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Biomedical subjects

Richard Wenstone

Publications and source records attributed to Richard Wenstone.

8 recordsLinked to original sources
PubMed2005

Markers of oxidative damage, antioxidant status and clinical outcome in critically ill patients.

BACKGROUND: Oxidative stress is a consequence of critical illness, and may have an impact on survival. We studied markers of oxidative damage and antioxidant (AO) protection and compared them with clinical scores and outcome. METHODS: Blood sampling and clinical scoring was carried out on 60 consecutively admitted intensive therapy unit (ITU) patients within 24 h of admission and then every three days of ITU stay. The patients included 30 surgical and 30 medical patients, of whom 46 survived their stay in ITU. Clinical scoring was by Acute Physiology and Chronic Health Evaluation (APACHE) II score, multiple organ dysfunction (MOD) score and sepsis rating. Oxidative damage was assessed by measurement of plasma malondialdehyde (MDA) and F2 isoprostanes (F2 IsoPs). AO protection was assessed by measurement of plasma total AO status, AO gap, ascorbic acid and the enzymes glutathione peroxidase and superoxide dismutase. RESULTS: Both clinical markers, APACHE II and MOD, and oxidative damage markers MDA and F2 IsoPs were significantly higher in non-survivors (NS) than in survivors (S) at the time of admission. Median (interquartile ranges) were (APACHE II), 14[12--17] (S), 20.5[16.7--22.2] (NS),P<0.0001; (MOD), 3.0[2.0--5.0] (S), 8.0[4.7--9.2] (NS), P<0.0005; (MDA, mumol/L), 0.22[0.19--0.27] (S), 0.25[0.20--0.34] (NS), P=0.04 and (F2 IsoPs, pg/mL), 9.7[6.0--9.9] (S), 11.0[9.0--12.0] (NS), P=0.01. Oxidative damage markers reduced (improved) in the survivors but increased in the non-survivors. There was little difference between the groups in AO protection markers. There was a significant positive correlation between MOD and markers of oxidative damage at the time of admission (r=0.40, P=0.003, F2 IsoPs; r=0.28, P=0.035, MDA) and between the oxidative damage markers themselves (r=0.32, P=0.017). CONCLUSION: Increased oxidative stress is associated with poor outcome in critically ill patients, and may be a prognostic indicator. Oxidative damage markers are more useful than AO protection markers in predicting outcome.

Antioxidants↗
PubMed2004

HLA-DR regulation and the influence of GM-CSF on transcription, surface expression and shedding.

Low surface HLA-DR expression is a feature in sepsis. However, the mechanisms that regulate HLA-DR expression have not been elucidated. The current study investigates regulation of HLA-DR gene transcription, post transcriptional events and shedding of surface HLA-DR, as well as the regulation of HLA-DR by GM-CSF and an immunomodulatory cytokine. Plasma and PBMC were collected from septic patients and healthy volunteers. An ELISA was developed to measure soluble HLA. PCR techniques were used to determine HLA-DR mRNA levels, and flow cytometry and fluorescent microscopy were used for measurement of surface expressed and intracellular HLA-DR. Septic patients fulfilling the criteria of the American College of Chest Physicians (ACCP) for sepsis were recruited for the study (n=70). HLA-DR was measured on three consecutive days, days seven and fourteen. Patients were excluded from the study if on immunosuppressive therapy. Results: Higher levels of shed HLA-DR were found in the plasma of septic patients compared to healthy controls. The level of HLA-DR mRNA was significantly lower in septic patients compared to healthy controls, however an increased intracellular HLA-DR expression was observed. When HL-60 cells were treated with GM-CSF, gene transcription, surface expression and shedding of HLA-DR were all up-regulated. These results indicate that the mechanisms involved in the regulation of HLA-DR in sepsis include shedding of HLA-DR from the cell surface and regulation of HLA-DR gene transcription. Post-translational processing of HLA-DR was also seen to be compromised. GM-CSF was shown to regulate HLA-DR at all these levels.

Journal Article↗
PubMed2003

Is low monocyte HLA-DR expression helpful to predict outcome in severe sepsis?

OBJECTIVE: Low monocyte human leukocyte antigen-DR (HLA-DR) expression has been reported to be an indicator of poor survival in critically ill septic patients. We assessed its usefulness as a prognostic indicator in order to identify possible interventions to normalise HLA-DR expression in those patients with lowered monocyte HLA-DR. DESIGN: HLA-DR expression was measured on separated monocytes of septic patients, using flow cytometry, and HLA-DR upregulation was measured by the same techniques after ex vivo stimulation with granulocyte macrophage colony stimulating factor (GM-CSF). APACHE II score, age, sex and outcome were determined for all patients. SETTING: A single-centre study at the Royal Liverpool University Hospital in a medico-surgical 13-bed intensive care unit. PATIENTS AND PARTICIPANTS: All septic patients ( n=70) fulfilling the criteria of the ACCP for the diagnosis of sepsis were recruited for the study with informed consent from day 1 of diagnosis of sepsis and monocyte HLA-DR expression measured on 3 consecutive days. Patients were excluded from the study if they were on immunosuppressive therapy. Normal healthy volunteers ( n=45) were included. RESULTS: Low monocyte surface expression and median fluorescence density HLA-DR expression was not associated with a high mortality. High APACHE II scores were not correlated with low HLA-DR expression. However, in those patients where HLA-DR expression was lowered, this could be restored ex vivo by GM-CSF. CONCLUSIONS: In the group of septic patients under study, HLA-DR was not a useful prognostic marker of outcome. We did not find a higher mortality in the group of patients who had low expression. These findings are contradictory to some previously reported findings, and the possible reasons are discussed.

Adult↗
PubMed2002

Early identification of sepsis and mortality risks through simple, rapid clot-waveform analysis. Implications of lipoprotein-complexed C reactive protein formation.

OBJECTIVE: To determine if the rapid waveform profile of the activated partial thromboplastin time (aPTT) assay, which detects lipoprotein-complexed C reactive protein (LCCRP) formation, predicts sepsis and mortality in critically ill patients. DESIGN: Observational, cohort study. SETTING: General intensive therapy unit (ITU) of a tertiary care hospital. PATIENTS AND PARTICIPANTS: A total of 1187 consecutive patients admitted to the ITU. INTERVENTION: Activated partial thromboplastin time transmittance waveform analysis was performed within the first hour of admission to the ITU. The degree of change causing a biphasic waveform was quantified through the drop in light transmittance level. MEASUREMENTS AND RESULTS: Three hundred forty-six patients had a biphasic waveform on admission to the ITU with a mortality rate of 44% compared with 26% for those with normal waveforms. Logistic regression models showed direct correlation between the likelihood for sepsis and in-patient mortality with increasing waveform abnormalities. The mortality fraction was 0.3 with normal waveforms versus 0.6 when the light transmittance decreased by 30%. The odds ratio (OR) for mortality and sepsis were 4.5 and 11, respectively, from the most abnormal to normal aPTT waveforms. These were comparable with APACHE II scores and superior to those estimated by CRP for mortality (OR 2.3) / sepsis (OR 6.4) prediction. CONCLUSION: Waveform analysis within the first hour of ITU admission is a single, simple and rapid method of identifying the risks of mortality and sepsis. Its measure of LCCRP formation shows superior prediction over CRP alone and it warrants further assessment as a tool to triage and target prompt, appropriate treatment in the ITU.

C-Reactive Protein↗
PubMed2002

Biphasic transmittance waveform in the APTT coagulation assay is due to the formation of a Ca(++)-dependent complex of C-reactive protein with very-low-density lipoprotein and is a novel marker of impending disseminated intravascular coagulation.

A decrease in light transmittance before clot formation, manifesting as a biphasic waveform (BPW) pattern in coagulation assays, was previously correlated with the onset of disseminated intravascular coagulation (DIC). In this study of 1187 consecutive admissions to the intensive care unit, the degree of this change on admission predicts DIC better than D-dimer measurements. Additionally, the BPW preceded the time of DIC diagnosis by 18 hours, on average, in 56% (203 of 362) of DIC patients. The BPW is due to the rapid formation of a precipitate and coincident turbidity change on recalcification of plasma. The isolated precipitate contains very-low-density lipoprotein (VLDL) and C-reactive protein (CRP). The addition of CRP and Ca(++) to normal plasma also causes the precipitation of VLDL and IDL, but not LDL or HDL. The K(d) of the CRP/VLDL interaction is 340 nM, and the IC(50) for Ca(++) is 5.0 mM. In 15 plasmas with the BPW, CRP was highly elevated (77-398 microg/mL), and the concentration of isolated VLDL ranged from 0.082 to 1.32 mM (cholesterol). The turbidity change on recalcification correlates well with the calculated level of the CRP-VLDL complex. Clinically, the BPW better predicts for DIC than either CRP or triglyceride alone. The complex may have pathophysiological implications because CRP can be detected in the VLDL fraction from sera of patients with the BPW, and the VLDL fraction has enhanced prothrombinase surface activity. The complex has been designated lipoprotein complexed C-reactive protein.

Biomarkers↗
PubMed2002

Low plasma granulocyte-macrophage colony stimulating factor is an indicator of poor prognosis in sepsis.

OBJECTIVE: Monocyte dysfunction has been shown to be associated with adverse consequences in septic patients. The cytokine growth factor granulocyte-macrophage colony stimulating factor (GM-CSF) may be required for optimal monocyte function in these patients. The current study investigates whether plasma GM-CSF levels were significantly different in septic patients and whether there was an association with prognosis. DESIGN: Plasma samples were collected from all septic patients from day 1 of the diagnosis of sepsis for 3 days. Healthy volunteer plasma served as control samples. A novel enzyme-linked immuno-adsorbent assay was developed with suitable sensitivity for detection of GM-CSF in patient and normal plasma. APACHE II score, age, sex and outcome were determined for all patients. SETTING: A single centre study at the Royal Liverpool University Hospital in a medico-surgical 13 bed intensive care unit. PATIENTS: All septic patients (n = 53) fulfilling the criteria of the APCC for the diagnosis of sepsis, were recruited for the study with informed consent from day 1 of the diagnosis of sepsis and plasma GM-CSF measured on three consecutive days. Patients were excluded from the study if on immunosuppressive therapy. Normal healthy volunteers (n = 33) were included in the study to serve as controls. RESULTS: Plasma GM-CSF levels were statistically significantly depressed in patients who died compared with those who survived, who had levels comparable with healthy controls. CONCLUSIONS: The results indicate that low plasma GM-CSF is associated with adverse consequences for septic patients. The measurement of GM-CSF in the plasma of septic patients merits further study for use as a prognostic marker and also to identify the type of immunotherapy the patient may benefit from.

APACHE↗
PubMed2002

Lipoprotein-complexed C-reactive protein and the biphasic transmittance waveform in critically ill patients.

The 'biphasic transmittance waveform' (BTW) refers to a decrease in light transmittance that often occurs prior to clotting in coagulation assays of critically ill patient plasmas. It correlates with disseminated intravascular coagulation and mortality. The present work shows that the BTW is due to the rapid formation of a precipitate and a coincident change in turbidity in re-calcified plasma. The precipitate was isolated from patient plasma and contained lipids typical of very low density lipoprotein (VLDL), plus the proteins apolipoprotein B-100 and C-reactive protein (CRP). Precipitation also occurred in normal plasma supplemented with CRP. In addition, CRP precipitated with VLDL and intermediate density lipoprotein, but not low density lipoprotein or high density lipoprotein. The Kd value for the CRP/VLDL interaction is 340 nM. The IC50 value of Ca2+ for complex formation is 5.0 mM, and epsilon-aminocaproic acid inhibits the process. In 15 plasmas with the BTW from critically ill patients, CRP was highly elevated (77-398 microg/mL) and VLDL cholesterol ranged from 0.082 to 1.32 mM. The magnitude of the turbidity change on re-calcification correlated well with the calculated level of the CRP/VLDL complex. Thus, the Ca2+-dependent formation of a complex between CRP and VLDL accounts for the BTW.

C-Reactive Protein↗