Biomedical subjects

A Dewar

Publications and source records attributed to A Dewar.

At least 37 records · Page 2Linked to original sources

PubMed2000

Automated quantitation of circulating neutrophil and eosinophil activation in asthmatic patients.

BACKGROUND: Asthma has been associated with eosinophil activation, measured in serum, sputum, bronchoalveolar lavage (BAL) fluid, and urine. A whole blood automated method was developed to assess eosinophil and neutrophil activity in terms of peroxidase content and cell morphology using the Bayer haematology analyser. The method was applied to an in vitro stimulation model when fMLP was added to whole blood and the samples were then analysed for changes in granularity and shape. In addition, cells stimulated with interleukin (IL)-8 were examined by electron microscopy. METHODS: A cross sectional analysis was performed on venous blood from non-atopic, non-asthmatic normal subjects (n = 37), mild (n = 46) and symptomatic (n = 22) asthmatic patients on inhaled beta(2) agonist only, and more severe asthmatic patients (n = 17) on inhaled and oral corticosteroid therapy. Samples were analysed by the haematology analyser and peroxidase leucograms gated using the WinMDI software program. RESULTS: There were significant differences in the amount of light scatter by the neutrophil populations in the symptomatic (p = 0.007) and severe asthmatic (p = 0.0001) groups compared with the control group. However, abnormalities in eosinophil populations were not observed. In vitro activation of whole blood with fMLP caused similar changes in neutrophil light scatter, suggesting that neutrophil activation is present in peripheral blood of symptomatic asthmatic patients. IL-8 caused a change in shape of the neutrophils seen using transmission electron microscopy. CONCLUSIONS: Evidence of neutrophil activation can be seen in whole blood from patients with asthma using a novel automated method. This may potentially be applied to other inflammatory diseases.

Adult↗

PubMed1999

The extra- and intracellular barriers to lipid and adenovirus-mediated pulmonary gene transfer in native sheep airway epithelium.

Gene transfer to the respiratory epithelium is currently suboptimal and may be helped by the identification of limiting biological barriers. We have, therefore, developed an ex vivo model which retains many of the characteristics of in vivo native airways including mucociliary clearance, mucus coverage and an intact cellular structure. Using this model we have demonstrated several barriers to gene transfer. Liposome-mediated gene transfer was inhibited by normal mucus, with removal of this layer increasing expression approximately 25-fold. In addition both liposome and adenovirus were inhibited by CF sputum. The apical membrane represented a significant barrier to both agents. Adenovirus-mediated expression could be significantly augmented by increasing contact time or by pre-treatment of tissues with a nominally calcium-free medium. The presence of these extracellular and plasma membrane barriers appeared to be the key parameters responsible for the approximately three log difference in gene expression found in vitro compared with our ex vivo model. Cytoskeletal elements and the cell cycle also influenced in vitro gene transfer, and represent further barriers which need to be overcome.

Adenoviridae↗

PubMed1999

Pain and the administration of analgesia: what nurses say.

Pain of moderate to severe intensity continues to be an important problem for many hospitalized patients. Nurses spend more time with patients than any other health professional group and have a key role to play in the management of patients' pain. This paper reports the findings from a series of focus group interviews which were undertaken to explore nurses' perceptions regarding pain and the administration of narcotic analgesia. Themes identified from participants' comments related to (1) the pivotal role of nurses in pain management; (2) nursing assessment and pain management decisions (3) individual factors influencing nurses' pain management decisions and (4) the influence of others on nurses' pain management decisions.

Analgesics, Opioid↗

PubMed1999

Evaluation of angiographic contrast media and platelet function with impedance aggregometry and the PFA-100 'platelet function analyser'.

BACKGROUND: Angiographic contrast media are used in balloon angioplasty and may influence thrombotic complications of the procedure. We studied the effect of different media on platelet aggregation in whole blood using impedance aggregometry and the PFA-100 'platelet function analyser' (Dade, USA). METHODS: Venous blood samples from 18 healthy volunteers were split into four aliquots and mixed with 10% normal saline control, non-ionic medium (iohexol), low-molecular weight ionic medium (ioxaglate) and high-molecular weight ionic medium (diatrizoate). Samples were studied with impedance aggregometry and the PFA-100. RESULTS: All media caused significant inhibition of aggregation compared with control with both methods (P<0.001). Antiplatelet potency was greatest with diatrizoate, intermediate with ioxaglate and least with iohexol with both methods (P<0.01). Electron microscopy of the PFA-100 membrane demonstrated occlusion of the experimental aperture with platelet thrombus in the control. Inhibition of platelet thrombus was seen with all media, greatest with diatrizoate, intermediate with ioxaglate and least with iohexol. CONCLUSIONS: The media studied significantly inhibited platelet aggregation in vitro and potency was greater with ionic than non-ionic media. These methods use a combination of shear and chemical agonist with whole blood and may reproduce in vivo arterial conditions better than other techniques.

Journal Article↗

PubMed1999

Reduction in the adherence of Pseudomonas aeruginosa to native cystic fibrosis epithelium with anti-asialoGM1 antibody and neuraminidase inhibition.

The high incidence of colonization of the cystic fibrosis (CF) airway with Pseudomonas aeruginosa has been attributed to several mechanisms including increased numbers of asialoglycolipid receptors, which may be further increased by exposure to the bacterial exoproduct, neuraminidase. This study examined whether the adherence of P. aeruginosa to fresh CF respiratory epithelial cells can be reduced in vitro by anti-asialoGM1 (anti-aGM1) antibody, neuraminidase inhibition, or the use of asialoGM1 tetrasaccharide as a competitive inhibitor. CF nasal epithelial cells were incubated with a nonmucoid strain of P. aeruginosa, in the presence or absence of a polyclonal anti-aGM1 antibody, the neuraminidase inhibitor 2,3-dehydro-2-deoxy-N-acetyl-neuraminic acid (DANA), or the tetrasaccharide moiety of aGM1. Adherence of bacteria to the apical surface of ciliated epithelial cells was quantified using scanning electron microscopy. Incubation of the cells with bacteria in the presence of either anti-aGM1 antibody or DANA significantly reduced bacterial adherence by 51(7)%, (p<0.01), and 34(9)%, (p<0.01), respectively. In contrast, no significant effect on P. aeruginosa binding was seen in the presence of aGM1 tetrasaccharide. The data are consistent with previous studies on cultured cells, and suggest that the in vivo effects of such interventions should be explored as potential mechanisms to reduce Pseudomonas aeruginosa colonization in cystic fibrosis.

Adult↗

PubMed1998

The prevalence and perception of pain amongst hospital in-patients.

The aim of this paper is to describe the prevalence and perceptions of pain and pain management amongst hospital in-patients. A cross-sectional descriptive survey of 205 patients was conducted. Presence and severity of pain was assessed using verbal descriptor and visual analogue scales, and perceptions of pain were assessed using multi-item scales. Although the severity of pain reported was consistent across age groups and clinical areas, women in the study sample were significantly more likely to report high levels of pain than men. Differences in how men and women communicate their pain were observed, with women indicating that they were less willing to ask for help with their pain. Results suggest that pain continues to be an important problem for a large number of men and women in hospital, and that the experience of pain impacts negatively upon their well-being. Gender differences in the experience of and response to pain remain important considerations for clinical nurses who have major responsibilities for the management of pain in hospitalized patients.

Adolescent↗

PubMed1997

Pulmonary surfactant composition early in development of acute lung injury after cardiopulmonary bypass: prophylactic use of surfactant therapy.

Cardiopulmonary bypass surgery (CPB) causes lung injury and at least 2% of adult patients and more children develop the most severe from acute respiratory distress syndrome (ARDS). Pulmonary surfactant deficiency contributes to the pathogenesis of ARDS. It has been proposed that surfactant therapy immediately after CPB might arrest progression to ARDS. However, many patients develop only mild lung injury after CPB. Thus early markers are needed to identify those patients at highest risk to guide selection for treatment. The aim of this study was to determine whether changes in surfactant phospholipids occur, and reflect severity of lung injury within the first few hours after bypass. Because of the relatively low incidence of ARDS in adult patients, this study was conducted using young pigs highly susceptible to bypass-induced lung injury. Eight pigs were given 2 hours bypass. Six controls underwent 'sham' bypass. At 3 h after bypass pulmonary vascular endothelial permeability was assessed by transcapillary leakage of radiolabelled transferrin. A 4 hour broncho-alveolar lavage (BAL) was used to assess intra-alveolar levels of surfactant, inflammatory cells and oedema protein. Bypass caused falls in arterial oxygenation and lung compliance (P < 0.01), but at this early stage in progression of lung injury BAL surfactant phospholipid and albumin levels were within the control range indicating that the alveolar epithelium had not yet suffered major damage. The main abnormalities were increases in vascular endothelial permeability (P < 0.01), BAL neutrophils (P < 0.01), total protein and sphingomyelin (SM) (P < 0.05). Lung histology showed that the main damage was interstitial oedema located around the bronchioles and their associated vessels. A single instilled dose of surfactant phospholipids in 5 animals caused excess in vivo supplementation and did not reduce the early pathophysiologic changes. Our findings suggest that surfactant phospholipid deficiency does not make a major contribution in the initial stages of lung injury after CPB, and that excessive phospholipid supplementation at this stage can be deleterious.

Animals↗

PubMed1997

Effect of salmeterol on Pseudomonas aeruginosa infection of respiratory mucosa.

We have studied the effect of salmeterol on both P. aeruginosa interactions with the mucosa of nasal turbinate organ cultures and on pyocyanin-induced (20 microg/ml) and elastase-induced (100 microg/ml) damage to nasal epithelial cells. Organ cultures were exposed to salmeterol either by preincubation with 4 x 10(-7) M salmeterol for 30 min or by pipetting 20 microl of 4 x 10(-7) M salmeterol onto the organ culture surface immediately prior to bacterial inoculation. Infected organ cultures (8 h) had significantly (p < or = 0.01) increased epithelial damage, and P. aeruginosa was predominantly associated with damaged epithelium and mucus. Salmeterol significantly (p < or = 0.02) reduced epithelial damage caused by infection and the total number of adherent bacteria (p < or = 0.05), but bacterial distribution on the mucosa was unchanged. Nasal epithelial cells incubated with pyocyanin (20 microg/ml) or elastase (100 microg/ml) for 3 h had significantly (p < or = 0.05) increased cytoplasmic blebbing and mitochondrial damage versus control values. Elastase also significantly (p < or = 0.05) increased cell projection and reduced the level of ciliation. Cells preincubated with salmeterol (2 x 10(-7) M) showed a significant reduction in some features of cell damage caused by both toxins, which was inhibited by the beta2-adrenoceptor antagonist propranolol. Our results indicate that salmeterol reduces P. aeruginosa-induced damage to both organ culture and nasal epithelium.

Adrenergic beta-Agonists↗

PubMed1997

CFTR gene transfer reduces the binding of Pseudomonas aeruginosa to cystic fibrosis respiratory epithelium.

Much of the morbidity and mortality seen in cystic fibrosis (CF) is related to chronic infection of the respiratory tract with Pseudomonas aeruginosa. Some studies have attributed the strong relationship between CF and Pseudomonas colonization to the presence of increased numbers of specific cell-surface receptors, although other work suggests that this relates to the presence of mucus. Several groups are now assessing the use of gene transfer as a novel form of treatment for CF. We have examined whether P. aeruginosa binding to freshly obtained CF respiratory epithelial cells is increased, and have studied the effects of transfer of the CF transmembrane conductance regulator (CFTR) gene on this attachment. Binding of P. aeruginosa to noncultured nasal epithelial cells from both CF patients (n = 31) and healthy controls (n = 15) was studied with scanning electron microscopy. Binding was also assessed for CF cells following transfection with CFTR/liposome complexes. Epifluorescence microscopy was used to assess the effects of gene transfer on chloride fluxes. Adherence of P. aeruginosa directly to the cell surface of CF airway epithelium was significantly (P < 0.001) increased over that in non-CF controls. Liposome-mediated CFTR gene transfer resulted in a significant (P < 0.01) reduction in the numbers of bacteria bound to ciliated epithelial cells. Fluorescence microscopy confirmed correction of the basic chloride defect. Thus, in CF, the absence of normal CFTR results in increased binding of P. aeruginosa to respiratory epithelial cells. This abnormality can be corrected in vitro by restoration of CFTR function. This has important implications both for the pathogenesis of CF and for the future application and assessment of gene therapy for this disease.

Bacterial Adhesion↗

PubMed1996

An anti-platelet-endothelial cell adhesion molecule-1 antibody inhibits leukocyte extravasation from mesenteric microvessels in vivo by blocking the passage through the basement membrane.

Platelet-endothelial cell adhesion molecule-1 (PECAM-1, CD31) plays an active role in the process of leukocyte migration through cultured endothelial cells in vitro and anti-PECAM-1 antibodies (Abs) inhibit accumulation of leukocytes into sites of inflammation in vivo. Despite the latter, it is still not clear at which stage of leukocyte emigration in vivo PECAM-1 is involved. To address this point directly, we studied the effect of an anti-PECAM-1 Ab, recognizing rat PECAM-1, on leukocyte responses within rat mesenteric microvessels using intravital microscopy. In mesenteric preparations activated by interleukin (IL)-1 beta, the anti-PECAM-1 Ab had no significant effect on the rolling or adhesion of leukocytes, but inhibited their migration into the surrounding extravascular tissue in a dose-dependent manner. Although in some vessel segments these leukocytes had come to a halt within the vascular lumen, often the leukocytes appeared to be trapped within the vessel wall. Analysis of these sections by electron microscopy revealed that the leukocytes had passed through endothelial cell junctions but not the basement membrane. In contrast to the effect of the Ab in mesenteric preparations treated with IL-1 beta, leukocyte extravasation induced by topical or intraperitoneal administration of the chemotactic peptide formyl-methionyl-leucyl-phenylalanine was not inhibited by the anti-PECAM-1 Ab. These results directly demonstrate a role for PECAM-1 in leukocyte extravasation in vivo and indicate that this involvement is selective for leukocyte extravasation elicited by certain inflammatory mediators. Further, our findings provide the first in vivo indication that PECAM-1 may have an important role in triggering the passage of leukocytes through the perivascular basement membrane.

Animals↗

PubMed1996

Ciliary disorientation alone as a cause of primary ciliary dyskinesia syndrome.

Ciliary disorientation has been proposed as a variant of primary ciliary dyskinesia (PCD); cilia have normal ultrastructure and normal or near normal ciliary beat frequency (CBF) but lack efficacy because their beat direction is disorientated. We have identified 11 patients, including two siblings, with the clinical features of PCD, who satisfy these criteria. A chest radiograph, pulmonary function tests, nasal mucociliary clearance (NMCC), CBF, ciliary ultrastructure, and orientation were assessed in each subject. One patient had biopsies taken from the nose and both main bronchi. Eight patients had a computed tomography scan (CT) of the thorax; the clinical features were compatible with PCD. Cilia ultrastructure was normal and NMCC was absent in all cases. Mean CBF was normal (11.6-14.9 Hz) in five cases and slow in six (range 8.4-9.7 Hz). Ciliary beat pattern was stiff in seven cases, six of which had slow CBF. The cilia were disorientated when measured by both the central pair (range, 21.8 degrees - 26.4 degrees) and basal feet (range, 20.6 degrees - 28.9 degrees) compared with 16 normal controls (range, 11.0 degrees - 15.5 degrees and 12.3 degrees - 17.6 degrees, respectively). Two siblings had the clinical features of PCD and ciliary disorientation alone on repeated biopsies taken 10 yr apart. Orientation of cilia from the nose and bronchus was similar. Two cases had unchanged ciliary disorientation after 3 mo of treatment with antibiotics and topical corticosteroids. We concluded that ciliary disorientation alone can lead to the clinical syndrome of PCD.

Administration, Topical↗

PubMed1996

A human respiratory-tissue organ culture incorporating an air interface.

The immersion of respiratory tissue in organ cultures is unphysiologic and may influence the interactions of the tissue with experimental agents. We have assessed an organ culture of human nasal turbinate tissue with an air interface by light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), with and without replacement of culture medium. Without replacement of medium, ciliary beat frequency (CBF) was normal (11.3 +/- 0.5 Hz) at 5 d, but fell significantly (p<0.05) to 7.9 +/- 0.8 Hz at 10 d. The degree of ciliation decreased significantly (p<0.05) at 4 and 10 d. Nuclear heterochromatin in all cell types was significantly (p<0.05) reduced at 5 d. Significant (p<0.05) mitochondrial abnormalities occurred in ciliated cells at 5 d and in both ciliated and unciliated cells at 10 d. With daily replacement of medium, CBF fell significantly (p<0.05) from 11.6 +/- 0.2 Hz at Time 0 to 10.6 +/- 0.3 Hz after 20 d. The proportions of ciliated and nonciliated cells did not change after 20 d, but the proportion of mucus cells was higher at 20 d (26.3 +/- 5.4%) than at Time 0 (9.8 +/- 2.7%). No mitochondrial abnormalities, changes in nuclear heterochromatin levels, or reduction in cilial density on ciliated cells were present. The amount of damaged epithelium was less at 20d (7.2 +/- 3.8%) than at Time 0 (19.0 +/- 5.8%). This model more closely reproduces physiologic conditions in vitro than do models involving the immersion of respiratory tissue in media. Its long viability will permit studies of virus and bacterial infections, and of the effects of pharmacologic agents and environmental factors.

Air↗

PubMed1995

Pain: the views of elderly people living in long-term residential care settings.

While an individual's beliefs and attitudes have long been considered important factors in how people respond to pain, few studies have attempted to provide in-depth descriptions of the nature of such pain beliefs and attitudes. The aim of this research was to investigate the views of pain and pain management practices held by elderly people living in long-term residential care settings. Ten 60-90 minute focus group interviews, each involving around five elderly people, were conducted in four large, long-term residential care settings in Brisbane, Australia. Categories of beliefs and attitudes regarding pain were identified following analysis of the verbatim transcripts of these interviews. Findings suggest that many elderly people living in long-term residential care settings may have become resigned to pain, that they are ambivalent about the benefit of any action for their pain and that they may be reluctant to express their pain. Implications of these beliefs and attitudes are discussed.

Aged↗

PubMed1995

The effect of variations in the expression of pili on the interaction of Neisseria meningitidis with human nasopharyngeal epithelium.

Bacterial adherence is essential to colonization of the nasopharynx by Neisseria meningitidis, and pili may facilitate adherence. Scanning electron microscopy and immunogold labeling were used to study the interaction of 2 piliated and 1 nonpiliated variant of N. meningitidis with nasopharyngeal mucosa in an adenoid organ culture system with an air-mucosal interface. Meningococcal infection caused epithelial damage, loss of ciliated epithelium, and ciliary disorganization, which progressed with time and were greater with the piliated strains. Pili increased adherence of meningococci to the mucosa, and there was tropism of piliated strains for nonciliated cells containing microvilli, damaged epithelium, and sites of cell separation. Bacterial adherence was associated with a change in the appearance of the microvilli.

Adenoids↗

PubMed1995

Interaction of pneumolysin-sufficient and -deficient isogenic variants of Streptococcus pneumoniae with human respiratory mucosa.

Streptococcus pneumoniae is the most common cause of community-acquired pneumonia, and pneumolysin, a hemolytic toxin, is thought to be an important virulence factor. We have studied the interaction of a pneumolysin-sufficient type II S. pneumoniae strain (PL+) and an otherwise identical pneumolysin-deficient derivative (PL-) with human respiratory mucosa in an organ culture with an air interface for up to 48 h. Ciliary beat frequency (CBF) was measured by a photometric technique, and adherence to and invasion of the epithelium were assessed by scanning and transmission electron microscopy. PL+ and PL- caused a progressive fall in CBF compared with the control which became significant (P < 0.01) at 24 h for PL+ and at 48 h for PL-. At 24 h, there was a significant increase in the percentage of the mucosa of the organ culture that was damaged for PL+ compared with the control (P < 0.01) and PL- (P < 0.02). At 48 h, there was a significant increase in mucosal damage for both PL+ (P < 0.005) and PL- (P < 0.05) compared with the control. At 24 and 48 h, PL+ and PL- adhered predominantly to mucus and damaged cells. PL+ infection alone caused separation of tight junctions between epithelial cells, and at 48 h PL+ cells were adherent to the separated edges of otherwise healthy unciliated cells. PL+ and PL- both caused damage to the epithelial cell ultrastructure. S. pneumoniae infection caused patchy damage to the respiratory mucosa and a lowered CBF. These changes were more severe and occurred earlier with the pneumolysin-sufficient variant.

Adenoids↗

PubMed1995

Ciliary disorientation in patients with chronic upper respiratory tract inflammation.

Random ciliary orientation was recently described as a possible variant of primary ciliary dyskinesia (PCD). The cilia have normal ultrastructure and nearly normal ciliary beat frequency (CBF) but lack efficacy because the beat direction is disoriented. However, delayed mucociliary clearance (MCC), transitory changes in ultrastructure, and slowed CBF can all occur in the presence of inflammation. This study investigated groups of patients with upper respiratory tract inflammation caused by infection to assess whether ciliary disorientation was present and its relation to MCC. The study population consisted of 10 healthy nonatopic nonsmoking volunteers, 15 patients with idiopathic bronchiectasis and chronic mucopurulent sinusitis, 12 patients with cystic fibrosis, and two patients with the clinical features of PCD but normal CBF and ciliary ulstrastructure. Ciliary disorientation was significantly (p < 0.05) increased in the three patient groups compared with the volunteers, being greatest in the two patients with the clinical features of PCD and in bronchiectasis patients with P. aeruginosa, and was positively correlated (r = 0.9) with MCC but not with CBF. Treatment of one patient with antibiotics and topical corticosteroids for a prolonged period resulted in ciliary disorientation returning to normal. Ciliary disorientation may therefore occur secondary to inflammation caused by infection, and the study suggests that ciliary disorientation rather than ultrastructural abnormalities or slow CBF results in delayed MCC.

Biopsy↗

PubMed1995

In vivo corrosion of cobalt-chromium and titanium wear particles.

Tissue reaction to wear particles from metal implants may play a major role in the aseptic loosening of implants. We used electron microprobe elemental analysis to determine the chemical composition of wear particles embedded in the soft tissues around hip and knee implants from 11 patients at revision surgery for aseptic loosening. The implants were made of cobalt-chromium-molybdenum alloy or titanium-aluminium-vanadium alloy. Histological examination showed a widespread giant-cell reaction to the particles. Elemental analysis showed that the chemical composition of the particles was different from that of the implanted alloys: cobalt and titanium were reduced, often down to zero, whereas chromium and aluminium persisted. Our findings indicate that corrosion is continually changing the shape, size and chemical composition of the implanted alloy. This may alter the biochemical environment of the tissue surrounding an implant to favour bone resorption.

Aluminum↗

PubMed1994

Atypical carcinoid tumour of the lung: a study of 33 cases with prognostic features.

Atypical carcinoids of the lung (well-differentiated neuroendocrine carcinomas) are rare tumours of uncertain prognosis. We have studied 33 cases--male to female ratio 2:1, age range 22-75 years, mean 55 years, 80% smokers, 15 peripheral and 18 central, tumour size 1.2-9.5 cm. Microscopically they had a nesting/insular, trabecular or lobular pattern. Nuclear morphology was variable, round cells, large cells and spindle cells being identified with small cell areas in five tumours. Mitotic activity varied from 4 to 80 per 1.52 mm2. Areas of necrosis were seen in all tumours. All 33 tumours were cytokeratin positive (AE1/AE3 and CAM5.2), 32 were positive for neuron-specific enolase, synaptophysin and chromogranin A. Electronmicroscopy showed dense core granules in 29 available cases. Nineteen cases were stage I, nine stage II, four stage III and one stage IV. Follow-up information was available for 22 cases. Size, location, stage and large cell/small cell morphology were important prognostic indicators. Large tumour size, large cell or mixed large cell/small cell morphology, peripheral localization and advanced stage were adverse prognostic indicators. Mitotic activity and the presence of necrosis did not appear to influence stage or behaviour.

Adult↗