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PubMed1999

Biomarkers of Alzheimer disease.

A definitive diagnosis of Alzheimer disease (AD) depends on finding widespread neurofibrillary tangles and plentiful neuritic plaques in the brain of an individual with a clinical diagnosis of progressive dementia. Using contemporary diagnostic criteria, the antemortem diagnosis of probable AD in centers specialized for AD is confirmed 80% to 90% of the time. There is the suspicion, but no firm data, that diagnostic accuracy is much lower outside of practices dedicated to patients with dementia. Furthermore, the diagnostic workup is expensive. In most settings, the evaluation generally includes a careful medical history and physical examination; neurologic examination (and psychiatric consultation as indicated); laboratory blood studies to exclude underlying metabolic and medical illnesses that masquerade as AD; a mental status assessment and formal cognitive tests; and a computed tomographic scan or magnetic resonance imaging of the brain. Because these procedures are time-consuming and costly, there is a need to identify biological tests that can circumvent aspects of this workup and point the physician to the correct diagnosis. It would be highly desirable to measure a substance or substances in blood or urine samples or cerebrospinal fluid (CSF) that would lead to a positive diagnosis of AD without the need for specialized dementia clinics and the expense and time of standard diagnostic evaluations. In response to this need, the Reagan Research Institute of the Alzheimer's Association and the National Institute on Aging convened a working group in 1997 to examine the status of various antemortem markers for AD. The consensus statement of this group, entitled "Molecular and Biochemical Markers of AD," was published in 1998. The consensus statement first defined the characteristics of an ideal biomarker, and then outlined the steps required for a proposed biomarker to achieve acceptance by the medical community. Finally, the statement reviewed the current state of all proposed biological markers. The workshop participants observed that none of the current biomarkers had yet achieved universal acceptance and concluded none fully met the consensus criteria for an ideal marker. Nonetheless, several tests were identified as good markers for familial AD, and several other tests showed promise as a diagnostic aid for sporadic AD. The purpose of this review is to put these recommendations into a practical context. What does the consensus statement tell the practicing clinician? How do the opinions in the consensus statement affect clinical practice in diagnosing and treating patients with dementia?

Alzheimer Disease↗
PubMed1983

Report of the Graduate Medical Education National Advisory Committee and health manpower development.

The federally chartered Graduate Medical Education National Advisory Committee projected a shortage of approximately 12,000 general and child psychiatrists by 1990. The committee's methods of analysis and recommendations have been criticized on grounds ranging from the accuracy of its data to the appropriateness of federal involvement in free-market issues. Yet the GMENAC report appears to have contributed to a recent reversal of psychiatric recruitment trends, and psychiatrists should be aware of its further implications for clinical and academic psychiatry. We analyzed the GMENAC process as one element among many that will determine future health care personnel development trends.

Child Psychiatry↗
PubMed1996

Development of use and cost measures in a nursing intervention for family caregivers and frail elderly patients.

The purpose of this pilot study was to refine and evaluate methods of measuring costs of an innovative home-health nursing intervention designed to support frail, older persons and their family caregivers. We evaluated a multifaceted strategy to collect a detailed utilization profile from 22 caregiver/care receiver dyads for hospital, ambulatory, home health, nursing home, and community services. The strategy was feasible for most participants, maximized accuracy of cost data, and minimized research burden on study participants. Lower overall costs were found in the intervention group, but the difference was not significant. Approaches to the measurement of costs in this study can serve as models for evaluating other innovations in nursing, home care, and long-term care.

Aged↗
PubMed2001

Assessment of muscarinic receptor concentrations in aging and Alzheimer disease with [11C]NMPB and PET.

Cerebral cholinergic deficits have been described in Alzheimer disease (AD) and as a result of normal aging. At the present time, there are very limited options for the quantification of cholinergic receptors with in vivo imaging techniques such as PET. In the present study, we examined the feasibility of utilizing [11C]N-methyl-4-piperidyl benzilate (NMPB), a nonselective muscarinic receptor ligand, in the study of aging and neurodegenerative processes associated with cholinergic dysfunction. Based on prior data describing the accuracy of various kinetic methods, we examined the concentration of muscarinic receptors with [11C]NMPB and PET using two- and three-compartment kinetic models. Eighteen healthy subjects and six patients diagnosed with probable AD were studied. Pixel-by-pixel two-compartment model fits showed acceptable precision in the study of normal aging, with comparable results to those obtained with a more complex and less precise three-compartment model. Normal aging was associated with a reduction in muscarinic receptor binding in neocortical regions and thalamus. In AD patients, the three-compartment model appeared capable of dissociating changes in tracer transport from changes in receptor binding, but suffered from statistical uncertainty, requiring normalization to a reference region, and therefore limiting its potential use in the study of neurodegenerative processes. After normalization, no regional changes in muscarinic receptor concentrations were observed in AD.

Adult↗
PubMed2000

Antibiotics for acute bacterial conjunctivitis.

BACKGROUND: There are concerns regarding whether antibiotic therapy confers significant benefit in the treatment of acute bacterial conjunctivitis. OBJECTIVES: The aim of this review is to assess the benefit and harm of antibiotic therapy in the management of acute bacterial conjunctivitis. SEARCH STRATEGY: We searched the Cochrane Eyes and Vision Group specialised register, the Cochrane Controlled Trials Register - Central, MEDLINE and the reference lists of identified trial reports. We used the Science Citation Index to look for articles that cited the relevant studies, and we contacted investigators and pharmaceutical companies for information about additional trials. The most recent searches were carried out in September 1998. SELECTION CRITERIA: We included double masked randomised controlled trials in which any form of antibiotic treatment had been compared with placebo in the management of acute bacterial conjunctivitis. This included topical, systemic and combination (for example, antibiotics and steroids) antibiotic usage. DATA COLLECTION AND ANALYSIS: One reviewer extracted data and the accuracy was checked by a second reviewer. Relative risks were summarised. We tested for heterogeneity between studies. MAIN RESULTS: Six published trials were identified of which three fulfilled the eligibility criteria for inclusion in this review. One trial was single masked and therefore excluded. A second report, when translated, was found to have no placebo group and was therefore excluded. One trial is currently 'awaiting assessment'. This has been published in abstract form and has yet to be fully reported. All the trials thus far identified appear to have been conducted on a selected specialist care patient population. The trials were heterogeneous in terms of their inclusion and exclusion criteria, the nature of the intervention, and the outcome measures assessed. Meta-analysis indicates that acute bacterial conjunctivitis is frequently a self-limiting condition, as clinical remission (cure or significant improvement) occurred by days two to five in 64% (95% confidence interval (CI) 57% to 71%) of those treated with placebo. Treatment with antibiotics was, however, associated with significantly better rates of clinical remission (days two to five: relative risk (RR) 1.31 95% CI 1.11 to 1.55, NNT=5) with a suggestion that this benefit was maintained for late clinical remission (days six to 10: RR 1.27 95% CI 1.00 to 1.61, NNT=5). Antibiotic treatment was associated with rates of microbiological remission (pathogen eradication or reduction). No serious outcomes were reported in either the active or placebo arms of these trials, indicating that important sight-threatening complications are an infrequent occurrence. REVIEWER'S CONCLUSIONS: Acute bacterial conjunctivitis is frequently a self-limiting condition but the use of antibiotics is associated with significantly improved rates of early clinical remission and early and late microbiological remission. Since trials to-date have been conducted in selected specialist care patient populations these results may not necessarily be generalisable to a primary care based population. A trial based in primary care designed to assess the cost-effectiveness of commonly prescribed antibiotic(s) versus placebo in acute bacterial conjunctivitis is warranted.

Acute Disease↗
PubMed1999

Diagnosis of crystal-induced arthritis by synovial fluid examination for crystals: lessons from an imperfect test.

OBJECTIVE: Diagnosis of the crystal-induced arthritides is primarily based on microscopic identification of crystals in synovial fluid. Therefore, we aimed to estimate the operating characteristics of this test and demonstrate its clinical use. METHODS: Medline was searched for relevant studies. Sensitivity and specificity of identification of crystals were calculated, as were measures of interobserver agreement. Likelihood ratios were calculated and curves constructed using the solutions to the Bayesian equations. RESULTS: Four studies were identified. The rates of interobserver agreement were low; the false-negative rates in identifying calcium pyrophosphate crystals were particularly high. Only one study allowed calculation of the test operating characteristics, and this was a study that used synthetic crystals and therefore may not be directly useful in a clinical setting. CONCLUSION: There is a paucity of data about the accuracy of crystal identification. As it is clearly not a perfectly sensitive and specific test, the most prudent diagnostic strategy, as with essentially all diagnostic tests, is to establish a posterior probability of disease from a prior probability, based on the clinical features of the patient. Determining the operating characteristics of this test in conventional and reference laboratories should be a research priority for high quality clinical research on crystal arthropathies.

Adult↗
PubMed2004

Application of voltammetric methods for the analysis of gold and other transition metals in quartzite rock.

Simple, rapid and accurate voltammetric methods viz. DCP, DPP and DPASV have been presented for the trace determination of gold and other transition metals in quartzite rock sample. The analysis has been performed using 0.1 M(NH4)2 tartrate, 0.1 M NaClO4 and 1 M NaOH as supporting electrolyte with 0.001% gelatin as maximum suppressor. The results show the presence of CuII(10.70), CoII(4.72), FeIII(66.96), AuIII(0.066), ZnII(1.68) and CdII(0.62) mg x g(-1) metal ions from the sample. Gold produced a well defined wave/peak with E1,2/Ep = -0.61 V/-0.64 V vs SCE, in 1 M NaOH supporting electrolyte. The quantitative analysis of metal inos was carried out by the method of standard addition. Statistical treatment of the observed voltammetric data reveals high accuracy and good precision of determination. The observed voltammetric results are comparable with those obtained using AAS method.

Chemistry Techniques, Analytical↗
PubMed2004

Physicochemical studies of cadmium(II) biosorption by the invasive alga in Europe, Sargassum muticum.

In recent years, there has been a significant increase in the studies concerning brown seaweed as biosorbents for metal removal owing to their high binding ability and low cost. This work reports the results of a study regarding the cadmium binding equilibria of dead biomass from the seaweed Sargassum muticum; this alga is a pest fouling organism that competes with the local fucalean species and may also interfere with the "sea industry"; therefore, it would constitute an ideal material to be used as biosorbent. Seven different treatments were tested in order to obtain a stable biomass that could be suitable for industrial use under a broad range of operational conditions. The treatments employed were protonation, chemical cross-linking with formaldehyde, KOH, Ca(OH)(2) and CaCl(2) or physical treatments with acetone and methanol. The equilibrium adsorption isotherms of Langmuir, Freundlich, and Langmuir-Freundlich were obtained for the quantitative description of the cadmium uptake. The effect of pH on biosorption equilibrium was studied at values ranging from 1 to 6, demonstrating the importance of this parameter for an accurate evaluation of the biosorption process. Maximum biosorption was found pH higher than 4.5. The maximum biosorption uptake for the raw biomass was 65 mg g(-1), while for formaldehyde cross-linking biomass the uptake increases to 99 mg g(-1) and for protonated biomass to 95 mg g(-1). Potentiometric titrations were carried out to estimate the total number of weak acid groups and to obtain their apparent pK value, 3.85, using the Katchalsky model. Kinetic studies varying cadmium concentration, algal dose, and ionic strength were carried out. Over 95% of the maximum cadmium uptake was achieved within 45 min, so the process can be considered relatively fast. A pseudo-second-order model, for the kinetics of cadmium biosorption, was shown to be able to reproduce experimental data points with accuracy.

Adsorption↗
PubMed1988

Nonselective enrichment for yeast adenine mutants by flow cytometry.

The expression of certain adenine biosynthetic mutations in the yeast Saccharomyces cerevisiae results in a red colony color. This phenomenon has historically provided an ideal genetic marker for the study of mutation, recombination, and aneuploidy in lower eukaryotes by classical genetic analysis. In this paper, it is reported that cells carrying ade1 and/or ade2 mutations exhibit primary fluorescence. Based on this observation, the nonselective enrichment of yeast cultures for viable adenine mutants by using the fluorescence-activated cell sorter has been achieved. The advantages of this approach over conventional genetic analysis of mutation, recombination, and mitotic chromosomal stability include speed and accuracy in acquiring data for large numbers of clones. By using appropriate strains, the cell sorter has been used for the isolation of both forward mutations and chromosomal loss events in S. cerevisiae. The resolving power of this system and its noninvasiveness can easily be extended to more complex organisms, including mammalian cells, in which analogous metabolic mutants are available.

Adenine↗
PubMed1997

Enantioselective determination of methadone and its main metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in serum, urine and hair by capillary electrophoresis.

A capillary electrophoresis method has been developed for the enantioselective determination of methadone and its main metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in serum and urine. After addition of the internal standard diphenhydramine, the serum and urine samples were extracted at pH 9-10 with n-hexane. Different cyclodextrins were tested for use as chiral selectors. The best results for simultaneous separation of methadone and EDDP were obtained using heptakis-(2,6-di-O-methyl)-beta-cyclodextrin (DIMEB). Data on the accuracy and precision of the method are presented. The method was applied to serum, urine, and hair samples, from individuals undergoing methadone therapy, under consideration of multi-drug abuse.

Electrophoresis, Capillary↗
PubMedDate not supplied

Machine learning approaches for prediction of linear B-cell epitopes on proteins.

Identification and characterization of antigenic determinants on proteins has received considerable attention utilizing both, experimental as well as computational methods. For computational routines mostly structural as well as physicochemical parameters have been utilized for predicting the antigenic propensity of protein sites. However, the performance of computational routines has been low when compared to experimental alternatives. Here we describe the construction of machine learning based classifiers to enhance the prediction quality for identifying linear B-cell epitopes on proteins. Our approach combines several parameters previously associated with antigenicity, and includes novel parameters based on frequencies of amino acids and amino acid neighborhood propensities. We utilized machine learning algorithms for deriving antigenicity classification functions assigning antigenic propensities to each amino acid of a given protein sequence. We compared the prediction quality of the novel classifiers with respect to established routines for epitope scoring, and tested prediction accuracy on experimental data available for HIV proteins. The major finding is that machine learning classifiers clearly outperform the reference classification systems on the HIV epitope validation set.

Algorithms↗
PubMed2002

Validated assay for quantification of oxcarbazepine and its active dihydro metabolite 10-hydroxycarbazepine in plasma by atmospheric pressure chemical ionization liquid chromatography/mass spectrometry.

Oxcarbazepine (OX), a new antiepileptic, may lead to unwanted side-effects or even life-threatening intoxications after overdose. Therefore, a validated liquid chromatographic/mass spectrometric (LC/MS) assay was developed for the quantification of OX and its pharmacologically active dihydro metabolite (dihydrooxcarbazepine, DOX, often named 10-hydroxycarbazepine). OX and DOX were extracted from plasma by the authors' standard liquid/liquid extraction and were separated on a Merck LiChroCART column with Superspher 60 RP Select B as the stationary phase. Gradient elution was performed using aqueous ammonium formate and acetonitrile. The compounds were quantified in the selected-ion monitoring mode using atmospheric pressure chemical ionization electrospray LC/MS. The assay was fully validated. It was found to be selective. The calibration curves were linear from 0.1 to 50 mg l(-1) for OX and DOX. Limits of quantification were 0.1 mg l(-1) for OX and DOX. The absolute recoveries were between 60 and 86%. The accuracy and precision data were within the required limits. The analytes in frozen plasma samples were stable for at least 1 month. The method was successfully applied to several authentic plasma samples from patients treated or intoxicated with OX. The measured therapeutic plasma levels ranged from 1 to 2 mg l(-1) for OX and from 10 to 40 mg l(-1) for DOX. The validated LC/MS assay proved to be appropriate for quantification of OX and DOX in plasma for clinical toxicology and therapeutic drug monitoring purposes. The assay is part of a general analysis procedure for the isolation, separation and quantification of various drugs and for their full-scan screening and identification.

Anticonvulsants↗
PubMed2003

Screening, library-assisted identification and validated quantification of fifteen neuroleptics and three of their metabolites in plasma by liquid chromatography/mass spectrometry with atmospheric pressure chemical ionization.

A liquid chromatographic/mass spectrometric assay with atmospheric pressure chemical ionization (APCI-LC/MS) is presented for the fast and reliable screening and identification and for the precise and sensitive quantification of 15 neuroleptic (antipsychotic) drugs and three of their relevant metabolites in plasma. It allows confirmation of the diagnosis of a neuroleptic overdose and monitoring of psychiatric patients' compliance. The neuroleptics amisulpride, bromperidol, clozapine, droperidol, flupenthixol, fluphenazine, haloperidol, melperone, olanzapine, perazine, pimozide, risperidone, sulpiride, zotepine and zuclopenthixol and the pharmacologically active metabolites norclozapine, clozapine N-oxide and 9-hydroxyrisperidone were extracted from plasma using solid-phase extraction and were separated on a Merck LiChroCART column with Superspher 60 RP Select B as the stationary phase. Gradient elution was performed using aqueous ammonium formate and acetonitrile. After screening and identification in the scan mode using the authors' new LC/MS library, the neuroleptics were quantified in the selected-ion mode. The quantification assay was fully validated. It was found to be selective and proved to be linear from sub-therapeutic to over therapeutic concentrations for all analytes. The corresponding reference levels are listed. The accuracy and precision data were within the required limits. The analytes were stable in frozen plasma for at least 1 month. The method was successfully applied to several authentic plasma samples from patients treated or intoxicated with various neuroleptics. The validated LC/MS assay has proved to be appropriate for the isolation, separation, screening, identification and quantification of various neuroleptics in plasma for clinical toxicology and therapeutic drug monitoring purposes.

Antipsychotic Agents↗
PubMed1985

Reliability after repeated use of a torque screwdriver employed for halo pin fixation.

It has been recommended that halo torque screwdrivers be used only once. To determine if this advice is justified on biomechanical grounds, five commercially available torque screwdrivers were cycled 1,600 times each in an Instron testing machine over a 7-day period. The screwdrivers displayed an initial error from the dial reading at both 6 and 10 in-lb of only +/- 0.3 in-lb. After cyclic loading and retesting, the percent deviation from original calibration was 8% at both 6 and 10 in-lb. These data demonstrate the accuracy and dependability of the torque screwdrivers and imply that repeated use of these devices should be safe.

Biomechanical Phenomena↗
PubMed2004

High-throughput determination of the free fraction of drugs strongly bound to plasma proteins.

Quantification of protein binding of new chemical entities is an important early screening step during drug discovery and is of fundamental interest for the estimation of safety margins during drug development. In this publication, we describe the development of a new high-throughput assay for the determination of the free drug fraction in plasma (fu). The new technique is an enhancement of the previously published erythrocytes partition method. It is based on the distribution of drugs between plasma water, plasma proteins, and solid-supported lipid membranes (Transil). The execution of protein binding studies by partitioning is dramatically simplified by substituting erythrocytes with commercially available Transil beads, and makes the method particularly suitable for high-throughput studies. Eight Bayer compounds from different compound classes covering a wide range of lipophilicities (log P = 1.9-5.6) and fu values (0.018-35%) were selected for validation of the assay. The results obtained by the new method and by either the erythrocytes partitioning technique or more conventional methods (ultrafiltration and equilibrium dialysis) are identical, confirming that the new method produces valid results even for drugs that are strongly bound to plasma proteins. Precision and accuracy of the data in the cases of very low and high fu values are comparable, indicating that the method is especially suited for highly lipophilic drugs that tend to adsorb to surfaces compared with other methods, like ultrafiltration or equilibrium dialysis, that may produce biased data. The method is also useful for the determination of binding parameters and the pH dependence of fu. In summary, this assay is well suited for high-throughput determination of protein binding during drug discovery and for extended protein binding studies during drug development.

Animals↗
PubMed1984

High-performance liquid chromatographic assay for sodium levothyroxine in tablet formulations: content uniformity applications.

Sodium levothyroxine was quantitated in 25-300 micrograms/tablet formulations. The procedure consisted of pulverization of a suitable sample, extraction into acetonitrile-water (40:60, v/v) containing 0.05% o-phosphoric acid, and injection onto a bonded-phase cyanopropyl column; the effluent was monitored by UV detection at 225 nm. Spiked placebo recovery studies demonstrated the linearity of the method over the range of 80-120% of the label claim. Stability studies indicated that no degradation products or excipients interfered with the quantitation of the intact drug. Data demonstrating the accuracy and precision of this assay are presented, and the method was applied to the measurement of single-tablet content uniformity.

Chromatography, High Pressure Liquid↗
PubMed1986

Relative bioavailability of metaproterenol in humans utilizing a single dose, stable isotope approach.

The relative bioavailability of metaproterenol (3,5-dihydroxy-alpha-[(isopropylamino)methyl]benzyl alcohol) following a single dose (10-mg metaproterenol sulfate tablet) was studied in six normal male volunteers using coadministration of a solution of a deuterated analogue (metaproterenol-d7 sulfate). The bioavailability of the tablet formulation relative to that of the oral solution was 92 +/- 9%, with excellent power at the 5% significance level. Comparison of the coadministration of the labeled and unlabeled metaproterenol sulfate solutions in two subjects after a one-week washout demonstrated the absence of an isotope effect on either absorption or elimination. A GC-MS assay for metaproterenol was developed to measure plasma concentrations resulting from oral administration. The assay was linear over the range of 0.5-8 ng/mL, corresponding to typical plasma metaproterenol concentrations obtained after a single 10-mg oral dose. Accuracy and precision data were obtained at metaproterenol concentrations of 1.0 and 2.0 ng/mL plasma to demonstrate the applicability of the assay for bioavailability studies. Following oral administration, metaproterenol showed peak plasma concentrations of 2.2 to 13 ng/mL at 0.75 to 3.0 h, with a terminal harmonic mean half-life of 2.1 h over the plasma concentration range studied. The renal clearance of 133-158 mL/min for metaproterenol slightly exceeds the glomerular filtration rate in humans.

Administration, Oral↗
PubMed2005

The full evaporation technique: a promising alternative for residual solvents analysis in solid samples.

The static headspace technique is the most common approach to residual solvent analysis in pharmaceutical and environmental matrices. This paper presents an alternative tool where the volatile impurities are released from the matrix by working directly on a small amount of sample at a high equilibration temperature: the so-called Full Evaporation Technique (FET). The capability of this method was evaluated on a mixture of nine solvents, which belong to Class 3 in the classification of the European Pharmacopoeia Agency for residual solvents, at various levels of concentration: ethanol, acetone, 2-propanol, methyl acetate, 2-butanone, ethyl acetate, tetrahydrofuran, 2-methyl-1-propanol, 1-butanol. Data on linearity, accuracy, precision and sensitivity are reported. Use of an internal standard proved to be necessary when using such a method. The method is then successfully applied to the analysis of solvent traces in permethylated beta-cyclodextrin.

Chromatography↗