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At least 667 records · Page 37Linked to original sources
PubMed1985

Priming procedure and hormone preparations influence rat granulosa cell response.

The FSH activity in equine (e) FSH, eLH, eCG, and ovine LH were examined and compared to that in the standard reference preparation NIH FSH-S13 by three types of assay: the FSH radioreceptor assay with rat testicular homogenate and the stimulation of plasminogen activator production and steroidogenic activity in granulosa cells from diethylstilbestrol (DES)- or eCG-primed donor rats. The difference in the two types of granulosa cells was that the eCG-primed cells have already acquired significant aromatase activity. With the exception of oLH, which showed very little FSH activity (approximately 0.03-0.08 X NIH FSH-S13) throughout the three assays, the equine gonadotropins exhibited great variations in activity with respect to each assay. eFSH, the most active molecule in these assays, had an activity of 44 X NIH FSH-S13 in the receptor binding assay, 8.75 X NIH FSH-S13 in plasminogen activator production, and 4-5 X NIH FSH-S13 in steroid production when assayed in the DES-primed granulosa cells. In the eCG-primed cells, eFSH showed an activity of 4.2 X NIH FSH-S13 in plasminogen activator production and 8.2 X NIH FSH-S13 in progesterone production. eLH had an activity of 10 X NIH FSH-S13 in FSH radioreceptor assay, but showed very little activity and behaved like oLH in stimulation of the cellular responses of DES-primed granulosa cells. However, when eLH was assayed in the eCG-primed cells, it did show stimulating activity with respect to the production of plasminogen activator and progesterone; however, the dose-response curves were not parallel to those of eFSH and eCG. eCG had much less FSH receptor-binding activity (0.29 X NIH FSH-S13) than eLH. It behaved like a LH molecule in DES-primed granulosa cells, but did show activity (approximately 1 X NIH FSH-S13) in stimulating the production of plasminogen activator and progesterone in eCG-primed granulosa cells. From these results, we conclude that under our culture conditions, neither eLH nor eCG was active in the DES-primed granulosa cells, but both were active in the eCG-primed cells, and that the choice of assay conditions and reference standards is very important. Different types of assay may give rise to completely different comparisons for the same molecules. The equine gonadotropins provide a particularly dramatic example of such differences.

Animals↗
PubMed1987

Combined evaluation of circulating immune complexes and antibodies to Pseudomonas aeruginosa as an immunologic profile in relation to pulmonary function in cystic fibrosis.

We developed a solid-phase radioimmunoassay with a reference standard pseudomonas antigen and used this with 125I-labeled anti-human immunoglobulin to evaluate specific antibodies to Pseudomonas aeruginosa, qualitatively and quantitatively, in sera from children with cystic fibrosis (CF) whose lungs were colonized by this bacterium. The results of this IgG assay correlated with the number of precipitin antibodies to the standard reference antigen determined by cross-immunoelectrophoresis in the same sera. Forced expiratory volume (FEV1; percentage predicted), determined as an indicator of lung injury in CF, was evaluated as an immunologic response to pseudomonas, against a profile derived from combined serial data on both the circulating immune complexes (CIC) and the Ps. aeruginosa antibodies (N = 25 CF patients; 108 sera). This revealed that in CF patients who had no specific IgG antibodies to Ps. aeruginosa and no IgG-CIC had the best pulmonary function (FEV1 = 115 +/- 14.52%) and those with high levels of antibodies to this organism and high IgG-CIC levels had the poorest lung function (FEV1 = 69.75 +/- 10.99%) (P less than 0.05). We believe that this indicates an immunologic basis for lung injury in cystic fibrosis.

Antibodies, Bacterial↗
PubMed1987

The ageing ear. A clinico-pathological classification.

While it is clear that the majority of the world's population suffers some deterioration of hearing--especially at high frequencies--with the advance of age, it is equally clear that some individuals reach very old age with clinically normal hearing. It is often difficult to separate the biological changes of senility from the effects of auditory environmental changes, and of specific pathological changes associated with specific disease entities. A better understanding of the etiology of presbyacusis is needed. The first step towards this end is the recognition that not all hearing impairment in the aged is due to biological ageing. This is important because hearing loss due to the acceleration of biological and environmental effects (accelerated presbyacusis) may be preventable, while hearing loss due to biological ageing (presbyacusis) is not treatable. The second step is the realization that not all hearing impairment over age 65 is due to ageing. Hearing impairments that are rapidly progressive, profound, asymmetrical, or fluctuating, and those associated with a marked conductive element or severe dizziness might well be associated with specific ear disease (Nosoacusis) such as infection, otosclerosis, Menière's disease, or acoustic tumor. A full neuro-otological evaluation including ABR, CT scan, ENG and others should be done in any patient over 65 suspected of having a specific ear disease. The classification presented demonstrates the need to revise the criteria used in determining 'Presbyacusis Curves'. These provide a reference standard for normal hearing at any age or decade. There are too many variables in the averages obtained from different subjects to make those averages a dependable standard reference.

Aged↗
PubMed2005

Extraction and quantitative analysis of iodine in solid and solution matrixes.

129I is a contaminant of interest in the vadose zone and groundwater at numerous federal and privately owned facilities. Several techniques have been utilized to extract iodine from solid matrixes; however, all of them rely on two fundamental approaches: liquid extraction or chemical/heat-facilitated volatilization. While these methods are typically chosen for their ease of implementation, they do not totally dissolve the solid. We defined a method that produces complete solid dissolution and conducted laboratory tests to assess its efficacy to extract iodine from solid matrixes. Testing consisted of potassium nitrate/potassium hydroxide fusion of the sample, followed by sample dissolution in a mixture of sulfuric acid and sodium bisulfite. The fusion extraction method resulted in complete sample dissolution of all solid matrixes tested. Quantitative analysis of 127I and 129I via inductively coupled plasma mass spectrometry showed better than +/-10% accuracy for certified reference standards, with the linear operating range extending more than 3 orders of magnitude (0.005-5 microg/L). Extraction and analysis of four replicates of standard reference material containing 5 microg/g 127I resulted in an average recovery of 98% with a relative deviation of 6%. This simple and cost-effective technique can be applied to solid samples of varying matrixes with little or no adaptation.

Journal Article↗
PubMed1985

Anorexia and weight loss: indicators of cachexia in small cell lung cancer.

A study was conducted to determine the incidence and extent to which anorexia, a decrease in spontaneous food intake, contributes to the occurrence of cancer cachexia. Data for ten male subjects with small cell carcinoma of the lung are reported for a five-month period following diagnosis. Although body weights of the subjects at the time of diagnosis averaged less than 95% of the usual weight (weight 6 months prior to diagnosis), they were greater than 109% of the mean ideal weight. At five months, the mean weight (N = 8) was 88% of the preillness weight. From the time of diagnosis, there was a mean loss of 7.2 kg (15.8 lb). The urinary creatinine excretion was below the normal range, whereas the urinary urea nitrogen values were within the normal range. At the time of diagnosis, the mean triceps skin-fold measurements were approximately 80% of the standard reference for males. During the five-month period, the mean midarm muscle circumference determinations remained greater than 90% of the reference standard. The mean serum transferrin values were 10% or more below the reported lower range of normal, whereas the great majority of the serum albumin values were 3.0 g/dl or above during the five-month period. The mean caloric intake of 2,204 kcal at the time of diagnosis was only 86% of the estimated basal energy expenditure (BEE) times a factor of 1.5 used to account for moderate activity. Four months following diagnosis, the mean caloric intake had fallen to 1,702 kcal, only 67% of the BEE X 1.5 (calculated from the weight at diagnosis). The findings provide evidence of a decline in spontaneous food intake, a small decrease in body fat, and a greater than 13% weight loss. The oral intake was less than adequate for any activity beyond the basal state. Decreased intake could account for most of the weight loss observed in the subjects.

Adult↗
PubMed2004

Comparison of the automated non-invasive oscillometric blood pressure monitor (BpTRU) with the auscultatory mercury sphygmomanometer in a paediatric population.

BACKGROUND: To directly compare the accuracy of the BpTRU (an automated oscillometric blood pressure device) with standard auscultatory mercury sphygmomanometry in a pediatric population. DESIGN: The BpTRU was connected in parallel with a standard mercury sphygmomanometer. Two observers measured the blood pressures at the same time as it was being measured by the BpTRU. The observers and the BpTRU were all blinded from each other. METHODS: For each of the demographic data--subject age, sex and arm sizes--the mean, standard deviation (SD) and range was calculated. The difference between the mean BpTRU and the standard reference measurements (observer average) was calculated with SD and ranges. The percentage of measurements within 5, 10 and 15 mmHg agreement was expressed. RESULTS: From the 36 subjects recruited aged 3-18 years, 162 pairs of sitting blood pressures were included. The difference between the mean BpTRU readings and the reference standard measurements (as determined by the observers) was 1.45+/-5.67 mmHg for systolic blood pressures, and -3.24+/-7.39 mmHg for diastolic pressure and 0.20+/-2.47 bpm for heart rate. CONCLUSION: The BpTRU is of similar accuracy in measuring blood pressure in children as it was in an adult population.

Adolescent↗
PubMed1987

Use of vectorcardiography in determination of the left ventricular muscle mass.

Many studies have investigated different ECG and vectorcardiographic (VCG): criteria for diagnosis of left ventricular hypertrophy (LVH). In some investigations VCG was more sensitive than ECG in this respect. This study was performed to elucidate whether it is possible also to determine the degree of LVH using VCG. Eighty cardiovascularly healthy subjects aged 15-39 were investigated with ECG, VCG (Frank system) and echocardiography. The echocardiographic left ventricular (LV) mass has been shown by others to correlate closely to the anatomical and the angiographically determined LV mass and was used as reference standard. Thirty-eight of the subjects were endurance sportsmen and had a LV mass above standard reference limits. The measured ECG variables were R-amplitude in a VL, I, V5, V6, S-amplitude in V1 and SV1 + RV5/V6 and the VCG variables were QRS spatial area and circumference and left maximal spatial vector. The sensitivity and specificity of single criteria tested were similar for ECG and VCG in the quantitative determination of LVH. The correlations between ECG-amplitudes and the magnitude of the LV mass were weak. The correlations were higher with the VCG-variables, QRS spatial circumference being superior to the others, but not good enough to permit an estimation of the LV mass in individual subjects. In conclusion, normal VCG variables were highly specific for a normal LV mass but in individuals with LVH, VCG was not useful for the estimation of the LV mass.

Adolescent↗
PubMed2006

GHB free acid: II. Isolation and spectroscopic characterization for forensic analysis.

A reference standard for gamma-hydroxybutyric acid (GHB) free acid is not commercially available, making its analysis in forensic exhibits more difficult. GHB free acid is typically encountered in aqueous solution and in the presence of the lactone, gamma-butyrolactone (GBL), presenting difficulty in Fourier transform infrared (FT-IR) analysis. The strong infrared (IR) absorptivity of the GBL carbonyl band, the shifting of the GBL carbonyl band in aqueous solutions, and the position of the O-H bend for water can mask the main carbonyl band for GHB free acid. Model solutions of beta-hydroxybutyric acid (BHB) and GBL were studied in order to further understand the masking of the GHB free acid carbonyl band in FT-IR analysis. The use of second derivative FT-IR spectroscopy was shown to provide resolution of the free acid carbonyl band, and a presumptive test for GHB free acid was developed and applied. An extension of this work included preparing, for use as a standard reference material, small amounts (< or = 10 mg) of GHB free acid. Preparation was based on the instantaneous reaction of GHB's sodium salt with a stoichiometric amount of hydrochloric acid in aqueous solution, and subsequent isolation of the free acid in neat liquid form. Both FT-IR and proton nuclear magnetic resonance spectra of the neat reference material were obtained and used to verify its identity. The isolation of GHB free acid from actual forensic exhibits is also presented, with identity confirmation using FT-IR.

Journal Article↗
PubMed1998

A multiresolution restoration method for cardiac SPECT imaging.

In this study we present a multiresolution based method for restoring cardiac SPECT projections. Original projections were decomposed into a set of sub-band frequency images by using analyzing functions localized in both the space and frequency domain. This representation allows a simple denoising and restoration procedure by discarding high-frequency channels and performing inversion only in low frequencies. The method was evaluated in bull's eye reconstructions of a realistic cardiac chest phantom with a custom-made liver insert and 99mTc liver-to-heart activity ratios (LHAR) of 0:1, 1.5:1, 2.5:1, and 3.5:1. The cardiac phantom in free air was used as the reference standard. Reconstructions were performed by filtered backprojection using (1) no correction; (2) restoration without attenuation correction; (3) attenuation correction without restoration; and (4) restoration and attenuation correction. The attenuation correction was carried out with the Chang's method for one iteration. Results were compared with those obtained using an optimized prereconstruction Metz filter. Quantitative analysis was performed by calculating the normalized chi-square measure and mean +/- s.d. of bull's eye counts. In reconstructions with high liver activity (LHAR > 2), attenuation correction without restoration severely distorted the polar maps due to the spill-over of liver activity into the inferior myocardial wall. Both restoration methods when combined with an attenuation correction compensated this artifact and yielded uniform polar maps similar to that of the standard reference. There was no visual or quantitative difference between the performance of Metz filtering and multiresolution restoration. However, the main advantage of the multiresolution method is that it states a more concise and straightforward approach to the restoration problem. Multiresolution based methods does not require information about the object image or optimization processes, such as in conventional nuclear medicine restoration filters. In addition, the method is easy to implement using DFT techniques and potentially can be extended to noniterative spatially shift-invariant restorations in SPECT.

Biophysical Phenomena↗
PubMed1999

[A relative bioavailability study of 2 oral formulations of omeprazole after their administration in repeated doses to healthy volunteers].

To determine the relative bioavailability of Ulceral (study formula) with respect to Losec (reference standard formula) and establish their bioequivalence daily doses of 20 mg of omeprazole were given during 5 consecutive days to 24 healthy volunteers. No significant differences were observed in the area under the curve (AUC0-t), a parameter directly related to the inhibition of acid secretion induced by omeprazole. The confidence interval of 90% for the difference between the two formulations for AUC0-t was within the interval of acceptance (0.80-1.25). The confidence interval for the difference between the two formulations for Cmax were also within the range of acceptance (0.70-1.43). In relation to the time for achieving (Cmax (tmax), the difference between the two formulations and the confidence interval of 95% for the tmax was 0.75 (-0.5-1.75) h indicating that no significant differences were observed between the two treatments. This study confirms the bioequivalence of Ulceral with the standard reference formulation as well as the tolerability of the two formulae.

Administration, Oral↗
PubMed2005

Consequences of different diagnostic "gold standards" in test accuracy research: Carpal Tunnel Syndrome as an example.

Test accuracy studies assume the existence of a well-defined illness definition and clear-cut diagnostic gold standards or reference standards. However, in clinical reality illness definitions may be vague or a mere description of a set of manifestations, mostly clinical signs and symptoms. This can lead to disagreements among experts about the correct classification of an illness and the adequate reference standard. Using data from a diagnostic accuracy study in carpal tunnel syndrome, we explored the impact of different definitions on the estimated test accuracy and found that estimated test performance characteristics varied considerably depending on the chosen reference standard. In situations without a clear-cut illness definition, randomized controlled trials may be preferable to test accuracy studies for the evaluation of a novel test. These studies do not determine the diagnostic accuracy, but the clinical impact of a novel test on patient management and outcome.

Carpal Tunnel Syndrome↗
PubMed2006

Mammographic density measured with quantitative computer-aided method: comparison with radiologists' estimates and BI-RADS categories.

PURPOSE: To retrospectively compare computer-aided mammographic density estimation (MDEST) with radiologist estimates of percentage density and Breast Imaging Reporting and Data System (BI-RADS) density classification. MATERIALS AND METHODS: Institutional Review Board approval was obtained for this HIPAA-compliant study; patient informed consent requirements were waived. A fully automated MDEST computer program was used to measure breast density on digitized mammograms in 65 women (mean age, 53 years; range, 24-89 years). Pixel gray levels in detected breast borders were analyzed, and dense areas were segmented. Percentage density was calculated by dividing the number of dense pixels by the total number of pixels within the borders. Seven breast radiologists (five trained with MDEST, two not trained) prospectively assigned qualitative BI-RADS density categories and visually estimated percentage density on 260 mammograms. Qualitative BI-RADS assessments were compared with new quantitative BI-RADS standards. The reference standard density for this study was established by allowing the five trained radiologists to manipulate the MDEST gray-level thresholds, which segmented mammograms into dense and nondense areas. Statistical tests performed include Pearson correlation coefficients, Bland-Altman agreement method, kappa statistics, and unpaired t tests. RESULTS: There was a close correlation between the reference standard and radiologist-estimated density (R = 0.90-0.95) and MDEST density (R = 0.89). Untrained radiologists overestimated percentage density by an average of 37%, versus 6% for trained radiologists (P < .001). MDEST showed better agreement with the reference standard (average overestimate, 1%; range, -15% to +18%). MDEST correlated better with percentage density than with qualitative BI-RADS categories. There were large overlaps and ranges of percentage density in qualitative BI-RADS categories 2-4. Qualitative BI-RADS categories correlated poorly with new quantitative BI-RADS categories, and 16 (6%) of 260 views were erroneously classified by MDEST. CONCLUSION: MDEST compared favorably with radiologist estimates of percentage density and is more reproducible than radiologist estimates when qualitative BI-RADS density categories are used. Qualitative and quantitative BI-RADS density assessments differed markedly.

Adult↗
PubMed1985

Steady-state bioavailability of dexbrompheniramine and pseudoephedrine from a repeat-action combination tablet.

The steady-state bioavailabilities of dexbrompheniramine and pseudoephedrine were evaluated following multiple-dose administrations of a repeat-action combination tablet containing 6 mg of dexbrompheniramine maleate with 120 mg of pseudoephedrine sulfate every 12 h for 7 d compared with reference standards. The reference standards used in this study were concomitant administration of conventional 2-mg dexbrompheniramine maleate tablets every 4 h and 120-mg pseudoephedrine sulfate repeat-action tablets every 12 h, each for 7 d. Twelve healthy adult male volunteers completed this randomized two-way crossover study. Blood samples for subsequent assay were obtained at frequent time intervals throughout each 7-d dosing phase. Sensitive and specific gas-liquid chromatographic methods were used for the determination of dexbrompheniramine and pseudoephedrine in plasma. Based on the plasma levels, the times to reach steady state were determined. In addition, the major bioavailability parameters (Cmin, Cmax, tmax, and AUC) for days 6 and 7 of dosing were determined and statistically evaluated. The results of this study demonstrate that, at steady state, the repeat-action combination tablet and concomitant administration of the reference standards are bioequivalent.

Biological Availability↗
PubMed1999

A contribution to the improvement of accuracy in the quantitation of THC.

The accuracy of a quantitative analysis is highly dependent on the quality of the reference standard. Although reference standards are more and more supplied with a certificate, laboratories may feel the need for additional acceptance testing. In general, confirmation of the purity of many solid reference substances can be obtained by a number of simple tests. However, verification of the true content of reference solutions may be complicated. A number of problems with the THC quantitation caused our interest for a verification method for the THC reference solution. The quantitation of THC is performed by gas chromatography with flame ionisation detector. The effective carbon number concept was used to predict GC/FID response factors. Equations and data are presented to calculate theoretical response ratios of cannabinoids. The experimental data for CBD and CBN were in excellent agreement with the theoretical ones. The paper shows that the response factors of CBD and/or CBN can be used for the calculation of the THC content of either reference solutions or cannabis samples.

Bias↗
PubMed1987

Comparison of four leukocyte differential methods with the National Committee for Clinical Laboratory Standards (NCCLS) reference method.

The authors compared four leukocyte differential counting methods with the National Committee for Clinical Laboratory Standards Reference Leukocyte Differential Method H20-T to determine the clinical sensitivity of the methods. The three-part differential performed by the Coulter Counter Model S-Plus IV and the Toa E-5000, when combined with instrument flags and defined laboratory checking limits for red blood cell and platelet values, are safe and efficacious screening methods for the presence of morphologic abnormalities. The Geometric Data Hematrak 590 proved comparable in clinical sensitivity to a random 100-cell eye-count differential.

Adolescent↗