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T R Martin

Publications and source records attributed to T R Martin.

At least 91 records · Page 5Linked to original sources
PubMed1995

Effects of endotoxin in the lungs of neonatal rats: age-dependent impairment of the inflammatory response.

Age-dependent maturation of the intrapulmonary inflammatory responses to bacterial lipopolysaccharide (LPS) was studied because nosocomial gram-negative infections cause morbidity in newborn infants. Escherichia coli LPS or live E. coli were injected into the airways of neonatal or adult rats; intrapulmonary recruitment of leukocytes was measured 6 h later. Neonates showed age- and dose-dependent impairment of intrapulmonary neutrophil recruitment after intratracheal administration of LPS or live E. coli that persisted for the first 28 days of life. Neonatal and adult alveolar macrophages released similar amounts of neutrophil chemotactic activity and tumor necrosis factor in response to incubation with LPS in vitro. Treatment of neonates with intratracheal or systemic interferon-gamma did not augment the response to LPS. Thus, intrapulmonary inflammatory responses to LPS and gram-negative bacteria are impaired early in life and do not approach adult levels until approximately 4 weeks of age.

Aging↗
PubMed1995

Deposition of particles in the lungs of infant and adult rats after direct intratracheal administration.

The study of neonatal pulmonary defense mechanisms has been limited by difficulty in administering foreign material into the lungs of newborn animals. We have developed and standardized a simple method for the intratracheal instillation of particles into the distal airways of newborn rats. We used this method to compare intrapulmonary particle deposition in neonatal and adult rats. We instilled 51Cr-labeled microspheres (11 microns diameter) by direct intratracheal inoculation into the lungs of neonatal (< 2- or 19-h-old) and adult (6-week-old) Sprague-Dawley rats. Immediately after microsphere instillation, the lobar distribution of the particles was analyzed by scintillation counting. The anatomic location of the particles was determined by autoradiography. The instilled microspheres reached all lobes in both lungs of neonatal and adult rats. The pattern of distribution in the right lung was nearly identical in the neonatal and adult rats. In the left lung, however, particles deposited preferentially in the cranial lobe in neonates but in the caudal lobe of adult rats. Analysis of the location of particle deposition in the lungs indicated that 64% +/- 6.85 (n = 4) reached the distal airways in the neonates vs. 85% +/- 3.3 (n = 6) in the adults, whereas the remainder deposited in the conducting airways. This method provides an effective means of delivering particles into distal airspaces of neonatal rats and can be used to study pulmonary defense mechanisms in newborn animals.

Animals↗
PubMed1994

Cloning of two rabbit GRO homologues and their expression in alveolar macrophages.

We cloned two rabbit GRO homologue cDNAs from a lipopolysaccharide-stimulated rabbit alveolar macrophage (AM) cDNA library. One cDNA contains the complete coding sequence for a new mature GRO protein, RabGRO, which shares 68, 78 and 70% amino-acid identity with human GRO-alpha, -beta and -gamma, respectively. The other cDNA contains previously unreported sequence encoding a second GRO protein, rabbit permeability factor 2. The two Rab GRO proteins share 93% identity. Northern analysis shows that Rab AM GRO expression is rapidly induced by lipopolysaccharide. These findings suggest that GRO chemokines may be important in the pulmonary inflammation that occurs with septic lung injury.

Amino Acid Sequence↗
PubMed1994

Active anaphylaxis in IgE-deficient mice.

The IgE-triggered release of mast cell mediators in response to antigen is thought to be the primary event in immediate hypersensitivity reactions such as systemic anaphylaxis. Although mast cells and basophils can be activated in vitro by non-IgE stimuli, it is not known whether these triggers lead to physiological changes in vivo. To investigate this possibility, we generated mice with a homozygous null mutation of the C epsilon gene. Such mice make no IgE, but produce other immunoglobulin isotypes normally. We report that despite the IgE deficiency, sensitized mutant mice become anaphylactic on antigen challenge and display tachycardia and pulmonary function changes similar to those seen in wild-type animals. These responses are accompanied by vascular leak, sharply elevated plasma histamine and rapid death. IgE-independent anaphylaxis does not depend on complement activation, but, as indicated in studies using genetically immunodeficient RAG-2- and SCID mice, does require a functional immune system. Such results clearly demonstrate that non-IgE pathways for hypersensitivity reactions exist in mice.

Anaphylaxis↗
PubMed1994

The CD14 differentiation antigen mediates the development of endotoxin responsiveness during differentiation of mononuclear phagocytes.

The CD14 antigen was originally described as a differentiation antigen on mononuclear cells. The purpose of this study was to investigate the relationship between the appearance of surface CD14 and the acquisition of lipopolysaccharide (LPS) responsiveness during maturation of mononuclear phagocytes. Immature THP-1 cells responded poorly to LPS in the absence or presence of serum. Treatment with the maturational agent calcitriol caused a dose- and time-dependent increase in CD14 mRNA and surface CD14 and enhanced the responsiveness of THP-1 cells to smooth and rough form LPS, complexes of LPS and lipopolysaccharide-binding protein (LBP), and LPS in low concentrations of serum. Monoclonal antibodies to CD14 blocked the responses of THP-1 to LPS, LPS-LBP complexes and LPS in serum. Immunodepletion of LBP from serum also inhibited the effect of LPS in serum. The data show that maturation of the response of THP-1 cells to LPS and LPS-LBP complexes depends on the appearance of CD14 on the cell surface. Maturation of the response to LPS in serum depends in large part on the appearance of CD14 on the cell surface and the presence of LBP in serum.

Actins↗
PubMed1994

Intratracheal interferon-gamma augments pulmonary defenses in experimental legionellosis.

To study the effects of recombinant interferon-gamma (IFN-gamma) on pulmonary defenses in vivo, we measured Ia antigen expression by alveolar macrophages and whole-lung clearance of inhaled Legionella pneumophila in normal and corticosteroid-treated rats. We found that Ia antigen was expressed by 7, 29, 50, and 65% of alveolar macrophages harvested from normal rats 24 h after intratracheal administration of 0, 10(3), 10(4), or 10(5) U of IFN-gamma, respectively, and by 76% of alveolar macrophages harvested from corticosteroid-treated rats given 10(5) U of IFN-gamma. Corticosteroid-treated rats exhibited a marked impairment in the clearance of inhaled L. pneumophila, associated with diminished release of IFN-gamma by antigen-stimulated splenocytes and blunted up-regulation of Ia antigen by alveolar-exudate macrophages. Daily intratracheal injections of IFN-gamma starting 1 day before or 1 day after infection had little effect on bacterial clearance in normal rats but markedly reduced the intrapulmonary replication of L. pneumophila and the number of bronchoalveolar neutrophils in corticosteroid-treated animals. Intraperitoneally administered IFN-gamma had no effect on Ia expression by alveolar macrophages or on bacterial clearance. IFN-gamma may be useful in the treatment of intracellular infections when targeted to the site of infection in immunosuppressed hosts.

Animals↗
PubMed1994

Evolution of bronchoalveolar cell populations in the adult respiratory distress syndrome.

To characterize the evolution of inflammation in the adult respiratory distress syndrome (ARDS) and test the hypothesis that sustained alveolar inflammation is associated with a poor outcome in patients with ARDS, we performed fiberoptic bronchoscopy and bronchoalveolar lavage (BAL) in 125 patients and compared BAL cells and protein concentrations in survivors and nonsurvivors. ARDS followed sepsis syndrome in 35 patients, major trauma in 41, and other causes in 49. When possible, BAL was performed on Days 3, 7, and 14 after the onset of ARDS. Sixty-five patients (52%) had more than one BAL. We first performed analyses on each BAL day using information from all 212 BAL in the 125 patients (cross-sectional analysis). All patients had increased leukocytes and total protein in the first BAL (Day 3 after onset of ARDS). In patients with ARDS following sepsis, the percentage of BAL polymorphonuclear leukocytes (PMN) was higher on Day 7 (p = 0.11) and particularly Day 14 (p = 0.02) in patients who died; there was a consistent trend of a higher PMN concentration on all days in patients who died then in those who lived. In patients with ARDS following trauma and other risks, however, BAL PMN measures did not distinguish survivors from patients who died. Analysis of serial data from the patients with more than one BAL showed that alveolar macrophages (AM) increased in survivors of ARDS, both in absolute numbers and as a percentage of total cells; this pattern was most pronounced in the sepsis patients. The cross-sectional data analysis suggests that sustained alveolar inflammation occurs frequently in patients with ARDS following sepsis and is associated with a high mortality.

Adolescent↗
PubMed1994

Serotonin-induced pulmonary responses are mediated by the 5-HT2 receptor in the mouse.

C57BL/6 mice exhibit acute transient decreases in lung conductance (GL) and dynamic compliance (Cdyn) after intravenous administration of serotonin (5-HT). To identify the specific agonist receptor subtypes responsible for this bronchoconstriction, we measured changes in pulmonary function in C57BL/6 mice in response to intravenous infusion of 5-HT receptor subtype-selective agonists and to 5-HT in the presence of antagonists selective for the 5-HT2 or 5-HT3 receptor subtypes. Agonists selective for the 5-HT1A/1B/1D or 5-HT3 receptor subtypes induced minimal or undetectable pulmonary responses, whereas infusion of alpha-methyl-5-hydroxytryptamine, a 5-HT2 receptor-selective agonist, led to dose-related decreases in Cdyn and GL. The selective 5-HT3 receptor antagonist, LY278584 maleate, (1.0 mg/kg i.v.) caused no detectable reduction in the response to 100 micrograms/kg of 5-HT. In contrast, treatment with the 5-HT2 receptor antagonist LY53857 (10 micrograms/kg i.v.) resulted in a significant diminution of the pulmonary response observed after infusion of 100 micrograms/kg of 5-HT. Dose-response relationships were established for 5-HT in experiments in which each mouse was treated with a single dose of 5-HT without antagonist or after LY53857. Compared with responses to doses of 5-HT of more than 100 micrograms/kg in the absence of antagonist, pulmonary responses to 5-HT after infusion of 10 micrograms/kg of LY53857 were significantly reduced; 100 micrograms/kg of LY53857 nearly abolished the responses to all doses of 5-HT.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Mast cells contribute to the changes in heart rate, but not hypotension or death, associated with active anaphylaxis in mice.

The mast cell is widely thought to contribute importantly to the cardiopulmonary changes associated with anaphylaxis, but much of the evidence for this is indirect. We, therefore, performed a detailed assessment of heart rate and pulmonary function during active anaphylaxis in genetically mast cell-deficient W/Wv or S1/S1d mice, the congenic normal (+/+) mice, and W/Wv mice repaired of their mast cell deficiency by transplantation of bone marrow from the congenic +/+ mice (+/+ BM-->W/Wv mice). For all five groups of mice, Ag challenge resulted in the death of more than two-thirds of the sensitized animals, whereas none of the nonsensitized control mice died as a result of Ag infusion. Sensitized normal (WBB6F1(-)+/+ or WCB6F1(-)+/+) mice and +/+BM-->W/Wv mice developed increases in heart rate that were significantly greater than those of nonsensitized +/+ mice or those of sensitized mast cell-deficient mice, indicating that mast cells contribute to the tachycardia observed in this form of active anaphylaxis. By contrast, even though some of the pulmonary changes associated with active anaphylaxis were more severe in +/+ than in mast cell-deficient mice, it was not clear to what extent this difference was mast cell dependent. W/Wv mice undergoing active anaphylaxis developed decreases in systemic arterial blood pressure that occurred more rapidly and were more severe than those observed in the congenic +/+ mice, indicating that the hypotension associated with this model of anaphylaxis also can occur by mast cell-independent mechanisms. We conclude that in this model of anaphylaxis mast cells: 1) are required for the development of the tachycardia response; 2) may contribute to, but are not essential for, production of decreases in lung function; and 3) are not necessary for the development of hypotension or death.

Age Factors↗
PubMed1993

Neutrophil-activating peptide-2 in patients with pulmonary edema from congestive heart failure or ARDS.

We carried out studies to determine whether the neutrophil-activation peptide-2 (NAP-2) plays a role in the recruitment and/or degranulation of neutrophils into the lungs of patients with the adult respiratory distress syndrome (ARDS) or congestive heart failure (CHF). NAP-2 precursors plus NAP-2 (beta-thromboglobulin-like antigen) were measured in lung fluids and plasmas with a radioimmunoassay, and NAP-2 was separated from its precursors by high-performance liquid chromatography. Pulmonary edema fluids (PEFs) from patients with CHF contained higher concentrations of the beta-thromboglobulin-like antigen than PEFs from patients with ARDS, and bronchoalveolar lavage fluids (BALs) from patients with ARDS contained higher concentrations of beta-thromboglobulin-like antigen than BALs from normal subjects. beta-Thromboglobulin-like antigen concentration was 4.1-fold greater in PEFs from patients with CHF than in their plasmas. Chemotactically active NAP-2 was also demonstrated in PEFs but not in plasmas from patients with CHF and ARDS. These data suggest that significant platelet degranulation occurred into the lungs of the patients with CHF and that NAP-2 and other platelet constituents may contribute to fluid formation in patients with CHF.

Bronchoalveolar Lavage Fluid↗
PubMed1993

Mast cell activation enhances airway responsiveness to methacholine in the mouse.

Mast cell-deficient mutant mice and their normal littermates were used to determine whether activation of mast cells by anti-IgE enhances airway responsiveness to bronchoactive agonists in vivo. Pulmonary conductance was used as an index of airway response as the mice were challenged with increasing intravenous doses of methacholine (Mch) or 5-hydroxytryptamine (5-HT). Mast cell activation with anti-IgE enhanced pulmonary responsiveness to Mch in both types of normal mice (P < 0.0001 by analysis of variance) but not in either genotype of mast cell-deficient mouse. Additionally, anti-IgE pretreatment of genetically mast cell-deficient W/Wv mice whose mast cell deficiency had been repaired by infusion of freshly obtained bone marrow cells or bone marrow-derived cultured mast cells from congenic normal mice led to significant (P < 0.0001) enhancement of Mch responsiveness. 5-HT responsiveness was not significantly influenced by anti-IgE pretreatment in any of the mice studied. The data support the hypothesis that IgE-mediated activation of mast cells enhances pulmonary responsiveness to cholinergic stimulation.

Analysis of Variance↗
PubMed1993

Effects of chronic treatment with the c-kit ligand, stem cell factor, on immunoglobulin E-dependent anaphylaxis in mice. Genetically mast cell-deficient Sl/Sld mice acquire anaphylactic responsiveness, but the congenic normal mice do not exhibit augmented responses.

We treated genetically mast cell-deficient WCB6F1-Sl/Sld mice and the congenic normal (WCB6F1(-)+/+) mice with the c-kit ligand recombinant rat stem cell factor164 (rrSCF164; 100 micrograms/kg per d, subcutaneously) or with vehicle for 21 d, then passively sensitized the mice with anti-dinitrophenol30-40 immunoglobulin E (IgE) antibodies, and 1 d later measured the changes in heart rate, pulmonary dynamic compliance, and pulmonary conductance, and assessed the death rates associated with intravenous challenge of these animals with specific antigen. rrSCF164 treatment induced the development of mast cells in Sl/Sld mice, and these mice exhibited tachycardia, but not death, after challenge with IgE and antigen. rrSCF164 treatment induced mast cell hyperplasia in +/+ mice, but the cardiopulmonary changes associated with passive anaphylaxis in these mice were virtually indistinguishable from those observed in control +/+ mice treated with vehicle instead of rrSCF164. Moreover, the highest dose of antigen challenge produced significantly fewer fatalities in rrSCF164-treated than in vehicle-treated +/+ mice (1/11 vs. 8/11, respectively, P < 0.01). Thus, in normal mice, chronic treatment with rrSCF164 induces mast cell hyperplasia but does not increase, and in certain respects diminishes, the severity of IgE-dependent anaphylactic reactions.

Anaphylaxis↗
PubMed1992

Molecular cloning of porcine alveolar macrophage-derived neutrophil chemotactic factors I and II; identification of porcine IL-8 and another intercrine-alpha protein.

Alveolar macrophages (AM) mediate lung inflammation by producing lipid and peptide molecules that attract neutrophils (PMN) to the lung. Recently we described two porcine proteins called alveolar macrophage-derived chemotactic factors, AMCF-I and -II, that are potent, efficacious, and specific PMN chemoattractants both in vitro and in vivo. We report here the cloning of the full-length cDNAs which code for each protein. Porcine AM were stimulated for 4 h in vitro with Escherichia coli endotoxin (LPS), and a cDNA library was created from poly(A)(+)-selected mRNA. Specific oligonucleotide probes for AMCF-I and AMCF-II were amplified from the porcine AM cDNA library by the polymerase chain reaction using degenerate oligonucleotide primer pairs derived from the N-terminal amino acid sequences of the proteins. These probes were used to isolate 2 full-length cDNAs of 1466 (AMCF-I) and 1515 (AMCF-II) base pairs. Both cDNAs code for proteins with four cysteine residues containing the C-X-C sequence characteristic of the intercrine-alpha family of neutrophil chemoattractants. AMCF-I shares 74% identity with human IL-8 and 84% identity with rabbit IL-8, and likely represents the porcine homologue of IL-8. By contrast, AMCF-II has no obvious human homologue. AMCF-II shares 53% identity with human neutrophil activating peptide 2. Its shared identity with the GRO-related proteins is as high as 61% (rat CINC/GRO), and its shared identity with the 78 amino acid epithelial cell-derived neutrophil activator (ENA-78) is 67%. AMCF-II may represent a new member of the intercrine-alpha family of neutrophil chemoattractants.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

Cytokine-stimulated human mesothelial cells produce chemotactic activity for neutrophils including NAP-1/IL-8.

To test the hypothesis that mesothelial cells play a role in regulating inflammatory responses within the pleural space, we examined neutrophil chemotactic activity released by cytokine-stimulated mesothelial cells. Human mesothelial cells were isolated from patients with transudative pleural effusions and cultured. The purity of the cell population was assessed by morphologic, immunocytochemical, and biochemical characteristics. Confluent fourth passage mesothelial cell plates were exposed to varying concentrations of the recombinant human cytokines IL-1 alpha, TNF-alpha, or IFN-gamma, or Escherichia coli endotoxin (LPS). Polymorphonuclear neutrophil (PMN) chemotactic activity in the conditioned media was measured in microchemotaxis chambers. Although none of the cytokines demonstrated inherent chemotactic activity, each stimulated mesothelial cells to produce PMN chemotactic activity in a dose-dependent manner. TNF-alpha stimulated the release of the greatest quantity, whereas stimulation with IFN-gamma and IL-1 alpha resulted in the release of lesser but still significant quantities of PMN chemotactic activity. By contrast, LPS did not increase the basal level of chemotactic activity produced by the cells. The cytokine-induced chemotactic activity was proteinaceous, required de novo synthesis, and had a predominant m.w. of 10,000. Significant quantities of immunoreactive neutrophil-activating peptide-1 (NAP-1)/IL-8 were detected in mesothelial cell supernatants after stimulation with each of the cytokines. The neutrophil chemotactic activity of supernatants from mesothelial cells stimulated with either IL-1 alpha or IFN-gamma was completely neutralized with rabbit anti-human NAP-1/IL-8 polyclonal antiserum. The same antiserum neutralized the majority, but not all, of the neutrophil chemotactic activity in supernatants from TNF-stimulated mesothelial cells. Stimulated mesothelial cells also expressed an inducible mRNA transcript that hybridized with a specific oligonucleotide probe for human NAP-1/IL-8. These observations provide a mechanism whereby mesothelial cells could respond to inflammatory stimuli in the underlying lung and regulate inflammatory responses within the pleural space.

Base Sequence↗
PubMed1992

The effect of type-specific polysaccharide capsule on the clearance of group B streptococci from the lungs of infant and adult rats.

To study the importance of the type-specific polysaccharide capsule of group B streptococci (GBS) in the pathogenesis of lung infections, bacterial clearance rates and lung cellular responses to encapsulated and unencapsulated variants of types III and Ia GBS strains were investigated in rats. Bacteria were instilled by direct intratracheal inoculation to simulate aspiration during parturition. Neonates failed to eliminate encapsulated or unencapsulated GBS strains within 6 h of inoculation, whereas adults cleared greater than 90% of each strain within 6 h. Neutrophils accumulated rapidly in the lungs of neonates and adults in response to all GBS strains. Immediately after inoculation, neonatal alveolar macrophages contained fewer encapsulated GBS than did adult alveolar macrophages and fewer encapsulated than unencapsulated GBS, suggesting that the capsule impairs the initial phagocytosis of GBS in the lungs of neonates. Animal age was a more important determinant of bacterial elimination from the lung than the type-specific GBS capsule. However, both age and the bacterial capsule were important determinants of systemic dissemination.

Animals↗