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PubMed2000

Echinacea for preventing and treating the common cold.

BACKGROUND: Extracts of the plant Echinacea (family Compositae) are widely used in some European countries and the USA for upper respiratory tract infections. OBJECTIVES: The objective of this review was to assess the effects of preparations containing extracts of Echinacea in the prevention and treatment of the common cold. SEARCH STRATEGY: We searched the Cochrane Acute Respiratory Infections Group and Complementary Medicine Field's trials registers, MEDLINE, EMBASE, Phytodok and reference lists of articles. We also contacted researchers and manufacturers. Date of last search: Spring 1998. SELECTION CRITERIA: Randomised and quasi-randomised trials comparing preparations containing an extract of Echinacea compared with a placebo, no treatment, or another treatment for common colds. DATA COLLECTION AND ANALYSIS: At least two independent reviewers assessed trial quality and extracted data. MAIN RESULTS: Sixteen trials (eight prevention trials, and eight trials on treatment of upper respiratory tract infections) with a total of 3396 participants were included. Variation in preparations investigated and methodological quality of trials precluded quantitative meta-analysis. Overall, the results suggested that some Echinacea preparations may be better than placebo. REVIEWER'S CONCLUSIONS: The majority of the available studies report positive results. However there is not enough evidence to recommend a specific Echinacea product, or Echinacea preparations for the treatment or prevention of common colds.

Common Cold↗

PubMed2003

Varying cost and free nicotinic acid content in over-the-counter niacin preparations for dyslipidemia.

BACKGROUND: Nicotinic acid is an effective treatment for dyslipidemia, but the content of over-the-counter niacin is not federally regulated. As a result, patients may use preparations of over-the-counter niacin that do not contain free nicotinic acid. OBJECTIVE: To characterize the types, costs, and free nicotinic acid content of over-the-counter niacin preparations and to review literature on the use of over-the-counter niacin for dyslipidemia. DATA SOURCES: Commonly used over-the-counter niacin preparations (500-mg tablets or capsules) from the 3 categories of immediate-release, sustained-release, and no-flush were purchased at health food stores and pharmacies and from Internet-based vitamin companies. Pertinent literature on the use of over-the-counter niacin was obtained by searching PubMed. MEASUREMENTS: For each preparation studied, the monthly cost of therapy (at 2000 mg/d) and the free nicotinic acid content (quantified by high-performance liquid chromatography) were reported. DATA SYNTHESIS: On average, immediate-release niacin preparations cost 7.10 dollars per month, sustained-release preparations cost 9.75 dollars per month, and no-flush preparations cost 21.70 dollars per month. The average content of free nicotinic acid was 520.4 mg for immediate-release niacin, 502.6 mg for sustained-release niacin, and 0 for no-flush niacin. CONCLUSIONS: No-flush preparations of over-the-counter niacin contain no free nicotinic acid and should not be used to treat dyslipidemia. Over-the-counter sustained-release niacin contains free nicotinic acid, but some brands are hepatotoxic. Immediate-release niacin contains free nicotinic acid and is the least expensive form of over-the-counter niacin.

Chromatography, High Pressure Liquid↗

PubMed2006

Accuracy of optimized chemical-exchange parameters derived by fitting CPMG R2 dispersion profiles when R2(0a) not = R2(0b).

The transverse relaxation rate, R2, measured as a function of the effective field (R2 dispersion) using a Carr-Purcell-Meiboom-Gill (CPMG) pulse train, is well suited to detect conformational exchange in proteins. The dispersion data are commonly fitted by a two-site (sites a and b) exchange model with four parameters: the relative population, pa, the difference in chemical shifts of the two sites, deltaomega, the correlation time for exchange, tau(ex), and the intrinsic relaxation rate (i.e., transverse relaxation rate in the absence of chemical exchange), R2(0). Although the intrinsic relaxation rates of the two sites, R2(0a) and R2(0b), can differ, they are normally assumed to be the same (i.e., R2(0a) = R2(0b) = R2(0)) when fitting dispersion data. The purpose of this investigation is to determine the magnitudes of the errors in the optimized exchange parameters that are introduced by the assumption that R2(0a) = R2(0b). In order to accomplish this goal, we first generated synthetic constant-time CPMG R2 dispersion data assuming two-site exchange with R2(0a) not equal R2(0b), and then fitted the synthetic data assuming two-site exchange with R2(0) = R2(0a) = R2(0b). Although all the synthetic data generated assuming R2(0a) not equal R2(0b) were well fitted (assuming R2(0a) = R2(0b)), the optimized values of pa and tau(ex) differed from their true values, whereas the optimized values of deltaomega values did not. A theoretical analysis using the Carver-Richards equation explains these results, and yields simple, general equations for estimating the magnitudes of the errors in the optimized parameters, as a function of (R2(0a) - R2(0b)).

Bias↗

PubMed1982

Respiratory monitoring in acute multiple organ system failure.

Respiratory failure is a common sequel to and a major cause of death in patients with multiple organ system injury. Detailed patient care requires monitoring of lung mechanical properties, gas-exchange, and oxygen transport in the blood. Furthermore, early recognition of lung edema, lung infection, or impaired respiratory muscle function may permit therapeutic maneuvers to prevent progressive deterioration of lung function. Unfortunately, each intervention carries with it a significant risk. Consequently, monitoring must include assessment of the adverse effects of oxygen, mechanical ventilation, artificial airways, and intravascular catheters. Shrewd analysis of limited data may commonly be more effective than sophisticated invasive monitoring with its attendant risks.

Bacterial Infections↗

PubMed2006

Searching for convergence in phylogenetic Markov chain Monte Carlo.

Markov chain Monte Carlo (MCMC) is a methodology that is gaining widespread use in the phylogenetics community and is central to phylogenetic software packages such as MrBayes. An important issue for users of MCMC methods is how to select appropriate values for adjustable parameters such as the length of the Markov chain or chains, the sampling density, the proposal mechanism, and, if Metropolis-coupled MCMC is being used, the number of heated chains and their temperatures. Although some parameter settings have been examined in detail in the literature, others are frequently chosen with more regard to computational time or personal experience with other data sets. Such choices may lead to inadequate sampling of tree space or an inefficient use of computational resources. We performed a detailed study of convergence and mixing for 70 randomly selected, putatively orthologous protein sets with different sizes and taxonomic compositions. Replicated runs from multiple random starting points permit a more rigorous assessment of convergence, and we developed two novel statistics, delta and epsilon, for this purpose. Although likelihood values invariably stabilized quickly, adequate sampling of the posterior distribution of tree topologies took considerably longer. Our results suggest that multimodality is common for data sets with 30 or more taxa and that this results in slow convergence and mixing. However, we also found that the pragmatic approach of combining data from several short, replicated runs into a "metachain" to estimate bipartition posterior probabilities provided good approximations, and that such estimates were no worse in approximating a reference posterior distribution than those obtained using a single long run of the same length as the metachain. Precision appears to be best when heated Markov chains have low temperatures, whereas chains with high temperatures appear to sample trees with high posterior probabilities only rarely.

Bayes Theorem↗

PubMed2006

Methods for handling missing data in palliative care research.

Missing data is a common problem in palliative care research due to the special characteristics (deteriorating condition, fatigue and cachexia) of the population. Using data from a palliative study, we illustrate the problems that missing data can cause and show some approaches for dealing with it. Reasons for missing data and ways to deal with missing data (including complete case analysis, imputation and modelling procedures) are explored. Possible mechanisms behind the missing data are: missing completely at random, missing at random or missing not at random. In the example study, data are shown to be missing at random. Imputation of missing data is commonly used (including last value carried forward, regression procedures and simple mean). Imputation affects subsequent summary statistics and analyses, and can have a substantial impact on estimated group means and standard deviations. The choice of imputation method should be carried out with caution and the effects reported.

Adult↗

PubMed2001

Data sharing and dissemination strategies for fostering competition in health care.

OBJECTIVES: To introduce the concept of common models for data sharing and dissemination, highlight the current operational, technical, and political issues surrounding existing data sharing and dissemination initiatives in a health care market, and suggest an ideal model for future data initiatives. DATA SOURCES/STUDY SETTING: A literature review and case studies of existing data sharing and dissemination initiatives that promote the collection and use of comparative information on provider cost and quality. PRINCIPAL FINDINGS: Three broad types of common models for data sharing and dissemination have evolved over the past decade or so: (1) provider-initiated initiatives developed through collaboration among providers of health care; (2) purchaser-initiated activities driven by a coalition of purchasers; and (3) indirect collaboration-data-sharing initiatives between providers and purchasers with a significant facilitating or regulating role by a third group of stakeholders. The success of a data-sharing and dissemination strategy is determined by how the complex operational, technical, and political issues are addressed. General principles by which a health data initiative might abide include the following: standardized databases as the physical foundation, indicators that reflect the changing market; linkages between and across data sets for comprehensive and complete data; economic value; policy relevance; use of evolving technologies to collect, integrate, and disseminate data; and stakeholder support. CONCLUSIONS: Regulatory solutions alone will not overcome the complex political and technical challenges to data sharing and dissemination. The "ideal" model or process nurturing a market for health care information will incorporate compromise and negotiation to address the issues of data ownership and proprietary concerns, therefore securing the necessary political and financial support of the private sector.

Cooperative Behavior↗

PubMed2005

Marginal analysis for clustered failure time data.

Clustered failure time data are commonly encountered in biomedical research where the study subjects from the same cluster (e.g., family) share the common genetic and/or environmental factors such that the failure times within the same cluster are correlated. Two approaches that are commonly used to account for the intra-cluster association are frailty models and marginal models. In this paper, we study the marginal proportional hazards model, where the structure of dependence between individuals within a cluster is unspecified. An estimation procedure is developed based on a pseudo-likelihood approach, and a risk set sampling method is proposed for the formulation of the pseudo-likelihood. The asymptotic properties of the proposed estimators are studied, and the related issues regarding the statistical efficiencies are discussed. The performances of the proposed estimator are demonstrated by the simulation studies. A data example from a child vitamin A supplementation trial in Nepal (Nepal Nutrition Intervention Project-Sarlahi, or NNIPS) is used to illustrate this methodology.

Cluster Analysis↗

PubMed2003

Mumbai disease in far western Nepal: HIV infection and syphilis among male migrant-returnees and non-migrants.

OBJECTIVE: To measure the seroprevalence of human immunodeficiency virus (HIV) infection and syphilis, and to assess the behavioural risk factors for these infections among migrant-returnees and non-migrants in far western Nepal. METHODS: In April 2001, we recruited 97 male migrant-returnees and 40 non-migrants from five rural villages in Doti district where migration to Mumbai is common. For data collection, we conducted a serological examination for HIV and syphilis, and a perception and behaviour survey on HIV and other sexually transmitted infections. RESULTS: We found that 11 of 137 men (8%) were positive for HIV infection and 30 men (22%) for syphilis. The respondents, especially the migrant-returnees from Mumbai, were engaging in risky behaviours such as pre- or extramarital sex, and sex with multiple partners, including sex workers. CONCLUSIONS: This study revealed high HIV and syphilis prevalence among the male migrant-returnees and non-migrants in far western Nepal where migration to Mumbai is common. The prevalent behaviours, particularly among the migrant-returnees, imply urgent needs of the behavioural modification programme in this area to prevent the spread of HIV infection to general population.

Acquired Immunodeficiency Syndrome↗

PubMed2001

A seven-year experience of data collection on the Insall-Burstein II total knee arthroplasty. A prospective study.

We describe a method of audit of a type of total knee replacement, including some details of the organisational difficulties of administering multicentre studies, and draw attention to how this can be done using industrial funding without prejudicing the study. This is a prospective record of 1439 patients who had an Insall-Burstein II (IBII) prosthesis implanted between 1990 and 1994. The data were collected using the American Knee Society scoring system. A method of storing radiographs digitally at low cost is also described. The results emphasise the need for the long-term collection of data on commonly used devices implanted by a cross-section of surgeons. We conclude that for most patients the IBII cemented, posteriorly stabilised, cruciate-substituting prosthesis will relieve pain and give excellent functional results throughout the patients' remaining years with a very small incidence of revision, except in cases of infection.

Adolescent↗

PubMed2006

Characteristics of 32 supercentenarians.

OBJECTIVES: To report phenotypic characteristics of 32 age-validated supercentenarians. DESIGN: Case series. SETTING: U.S.-based recruitment effort. PARTICIPANTS: Thirty-two supercentenarians. MEASUREMENTS: Multiple forms of proof were used to validate age claims. Sociodemographic, activities of daily living, and medical history data were collected. RESULTS: Age range was 110 to 119. Fifty-nine percent had Barthel Index scores in the partially to totally dependent range, whereas 41% required minimal assistance or were independent. Few subjects had a history of clinically evident vascular-related diseases, including myocardial infarction (n=2, 6%) and stroke (n=4, 13%). Twenty-two percent (n=7) were taking medications for hypertension. Twenty-five percent (n=8) had a history of cancer (all cured). Diabetes mellitus (n=1, 3%) and Parkinson's disease (n=1, 3%) were rare. Osteoporosis (n=14, 44%) and cataract history (n=28, 88%) were common. CONCLUSION: Data collected thus far suggest that supercentenarians markedly delay and even escape clinical expression of vascular disease toward the end of their exceptionally long lives. A surprisingly substantial proportion of these individuals were still functionally independent or required minimal assistance.

Activities of Daily Living↗

PubMed2003

Deconvolution algorithm based on automatic cutoff frequency selection for EPR imaging.

The large line-width associated with electron paramagnetic resonance imaging (EPRI) requires effective algorithms to deconvolve the true spatial profiles of spins from the measured projection data. The commonly used Fourier transform (FT) deconvolution algorithm is easy to implement but suffers from the division-by-zero problem. As a result, a couple of parameters are used to control the deconvolution performance. However, this is inconvenient and the deconvolution results are subject to the experience of the operators. In the present work we examined FT deconvolution for EPRI, and proposed an automatic algorithm to determine the cutoff frequency by calculating the piecewise variance of the division result of the Fourier amplitude spectra. The deconvolution algorithm and the filtered back-projection image reconstruction algorithm were implemented and validated using 3D phantom and in vivo imaging data. It was clearly observed that the image resolution improved after deconvolution with the proposed algorithm.

Algorithms↗

PubMed1998

Evaluation of routine antepartum and postpartum blood counts.

OBJECTIVE: To evaluate routine screening 28-week, admission and postpartum complete blood counts (CBCs) during a six-month period on the labor and delivery service and to correlate the laboratory data with clinical characteristics of the patients, to determine if routine CBCs are necessary in evaluating blood loss in low-risk patients and to determine whether routine admission screening for thrombocytopenia is necessary prior to epidural placement is necessary in low-risk patients. STUDY DESIGN: Laboratory data form all patients were obtained from a centralized computer system. Clinical characteristics were obtained from the medical record. RESULTS: Blood loss was determined by a change in hematocrit on admission and postpartum, and the mean of this data was used for analysis. First, the data reflected common clinical assumptions about delivery blood loss. The mean change in hematocrit for operative deliveries (7.93 +/- 5.10, 6.19 +/- 4.42; forceps and cesarean, respectively) was higher than that of spontaneous vaginal deliveries (4.31 +/- 3.78). Forcep deliveries had a larger decrease in hematocrit than repeat or primary cesarean sections combined, although it was not statistically significant (P = .04). More extensive vaginal lacerations were associated with larger decreases in hematocrit. There was a low percentage of patients requiring transfusion (1.3%) during the study period. All these patients had an estimated blood loss of > 1500 mL and delivery circumstances that would alert the clinician to the possibility of transfusion. Second, our data showed that the 28-week platelet count is predictive of the admission platelet count, with a regression coefficient of. 71. CONCLUSION: Often clinical assessment of blood loss, including history and physical examination, will predict the results of routine screening CBCs, and we question the need for routine screening of blood loss in uncomplicated deliveries. Our data on the 28-week and admission platelet counts support other authors' data showing that this screen is not necessary prior to epidural placement in low-risk patients.

Adolescent↗

PubMed2006

Baseline use of concomitant psychotropic medications to treat schizophrenia in the CATIE trial.

OBJECTIVE: This study examined the prevalence and correlates of concomitant psychotropic medications and use of anticholinergic drugs to treat schizophrenia. METHODS: Concomitant medication use was studied at baseline for participants in the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) trial. RESULTS: Of the 1,380 patients with baseline medication data, 82 percent were taking psychotropic medications. Of this group, 6 percent were taking two antipsychotics (one first generation and one second generation); 38 percent, antidepressants; 22 percent, anxiolytics; 4 percent, lithium, and 15 percent, other mood stabilizers. The strongest predictors of taking several medications were having anxiety or depression, being female, and taking second-generation antipsychotics. Conversely, African Americans and those with better neurocognitive functioning were less likely to be taking several concomitant psychotropic medications. In some cases symptoms that were likely targets of polypharmacy, such as depression, remained prominent, suggesting only partial response. CONCLUSIONS: Concomitant use of psychotropic medications to treat people with schizophrenia is common. Empirical data demonstrating the effectiveness of many of these agents for this population are lacking.

Adult↗

PubMed2006

Clustered data in sports research.

Clustered, or dependent, data, arise commonly in sports medicine and sports science research, particularly in studies of sports injury and biomechanics, particularly in sports injury trials that are randomised at team or club level, in cross-sectional surveys in which groups of individuals are studied and in studies with repeated measures designs. Clustering, or positive correlation among responses, arises because responses and outcomes from the same cluster will usually be more similar than from different clusters. Study designs with clustering will usually required an increased sample size when compared to those without clustering. Ignoring clustering in statistical analyses can also lead to misleading conclusions, including incorrect confidence intervals and p-values. Appropriate statistical analyses for clustered data must be adopted. This paper gives some examples of clustered data and discusses the implications of clustering on the design and analysis of studies in sports medicine and sports science research.

Cluster Analysis↗

PubMed1999

Vitamin K: a practical guide to the dietary management of patients on warfarin.

Warfarin has been successfully used in the medical management of thromboembolic disease for nearly six decades. It is widely assumed that a dietary vitamin K-warfarin interaction exists. To avoid this potential interference with the efficacy of warfarin in stable anticoagulation, patients typically receive instructions to consume a constant dietary intake of vitamin K. While dark, green vegetables are primary sources of dietary vitamin K, these foods are not commonly consumed on a daily basis in the United States. However, there still exists dietary resistance to warfarin that is attributable to vitamin K. Based on food analysis studies on vitamin K, it is now known that dietary vitamin K is found in certain plant oils and prepared foods containing these plant oils, such as baked goods, margarines, and salad dressings. The preparation of foods with vitamin K-rich oils may also contribute to a diet-warfarin interaction, although this has yet to be confirmed in a clinical trial. A dose-response of vitamin K on the effect of warfarin anticoagulation has not yet been established. However, there are sufficient data to suggest that a constant dietary intake of vitamin K that meets current dietary recommendations of 65-80 micrograms/day is the most acceptable practice for patients on warfarin therapy. Vitamin K composition data for commonly consumed foods are now available and may facilitate successful anticoagulation for patients being treated with warfarin.

Anticoagulants↗

PubMed2001

Methods and approaches in the analysis of gene expression data.

The application of high-density DNA array technology to monitor gene transcription has been responsible for a real paradigm shift in biology. The majority of research groups now have the ability to measure the expression of a significant proportion of the human genome in a single experiment, resulting in an unprecedented volume of data being made available to the scientific community. As a consequence of this, the storage, analysis and interpretation of this information present a major challenge. In the field of immunology the analysis of gene expression profiles has opened new areas of investigation. The study of cellular responses has revealed that cells respond to an activation signal with waves of co-ordinated gene expression profiles and that the components of these responses are the key to understanding the specific mechanisms which lead to phenotypic differentiation. The discovery of 'cell type specific' gene expression signatures have also helped the interpretation of the mechanisms leading to disease progression. Here we review the principles behind the most commonly used data analysis methods and discuss the approaches that have been employed in immunological research.

Classification↗

PubMed1995

A cladistic analysis of phenotypic associations with haplotypes inferred from restriction endonuclease mapping or DNA sequencing. V. Analysis of case/control sampling designs: Alzheimer's disease and the apoprotein E locus.

Present-day associations between haplotypes at a candidate locus and phenotypes exist when phenotypically important mutations occurred at some point during the evolution of the current array of genetic variation. A cladistic statistical design can be defined that focuses power by using the evolutionary history of the candidate DNA region. This paper shows how cladistic methodology is used for the analysis of case/control data, a common sampling design in genetic/disease association studies. A worked example is presented of the associations for sporadic early and late-onset forms of Alzheimer's disease with the 19q13.2 chromosomal region that includes the loci for apoproteins E, CI, and CII. This analysis confirms earlier reports of a strong association of the ApoE epsilon 4 allele with Alzheimer's disease but indicates that it is premature to consider this association causal, particularly for early onset cases. Associations were also found with the epsilon 2 allele, as previously reported, and with the 1 allele at the ApoCI locus. However, this analysis indicates that it is inappropriate both statistically and medically to use single markers as risk predictors when haplotype data are available, even when the mutation leading to the marker is identified as having a strong phenotypic association.

Age of Onset↗