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PubMed2007

Role of functional MR in determining language dominance in epilepsy and nonepilepsy populations: a Bayesian analysis.

PURPOSE: To determine the role of functional magnetic resonance (MR) imaging in assessing hemispheric language dominance in epilepsy and nonepilepsy populations. MATERIALS AND METHODS: A Bayesian analysis study was performed. The study was based on data from the published literature; thus, institutional review board approval was not required. The literature was reviewed to obtain pretest probabilities and likelihood ratios, which were analyzed to determine the posttest probability of language dominance by using functional MR imaging. Pretest probabilities of different hand dominances in epilepsy and nonepilepsy populations were obtained from the largest studies available in the literature. Likelihood ratios were derived from the sensitivity and specificity of functional MR imaging by using electrocortical stimulation (ECS) and the Wada test as reference standards. RESULTS: Likelihood ratios for functional MR in determining language dominance were 9.3 and 12.3 with ECS and the Wada test as reference standards, respectively. Use of functional MR increased the final posttest probabilities of hemispheric language dominance in epilepsy and nonepilepsy populations. In the nonepilepsy population, regardless of hand dominance, there was very high posttest probability (>or=96%) of a correlation between functional MR hemisphere activation and definite left-hemisphere language dominance. In the epilepsy population with right-hand dominance or ambidexterity, there was very high posttest probability (>or=95%) of a correlation between functional MR hemisphere activation and definite left-hemisphere language dominance. In the left-handed nonepileptic subjects, there was high posttest probability (81%-83%) of a correlation between functional MR hemisphere activation and definite right-hemisphere language dominance. In the left-handed epilepsy population, there was high posttest probability (80%-97%) of a correlation between functional MR hemisphere activation and definite left-hemisphere language dominance. In the epilepsy population with ambidexterity, there was high posttest probability (80%-87%) of correlations between functional MR hemisphere activation and both definite right-hemisphere and bilateral language dominance. CONCLUSION: Use of functional MR increases importantly the posttest probabilities of hemispheric language dominance in multiple subgroups of individuals with and without epilepsy.

Bayes Theorem↗
PubMed1992

Spectral evidence for the oxidation of beta-hydroxybutyrate to acetoacetate: diminution of spectra by glucose and chloride.

Chemical oxidation of beta-hydroxybutyrate (beta-OHB) to acetoacetate (AcAc) has been carried out by a simple and new method employing potassium persulphate as an oxidising agent. Under the conditions of assay, beta-OHB (0.079-0.395 microM) was instantaneously oxidised to AcAc and the authenticity of the oxidised product was proved by absorption spectroscopy. A common absorption maxima at about 446 nm was observed in all the spectra recorded for the product (AcAc-complex) obtained after the oxidation of beta-OHB (0.079-0.395 microM) to AcAc followed by coupling with diazotized p-nitroaniline. This absorption maxima was almost equal to that obtained for AcAc-complex using AcAc as reference standard. It implies that AcAc formed by the chemical oxidation of beta-OHB is identically similar to the AcAc used as reference standard for the study. This fact was further strengthened when absorption spectra, recorded either individually or in combination (mixed-type), exhibited a single peak with a common absorption maxima at about 446 nm. Absorption spectra was found to be partially diminished by glucose (1.77 microM) and chloride (17.1 microM), while almost complete diminution of absorption spectra was observed at higher concentration of glucose (8.88 microM) and chloride (51.3 microM).

3-Hydroxybutyric Acid↗
PubMed1997

Synthesis of some indane derivatives of central muscle relaxant and anticonvulsant profiles.

A series of 2,2-bis(hydroxymethyl)indane derivatives 1a-f, 2a-e and 3a-f were synthesized to investigate their central muscle relaxant and anticonvulsant activities. The synthesized compounds 1a-f, 2a-e and 3a-f were found to be devoid of central muscle relaxant activity using meprobamate (100 mg/kg) as a reference standard. However, they showed remarkable anticonvulsant properties in a dose of 80 mg/kg (s.c.) compared with diphenylhydantoin sodium (80 mg/kg) as a reference standard.

Animals↗
PubMed1987

Rapid multielement analysis of oyster and cockle tissue using X-ray fluorescence spectrometry, with application to reconnaissance marine pollution investigations.

Forty-two elements in four standard reference materials and oyster and cockle tissue were analysed by the X-ray fluorescence spectrometry (XRF) method. Comparisons between certified values for standard reference materials and those of the authors indicate that XRF is suitable for determining Ba, Br, Cu, Fe, Mn, Pb, Rb, Sr, and Zn in organic matrix. Results for As, Cd, Cr, and Ni indicate that XRF is not reliable when analysing within approximately 2 mg kg-1 of the detection limits for these elements. XRF has been used to show that cockles accumulate Fe, Hg, I, Pb, Sr, Ti and Zn and oysters accumulate Cr, Cu, Fe, La, Ni, Ti, Yb, and Zn in moderately polluted areas. Values for As, Cu, Fe, Hg, Ni, Pb, Ti and Zn have been verified using atomic absorption spectroscopy. Whilst Hg was successfully determined, its limit of detection using XRF (9 mg kg-1) is too high if results are to be compared with the commonly used health standard for Hg in edible marine biota (0.5 mg kg-1 wet wt.). XRF has the capacity however to give an accurate linear response to a broad range of elements in approximately the 0-500 mg kg-1 range and is sensitive to much higher values without further sample manipulation. Hence, XRF has potential to be employed more extensively than is presently the case for elemental monitoring in broad-ranging reconnaissance marine pollution studies.

Animals↗
PubMed1983

Mojonnier method as reference for infrared determination of fat in meat products.

The Mojonnier method was compared with the conventional Soxhlet method for the determination of fat in 7 different meat products to assess its use as a standard reference method for calibration of commercial quantitative infrared transmission analyzers (e.g., Multispec M, Milkoscan 300 or 104). Results for the meat samples obtained by the Mojonnier method did not differ significantly from those obtained by the Soxhlet method. In addition, the Mojonnier method was less time-consuming and more precise than the Soxhlet; therefore, it can be used as a standard reference procedure for the calibration and assessment of infrared milk analyzers in their potential application to the rapid determination of fat in meat and meat products.

Animals↗
PubMed2001

Technologic advances for evaluation of cervical cytology: is newer better?

Among those women who have cervical cancer and have been screened, 14% to 33% of the cases represent failure to detect abnormalities that existed at the time of screening. New technologies intended to improve detection of cytologic abnormalities include liquid-based, thin-layer cytology (ThinPrep, AutoCyte), computerized rescreening (PAPNET), and algorithm-based computer rescreening (AutoPap). This report combines evidence reviews conducted for the U.S. Preventive Services Task Force and the Agency for Healthcare Research and Quality, in which we systematically identified articles on cervical neoplasia, cervical dysplasia, and screening published between January 1966 and March 2001. We note the challenges for improving screening methods, providing an overview of methods for collecting and evaluating cytologic samples, and examining the evidence about the diagnostic performance of new technologies for detecting cervical lesions. Using standard criteria for evaluation of the diagnostic tests, we determined that knowledge about the sensitivity, specificity, and predictive values of new technologies is meager. Only one study of liquid-based cytology used a reference standard of colposcopy, with histology as indicated, to assess participants with normal screening results. Lack of an adequate reference standard is the overwhelming reason that test characteristics cannot be properly assessed or compared. Most publications compare results of screening using the new technology with expert panel review of the cytologic specimen. In that case, the tests are not independent measures and do nothing to relate the screening test findings to the true status of the cervix, making determination of false-negatives, and thus sensitivity, specificity, and negative predictive value, impossible. We did not identify any literature about health outcomes or cost effectiveness of using these tools in a system of screening. For the purposes of guiding decision making about choice of screening tools, the current evidence is inadequate to gauge whether new technologies are "better" than conventional cytology..

Colposcopy↗
PubMed2001

Testing the basic assumption of the hydrogeomorphic approach to assessing wetland functions.

The hydrogeomorphic (HGM) approach for developing "rapid" wetland function assessment methods stipulates that the variables used are to be scaled based on data collected at sites judged to be the best at performing the wetland functions (reference standard sites). A critical step in the process is to choose the least altered wetlands in a hydrogeomorphic subclass to use as a reference standard against which other wetlands are compared. The basic assumption made in this approach is that wetlands judged to have had the least human impact have the highest level of sustainable performance for all functions. The levels at which functions are performed in these least altered wetlands are assumed to be "characteristic" for the subclass and "sustainable." Results from data collected in wetlands in the lowlands of western Washington suggest that the assumption may not be appropriate for this region. Teams developing methods for assessing wetland functions did not find that the least altered wetlands in a subclass had a range of performance levels that could be identified as "characteristic" or "sustainable." Forty-four wetlands in four hydrogeomorphic subclasses (two depressional subclasses and two riverine subclasses) were rated by teams of experts on the severity of their human alterations and on the level of performance of 15 wetland functions. An ordinal scale of 1-5 was used to quantify alterations in water regime, soils, vegetation, buffers, and contributing basin. Performance of functions was judged on an ordinal scale of 1-7. Relatively unaltered wetlands were judged to perform individual functions at levels that spanned all of the seven possible ratings in all four subclasses. The basic assumption of the HGM approach, that the least altered wetlands represent "characteristic" and "sustainable" levels of functioning that are different from those found in altered wetlands, was not confirmed. Although the intent of the HGM approach is to use level of functioning as a metric to assess the ecological integrity or "health" of the wetland ecosystem, the metric does not seem to work in western Washington for that purpose.

Conservation of Natural Resources↗
PubMed2006

Literature search parameters marginally improved the pooled estimate accuracy for ultrasound in detecting deep venous thrombosis.

BACKGROUND AND OBJECTIVES: Data collection remains of utmost importance to avoid publication bias in systematic reviews. Our objectives were to compare search strategies with and without methodological terms in Medline, to find out how other databases complement Medline, and how these strategies affect the pooled estimates of the accuracy. STUDY DESIGN AND SETTING: A study was eligible if it prospectively compared ultrasound to venography for the diagnosis of deep venous thrombosis in the lower limbs. All relevant articles found with all databases, searched from 1966 through 2003, constitute the reference standard. Sensitivity was defined as the proportion of relevant studies found by Medline searches divided by the total number of articles in the reference standard. RESULTS: Of a total of 1,473 citations, 237 abstracts were included. The sensitivity of strategies without methodological terms was higher (96%) than those with (95%, 76%, and 95%). Searches of multiple databases found seven articles not found with Medline. Searches of congress proceedings (International Society of Thrombosis and Haemostasis) found three abstracts not published in full. The diagnostic odds ratio OR was 5.66 (95% confidence interval CI = 4.84-6.48) when multiple databases were searched and 5.57 (95% CI = 3.49-7.65) when only English-language articles in Medline were identified. CONCLUSION: Medline searches combining free text and MeSH terms were more sensitive. Single Medline search affects only marginally the pooled estimate accuracy.

Abstracting and Indexing↗
PubMed2006

Rapid method for determination of dioxin-like polychlorinated biphenyls and other congeners in marine sediments using sonic extraction and photodiode array detection.

A rapid method has been developed to measure dioxin-like polychlorinated biphenyl (PCB) congeners as well as other selected PCBs in sediment. The analytes were extracted from sediment by sonication with dichloromethane, and the PCBs were separated from interfering compounds on a gravity-flow cleanup column packed with acidic, basic, and neutral silica gels eluted with 1:1 hexane:pentane (v/v). Subsequently, the dioxin-like PCB congeners were resolved from nonplanar PCBs and other chlorinated compounds by high-performance liquid chromatography (HPLC). Two important advantages of PDA over conventional UV detection are the ability to identify individual analytes by comparing their UV spectra with those of reference standards and the ability to establish the spectral homogeneity (purity) of the analytes by comparing spectra within a peak to the apex spectrum. The HPLC-PDA method was tested with reference and marine sediment samples. Concentrations of selected dioxin-like PCBs, selected nonplanar PCBs, and summed PCBs in sediments and National Institute of Standards and Technology standard reference materials determined by our rapid HPLC-PDA method were comparable with the levels in the same samples analyzed by alternative comprehensive methods (i.e., gas chromatography-electron capture detection or high-resolution gas chromatography-high-resolution mass spectrometry).

Chromatography, High Pressure Liquid↗
PubMed2002

[Quality evaluation of essential oils].

Essential oils on the market were analyzed using GC-MS and the main ingredients of each essential oil were quantified. Analysis of the essential oil of Lavandula officinalis (lavender oil) showed that each sample had a different ratio of the contents of main ingredients, such as linalool, linalyl acetate, and camphor. In addition, some commercial lavender oils were analyzed by GC-MS for comparison with the Lavandula flagrans (lavandin oil) and the reference standard. As a result of this analysis, although the components of almost all commercial lavender oils were approximately the same as those of the reference standard, there were a few products that contained more than 0.5% of the amount of camphor in lavandin oil. This suggests that some lavender oil samples are mixed with lavandin oil to lower the price. Commercial essential oils of Melaleuca alternifolia (teatree oil) and Mentha piperita (peppermint oil) were also analyzed by GC-MS. Each of the peppermint oil samples had a different ratio in the content of its main ingredient. With respect to teatree oils, the amount of terpinens in each sample differed. These results led to concern about the efficacy of essential oils. For achieve the expected efficacy of essential oils, correct information on their ingredients should be available and quality control using instrumental analysis should be introduced.

Gas Chromatography-Mass Spectrometry↗
PubMed2003

Antibacterial and antifungal activities of Quassia undulata and Quassia amara extracts in vitro.

Extracts of Quassia undulata and Quassia amara (Simaroubaceae) were screened for in vitro antibacterial and antifungal properties respectively. A total of eight extracts, comprising hexane and methanol extracts of the leaves and stems of each of the two plants were investigated. At a concentration of 5 mg/ml all eight extracts exhibited marked antibacterial and antifungal activities in most cases higher than the standard reference drugs included in the study. The extracts inhibited the growth of Escherichia coli, Streptococcus faecalis, Stapylococcus aureus and Aspergillus niger, even when the standard reference drugs utilized in the study did not. Quassia amara leaf methanol extract singularly exhibited the highest activities in both assays, which included the use of six clinical strains of bacteria and five fungi. The agar cup (10 mm diameter) diffussion and broth dilution techniques were used in both assays, utilising eleven human pathogenic microorganisms. Ampicillin and tioconazole were also included in the assay as reference compounds, while methanol was used as control. Diameter of zones of inhibition ranged between 11.0-29.0 mm for the tested extracts/drugs. All the extracts have shown impressive activities against the commonly encountered microorganisms and have thus confirmed the folklore uses of the plants in the African ethnomedicine.

Anti-Bacterial Agents↗
PubMed2004

Prospective comparison of small bowel meal with pneumocolon versus ileo-colonoscopy for the diagnosis of ileal Crohn's disease.

BACKGROUND AND AIMS: Both endoscopy and barium radiography are used routinely to diagnose terminal ileal (TI) Crohn's disease (CD). A prospective study was undertaken to compare ileoscopy with biopsy to small bowel meal with pneumocolon (SBMP) in patients with suspected TI CD. METHODS: A cohort of outpatients investigated for diarrhea with features of TI disease underwent SBMP followed by colonoscopy with ileal intubation and biopsy within 21 days. All results were reported in a standardized, sequential format to assign SBMP TI diagnoses by the duty radiologist and by dual reading with consensus, ileoscopy by the attending endoscopist, and ileoscopy with biopsy by a blinded panel of endoscopists and pathologists. Reference standard TI diagnoses were determined by a consensus panel with full access to medical records. RESULTS: Among 120 subjects, the reference standard TI diagnosis was normal in 47 (39.1%), lymphoid nodular hyperplasia (LNH) in 24 (20.0%), CD in 48 (40.0%), and NSAID enteropathy in 1 (0.9%). Colonoscopy provided TI images and/or biopsies in 97 cases (80.8%), while SBMP provided TI images in 119 (99.1%). When ileoscopy with biopsy succeeded, its accuracy was similar to SBMP with dual reading (89.7%vs 89.9%, p = NS) but superior to SBMP if interpreted only by the duty radiologist (80.0%, p < 0.05). Biopsy improved the accuracy of ileoscopy, while dual reading improved that of SBMP. Both ileoscopy with biopsy and SBMP with dual reading are highly accurate for diagnosing TI CD. Choice of initial test should reflect local expertise and availability, and the likelihood of associated disease in the proximal small bowel or colon.

Adolescent↗
PubMed2005

Identifying palliative care patients with symptoms of depression: an algorithm.

INTRODUCTION: Even though depression has serious and wide-ranging effects on outcomes in palliative care, errors in the identification of depressed patients are common. OBJECTIVES: To examine the clinical validity of widely publicised one- and two-question screening tools for depression in two palliative care settings. Also, to examine the construct validity and acceptability of a new empirically derived algorithm. METHOD: Participants were Australian palliative care patients in an inpatient hospice (n=22) or the community (n=69). Patients completed an unstructured interview about their feelings, questions relevant to three reference standards, two screening questions for depression and questions about the acceptability of the screening questions. RESULTS: The clinical validity of the one- and two-question screening tools did not generalise across the two care settings. In contrast, the algorithm met stringent criteria for clinical validity for two reference standards in both settings. The algorithm also selectively identified patients whose unstructured interviews referred to themes consistent with depression. The algorithm includes potentially sensitive questions about anhedonia and depressed affect. However, almost all patients and staff reported that asking such questions soon after referral was acceptable. CONCLUSIONS: A four-question algorithm designed to identify patients who warrant follow-up for depression showed clinical validity, generalizability and construct validity, and the content was acceptable to patients and clinicians.

Adult↗
PubMed1996

Accurate calibration of TXRF using microdroplet samples.

TXRF has been applied in combination with VPD to the analysis of trace impurities in the native oxide layer of Si wafer surfaces down to the range of 10(8) atoms. cm(-2). Proper quantification of VPD/TXRF data requires calibration with microdroplet standard reference wafers. The precision of calibration function has been evaluated and found to allow quantification at a high level of 3 sigma confidence with microdroplet standard reference.

Journal Article↗
PubMed1982

Assessment of emetic and antiemetic activity.

Compounds having acute emetic or antiemetic activities have been quantitatively evaluated and compared with the reference standards, apomorphine and chlorpromazine, respectively. The bioassay for an emetic required the establishment of mean threshold emetic doses in groups of dogs for both the reference standard apomorphine and the test compound. The bioassay for antiemetics was based upon the degree to which the test drug elevated the threshold emetic dose for apomorphine. That effect was contrasted with the change in emetic threshold produced by equimolar concentrations of chlorpromaine.

Animals↗
PubMed1991

In vitro metabolism and toxicity assessment of N-methylcarbazole in primary cultured rat hepatocytes.

N-Methycarbazole (NMC), a carcinogen and mutagen in tobacco smoke, was converted to two major metabolites by primary cultured rat hepatocytes as measured by high performance liquid chromatography (HPLC): N-hydroxymethylcarbazole (NHMC) and carbazole. These two metabolites had comparable retention times and identical ultraviolet spectra as those of reference standards. Identical retention times and mass spectra were also observed as detected by gas chromatography-mass spectroscopy (GC-MS) for NHMC and its reference standard. The toxicities of NMC and its two metabolites were assessed by lactate dehydrogenase (LDH) leakage and neutral red (NR) uptake. The rank order of cytotoxicity of NMC and its metabolites was found to be: NHMC greater than NMC greater than carbazole. Thus, we conclude that the hydroxylation of NMC to NHMC may represent a toxification step, while the further dealkylation to carbazole is most likely a detoxication process.

Animals↗
PubMed1987

Characterization, purification, and analysis of solvent yellow 33 and solvent green 3 dyes.

Thin-layer chromatography and high-performance liquid chromatography (HPLC) with linear photodiode array detection (LPDA) were used to separate impurities from two commercial dyes. Gravity flow liquid chromatography was used to purify reference standards of the dyes. Normal phase HPLC with LPDA detection was used to determine purities of submitted samples by comparing responses to those of the reference standards. Electron impact mass spectrometry and nuclear magnetic resonance were utilized to confirm structures of the dyes and their impurities.

Anthraquinones↗
PubMed1998

A comparison of temperature measurements using three ear thermometers.

Following anecdotal and research-based reports of inaccuracies encountered with the use of ear thermometers in patient care settings, this two-phase study was designed to compare the accuracy of three ear thermometers when used in a multioperator environment. The within-subject variation (limits of agreement) in ear temperature measurements obtained with the three ear thermometers in a multioperator condition by using an oral temperature reference standard ranged from +/- 1.25 degrees F to 1.85 degrees F. In multioperator, multisubject patient care environments using a pulmonary artery catheter core temperature as the reference standard, the limits of agreement for ear temperature measurements obtained with the three different ear thermometers ranged from +/- 2.19 degrees F to 2.85 degrees F. These results suggest that there is substantial variation in ear measurements and raise questions about the use of ear thermometers when there are multiple personnel taking temperatures, as occurs in hospital-based clinical practice environments. Handedness of the operator, position of the patient, and the ear used for measurement did not produce clinically significant variability in ear temperature measurements.

Adult↗