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Biomedical subjects

A G Pockley

Publications and source records attributed to A G Pockley.

At least 37 records · Page 2Linked to original sources
PubMed2000

Influence of upper- and lower-limb exercise training on cardiovascular function and walking distances in patients with intermittent claudication.

PURPOSE: The effects of upper-limb (arm cranking) and lower-limb (leg cranking) exercise training on walking distances in patients with intermittent claudication was assessed. METHODS: Sixty-seven patients (33 to 82 years old) with moderate to severe intermittent claudication were recruited, and the maximum power generated during incremental upper- and lower-limb ergometry tests was determined, as were pain-free and maximum walking distances (by using a shuttle walk test). Patients were randomly assigned to an upper-limb training group (n = 26) or a lower-limb training group (n = 26). An additional untrained group (n = 15) was recruited on an ad hoc basis in parallel with the main trial by using identical inclusion criteria. This group was subsequently shown to possess a similar demographic distribution to the two exercise groups. Supervised training sessions were held twice weekly for 6 weeks. RESULTS: Both training programs significantly improved the maximum power generated during the incremental upper- and lower-limb ergometry tests (P <. 001), which may reflect an increase in central cardiovascular function that was independent of the training mode. More importantly, pain-free and maximum walking distances also improved in both training groups (P <.001). The improvements in the training groups were similar; there were no changes in the untrained control group. These findings suggest that the symptomatic improvement after upper-limb exercise training may result, in part, from systemic cardiovascular effects rather than localized metabolic or hemodynamic changes. CONCLUSION: Carefully prescribed upper-limb exercise training can evoke a rapid symptomatic improvement in patients with claudication, while avoiding the physical discomfort experienced when performing lower-limb weight-bearing exercise.

Adult↗
PubMed2000

Circulating heat shock protein 60 is associated with early cardiovascular disease.

The phylogenetically conserved nature of heat shock proteins (Hsp) has led to the proposition that they may provide a link between infection and the inflammatory component to vascular disease. Hypertension is associated with atherosclerosis. Here, we measured circulating heat shock protein and heat shock protein antibody levels in association with borderline hypertension. Seventy-two men with borderline hypertension patients and 75 normotensive control subjects (diastolic blood pressure 85 to 94 and <80 mm Hg, respectively) were selected from a population-screening program. The levels of Hsp60; Hsp70; and anti-human Hsp60, anti-human Hsp70, and anti-mycobacterial Hsp65 antibodies were determined with enzyme immunoassay. The presence of carotid atherosclerosis and the intima-media thickness values were determined with ultrasonography. A major novel observation in this report was the detection of circulating Hsp60, which was present at a significantly enhanced level in patients with borderline hypertension. Furthermore, serum Hsp60 was associated with intima-media thicknesses (P<0.01). Anti-Hsp65 antibody levels were higher in borderline hypertension (P<0.001), whereas Hsp70 and anti-Hsp70 antibody levels did not differ. In contrast to anti-Hsp65 antibody, anti-Hsp60 antibody levels were lower in borderline hypertension (P<0.03), although the difference was quantitatively small. None of the parameters evaluated were associated with atherosclerosis, metabolic factors, or smoking. We identified elevated Hsp60 levels in patients with borderline hypertension and an association between early atherosclerosis and Hsp60 levels. The physiological role of Hsp60 release has yet to be defined, but given the proinflammatory properties, these proteins could be involved in the induction/progression of both hypertension and atherosclerosis, as well as being markers for early cardiovascular disease.

Adult↗
PubMed2000

Cytokine regulation of CD44 expression on rat intestinal epithelial cells.

CD44 comprises a family of type I transmembrane glycoproteins that is expressed on a wide range of cells including those of epithelial, lymphoid and myeloid lineage. Although expression of CD44 in the small intestine is typically localised in the crypts of Lieberkuhn, we have reported the expression of CD44 on mature, intestinal villus epithelial cells during the development of small bowel allograft rejection. The mechanisms underlying CD44 up-regulation are unknown, although it may be influenced by localised cytokine production. This study used flow cytometry to assess the effects of recombinant IFN-gamma and TNF-alpha on CD44 expression and hyaluronan binding by the rat small intestinal epithelial cell lines, RIE and IEC 6. IFN-gamma upregulated CD44 expression on RIE (155% of unstimulated control) and IEC 6 (209% of unstimulated control) cells, whereas TNF-alpha had no effect. IFN-gamma had no qualitative effect on CD44, as binding of the ubiquitously expressed extracellular matrix polysaccharide hyaluronan was unchanged. RIE and IEC 6 cells expressed the 82 kDa and 130 kDa major isoforms of CD44, however cytokine stimulation did not affect the expression of these, nor did stimulation induce the expression of other variants. In summary, these findings demonstrate that CD44 expression by intestinal epithelial cells can be regulated by cytokines, yet their ability to bind hyaluronan and the isoform of the expressed CD44 remains unaltered. It appears that localised inflammatory conditions and cytokine production may modify epithelial cell expression of CD44, however the physiological role for such a response has yet to be elucidated.

Alternative Splicing↗
PubMed1999

Identification of human heat shock protein 60 (Hsp60) and anti-Hsp60 antibodies in the peripheral circulation of normal individuals.

Although primarily regarded as being intracellular, this study has identified the presence of heat shock protein 60 (Hsp60) in the peripheral circulation of normal individuals. The median Hsp60 concentration was approximately 3.5-fold higher in females than in males and significantly higher levels of anti-human Hsp60 antibodies were also detected in females. There were no differences in the levels of antibodies to mycobacterial Hsp60 between males and females, nor did antibody levels correlate with Hsp60 concentrations. Hsp60 was not released from mitogenically stimulated peripheral blood mononuclear cells. The potential physiological roles for circulating Hsp60 are unknown. Given the emerging evidence that inappropriate reactivity to heat shock proteins is involved in autoimmune disease and that T cells responsive to self Hsp60 appear to be protective, these findings suggest that circulating Hsp60 may be involved in the regulation of tolerance to self and immunity to bacterial forms of these widely expressed and structurally conserved proteins.

Adult↗
PubMed1998

Effect of ex vivo storage on human peripheral blood neutrophil expression of CD11b and the stabilizing effects of Cyto-Chex.

CD11b is the alpha sub-unit of the CD11b/CD18 heterodimeric complex that has a key role in neutrophil-endothelial cell interactions and early events in inflammatory responses. Accurate assessment of CD11b expression by neutrophils can be problematic since the procedures that isolate cells from whole blood can increase antigen expression. This study used whole blood flow cytometry to monitor neutrophil CD11b expression following 0, 1, 2, 3 and 4 h of ex vivo incubation at room temperature and examined the effects of storage at 4 degrees C and the cell stabilization solution, Cyto-Chex, on antigen expression. Cyto-Chex-treated samples were also re-analyzed after 7 days storage at 4 degrees C. Neutrophil CD11b expression was high (> 90%) in five of the seven samples studied and incubation at room temperature induced a progressive upregulation which was significant after 2, 3, and 4 h (p < 0.05). Storage at 4 degrees C tempered this effect, although an increased expression (from baseline) was still observed after 4 h (p < 0.05). Cyto-Chex had no effect on the light scatter characteristics of treated cells and prevented CD11b upregulation in samples stored at room temperature. Furthermore, expression in Cyto-Chex-treated samples after 7 days was not significantly different from that observed in baseline (time 0) samples. In two samples demonstrating low neutrophil CD11b expression, a temperature-independent increase in the proportion of CD11b+ cells was observed over time. However, this increase was attenuated by treatment with Cyto-Chex. These findings indicate that sample storage significantly affects CD11b expression and caution should be exercised when interpreting data. Given that Cyto-Chex had no effect on the light scatter properties of cells and prevents antigen upregulation, this reagent may be useful for studies involving analysis of neutrophil activation antigen expression.

Blood Preservation↗
PubMed1998

Detection of heat shock protein 70 (Hsp70) and anti-Hsp70 antibodies in the serum of normal individuals.

Heat shock or stress proteins (Hsp) are typically regarded as being intracellular proteins that have a range of functions including the maintenance of cellular integrity. Members of the Hsp70 family of molecules have been implicated in the processing and presentation of antigen and the cross reactivity of lymphocytes specific for pathogen-derived heat shock proteins with self Hsp70 has been suggested to be an underlying cause of certain autoimmune diseases. This study reports the presence of soluble Hsp70 in the peripheral circulation of normal individuals. Concentrations of soluble Hsp70 in females were approximately twice those in males. Circulating anti-Hsp70 antibodies were detected in all individuals assessed, but there were no differences between males and females. However, there was a significant correlation between soluble Hsp70 concentration and antibody levels in males, but not females. The physiological role for circulating heat shock proteins is intriguing, but currently unknown. These findings extend our previous observations that Hsp60 is present in the peripheral circulation and support the proposition that soluble heat shock proteins may play a regulatory role in either the prevention or protection of pathophysiological processes involving inadvertent immunorecognition or cross-recognition of heat shock proteins.

Adult↗
PubMed1997

Treatment of severe Raynaud's syndrome by injection of autologous blood pretreated by heating, ozonation and exposure to ultraviolet light (H-O-U) therapy.

OBJECTIVE: To determine the effect of re-injection of small samples of autologous blood, pretreated with heat, ozone and ultraviolet light (H-O-U therapy) in patients with severe Raynaud's syndrome. EXPERIMENTAL DESIGN: Open trial in 4 patients. SETTING: Temperature/humidity controlled vascular laboratory. PATIENTS: Severe Raynaud's syndrome of more than 5 years duration and defined as more than 5 attacks daily or 10 attacks in one week, at least half of which were painful and lasting for more than 30 minutes. Three patients were refractory to infusions of Iloprost. INTERVENTIONS: Patients were treated daily or on alternate days for a two to three weeks period by re-injection of citrated autologous blood pre-treated with heat, ozone and ultraviolet light (H-O-U therapy). MEASURES: Clinical observations; mean equilibrated hand temperature (infrared thermography); distributive and microcirculatory blood-flow (venous occlusion strain-gauge plethysmography, infrared photoplethysmography, laser Doppler flowmetry) iontophoresis of acetylcholine and sodium nitroprusside; estimations: serum levels of 6-keto-PGF1alpha and serum levels of anti-hsp65 antibody. RESULTS: Reduction or abolition of Raynaud's attacks for at least three months after treatment. Mean equilibrated hand temperature increased but did not normalise. Blood flow parameters improved but did not reach statistical significance. Iontophoresis of acetylcholine showed an increase in laser Doppler flowmetry which was statistically significant. Serum levels of 6-keto-PGF1alpha, fell significantly in three patients. Serum levels of anti-hsp65 antibody fell in the one patient which was followed sequentially. CONCLUSIONS: H-O-U therapy may prove useful in patients with severe Raynaud's syndrome.

6-Ketoprostaglandin F1 alpha↗
PubMed1996

Evidence that orthotopic transposition following rat heterotopic small bowel transplantation corrects overgrowth of potentially pathogenic bacteria.

An overgrowth of pathogenic organisms occurs following rat heterotopic small bowel transplantation. This study assessed whether the bacterial microflora return to normal following subsequent orthotopic transposition of the graft. After 14 days the heterotopic graft was placed into continuity following resection of 15 cm of the host midintestinal loop. Quantitative and qualitative analyses of the intraluminal bacteria were performed studying the resected host intestine, the heterotopic graft at 14 days, and the graft 14 days after transposition. A group of normal rats were used as controls. An overgrowth of Staphylococcus epidermidis evident in the heterotopic graft at 14 days returned to a more normal bacterial profile following orthotopic transposition. These findings suggest that early interposition of a small bowel graft into an orthotopic position may prevent an alteration in the small bowel ecology toward potentially pathogenic organisms capable of translocation.

Abdominal Muscles↗
PubMed1995

CD44 expression in rejecting rat small bowel allografts.

CD44 is a widely expressed cell surface protein that recognizes multiple ligands and is involved in extra- and intercellular adhesion. The precise role of CD44 in immune interactions is currently unknown, but it is believed to be a homing receptor involved in lymphocyte trafficking and inflammatory responses. This study investigated CD44 expression in intestinal tissue after heterotopic rat small bowel transplantation and assessed the effect of transplantation on intestinal epithelial cell proliferation using an antibody to the nuclear activation Ag Ki67. Lamina propria and intestinal epithelial cell expression of CD44 was graded blindly by five observers, and villus epithelial cells were noted as being positive or negative for Ki67 staining. CD44 expression was high in the lamina propria of both allografted and isografted animals; however, there was no significant difference between the two groups. In contrast, the expression of CD44 on the villus epithelium was greater in allografted animals and progressed toward the villus tips as rejection developed, declining thereafter because of loss of villus integrity. Ki67 positivity was also greater in allografted animals but did not progress toward the villus tip. This is the first reported observation of CD44 expression on intestinal epithelium that is not restricted to the crypts. The findings indicate the involvement of CD44 in the rejection process and demonstrate changes in the proliferative profile of rejecting small intestinal epithelium. Further studies into adhesion molecules, such as CD44, may help to improve understanding of graft failure and promote the development of new therapeutic approaches for controlling and preventing graft rejection.

Animals↗
PubMed1995

Differential expression of adhesion molecules during rat small bowel allograft rejection.

The adhesion molecules intercellular adhesion molecule 1 (ICAM-1), lymphocyte function-associated antigen-1 (LFA-1) (alpha and beta chains), and very late activation antigen-4 (VLA-4) have an essential role in cell-cell interactions and the initiation of immune responses. This study used an indirect immunoperoxidase technique to investigate the expression of these molecules in the lamina propria of allografts and isografts after heterotopic rat small bowel transplantation. Normal untransplanted small bowel served as additional controls. Overall, ICAM-1 and LFA-1 alpha expression was significantly higher in allografts, although there was variable expression of these molecules in isografted animals. There were temporal differences in the expression of ICAM-1 and LFA-1 alpha in that increased ICAM-1 expression was more pronounced in the the early posttransplant period, whereas there was a progressive increase in LFA-1 alpha as rejection developed. In contrast, there was no difference between allograft and isograft expression of LFA-1 beta and VLA-4. This study has demonstrated a preferential increase in adhesion molecule expression with developing rat small bowel allograft rejection and suggests that adhesion molecules are involved in the development and progression of allograft rejection. Although the observed differences in antigen expression are not as marked as those previously reported in other organ transplants, appropriate adhesion molecules may present suitable targets for immunotherapeutic protocols after small bowel transplantation.

Animals↗
PubMed1995

Development of an enzyme immunoassay for rat soluble interleukin-2 receptors.

This study describes the development of a sandwich enzyme immunoassay (ELISA) for rat soluble IL-2 receptors (sIL-2R) using a combination of monoclonal antibodies reactive with different epitopes on the rat IL-2R. Coating plates with NDS61 and NDS64 monoclonal antibodies produced similar dose-response curves when incubated with a standard sIL-2R preparation followed by biotinylated OX39, streptavidin-alkaline phosphatase and the substrate. Although normal rat serum inhibited the assay, the effects were more profound when NDS64 was used as the capture antibody and subsequent development of the assay was performed using NDS61. The intra- and interassay variations were typically less than 5%. This assay will be valuable for monitoring immune activation status in a variety of experimental models.

Animals↗
PubMed1995

Influence of soluble suture factors on in vitro macrophage function.

Suture materials may interact with immune competent cells and thereby affect localized immunity. Macrophages are central to the inflammatory response and coordinate wound healing. They are also involved in the clearance of foreign material, bacteria and malignant cells. We studied the influence of soluble factors associated with silk, steel, nylon, polyglactin, polydioxanone and chromic catgut sutures on macrophage adherence, phagocytosis and the production of lysozyme and tumour necrosis factor. Soluble factors from suture materials influenced macrophage behaviour in vitro causing cellular activation, functional impairment and alterations in secreted levels of the cytokine tumour necrosis factor and the bactericidal agent lysozyme. Of the six materials studied, polyglactin had the most extreme effect, causing significant inhibition of cell adherence and lysozyme production. Silk also exerted a considerable effect on macrophages, significantly inhibiting adherence. In contrast, steel and polydioxanone media caused minimal inhibition of macrophage function although, as with all materials, they did activate the cells. This study has demonstrated that sutures release immunotoxic factors which considerably influence macrophage behaviour in vitro. These effects may have important clinical implications.

Animals↗