Extracorporeal circulation material evaluation: microemboli.
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Biomedical subjects
Publications and source records attributed to A Murray.
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The gaseous microemboli (GME) production and gas transfer characteristics of two series of bubble oxygenators (Harvey H-1500 and Bentley BOS-10) were evaluated during clinical perfusion in 33 adult patients during open heart surgery for acquired valvular and ischaemic heart disease. For each oxygenator series, patients were divided into two groups, depending upon the method of measurement (intermittent or continuous) of the arterial PO2(PaO2). Using the data available, the perfusionist altered the gas:blood flow ratio in an attempt to maintain the PaO2 within the normal range. In the first group (I = intermittent), where PaO2 data were available only intermittently, the PaO2 values were well above normal, and large numbers of GME were detected in the arterial blood. In the second group (C = continuous), where the PaO2 data were available continuously, there was significantly better control of the PaO2 (P less than 0.001 and P less than 0.01 for the H-1500 and BOS-10, respectively) and significantly fewer GME (P less than 0.01 and P less than 0.05 for the H-1500 and BOS-10, respectively). The Bentley BOS-10 oxygenator used a lower gas:blood flow ratio to achieve physiological levels (range 9 to 13 kPa at 37 degrees C) of PaO2 than did the Harvey H-1500 oxygenator, but there was no difference in the number of GME detected. The lower gas:blood flow ratios for the BOS-10 oxygenators in group C resulted in significantly higher PaCO2 values well outside the physiological range (4 to 6 kPa at 37 degrees C) during the rewarming phase (mean PaCO2 = 7.6 +/- 0.8 kPa) of cardiopulmonary bypass than did the H-1500 oxygenator (mean PaCO2 = 6.3 +/- 0.7 kPa). Mean values for the PaCO2 for both oxygenators during other phases of bypass (cooling and hypothermia) were within the physiological range. If the CO2 retention was corrected by increasing the gas:blood flow ratio the PaO2 values and GME counts became elevated.
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Synthetic peptide constructs, co-linearly linking a MUC1 mucin B cell epitope peptide to a known murine T cell epitope, both in T-B and B-T orientations, show that induction of high murine anti-MUC1 antibody titers is dependent on the presence and orientation of the T cell determinant. However, the sequential order of the epitopes does not affect binding of anti-B cell epitope antibodies to the constructs. Haplotype mismatching leads to a significant lowering of the anti-MUC1 antibody responses, implicating a central role for the T cell epitope in eliciting anti-B cell epitope responses. Secondary structure analysis by circular dichroism spectroscopy reveals the T-B construct to be partially ordered, while the B-T peptide adopts a highly ordered conformation in trifluoroethanol. These studies suggest that the sequential order of epitopes may significantly alter the immunogenicity of the peptide but may not necessarily affect its antigenicity. Immunogenicity of the peptide constructs may be governed by subtle differences in secondary structure, leading to variation in the way peptides are presented or processed within cells governing immune responses. These findings have relevance for the construction of peptides to be utilized as potential synthetic vaccines and for the design of peptide immunogens.
Four specialised air mattresses had interface pressure measured under six body sites prone to pressure sores in 10 subjects, supine and sitting. The mattresses were the Clinirest (SSI) and FirstStep (KCI) continuous airflow mattress overlays, and Airwave (Pegasus) and Nimbus (Huntleigh) alternating pressure air mattresses. On the mattress overlays, average supine interface pressures were 2.33 kPa (scapula), 4.15 kPa (elbow), 1.94 kPa (sacrum) and 2.79 kPa (buttock), although they were higher at the occiput (7.97 kPa) and heel (11.7 kPa). The alternating pressure air mattresses had an average minimum interface pressure close to zero for three sites, rising to 4.28 kPa under the heel. Average maximum interface pressures were 8.61 kPa (occiput), 5.21 kPa (scapula), 4.90 (elbow), 4.85 kPa (sacrum), 4.61 kPa (buttock) and 13.2 kPa (heel). No accepted scientific method exists for comparing the two types of mattress. Our data suggest a clinical benefit at the occiput and heel (supine) in using an alternating pressure air mattress and a benefit in using a continuous airflow mattress overlay at other sites.
Pressures were measured on 10 subjects, supine and sitting, under six anatomical sites prone to bed sores on three different mattresses. Studied were the Clinifloat and Therarest specialist replacement mattresses, and a standard hospital mattress. Mean supine pressures were less than 5 kPa under four sites. Average supine buttock pressure was 2.93 kPa. Occiput and heel pressures were much higher than under other sites, being on average 2.6 and 4.5 times greater respectively than the mean buttock pressure. On sitting up, buttock pressure increased by a factor of 1.7 on average, to a level higher than the accepted capillary closing pressure. Measurements were consistent with mattress design, specific features of which can significantly affect pressure under certain sites.
This study was designed to evaluate the performance of a new automated assay system, the IMMULITE Automated Immunoassay Analyzer in comparison with more commonly used IRMA assays for measuring circulating tumour marker levels in breast cancer patients. The assays investigated measure the MUC1 mucin (CA15-3 antigen) or CEA. Serum samples from breast cancer patients with various stages of disease and from a group of normal individuals were analysed. Significant correlations were found between tumour marker levels measured using the IMMULITE BR-MA and the CA15-3 assays and between levels measured using the two CEA assay formats. Levels of IMMULITE BR-MA and CEA correlated with stage of disease suggesting that both are markers of tumour burden Levels in Stage III breast cancer patients were found to be significantly higher than those of normals using the IMMULITE system but not the IRMA assays. This would suggest a role for the automated system in the monitoring of breast cancer at an earlier stage than that at which tumour markers are routinely used. Elevated marker levels did not correspond to any particular site of metastasis however, a greater proportion of patients with multiple sites of metastasis had elevated levels compared with those with secondary disease at a single site. We conclude that the IMMULITE Automated Immunoassay Analyzer is of value in the routine surveillance of tumour marker levels.
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Prospective randomised trials indicate that the low air loss bed is a successful method of treatment for pressure sores. To study the properties of these beds interface pressures were measured in two different low air loss beds. Ten healthy volunteers had eight readings at six different body sites taken supine and sitting. Occipital and heel pressures for both products exceeded 4.7 kPa, the accepted capillary closing pressure, while pressures at other sites were below this. These findings suggest that pressure relief alone is not the sole reason for the clinical acceptance of low air loss beds in the treatment of pressure sores.
Many murine monoclonal antibodies against MUC1 mucin have been analysed for reactivity against short overlapping peptides with sequences based upon that of the 20 amino acid tandem repeat of the MUC1 protein core, in order to identify the minimum binding units or epitopes. This report summarises the findings using a set of overlapping heptamers to identify the epitopes of 5 established anti-MUC1 antibodies. The results are evaluated and reviewed in comparison to those obtained using other length peptides and other assay formats for epitope mapping using the Pepscan technique.