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Biomedical subjects

A Rodgers

Publications and source records attributed to A Rodgers.

At least 37 records · Page 2Linked to original sources
PubMed2002

Subarachnoid haemorrhage occurrence exhibits a temporal pattern - evidence from meta-analysis.

The aim of the present meta-analysis was to determine a temporal pattern of occurrence of subarachnoid haemorrhage (SAH). A MEDLINE 1966-2001 and EMBASE (1980-2001) literature search and hand search of relevant references were performed for population-based incidence studies that reported the time of SAH occurrence. Data from all identified relevant studies were combined into a pooled rate ratio (RR), with corresponding 95% confidence intervals (CI) using the Mantel-Haenszel method. Overall, eight population-based studies were included in the analysis. A total of 2533 first-ever cases of SAH were reported in the studies identified. Risk of SAH occurrence was the highest in the period between 6 am and 12 am (RR = 3.19; 95% CI 3.03-3.36; early morning as a reference variable) and between 12 p.m. and 6 p.m. (RR = 2.63; 95% CI 2.47-2.80), in winter and spring (RR = 1.10; 95% CI: 1.02-1.17; and RR = 1.07; 95% CI: 1.01-1.13, respectively; summer as a reference variable) and on Sunday (RR = 1.22; 95% CI 1.09-1.37; Monday as a reference variable). The evidence suggests that occurrence of SAH exhibits a seasonal (winter and spring) peak, diurnal (late morning peak) and daily (Sunday peak) pattern. It is suggested that the occurrence of some major acute vascular events (total ischaemic strokes, intracerebral haemorrhage and myocardial infarction) may be influenced by common triggering factors.

Circadian Rhythm↗
PubMed2001

Crystallization and preliminary X-ray analysis of the complex of the epsilon-subunit and the central domain of the gamma-subunit from the Escherichia coli ATP synthase.

A complex of the epsilon-subunit and the central domain of the gamma-subunit from the ATP synthase of Escherichia coli has been purified and crystallized and preliminary X-ray analysis has been carried out. The crystals belong to space group C222(1), with unit-cell parameters a = 76.7, b = 176.1, c = 67.1 A (at 100 K). Determination of the structure of this protein complex promises to greatly improve the understanding of energy coupling between the F(0) and F(1) sectors within the enzyme complex.

Base Sequence↗
PubMed2001

Determinants of social support among low-income mothers: a longitudinal analysis.

This study examined the reciprocal relationships between perceived mastery, stress, and three functional areas of social support: tangible support, informational support, and belongingness support. Data were collected during two face-to-face interviews with a sample of low-income, primarily African-American mothers, conducted approximately 1 year apart. Consistent with predictions, initial levels of mastery predicted higher subsequent levels of instrumental social supports (tangible and advice support), but were unrelated to belonging support. Conversely, initial levels of tangible support were predictive of later mastery. Perceived stress did not account for any additional variance in subsequent support, although initial levels of belonging support only did predict reduced stress at Time 2. Results suggest that successful attempts to garner instrumental supports is an important contributor to individuals' sense of self-efficacy, at the same time, self-efficacy leads to more successful use of existing social support systems. These findings point to the importance of having both available tangible support networks as well as close emotional supports for low-income parents. The importance of using longitudinal, multidimensional analyses to better understand the social support process is discussed.

Black or African American↗
PubMed2001

Random errors in the measurement of 10 cardiovascular risk factors.

Random errors in the measurement of 10 commonly investigated cardiovascular risk factors (systolic and diastolic blood pressure, blood cholesterol, blood glucose, pulse rate, body mass index (BMI), cigarette consumption, passive smoking, alcohol intake and physical exercise) were assessed in a general population cohort (n = 2517) and a workforce cohort (n = 8008). Random errors were estimated from regression dilution ratios (lower ratios imply greater random error, and a ratio of one implies no random error). All of the risk factors, except for BMI (which had regression dilution ratios of 0.93 and 0.98 in the two cohorts), were measured with substantial levels of random error. Particularly low regression dilution ratios were observed for physical exercise (0.28 and 0.39) and pulse rate (0.47 and 0.56). For each of these risk factors, with the possible exception of BMI, associations with long-term average values could be importantly biased toward the null unless appropriate corrections are made.

Bias↗
PubMed2001

The influence of a high-oxalate/low-calcium diet on calcium oxalate renal stone risk factors in non-stone-forming black and white South African subjects.

OBJECTIVE: To evaluate the influence of a high-oxalate/low-calcium diet on calcium oxalate stone risk factors in both black South Africans (who are largely immune to kidney stones) and white South Africans (in whom stones are more common). SUBJECTS AND METHODS: Urinary and dietary variables were examined in 11 black and 11 white South African men. None of the subjects had had a kidney stone or any metabolic illness. Their normal domestic food intake was assessed using a semiquantitative food frequency questionnaire. Subjects were given a standardized high-oxalate/low-calcium diet for 3 days; 24-h urine samples were collected before the protocol and during the final day. The samples were analysed using routine modern laboratory techniques. The urine analysis data were used to calculate the Tiselius risk index and the relative urinary supersaturations of calcium oxalate, uric acid and calcium phosphate. RESULTS: Urine analysis showed an intriguing anomaly; black subjects had significantly higher urinary pH and oxalate values than whites (6.50 vs 6.21 and 0.23 vs 0.14 mmol/24 h, respectively), while their urinary citrate was lower (1.47 vs 3.69 mmol/24 h). In addition, the Tiselius risk index and relative supersaturation of calcium oxalate were higher in black subjects. These results are contrary to those which might have been reasonably expected when comparing stone-free and stone-prone groups. After the dietary protocol, the only urinary variable which changed significantly was urinary oxalate, which increased by 57% in whites. CONCLUSION: Factors which are conventionally used to assess stone risk (pH, oxaluria, citraturia, relative supersaturation) are not helpful in identifying why South African blacks are relatively immune to stones. We suggest that relatively lower oxalate absorption rates may be a physiological feature of this racial group.

Black or African American↗
PubMed2000

Reduction of postoperative mortality and morbidity with epidural or spinal anaesthesia: results from overview of randomised trials.

OBJECTIVES: To obtain reliable estimates of the effects of neuraxial blockade with epidural or spinal anaesthesia on postoperative morbidity and mortality. DESIGN: Systematic review of all trials with randomisation to intraoperative neuraxial blockade or not. STUDIES: 141 trials including 9559 patients for which data were available before 1 January 1997. Trials were eligible irrespective of their primary aims, concomitant use of general anaesthesia, publication status, or language. Trials were identified by extensive search methods, and substantial amounts of data were obtained or confirmed by correspondence with trialists. MAIN OUTCOME MEASURES: All cause mortality, deep vein thrombosis, pulmonary embolism, myocardial infarction, transfusion requirements, pneumonia, other infections, respiratory depression, and renal failure. RESULTS: Overall mortality was reduced by about a third in patients allocated to neuraxial blockade (103 deaths/4871 patients versus 144/4688 patients, odds ratio=0.70, 95% confidence interval 0.54 to 0.90, P=0. 006). Neuraxial blockade reduced the odds of deep vein thrombosis by 44%, pulmonary embolism by 55%, transfusion requirements by 50%, pneumonia by 39%, and respiratory depression by 59% (all P<0.001). There were also reductions in myocardial infarction and renal failure. Although there was limited power to assess subgroup effects, the proportional reductions in mortality did not clearly differ by surgical group, type of blockade (epidural or spinal), or in those trials in which neuraxial blockade was combined with general anaesthesia compared with trials in which neuraxial blockade was used alone. CONCLUSIONS: Neuraxial blockade reduces postoperative mortality and other serious complications. The size of some of these benefits remains uncertain, and further research is required to determine whether these effects are due solely to benefits of neuraxial blockade or partly to avoidance of general anaesthesia. Nevertheless, these findings support more widespread use of neuraxial blockade.

Anesthesia, Epidural↗
PubMed2000

Non-steroidal anti-inflammatory drugs for preventing heterotopic bone formation after hip arthroplasty.

BACKGROUND: Heterotopic bone formation (HBF) in the soft tissues surrounding the hip joint is a frequent complication of hip surgery. Non-steroidal anti-inflammatory drugs (NSAIDs) administered in the immediate perioperative period reduce the risk of HBF. However, the magnitude of the effect on HBF, and the effects on other associated outcomes are uncertain. OBJECTIVES: To determine the effects of perioperative NSAID therapy versus control on the risk of HBF and other outcomes in patients undergoing hip arthroplasty. SEARCH STRATEGY: Medline, Current Contents and Cochrane Controlled Trials Register, and reference lists of all relevant reports were searched. Principal investigators and the manufacturers of the study drugs of eligible trials were approached. The most recent search was conducted in July 1998. SELECTION CRITERIA: All trials which enrolled patients scheduled to undergo hip arthroplasty with random or quasi-random allocation to perioperative NSAID or control and that recorded post-operative radiographically determined HBF. The primary outcome was post-operative radiographic HBF. Secondary outcomes were pain, disability, gastro-intestinal and other bleeding complications, and other causes of major morbidity or mortality. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed methodological quality and extracted data. All analyses were conducted on dichotomised outcomes. MAIN RESULTS: Twelve randomised and two quasi-randomised trials involving a total of 4,377 patients were included. Overall, in 13 trials that examined the effects of medium to high doses of NSAIDs, there was a reduced risk of developing HBF after hip surgery (62% reduction, 95% confidence interval 56% to 67% reduction). In contrast, one large trial examining low-dose aspirin, demonstrated no effect on the risk of HBF (2% reduction, 95% confidence interval 15% reduction to 12% increase). There was strong evidence of differences in the size of the treatment effects observed between the trials examining medium to high doses of NSAIDs, but reasons were not clearly identified. There was a non-significant one third increased risk of gastro-intestinal side effects among patients assigned NSAIDs (29% increase, 95% confidence interval 5% reduction to 76% increase). Most of this increase was due to an increased risk of minor gastro-intestinal complications. Data on the late post-operative outcomes of pain, impaired physical function and range of joint movement were few and no formal overviews of the effects of NSAIDs on these outcomes were possible. REVIEWER'S CONCLUSIONS: Perioperative NSAIDs appear to produce between a one half and two thirds reduction in the risk of HBF. With routine use, such agents may be able to prevent 15-20 cases of HBF (3-4 severe) among every 100 total hip replacements performed. However, while medium to high doses of perioperative NSAIDs clearly produce a substantial reduction in the incidence of radiographic HBF, there remains some uncertainty about short-term side effects of treatment and substantial uncertainty about effects on long-term clinical outcomes such as chronic pain and impaired physical function. The net effect of routine HBF prophylaxis with NSAIDs requires formal assessment in a randomised trial designed to determine the balance of benefits and risks for all outcomes.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2000

A systematic survey of 13 randomized trials of non-steroidal anti-inflammatory drugs for the prevention of heterotopic bone formation after major hip surgery.

We performed a systematic survey of randomized trials to determine the effects of perioperative NSAIDs on the occurrence of heterotopic bone formation, gastrointestinal side-effects and long-term clinical outcomes after major hip surgery. 13 trials involving 4,129 individuals were identified. Overall, in 12 small trials of medium-to-high-dose regimens, there was a 57% reduction (95% confidence interval 51%-63%) in the risk of heterotopic bone formation. The results of one large trial of low-dose aspirin differed markedly (2% reduction (95% CI 12% reduction to 15% increase)). The NSAID regimens studied had no definite effect on gastrointestinal complications, and data about the effects of NSAIDs on pain and function were too few, and too incompletely reported, to draw conclusions about their effects on these outcomes. Routine prophylaxis against heterotopic bone formation with NSAIDs may be a useful adjuvant therapy for patients undergoing major hip surgery, but the overall balance of risks and benefits requires assessment in a large-scale randomized trial.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2000

No effect of low-dose aspirin for the prevention of heterotopic bone formation after total hip replacement: a randomized trial of 2,649 patients.

2,649 patients scheduled for elective total hip replacement were recruited to the Heterotopic Bone Formation Sub-study of the Pulmonary Embolism Prevention Trial. Heterotopic bone formation was determined by radiographic examination and associated late postoperative outcomes were assessed by telephone interview. Heterotopic bone formation was observed in 627 (31%) of 2,048 radiographic examinations. There was no detectable effect of low-dose aspirin on the risks of heterotopic bone formation (RR 0.98; 95% CI 0.85-1.12), late postoperative pain (RR 1.10; 95%CI 0.91-1.35) or late postoperative impaired function (RR 1.03; 95% CI 0.94-1.12). The balance of benefits and risks of low-dose aspirin is determined by its effects on vascular events and bleeding, since it has no major effects on heterotopic bone formation or associated clinical outcomes.

Activities of Daily Living↗
PubMed2000

Phase III comparative study of vinorelbine combined with doxorubicin versus doxorubicin alone in disseminated metastatic/recurrent breast cancer: National Cancer Institute of Canada Clinical Trials Group Study MA8.

PURPOSE: This phase III study was performed to determine the superiority of doxorubicin (DOX) and vinorelbine (VNB) (arm 1) versus DOX alone (arm 2) in metastatic breast cancer (MBC) for overall survival (OS), time to treatment failure (TTF), toxicity, and quality of life (QOL). PATIENTS AND METHODS: Three hundred three patients were randomized to DOX 50 mg/m(2) intravenously (IV) on day 1 and VNB 25 mg/m(2) IV on days 1 and 8 (arm 1) or DOX 70 mg/m(2) IV on day 1 (arm 2). Both regimens were given every 3 weeks until a cumulative DOX dose of 450 mg/m(2). After 16 of the first 65 randomized patients experienced febrile neutropenia (FN), the doses were reduced to DOX 40 mg/m(2) on day 1 and VNB 20 mg/m(2) on days 1 and 8 versus DOX 60 mg/m(2) on day 1. Eligible patients were vinca alkaloid and anthracycline naive. Chemotherapy was first-line or second-line for MBC. RESULTS: Three patients were ineligible. Thus, 300 patients were assessable for toxicity and to determine time to disease progression (TTP), TTF, and OS. Two hundred eighty-nine patients were assessable for response, and 99 responders were assessable for response duration (RD). The response rates, QOL, and median RD, TTP, and TTF were not significantly different between the arms. Median OS was 13.8 months for arm 1 versus 14.4 months for arm 2 (P =.4). Grade 3 or 4 granulocytopenia was equivalent in both arms but more grade 3/4 neurotoxicity, mild venous toxicity, and FN were seen on arm 1. CONCLUSION: The survival with DOX and VNB is not superior to DOX alone in MBC.

Adult↗
PubMed2000

Reducing the global burden of blood pressure-related cardiovascular disease.

OBJECTIVE: To assist in prioritisation for strategies for the control of cardiovascular disease (CVD) worldwide, by estimating the size of the contribution of elevated blood pressure and, more importantly, the likely effects of its modification. DESIGN: We estimated the size of the disease burden attributable to increased blood pressure in Eastern Asia and describe a method for estimating the likely effects of blood pressure lowering strategies. METHODS: Attributable risk estimates were calculated to assess the likely contribution of increased blood pressure to death from CVD in Asia. Estimates were also made of the possible effects of population-wide (2% lower diastolic blood pressure [DBP] for all) and targeted (7% lower DBP for those with DBP > or =95 mm Hg) blood pressure lowering interventions. These estimates were based on data from several sources, including surveys of blood pressure values in Asian populations, estimates of the incidence of cardiovascular disease in Asia, studies of the associations of blood pressure with cardiovascular disease risks in Asia and elsewhere, and randomized trials of blood pressure lowering treatments. RESULTS: The results suggest that DBP values of 80 mm Hg or more account for about 57% of all stroke deaths and about 24% of all coronary heart disease deaths in Eastern Asian populations. The two intervention strategies proposed would each be expected to avert about 1 in 6 stroke deaths and about 1 in 20 coronary heart disease deaths. This would amount to about 1 million deaths per year throughout Asia by 2020, with about half of those deaths averted in the People's Republic of China. The benefits of the two different approaches would be approximately additive. CONCLUSIONS: Increased blood pressure levels are directly responsible for the majority of stroke deaths (more than 50%) and a substantial minority of deaths from coronary heart disease (about 25%) in Eastern Asia. Both modest population-wide blood pressure reductions and more moderate targeted reductions in those with hypertension could be expected to produce large reductions in the burden of cardiovascular disease in these and other Asian regions.

Adolescent↗
PubMed1999

Mortality after hip fracture: regional variations in New Zealand.

AIM: To determine the 35-day and one-year mortality rates following a hospital admission for hip fracture, among individuals aged 60 years or older in New Zealand. METHODS: New Zealand Health Information Service mortality data for the years 1988 to 1992 were examined to determine the case fatality rate among individuals aged 60 years or older admitted to hospital for fractures of the neck of femur (ICD-9 N-code 820). Case fatality rates assessed at 35 days and one year after admission to hospital were examined by age, gender, year of admission, place of residence, area health board region and cause of death. RESULTS: Between 1988 and 1992, the case fatality rate was 8% within 35 days of admission to hospital and 24% within one year of admission. Case fatality rates were found to be twice as high in men compared to women and four to five times higher in individuals aged 85 years and older, compared to people aged between 60 and 64 years. The only regional difference in hip fracture mortality was found in the Canterbury area health board region, which had a 30% higher rate of hip fracture mortality compared to all regions combined. The two main cited underlying causes of death after hip fracture were accidental falls (ICD E880-E888) and ischaemic heart disease (ICD 410-414). CONCLUSION: Over three-quarters of individuals aged 60 years or older who are hospitalised with a hip fracture in New Zealand survive for at least one year after admission. However, significant variations in mortality exist with age and gender. These data highlight the importance of preventive strategies for hip fracture in older people and the need to identify ways of improving post-admission care.

Age Distribution↗
PubMed1999

Effect of cola consumption on urinary biochemical and physicochemical risk factors associated with calcium oxalate urolithiasis.

Since stone formers are advised to increase their intake of fluid, the present study was undertaken to determine the effect of cola beverage consumption on calcium oxalate kidney stone risk factors. Fourteen males and 31 females provided 24-h urines before and after an acute load of cola. Relative supersaturations, activity products and empirical risk indices, ratios and quotients were calculated from urinary biochemical data to assess calcium oxalate crystal and stone formation risk. Several risk factors changed unfavourably following consumption of cola. In males, oxalate excretion, the Tiselius risk index and modified activity product increased significantly (P < 0.05). In females, oxalate excretion increased significantly while magnesium excretion and pH decreased significantly (P < 0.05). Scanning electron microscopy showed that urines obtained from both sexes after cola consumption supported calcium oxalate crystallization to a greater extent than the control urines. It is concluded that consumption of cola causes unfavourable changes in the risk factors associated with calcium oxalate stone formation and that therefore patients should possibly avoid this soft drink in their efforts to increase their fluid intake.

Adult↗
PubMed1999

Treatment of hospitalized patients with complicated gram-positive skin and skin structure infections: two randomized, multicentre studies of quinupristin/dalfopristin versus cefazolin, oxacillin or vancomycin. Synercid Skin and Skin Structure Infection Group.

Quinupristin/dalfopristin (Synercid), the first injectable streptogramin antibiotic available for the treatment of complicated gram-positive skin and skin structure infections, was compared with standard comparators (cefazolin, oxacillin or vancomycin) in one USA and one international trial. These two randomized, open-label trials of virtually identical design enrolled a total of 893 patients (450 quinupristin/dalfopristin, 443 comparator). The majority of patients had erysipelas, traumatic wound infection or clean surgical wound infection. Staphylococcus aureus was the most frequently isolated pathogen in both treatment groups and polymicrobial infection was more common in the quinupristin/dalfopristin group than in the comparator group. The clinical success rate (cure plus improvement) in the clinically evaluable population was equivalent between the two treatment groups (68.2% quinupristin/dalfopristin, 70.7% comparator; 95% CI, -10.1, 5.1) despite a shorter mean duration of treatment for quinupristin/dalfopristin patients. In the bacteriologically evaluable population, by-patient and by-pathogen bacteriological eradication rates were somewhat lower for quinupristin/dalfopristin (65.8% and 66.6%, respectively) than for the comparator regimens (72.7% and 77.7%, respectively). The lower bacteriological response rates in the quinupristin/dalfopristin group were, in part, due to a higher rate of polymicrobial infections and a higher incidence of patients classified as clinical failure, a category which included premature discontinuation of treatment because of local venous adverse events. The bacteriological eradication rate for quinupristin/dalfopristin was higher in monomicrobial infections than in polymicrobial infections (72.6% versus 63.3%, respectively), whereas the corresponding rate for the comparator regimens was lower for monomicrobial infections than polymicrobial infections (70.8% versus 83.1%). This finding was not unexpected, since the spectrum of quinupristin/dalfopristin is focused on gram-positive pathogens and additional antibiotics to treat gram-negative bacteria were not required per protocol. The systemic tolerability of both treatment regimens was qualitatively similar. A higher rate of drug-related venous adverse events was reported for quinupristin/dalfopristin (66.2%) than for the comparator regimen (28.4%). Premature discontinuation of study drug was primarily due to adverse clinical events for quinupristin/dalfopristin (19.1%), whereas the most common reason for discontinuation among those receiving the comparator regimens was treatment failure (11.5%). Quinupristin/dalfopristin is an effective alternative for the treatment of hospitalized patients with complicated skin and skin structure infections due to quinupristin/ dalfopristin-susceptible gram-positive organisms, including methicillin- and erythromycin-resistant S. aureus.

Adolescent↗
PubMed1999

Randomised studies of income supplementation: a lost opportunity to assess health outcomes.

BACKGROUND: Despite the wealth of evidence linking low income to ill health, there is little information from randomised studies on how much and how quickly these risks can be reversed by improvements in income. OBJECTIVE: To conduct a systematic review of randomised studies of income supplementation, with particular reference to health outcomes. DESIGN: Extensive searches of electronic databases and contact with previous authors. As well as searching for trials that were specifically designed to assess the effects of increased income, studies of winners and losers of lotteries were also sought: if winning is purely chance, such studies are, in effect, randomised trials of increased income. RESULTS: Ten relevant studies were identified, all conducted in North America, mostly in the late 1960s and 1970s. Five trials were designed to assess the effects of income supplementation on workforce participation and randomised a total of 10,000 families to 3-5 years of various combinations of minimum income guarantees and reduced tax rates. Two trials were designed to assess re-offending rates in recently released prisoners and randomised a total of 2400 people to 3-6 months of benefits. One trial was designed to assess housing allowances and randomised 3500 families to three years of income supplements. One trial assessed the health effects of 12 months of income supplementation in 54 people with severe mental illness. Finally, one study compared three groups of people who won different amounts of money in a state lottery. In all these studies the interventions resulted in increases in income of at least one fifth. However, no reliable analyses of health outcome data are available. CONCLUSIONS: Extensive opportunities to reliably assess the effects of increases in income on health outcomes have been missed. Such evidence might have increased the consideration of potential health effects during deliberations about policies that have major implications for income, such as taxation rates, benefit policies, and minimum wage levels. Randomised evidence could still be obtained with innovative new studies, such as trials of full benefit uptake or prospective studies of lottery winners in which different sized winnings are paid in monthly installments over many years.

Health Services Research↗
PubMed1999

Aspects of calcium oxalate crystallization: theory, in vitro studies, and in vivo implementation.

There are three main approaches to urolithiasis research: theory, basic science, and clinical implementation. Although each approach has yielded meaningful results, there does not appear to be complete synergy between them. This article examines these approaches as they pertain to urinary calcium oxalate crystallization processes. Theoretical calculations were performed to examine the role of oxalate concentration on calcium oxalate supersaturation. The effects of magnesium, citrate, and combinations thereof on calcium oxalate crystallization kinetics were examined in a mixed suspension, mixed product removal crystallizer. Finally, male volunteers were given supplements of calcium alone and binary combinations of calcium, magnesium, and citrate to investigate their effects on the urinary supersaturation of calcium oxalate. Calculations showed that oxalate is 23 times more potent than calcium in its effect on the supersaturation of calcium oxalate. In the in vitro experiments, magnesium and citrate reduced the growth and nucleation kinetics as well as the supersaturation. In combination, these two components were more effective than the individual components in reducing the growth rate and the supersaturation. All of the supplements favorably altered the kinetic and thermodynamic risk factors. Calcium was the most effective in reducing the urinary excretion of oxalate. Articulation of these three approaches is essential for the meaningful investigation and understanding of urolithiasis.

Calcium Oxalate↗