCK. CONCLUSIONS: These serial test-retest studies showed that the fasted gall bladder volume varied remarkably between individuals and that individual day-to-day variability had wide coefficients of variation. Improved knowledge of how to stimulate bile release using food ingredients will be useful to improve in vitro-in vivo correlation of bioavailability testing of hydrophobic drugs. It could improve performance of cholesterol-lowering plant stanol and sterol products and possibly aid understanding of some cholesterol gallstone disease.


Subject(s)
Cholecystokinin/metabolism , Diet , Dietary Fats/pharmacology , Gallbladder Emptying/drug effects , Gallbladder/drug effects , Adolescent , Adult , Female , Food , Gallbladder/physiology , Humans , Male , Postprandial Period , Single-Blind Method , Young Adult
4.
CBE Life Sci Educ ; 11(3): 239-47, 2012.
Article in English | MEDLINE | ID: mdl-22949421

ABSTRACT

The National Science Foundation GK-12 program has made more than 300 awards to universities, supported thousands of graduate student trainees, and impacted thousands of K-12 students and teachers. The goals of the current study were to determine the number of sustained GK-12 programs that follow the original GK-12 structure of placing graduate students into classrooms and to propose models for universities with current funding or universities interested in starting a program. Results from surveys, literature reviews, and Internet searches of programs funded between 1999 and 2008 indicated that 19 of 188 funded sites had sustained in-classroom programs. Three distinct models emerged from an analysis of these programs: a full-stipend model, in which graduate fellows worked with partner teachers in a K-12 classroom for 2 d/wk; a supplemental stipend model in which fellows worked with teachers for 1 d/wk; and a service-learning model, in which in-classroom activity was integrated into university academic coursework. Based on these results, potential models for sustainability and replication are suggested, including establishment of formal collaborations between sustained GK-12 programs and universities interested in starting in-classroom programs; development of a new Teaching Experience for Fellows program; and integration of supplemental fellow stipends into grant broader-impact sections.


Subject(s)
Science/education , Adolescent , Child , Faculty , Humans , Learning , Program Development , Program Evaluation , Students , Teaching , Training Support , United States , Universities
5.
Aliment Pharmacol Ther ; 35(7): 819-27, 2012 Apr.
Article in English | MEDLINE | ID: mdl-22372517

ABSTRACT

BACKGROUND: Diclofenac-potassium (diclofenac--K) 25 mg liquid capsule is absorbed more quickly than the tablet formulation. It offers potential for rapid pain relief, but may alter gastro-duodenal tolerability. AIM: To evaluate the gastro-duodenal tolerance of diclofenac-K 25 mg liquid capsules vs. diclofenac-K 12.5 mg tablets, acetylsalicylic acid (ASA) 500 mg tablets and ibuprofen 200 mg liquid capsules. METHODS: In an endoscopist-blinded, randomised, parallel-group study, volunteers received 15 doses of diclofenac-K 25 mg liquid capsules (n = 36), diclofenac-K 2 × 12.5 mg tablets (n = 36), ibuprofen 2 × 200 mg liquid capsules (n = 24) or ASA 2 × 500 mg tablets (n = 36) over 5 days. The primary outcome was the incidence of erosive gastro-duodenal lesions at Day 6. Secondary outcomes included modified Lanza score and change in gastric mucosal prostaglandin synthesis. RESULTS: The lowest incidence of erosive gastro-duodenal lesions was with diclofenac-K liquid capsules (53%), compared to 61% with diclofenac-K tablets (P = 0.52), 75% with ibuprofen (P = 0.08) and 94% with ASA (P = 0.001). Results were similar for the Lanza scores, although diclofenac-K liquid capsules were significantly superior to ibuprofen liquid capsules (P = 0.04). Diclofenac-K liquid capsules inhibited prostaglandin synthesis by 52% compared to 64% for diclofenac-K tablets (P = 0.10), 50% for ibuprofen (P = 0.85) and 79% for ASA (P = 0.002). With respect to safety, adverse events were most frequent in the ASA group, predominantly gastrointestinal events. CONCLUSIONS: Mucosal injury with diclofenac-K liquid 25 mg liquid capsules was similar to diclofenac-K 25 mg tablets, significantly lower than ASA 1 g tablets and showed some superiority over ibuprofen 400 mg liquid capsules (EudraCT Number 2009-011278-14).


Subject(s)
Analgesics/administration & dosage , Anti-Inflammatory Agents, Non-Steroidal/administration & dosage , Aspirin/administration & dosage , Diclofenac/administration & dosage , Ibuprofen/administration & dosage , Adolescent , Adult , Analgesics/adverse effects , Anti-Inflammatory Agents, Non-Steroidal/adverse effects , Aspirin/adverse effects , Capsules , Diclofenac/adverse effects , Drug Tolerance , Duodenum/drug effects , Endoscopy, Gastrointestinal , Female , Gastric Mucosa/drug effects , Humans , Male , Pain Measurement , Tablets , Time Factors , Young Adult
6.
Curr Top Dev Biol ; 75: 171-223, 2006.
Article in English | MEDLINE | ID: mdl-16984813

ABSTRACT

Water was called by Szent-Gyorgi "life's mater and matrix, mother and medium." This chapter considers both aspects of his statement. Many astrobiologists argue that some, if not all, of Earth's water arrived during cometary bombardments. Amorphous water ices of comets possibly facilitated organization of complex organic molecules, kick-starting prebiotic evolution. In Gaian theory, Earth retains its water as a consequence of biological activity. The cell cytomatrix is a proteinaceous matrix/lattice incorporating the cytoskeleton, a pervasive, holistic superstructural network that integrates metabolic pathways. Enzymes of metabolic pathways are ordered in supramolecular clusters (metabolons) associated with cytoskeleton and/or membranes. Metabolic intermediates are microchanneled through metabolons without entering a bulk aqueous phase. Rather than being free in solution, even major signaling ions are probably clustered in association with the cytomatrix. Chloroplasts and mitochondria, like bacteria and archaea, also contain a cytoskeletal lattice, metabolons, and channel metabolites. Eukaryotic metabolism is mathematically a scale-free or small-world network. Enzyme clusters of bacterial origin are incorporated at a pathway level that is architecturally archaean. The eucaryotic cell may be a product of serial endosymbiosis, a chimera. Cell cytoplasm is approximately 80% water. Water is indisputably a conserved structural element of proteins, essential to their folding, specificity, ligand binding, and to enzyme catalysis. The vast literature of organized cell water has long argued that the cytomatrix and cell water are an entire system, a continuum, or gestalt. Alternatives are offered to mainstream explanations of cell electric potentials, ion channel, enzyme, and motor protein function, in terms of high-order cooperative systems of ions, water, and macromolecules. This chapter describes some prominent concepts of organized cell water, including vicinal water network theory, the association-induction hypothesis, wave-cluster theory, phase-gel transition theories, and theories of low- and high-density water polymorphs.


Subject(s)
Cytoplasm/physiology , Macromolecular Substances/metabolism , Water/physiology , Animals , Cytoplasm/chemistry , Humans , Macromolecular Substances/chemistry , Water/chemistry
7.
J Membr Biol ; 211(1): 1-14, 2006 May.
Article in English | MEDLINE | ID: mdl-16909336

ABSTRACT

We review electrophysiological measures of turgor regulation in some siphonous green algae, primarily the giant-celled marine algae, Valonia and Ventricaria, with particular comparison to the well studied charophyte algae Chara and Lamprothamnium. The siphonous green algae have a less negative plasma membrane potential, and are unlikely to have a proton-based chemiosmotic transport system, dominated by active electrogenic K(+) uptake. We also make note of the unusual cellular structure of the siphonous green algae. Hypertonic stress, due to increased external osmotic pressure, is accompanied by positive-going potential difference (PD), increase in conductance, and slow turgor regulation. The relationship between these is not yet resolved, but may involve changes in K(+ )conductance (G (K)) or active K(+) transport at both membranes. Hypotonic turgor regulation, in response to decreased external osmotic pressure, is approximately 3 times faster than hypertonic turgor regulation. It is accompanied by a negative-going PD, although conductance also increases. The conductance increase and the magnitude of the PD change are strongly correlated with the magnitude of hypotonic stress.


Subject(s)
Electrophysiology , Eukaryota/physiology , Chara/physiology , Osmotic Pressure
8.
Cell Mol Biol (Noisy-le-grand) ; 51(7): 607-19, 2005 Dec 14.
Article in English | MEDLINE | ID: mdl-16359611

ABSTRACT

J.C. Bose (1858-1937) was one of the world's first biophysicists. He was the first person to use a semi conducting crystal to detect radio waves, and the ingenious inventor of a portable apparatus for generating and detecting microwaves (approximately 1 cm to 5 mm radio waves, frequency 12-60 GHz), as well as inventing many instruments now routinely used in microwave technology. Bose extended his specialist knowledge of the physics of electromagnetic radiation into insightful experiments on the life-processes of plants. He became a controversial figure in the west. He invented unique, delicate instruments for simultaneously measuring bioelectric potentials and for quantifying very small movements in plants. He worked with touch-sensitive plants, including Mimosa pudica, with plants that perform spontaneous movements, including the Indian telegraph plant Desmodium, and with plants and trees that did not make obvious rapid movements. Bose concluded that plants and animals have essentially the same fundamental physiological mechanisms. All plants co-ordinate their movements and responses to the environment through electrical signalling. All plants are sensitive explorers of their world, responding to it through a fundamental, pulsatile, motif involving coupled oscillations in electric potential, turgor pressure, contractility, and growth. His overall conclusion that plants have an electromechanical pulse, a nervous system, a form of intelligence, and are capable of remembering and learning, was not well received in its time. A hundred years later, concepts of plant intelligence, learning, and long-distance electrical signalling in plants have entered the mainstream literature.


Subject(s)
Plant Physiological Phenomena , Semiconductors , Biomechanical Phenomena , Electric Stimulation , Electromagnetic Phenomena/history , History, 19th Century , History, 20th Century , India , Nervous System Physiological Phenomena , Plant Development , Plants/anatomy & histology , Semiconductors/history , Signal Transduction
10.
Protoplasma ; 223(2-4): 79-91, 2004 Jun.
Article in English | MEDLINE | ID: mdl-15221513

ABSTRACT

Ventricaria ventricosa and its relatives have intrigued cell biologists and electrophysiologists for over a hundred years. Historically, electrophysiologists have regarded V. ventricosa as a large single plant cell with unusual characteristics including a small and positive vacuole-to-outside membrane potential difference. However, V. ventricosa has a coenocytic construction, with an alveolate cytoplasm interpenetrated by a complex vacuole containing sulphated polysaccharides. We present a theory relating the coenocytic structure to the unusual electrophysiology of V. ventricosa. The alveolate cytoplasm of V. ventricosa consists of a collective of uninucleate cytoplasmic domains interconnected by fine cytoplasmic strands containing microtubules. The cytoplasm is capable of disassociating into single cytoplasmic domains or aggregations of domains that can regenerate new coenocytes. The cytoplasmic domains are enclosed by outer (apical) and inner (basolateral) faces of a communal membrane with polarised K(+)-transporting functions, stabilised by microtubules and resembling a tissue such as a polarised epithelium. There is evidence for membrane trafficking through endocytosis and exocytosis and so "plasmalemma" and "tonoplast" do not have fixed identities. Intra- and extracellular polysaccharide mucilage has effects on electrophysiology through reducing the activity of water and through ion exchange. The vacuole-to-outside potential difference, at which the cell membrane conductance is maximal, reverses its sign from positive under hypertonic conditions to negative under hypotonic conditions. The marked mirror symmetry of the characteristics of current as a function of voltage and conductance as a function of voltage is interpreted as a feature of the communal membrane with polarised K(+) transport. The complex inhomogeneous structure of the cytoplasm places in doubt previous measurements of cytoplasm-to-outside potential difference.


Subject(s)
Eukaryota/cytology , Eukaryota/physiology , Cell Membrane/metabolism , Cytoplasm/chemistry , Cytoplasm/metabolism , Electrophysiology , Vacuoles/metabolism
11.
Ophthalmic Res ; 35(1): 42-7, 2003.
Article in English | MEDLINE | ID: mdl-12566862

ABSTRACT

To determine if the macrophage mannose receptor transcript is present in mouse, rat, pig, and human retinal pigment epithelium (RPE), primary cultures and/or freshly dissected retinal pigment epithelium from four different species were used to isolate total RNA. RT-PCR was used to amplify segments of the macrophage mannose receptor from each sample. Amplified products were sequenced and compared with known sequences of the macrophage mannose receptor. Macrophage mannose receptor transcripts were identified in all RPE samples. Comparison between sequences identified in RPE with macrophage sequences from the same species revealed 100% identity. Sequence homology between the different species was 74% or greater. These data are consistent with the transcription of a single mannose receptor gene by these two phagocytic cell types.


Subject(s)
Lectins, C-Type/genetics , Macrophages/metabolism , Mannose-Binding Lectins/genetics , Pigment Epithelium of Eye/metabolism , Receptors, Cell Surface/genetics , Transcription, Genetic , Animals , Base Sequence , Cells, Cultured , Humans , Mannose Receptor , Mice , Mice, Inbred C57BL , Molecular Sequence Data , RNA/isolation & purification , Rats , Rats, Long-Evans , Reverse Transcriptase Polymerase Chain Reaction , Sequence Homology, Nucleic Acid , Swine
12.
Eur Biophys J ; 31(5): 341-55, 2002 Sep.
Article in English | MEDLINE | ID: mdl-12202910

ABSTRACT

Mechanosensitive (MS) ion channels are activated by mechanical stress and then transduce this information into electrical signals. These channels are involved in the growth, development and response to environmental stress in higher plants. Detailed analyses of the electrophysiology in higher plants are difficult because such plants are composed of complex tissues. The large cells of the charophytes facilitate electrophysiological measurements and allow us to study MS ion channels at the level of single cells. We draw parallels between the process of touch-perception in freshwater Chara, and the turgor-regulating response to osmotic shock in salt-tolerant Lamprothamnium. In terms of electrophysiology, these responses can be considered in three stages: (1) stimulus perception, (2) signal transmission and (3) induction of response. In Chara the first stage is due to the receptor potential (RPD), a transient depolarization with a critical threshold that triggers action potentials, which are responsible for stages (2) and (3). Receptor potentials are generated by MS ion channels. Action potentials involve a transient influx of Ca(2+) to the cytoplasm, effluxes of K(+) and Cl(-) and a temporary decrease of turgor pressure. Reducing cell turgor increases sensitivity to mechanical stimulation. In Lamprothamnium, a hypotonic shock produces an extended depolarization that resembles an extended RPD and is responsive to osmotic rather than ionic changes. Like the action potential, a critical threshold depolarization triggers Ca(2+) influx, opening of Ca(2+)-sensitive Cl(-) channels and K(+) channels; effluxes that last over an hour and result in turgor regulation. These processes show us, in primal form and at the level of single cells, how mechanoperception occurs in higher plants. Recent progress in research into the role of MS ion channels in the freshwater and salt-tolerant Characeae is reviewed and the relevance of these findings to plants in general is considered.


Subject(s)
Cell Membrane/physiology , Chlorophyta/physiology , Ion Channel Gating/physiology , Mechanotransduction, Cellular/physiology , Osmotic Pressure/drug effects , Sodium Chloride , Cell Membrane/drug effects , Chlorophyta/classification , Homeostasis/physiology , Hypertonic Solutions/pharmacology , Hypotonic Solutions/pharmacology , Membrane Potentials/drug effects , Membrane Potentials/physiology , Models, Biological , Pressure , Species Specificity , Stress, Mechanical
13.
Am J Physiol Lung Cell Mol Physiol ; 281(3): L517-23, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11504674

ABSTRACT

Surfactant protein (SP) A and SP-D are members of the collectin superfamily. They are widely distributed within the lung, are capable of antigen recognition, and can discern self versus nonself. SPs recognize bacteria, fungi, and viruses by binding mannose and N-acetylglucosamine residues on microbial cell walls. SP-A has been shown to stimulate the respiratory burst as well as nitric oxide synthase expression by alveolar macrophages. Although nitric oxide (NO.) is a well-recognized microbicidal product of macrophages, the mechanism(s) by which NO. contributes to host defense remains undefined. The purpose of this symposium was to present current research pertaining to the specific role of SPs and reactive oxygen-nitrogen species in innate immunity. The symposium focused on the mechanisms of NO*-mediated toxicity for bacterial, human, and animal models of SP-A- and NO.-mediated pathogen killing, microbial defense mechanisms against reactive oxygen-nitrogen species, specific examples and signaling pathways involved in the SP-A-mediated killing of pulmonary pathogens, the structure and binding of SP-A and SP-D to bacterial targets, and the immunoregulatory functions of SP-A.


Subject(s)
Lung/microbiology , Nitric Oxide/physiology , Pulmonary Surfactants/physiology , Reactive Oxygen Species/metabolism , Animals , Bacterial Physiological Phenomena , Fungi/physiology , Humans , Virus Physiological Phenomena
14.
Immunol Res ; 23(2-3): 111-20, 2001.
Article in English | MEDLINE | ID: mdl-11444377

ABSTRACT

Resident alveolar macrophages play a key role in the initial defense against inhaled pathogens. Surface molecules bind opsonized as well as nonopsonized microbes and mediate their internalization by the macrophage. The recent discovery that specific C-type lectins can bind to the surface of a wide range of pathogens has led to the hypothesis that these lectins are involved in the initial phases of microbe recognition by the macrophage. Studies in our laboratory focus on the role of the lung-specific lectin surfactant associated protein A (SP-A) in host defense against pulmonary pathogens. SP-A contains a carbohdyrate recognition domain that appears to bind specifically to exposed carbohydrate residues on the surface of microorganisms. This lectin-microorganism interaction leads to entry of specific pathogens into macrophages and activation of intracellular pathways, resulting in the production of antimicrobial mediators such as nitric oxide. Many studies, including those involving SP-A-deficient mice, underscore the importance of this protein in pulmonary innate immunity. However, the intramacrophage mechanisms underlying the effects of SP-A are still unclear. This article describes our current knowledge of SP-A and its interactions with immune cells and pathogens with a focus on recent findings from our laboratory regarding SP-A interactions with mycobacteria.


Subject(s)
Lung/microbiology , Macrophages, Alveolar/physiology , Proteolipids/physiology , Pulmonary Surfactants/physiology , Animals , Bacterial Outer Membrane Proteins/metabolism , Bacterial Physiological Phenomena , Chemotaxis , Humans , Immunity, Innate , Inflammation Mediators/metabolism , Lectins/chemistry , Lectins/physiology , Macrophages, Alveolar/metabolism , Membrane Glycoproteins/metabolism , Mice , Mycobacterium/physiology , Opsonin Proteins/physiology , Phagocytosis , Proteolipids/chemistry , Pulmonary Surfactant-Associated Protein A , Pulmonary Surfactant-Associated Proteins , Pulmonary Surfactants/chemistry , Receptors, Cell Surface/metabolism , Signal Transduction
15.
J Membr Biol ; 181(2): 77-89, 2001 May 15.
Article in English | MEDLINE | ID: mdl-11420595

ABSTRACT

Lamprothamnium is a salt-tolerant charophyte that inhabits a broad range of saline environments. The electrical characteristics of Lamprothamnium cell membranes were modeled in environments of different salinity: full seawater (SW), 0.5 SW, 0.4 SW, and 0.2 SW. The cells were voltage-clamped to obtain the I/V (current-voltage) and G/V (conductance-voltage) profiles of the cell membranes. Cells growing at the different salinities exhibited one of three types of I/V profiles (states): pump-, background- and K(+)-states. This study concentrates on the pump- and background-states. Curved (pump-dominated) I/V characteristics were found in cells with resting membrane PDs (potential differences) of -219 +/- 12 mV (in 0.2 SW: 6 cells, 16 profiles), -161 +/- 12 mV (in 0.4 SW: 6 cells, 7 profiles), -151 +/- 12 mV (in 0.5 SW: 6 cells, 12 profiles) and -137 +/- 12 mV (in full SW: 8 cells, 13 profiles). The linear I/V characteristics of the background-state were found in cells with resting PDs of -107 +/- 12 mV (in 0.4 SW: 7 cells, 12 profiles), -108 +/- 12 mV (in 0.5 SW: 7 cells, 10 profiles) and -104 +/- 12 mV (in full SW: 3 cells, 5 profiles). The resting conductance (G) of the cells progressively increased with salinity, from 0.5 S x m(-2) (in 0.2 SW) to 22.0 S x m(-2) (in full SW). The pump peak conductance only rose from 2 S x m(-2) (0.2 SW) to 5 S x m(-2) (full SW), accounting for the increasingly depolarized resting PD observed in cells in more saline media. Upon exposure to hypertonic medium, both the pump and an inward K+ rectifier were stimulated. The modeling of the I/V profiles identified the inward K+ rectifier as an early electrical response to hypertonic challenge.


Subject(s)
Cell Membrane/drug effects , Models, Biological , Plant Cells , Plants/drug effects , Sodium Chloride/pharmacology , Cell Membrane/metabolism , Electric Conductivity , Osmotic Pressure/drug effects , Plant Physiological Phenomena/drug effects , Plants/metabolism , Proton Pumps/metabolism , Saline Solution, Hypertonic/pharmacology
16.
J Immunol ; 165(12): 7035-41, 2000 Dec 15.
Article in English | MEDLINE | ID: mdl-11120831

ABSTRACT

The mannose receptor is expressed on mature macrophages and immature dendritic cells, and functions to mediate phagocytosis of pathogens and capture of Ags for delivery to MHC class II-containing intracellular compartments. It has been previously reported that HIV-1-infected macrophages have reduced functions associated with the mannose receptor, including impaired Pneumocystis carinii phagocytosis and mannosylated albumin uptake. Several HIV-1-derived proteins including the Tat protein have been shown to transcriptionally repress host cell genes. The present study was undertaken to define the role of the HIV-1-derived protein Tat in HIV-mediated mannose receptor down-regulation. Cotransfection of the human macrophage cell line U937 with a Tat expression vector and a mannose receptor promoter-luciferase reporter construct resulted in down-regulation of mannose receptor promoter activity. This repression was targeted to the basal promoter. Expression of either one- or two-exon Tat resulted in decreased promoter activity. The addition of the transactivation response element (TAR) sequence enhanced the Tat-mediated repression. Down-regulation was also seen when transfected cells were treated with exogenously added Tat protein. These results are consistent with a mechanism whereby Tat reduces mannose receptor promoter activity by interfering with the host transcriptional initiation machinery, potentially resulting in decreased levels of surface mannose receptor available for Ag or pathogen capture.


Subject(s)
Gene Products, tat/physiology , HIV-1/immunology , Lectins, C-Type , Mannose-Binding Lectins , Promoter Regions, Genetic/immunology , Receptors, Cell Surface/antagonists & inhibitors , Receptors, Cell Surface/genetics , Repressor Proteins/physiology , Transcription, Genetic/immunology , Animals , Gene Expression Regulation, Viral/immunology , Gene Products, tat/biosynthesis , Gene Products, tat/genetics , Gene Products, tat/pharmacology , Genetic Vectors/immunology , HIV-1/genetics , Humans , Mannose/metabolism , Mannose Receptor , Plasmids/immunology , Rats , Repressor Proteins/biosynthesis , Repressor Proteins/genetics , Repressor Proteins/pharmacology , Response Elements/immunology , Transcriptional Activation/immunology , U937 Cells , tat Gene Products, Human Immunodeficiency Virus
17.
Am J Respir Cell Mol Biol ; 23(5): 586-92, 2000 Nov.
Article in English | MEDLINE | ID: mdl-11062136

ABSTRACT

Surfactant protein (SP)-A is a known opsonin for a variety of pulmonary pathogens. SP-A enhances ingestion of these pathogens by interaction with an SP-A receptor (SP-AR) found on phagocytic cells such as peripheral blood monocytes (PBMC) and alveolar macrophages. Respiratory syncytial virus (RSV) is the most important respiratory pathogen in children. Recent studies have indicated that SP-A levels may be decreased in RSV bronchiolitis and pneumonia. In this study we examined the role of SP-A in uptake of RSV by both PBMC and U937 macrophages, a human macrophage cell line known to express SP-ARs. In addition, we studied the effect of SP-A- mediated uptake of RSV on production of tumor necrosis factor (TNF)-alpha and interleukin (IL)-10 by these cells because incomplete immunity to recurrent RSV infection has been partially attributed to abnormal cytokine responses by macrophages. SP-A enhanced binding and uptake of fluorescently labeled RSV (RSV-FITC) by PBMC in a dose-dependent manner, with a maximal effect seen with 10 to 15 microg/ml SP-A as measured by both percent fluorescent monocytes and linear mean fluorescence (lmf) of individual cells. SP-A also enhanced uptake of RSV-FITC by U937 macrophages, with a maximal effect seen with 20 microg/ml SP-A as measured by both percent fluorescent monocytes and lmf. With respect to TNF-alpha levels, RSV alone slightly enhanced TNF-alpha production by PBMC and decreased TNF-alpha production by U937 macrophages measured at 12 h after addition of RSV. SP-A-mediated uptake of RSV significantly enhanced TNF-alpha production by PBMC and reversed the RSV-induced depression of TNF-alpha by U937 macrophages. RSV significantly enhanced IL-10 production by both cell types, which was reversed by SP-A-mediated uptake. These findings suggest that SP-A is an important opsonin for RSV and that SP-A-mediated uptake of RSV may alter some of the unusual cytokine responses that are postulated to be involved in incomplete immunity to recurrent infection.


Subject(s)
Macrophages/immunology , Monocytes/immunology , Pulmonary Surfactants/immunology , Respiratory Syncytial Virus Infections/immunology , Respiratory Syncytial Viruses/immunology , Humans , Macrophages/virology , Microscopy, Confocal , Monocytes/virology , Phagocytosis/immunology , U937 Cells
18.
Bone Marrow Transplant ; 26(5): 489-96, 2000 Sep.
Article in English | MEDLINE | ID: mdl-11019837

ABSTRACT

We studied the effect of the CD34+ cell dose on transplant-related mortality (TRM) and survival in 39 patients randomized to receive lenograstim-mobilized PBSCT (n = 20) or BMT (n = 19) from HLA-identical siblings. Both marrow and blood were harvested, and one infused in a double-blind fashion. The median nucleated (7.0 vs 3.2 x 10(8)/kg; P < 0.0001), CD34+ (3.7 vs 1.5 x 10(6)/kg; P = 0.002), CFU-GM (42 vs 19 x 10(4)/kg; P = 0.002), and CD3+ (1.9 vs 0.3 x 10(8)/kg; P < 0.0001) cell doses with PBSCT were higher. Thirteen patients (6 BMT and 7 PBSCT) experienced TRM at 15-733 days (median 57); 10 of 20 receiving <2 x 10(6) CD34+ cells/kg compared with three of 19 receiving > or =2. Eight of 20 patients receiving <2 x 10(6) CD34+ cells/kg are alive compared with 14 of 19 receiving > or =2. In Cox analysis, CD34+ cell dose > or =2 x 10(6)/kg was associated with lower TRM (RR 0.2, P = 0.01), and higher overall (RR 3.7, P = 0.01) and event-free (RR 3.2, P = 0.02) survival. Other cell populations and the source of stem cells did not affect TRM or survival. We conclude that 2 x 10(6) CD34+ cells/kg may be the ideal minimum cell dose for allogeneic transplantation although lower doses do not preclude successful therapy. Since the likelihood of obtaining this threshold CD34+ cell number is significantly greater from blood than marrow, PBSCT may be preferable to marrow for allografts from HLA-identical siblings.


Subject(s)
Antigens, CD34 , Bone Marrow Transplantation/mortality , Hematopoietic Stem Cell Transplantation/mortality , Adolescent , Adult , CD3 Complex/blood , Cell Count , Double-Blind Method , Female , Follow-Up Studies , Graft vs Host Disease , Hematologic Neoplasms/complications , Hematologic Neoplasms/mortality , Hematologic Neoplasms/therapy , Hematopoiesis , Hematopoietic Stem Cells/cytology , Hematopoietic Stem Cells/immunology , Histocompatibility , Humans , Male , Middle Aged , Multivariate Analysis , Nuclear Family , Survival Rate , Transplantation, Homologous/mortality , Transplantation, Isogeneic
19.
Am J Physiol Lung Cell Mol Physiol ; 279(2): L216-23, 2000 Aug.
Article in English | MEDLINE | ID: mdl-10926544

ABSTRACT

Surfactant-associated protein A (SP-A) is involved in surfactant homeostasis and host defense in the lung. We have previously demonstrated that SP-A specifically binds to and enhances the ingestion of bacillus Calmette-Guerin (BCG) organisms by macrophages. In the current study, we investigated the effect of SP-A on the generation of inflammatory mediators induced by BCG and the subsequent fate of ingested BCG organisms. Rat macrophages were incubated with BCG in the presence and absence of SP-A. Noningested BCG organisms were removed, and the release of tumor necrosis factor-alpha (TNF-alpha) and nitric oxide were measured at varying times. TNF-alpha and nitric oxide production induced by BCG were enhanced by SP-A. In addition, SP-A enhanced the BCG-induced increase in the level of inducible nitric oxide synthase protein. Addition of antibodies directed against SPR210, a specific macrophage SP-A receptor, inhibited the SP-A-enhanced mediator production. BCG in the absence of SP-A showed increased growth over a 5-day period, whereas inclusion of SP-A dramatically inhibited BCG growth. Inhibition of nitric oxide production blocked BCG killing in the presence and absence of SP-A. These results demonstrate that ingestion of SP-A-BCG complexes by rat macrophages leads to production of inflammatory mediators and increased mycobacterial killing.


Subject(s)
Macrophages/metabolism , Mycobacterium tuberculosis/immunology , Nitric Oxide/metabolism , Proteolipids/metabolism , Pulmonary Surfactants/metabolism , Animals , Antibodies/pharmacology , BCG Vaccine/immunology , Benzothiazoles , Blotting, Western , Cells, Cultured , Dose-Response Relationship, Drug , Enzyme Inhibitors/pharmacology , Female , Macrophages/cytology , Macrophages/drug effects , Mycobacterium tuberculosis/drug effects , Mycobacterium tuberculosis/metabolism , Nitric Oxide/pharmacology , Nitric Oxide Synthase/biosynthesis , Nitric Oxide Synthase Type II , Proteolipids/pharmacology , Pulmonary Surfactant-Associated Protein A , Pulmonary Surfactant-Associated Proteins , Pulmonary Surfactants/pharmacology , Rats , Rats, Sprague-Dawley , Thiazines/antagonists & inhibitors , Thiazines/metabolism , Thiazoles/antagonists & inhibitors , Thiazoles/metabolism , Tumor Necrosis Factor-alpha/antagonists & inhibitors , Tumor Necrosis Factor-alpha/biosynthesis , Uracil/metabolism , omega-N-Methylarginine/pharmacology
20.
Lancet ; 355(9211): 1231-7, 2000 Apr 08.
Article in English | MEDLINE | ID: mdl-10770306

ABSTRACT

BACKGROUND: Autologous transplantation with peripheral blood stem cells (PBSC) results in faster haematopoietic-cell repopulation than with bone marrow. We prospectively compared bone marrow and PBSC for allogeneic transplantation. METHODS: Adult HLA-identical sibling donors provided bone marrow and lenograstim-mobilised PBSC. 39 patients with malignant haematological disorders were infused with either bone marrow (n=19) or PBSC (n=20) after standard conditioning regimens in a double-blind, randomised fashion. The identity of the infused products for all patients remained masked until 1 year after the last patient had received transplantation. FINDINGS: The PBSC group had significantly faster neutrophil recovery to 0.5x10(9)/L (median 17.5 vs 23 days, p=0.002), and platelet recovery to 20x10(9)/L (median 11 vs 18 days, p<0.0001) and to 50x10(9)/L (median 20.5 vs 27 days, p=0.02) than the bone-marrow group. PBSC patients were discharged from hospital earlier than were bone-marrow patients (median 26 vs 31 days, p=0.01). At 4 weeks after transplantation, absolute lymphocytes (0.48 vs 0.63, p=0.08) and CD25 cells (0.04 vs 0.08, p=0.007) were higher in the PBSC group, and the proportion of patients with absolute lymphopenia (74% vs 33%, p=0.03) and CD4 lymphopenia (59% vs 24%, p=0.05) was significantly higher in the bone-marrow group. There was no significant difference in the occurrence of acute or chronic graft-versus-host disease and overall survival. The probability of relapse was significantly higher in the bone-marrow group than in the PBSC group (p=0.01); all five relapses occurred among bone-marrow recipients. INTERPRETATION: Our small study indicates that PBSCs are better than bone marrow for allogeneic transplantation from HLA-identical siblings in terms of faster haematopoietic and immune recovery, and have the potential to reduce disease recurrence.


Subject(s)
Bone Marrow Transplantation , Graft vs Host Disease/prevention & control , Hematologic Neoplasms/prevention & control , Hematologic Neoplasms/therapy , Stem Cell Transplantation , Adult , Blood Platelets/metabolism , Double-Blind Method , Female , Humans , Male , Middle Aged , Neutrophils/metabolism , Prospective Studies , Recurrence
SELECTION OF CITATIONS
SEARCH DETAIL
...