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Biomedical subjects

S Ridley

Publications and source records attributed to S Ridley.

At least 37 records · Page 2Linked to original sources
PubMed1999

Phospholipid hydroperoxide cysteine peroxidase activity of human serum albumin.

Human serum albumin (HSA) reduced the phospholipid hydroperoxide, 1-palmitoyl-2-(13-hydroperoxy-cis-9, trans-11-octadecadienoyl)-l-3-phosphatidylcholine (PLPC-OOH) to the corresponding hydroxy-derivative with a high apparent affinity (Km=9. 23+/-0.95 microM). Removal of bound lipid during purification increased this activity. At physiological concentration, HSA reduced the phospholipid hydroperoxide in the absence of a cofactor. However, in the presence of a cofactor (reductant), the rate of the reaction was increased. All of the major aminothiols in plasma could act as reductants, the best being the most abundant, cysteine (Km=600+/-80 microM). For every nanomole of PLPC-OOH reduced by HSA, 1.26 nmol of cystine was formed, indicating a reaction stoichiometry of 1 mol PLPC-OOH to 2 mol cysteine. We used chemical modification to determine which amino acid residues on HSA were responsible for the activity. Oxidation of thiol group(s) by N-ethylmaleimide led to a reduction in the rate of activity, whereas reduction of thiols by either dithiothreitol or the angiotensin-converting enzyme inhibitor, captopril, increased the activity. Both N-ethylmaleimide-modified HSA and dithiothreitol-treated HSA exhibited increased apparent affinities for PLPC-OOH. For a range of preparations of albumin with different modifications, the activity on PLPC-OOH was dependent on the amount of free thiol groups on the albumin (correlation coefficient=0.91). Patients with lowered albumin concentrations after septic shock showed lowered total plasma thiol concentrations and decreased phospholipid hydroperoxide cysteine peroxidase (PHCPx) activities. These results therefore show for the first time that HSA exhibits PHCPx activity, and that the majority of the activity depends on the presence of reduced thiol group(s) on the albumin.

Bilirubin↗
PubMed1999

The development of a method for comparative costing of individual intensive care units. The Intensive Care Working Group on Costing.

Intensive care is one of the most costly areas of hospital care. Unfortunately, because of the diversity of case mix, costing intensive care is difficult. Many described costing methods previously are limited by being cumbersome, laborious to apply and expensive. The aim of this study was to develop a method for costing intensive care which can be applied with ease but facilitate meaningful cost comparisons between intensive care units. The method developed was based on cost blocks where the major components were identified and costed in a 'top-down' manner. Using strict definitions, the cost blocks attempted to measure the costs of equipment, estates, nonclinical support services (such as hospital management costs), clinical support services (such as physiotherapy, laboratory services), consumables (such as drugs, fluids and disposables) and staff. The study found that clinical support services, consumables and staff costs accounted for approximately 85% of the total costs.

Cost Allocation↗
PubMed1999

A comparison of the effects of dopexamine and prostacyclin in systemic inflammatory response syndrome.

Forty critically ill patients fulfilling the definitions of systemic inflammatory response syndrome were enrolled in a double-blind cross-over interventional study assessing the effects of dopexamine and prostacyclin on splanchnic perfusion, cardiovascular function and oxygen flux. The cross-over design involved either dopexamine (1.25 micrograms.kg-1.min-1) or prostacyclin (0.5 ng.kg-1.min-1) being infused for 6 h followed by a 12-h washout period prior to an identical infusion sequence using the other agent. Preliminary analysis revealed a significant period effect, so data from the second infusion period were excluded from further analysis. Dopexamine caused a significant increase in heart rate (116 vs. 106 beat.min-1), and urine output (103 vs. 69 ml.h-1). Dopexamine produced a significant increase in oxygen delivery (infusion 548 ml O2.min-1.m-2; no infusion 492 ml O2.min-1.m-2) while prostacyclin caused a decrease (infusion 460 ml O2.min-1.m-2; no infusion 547 ml O2.min-1.m-2). The results indicate that dopexamine improves oxygen delivery and urine output more effectively than prostacyclin.

Adrenergic beta-Agonists↗
PubMed1999

Critically ill medical patients, their demographics and outcome.

There are few reports describing the demographic details and outcome of noncoronary medical patients on adult general intensive care units. It is not known how medical patients differ from other critically ill patients and how this may influence their outcome. Consequently, we recorded the demographic details of 374 critically ill medical patients and followed their survival for up to 3 years. Patients referred from medical specialties are younger, more severely ill and suffer a higher severity-of-illness-adjusted intensive care unit mortality than other patients. The short-term survival of medical patients is poor with a median survival of 40 days. Twenty per cent of medical patients die after discharge from intensive care but before 40 days. However, the long-term survival of medical patients is better than other patients and almost as good as the general population. Further research is required to identify those patients who are likely to survive beyond 40 days.

APACHE↗
PubMed1998

Deglycosylation of flavonoid and isoflavonoid glycosides by human small intestine and liver beta-glucosidase activity.

Flavonoid and isoflavonoid glycosides are common dietary phenolics which may be absorbed from the small intestine of humans. The ability of cell-free extracts from human small intestine and liver to deglycosylate various (iso)flavonoid glycosides was investigated. Quercetin 4'-glucoside, naringenin 7-glucoside, apigenin 7-glucoside, genistein 7-glucoside and daidzein 7-glucoside were rapidly deglycosylated by both tissue extracts, whereas quercetin 3,4'-diglucoside, quercetin 3-glucoside, kaempferol 3-glucoside, quercetin 3-rhamnoglucoside and naringenin 7-rhamnoglucoside remained unchanged. The Km for hydrolysis of quercetin 4'-glucoside and genistein 7-glucoside was approximately 32+/-12 and approximately 14+/-3 microM in both tissues respectively. The enzymatic activity of the cell-free extracts exhibits similar properties to the cytosolic broad-specificity -glucosidase previously described in mammals.

Cell Extracts↗
PubMed1998

Intensive care services; a crisis of increasing expressed demand.

Critical care services appear to face increasing demand. To attempt to identify factors which may predispose to such increases in demand, the patients and their treatment were reviewed. The patients' ages, referring specialty and their risk of hospital mortality were recorded on admission. The durations of respiratory and renal support (if required) were recorded. Pulmonary artery catheter insertion and the number of vasoactive drugs infused were also noted. During the study, the capacity of the intensive care unit was initially increased by one bed (from six to seven) and later by a six-bedded high-dependency unit. This capacity increase was not matched by a proportionate decrease in occupancy. The patients' mean ages increased by 1 year per year. The number of patients referred from general surgery consistently increased. The proportion of patients receiving vasoactive drugs and pulmonary artery catheters declined as did the duration of respiratory and renal support.

Adult↗
PubMed1998

The impact of a high-dependency unit on the workload of an intensive care unit.

While there has been recent support for high-dependency unit development, there are few data reporting the impact of such development on existing critical care facilities. Therefore the aim of this study was to examine the workload and capacity constraints of an adult general intensive care unit before and after the development of an adjacent high-dependency unit. Following the opening of the high-dependency unit, the total number of patients admitted increased by 49%. On the high-dependency unit, more elderly patients were admitted for longer and more frequently following midweek elective surgery. On the intensive care unit, patients' initial severity of illness was lower and their duration of admission decreased; fewer patients were admitted directly from the general wards. The financial benefits of high dependency care may be eroded by the increased use of the critical care services.

APACHE↗
PubMed1998

Severity of illness scoring systems and performance appraisal.

A large number of severity of illness scoring systems have been developed and they are widely used in intensive care practice. However, they are complex systems with their basis in mathematics. To use such systems effectively, it is important to appreciate what factors influence their performance so that they can be compared fairly and used most appropriately. The purpose of this review is to describe the methods commonly used to assess the various facets of performance in severity of illness scoring systems. The performance of the most frequently used scoring systems in adult intensive care practice are presented. The shortfalls, misuse and strengths of scoring systems are also discussed.

APACHE↗
PubMed1998

Classification trees. A possible method for iso-resource grouping in intensive care.

Classification and grouping of clinical data into defined categories or hierarchies is difficult in intensive care practice. Diagnosis-related groups are used to categorise patients on the basis of diagnosis. However, this approach may not be applicable to intensive care where there is wide heterogeneity within diagnostic groups. Classification tree analysis uses selected independent variables to group patients according to a dependent variable in a way that reduces variation. In this study, the influence of three easily identified patient attributes on their length of intensive care unit stay was explored using classification analysis. Two thousand five hundred and forty-five critically ill patients from three hospitals were classified into groups so that the variation in length of stay within each group was minimised. In 23 out of 39 terminal groups, the interquartile range of the length of stay was < or = 3 days.

Critical Care↗
PubMed1997

Outcome of intensive care in the elderly.

The long-term survival of elderly patients following critical illness in the United Kingdom has not previously been studied. The demographic (age, sex, diagnosis, severity of illness) and treatment details (admission type, length of treatment, prior surgery) of all critically ill patients aged over 70 years were recorded. The 1-year survival of such patients was measured and compared with that of a matched normal population. Of 474 patients aged over 70 years, 88 patients died on the intensive care unit (19% mortality) and a further 133 died within 1 year (total mortality 47%). The 1-year survival of patients aged < 85 years was 56% which was significantly better than that of patients over 85 years (27%). The survival of all critically ill elderly patients was significantly poorer than that of a matched normal population (1-year survival 93%). Logistic regression revealed that age, diagnosis and severity of illness are independent predictors of 1-year survival.

Age Factors↗
PubMed1997

Reliability of the next of kins' estimates of critically ill patients' quality of life.

The aim of this study was to determine the reliability and validity of relatives' assessment of patients' quality of life and to measure the agreement between patients' and relatives' responses to the Short Form 36 quality of life questionnaire, at discharge from and 6 months following intensive care treatment. Ninety-nine patient-relative pairs were studied. Reliability was quantified by using measures of internal consistency (Cronbach's alpha and correlation coefficients) and reliability coefficients. Relatives' responses met the required standards of reliability and validity, but reliability was consistently weaker in the mental health dimension. Relatives' and patients' scores differed significantly in six dimensions at discharge; however, agreement between patients' and relatives' responses, as measured by the Kappa statistic, was fair, improved over 6 months, and was greatest in aspects concerning physical health. We conclude that relatives are able to give a good proxy assessment of functional aspects of quality of life.

Adolescent↗
PubMed1997

Heterogeneity in intensive care units: fact or fiction?

Reports and guidelines concerning intensive care practice have been issued recently. However, the introduction of such centrally issued recommendations may be difficult because of marked heterogeneity between intensive care units. This study examined the facilities (number of beds, consultant sessions, nursing establishment), annual workload (number and types of patients admitted) and outcome (intensive care unit mortality) in the (old) Anglia Region. There were significant differences in the distribution of patients' ages, severities of illness, diagnoses, durations of admission and outcomes. Such heterogeneity may make multicentre trials more difficult to conduct and create problems when uniform measures designed to improve intensive care services are being planned.

APACHE↗
PubMed1997

Unilateral brain lesions and performance on Russell's version of the Wechsler Memory Scale in an African American population.

Studies of patients with unilateral lesions report hemisphere-specific and locus-specific impairments on Russell's (1975) Revision of the Wechsler Memory Scale (RWMS). In the current investigation "race-homogeneous" and "race-comparative" paradigms provide the context in which the generalizability of RWMS findings are examined in a population of African Americans with unilateral lesions. The performances of brain-damaged patients were impaired relative to normal controls on five of the six RWMS measures. However, patients with left and right hemisphere damage in our sample did not differ systematically on RWMS subtests. Likewise, among patients with lesions confined to one of the quadrants in the brain, there were no quadrant group differences in performance on RWMS subtests. But, right posteriors were impaired relative to controls on immediate and delayed VR subtests. The relative merits of the race-comparative and race-homogeneous paradigms are considered in the context of these findings.

Adult↗
PubMed1994

A cost-utility analysis of intensive therapy. II: Quality of life in survivors.

A questionnaire designed to assess changes in quality of life was sent to 56 survivors of critical illness one year after their admission to an intensive therapy unit. Forty-one patients completed the questionnaire, and for the majority, quality of life remained unchanged (n = 25). However significant decreases in quality of life were found in those patients who previously enjoyed a good quality of life or were admitted with respiratory problems. Survivors also recorded significant decreases in five aspects of their perceived quality of life (ability to think and remember, seeing family, their contribution to society, activities outside work and income). As part of a previous study, the costs incurred by each of these patients had been measured so that changes in quality of life detected in this study could be combined to the individual costs and expressed as cost per quality adjusted life year. The cost of intensive therapy for a patient surviving for one year after acute respiratory or cardiovascular disease was 2600 pounds. The total hospital cost per quality adjusted life year was estimated at 7500 pounds, which places intensive therapy at the higher end of health programme costs. If the costs of nonsurvivors are included in the cost per quality adjusted life year calculation, the cost of intensive care increases considerably.

Adult↗
PubMed1994

Quality of life after multiple trauma requiring intensive care.

A prospective observational study using structured interviews was used to assess changes in quality of life experienced by surviving trauma victims after management on a general intensive therapy unit in a district general hospital. Each patient's age, distribution of injuries, severity of illness on admission and duration of management were recorded. Deaths in the study group were excluded by examining the Hospital's 'Patient Administrative System'. Three attempts were then made to contact all known survivors and to assess their quality of life using three previously recognised and validated methods. Eighty-three survivors of multiple trauma were discharged but 19 were not studied. Of the remaining 64, 42 patients completed the questionnaire. After multiple trauma, patients reported significant decreases in their quality of life in relation to their overall health, happiness, ability to think and to pursue leisure activities, their income and their employment. Their mean Perceived Quality of Life Score decreased by 13% (95% confidence intervals 7.5-19.5%). Sixty-two percent of survivors experienced severe social disability and a modest or severe impairment at work. The Nottingham Health Profile identified major changes in 'psychological' aspects of quality of life, namely energy and emotional reactions.

Adult↗
PubMed1994

Survival after intensive care. Comparison with a matched normal population as an indicator of effectiveness.

The life expectancy for survivors of critical illness has not been reported in the United Kingdom. The aim of this study was to compare the long-term survival of intensive care patients with that of an age and sex-matched population. All patients admitted to a general intensive therapy unit over 4 years (n = 1168) were included in the study. Details of the survivors were forwarded to the Registrar General for Scotland, who then issued copies of death certificates as the survivors died. The survival curve of patients discharged from the intensive therapy unit was significantly different from that of the normal population. The risk of dying in the first year after discharge was 3.4 times higher (95% confidence intervals 2.7-4.2) than that in the normal population. It is not until the start of the fourth year after discharge that the probability of death matched that of the normal population.

APACHE↗