Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Reference Standards”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 991 records · Page 55Linked to original sources
PubMed2005

Impact of carbon dioxide on the susceptibility of key respiratory tract pathogens to telithromycin and azithromycin.

OBJECTIVES: To determine the quantitative differences in telithromycin and azithromycin MIC values against Streptococcus pneumoniae, Haemophilus influenzae and Streptococcus pyogenes obtained using two recommended and commonly used methodologies: CLSI reference standard broth microdilution in ambient air and Etest((R)) concentration gradient in CO(2). METHODS: Four hundred clinical isolates (S. pneumoniae, n = 200; H. influenzae, n = 100; S. pyogenes, n = 100) were evaluated in seven independent laboratories. Telithromycin and azithromycin MICs were determined using CLSI broth microdilution panels incubated in ambient air and Etest strips incubated in CO(2). Standard quality control reference strains-S. pneumoniae ATCC 49619 (n = 10) and H. influenzae ATCC 49247 (n = 10)-were also tested. RESULTS: Telithromycin and azithromycin Etest MICs in CO(2) were elevated for all organisms when compared with values obtained using broth microdilution in ambient air. Telithromycin geometric mean MIC values increased in CO(2) by 2.05, 1.00 and 1.78 log(2) dilutions for S. pneumoniae, H. influenzae and S. pyogenes, respectively. The corresponding values for azithromycin were 2.54, 1.21 and 3.0 log(2) dilutions, respectively. CONCLUSIONS: Telithromycin MICs measured using Etest in CO(2) are consistently elevated compared with those generated by CLSI broth microdilution measured in ambient air. These findings indicate that Etest should not be routinely used for the determination of telithromycin MICs against S. pneumoniae, H. influenzae and S. pyogenes, unless appropriate corrective factors are applied before reporting MICs or applying interpretive susceptibilities. Based on results from this study, Etest MIC breakpoints and quality control ranges are proposed.

Anti-Bacterial Agents↗
PubMed1986

Continuous noninvasive real-time monitoring of stroke volume and cardiac output by thoracic electrical bioimpedance.

Thoracic electrical bioimpedance (TEB) is a noninvasive method for the estimation of left ventricular stroke volume (SV). Objections to TEB in the past have included systematic overestimation of SV and cardiac output in normals, poor correlation in absolute terms with standard cardiac output reference techniques, motion and ventilation artifacts which distorted recorded waveforms except when patients remained in apnea during measurements, and lack of a computer to yield rapid heat-to-beat quantitation of SV and cardiac output. The present study entails real-time, beat-to-beat cardiac output determinations using TEB and assessing its agreement via a digital computer against a reference standard, thermodilution. A correlation coefficient of 0.88 is reported with 85% of data points falling within 20% confidence limits on either side of the line of identity.

Adult↗
PubMed2003

Gluten sensitivity in a subset of children with insulin dependent diabetes mellitus.

OBJECTIVES: The association between celiac disease and insulin dependent diabetes mellitus (IDDM) is well established. Rectal gluten challenge has been used in patients with celiac disease and in first degree relatives as a tool to assess the mucosal immune response to gluten. The aim of this study was to assess the mucosal immune response to gluten in IDDM children by rectal gluten challenge. METHODS: Rectal biopsy specimens were obtained from 19 children with IDDM before and 6 h after rectal challenge with 2 g of a peptic tryptic digest of gliadin. A total of 16 treated celiac patients and 10 control subjects were also investigated. Epithelium and lamina propria CD3(+) and gamma delta(+) lymphocytes were counted with reference to a standard reference area of muscularis mucosae (10(4) microm(2)). RESULTS: After a local instillation of gliadin, a significant (>mean + 1 SD) percentage increment of lamina propria and epithelium CD3(+) and of lamina propria and epithelium gamma delta(+) lymphocytes was observed in five IDDM children, as compared to 11 and 13 celiac patients and one and two controls, respectively. A discriminant analysis allowed correct classification of 100% of patients with celiac disease and controls. The same analysis classified four of 19 IDDM children in the group of celiac patients. The positivity was associated with normal serology (antigliadin antibody, antiendomysial antibody, and antitissue transglutaminase antibodies) and a morphologically normal jejunal mucosa. All four patients had HLA-DQ alleles associated with celiac disease. CONCLUSIONS: Approximately 20% of IDDM children react to rectal instillation of gliadin. Long term follow-up is necessary to establish whether these subjects are at increased risk for developing celiac disease.

Adolescent↗
PubMed1976

Preparation and properties of a national reference endotoxin.

A large pool of refined endotoxin was prepared from Escherichia coli O113 by extraction with hot acqueous phenol. It was characterized chemically and biologically and will be available for a reference standard designated as reference endotoxin EC.

Animals↗
PubMed2005

A luminous efficiency function, V*(lambda), for daylight adaptation.

We propose a new luminosity function, V*(lambda), that improves upon the original CIE 1924 V(lambda) function and its modification by D. B. Judd (1951) and J. J. Vos (1978), while being consistent with a linear combination of the A. Stockman & L. T. Sharpe (2000) long-wavelength-sensitive (L) and middle-wavelength-sensitive (M) cone fundamentals. It is based on experimentally determined 25 Hz, 2 degrees diameter, heterochromatic (minimum) flicker photometric data obtained from 40 observers (35 males, 5 females) of known genotype, 22 with the serine variant L(ser180), 16 with the alanine L(ala180) variant, and 2 with both variants of the L-cone photopigment. The matches, from 425 to 675 nm in 5-nm steps, were made on a 3 log troland xenon white (correlated color temperature of 5586 K but tritanopically metameric with CIE D65 standard daylight for the Stockman and Sharpe L- and M-cone fundamentals in quantal units) adapting field of 16 degrees angular subtense, relative to a 560-nm standard. Both the reference standard and test lights were kept near flicker threshold so that, in the region of the targets, the total retinal illuminance averaged 3.19 log trolands. The advantages of the new function are as follows: it forms a consistent set with the new proposed CIE cone fundamentals (which are the Stockman & Sharpe 2000 cone fundamentals); it is based solely on flicker photometry, which is the standard method for defining luminance; it corresponds to a central 2 degrees viewing field, for which the basic laws of brightness matching are valid for flicker photometry; its composition of the serine/alanine L-cone pigment polymorphism (58:42) closely matches the reported incidence in the normal population (56:44; Stockman & Sharpe, 1999); and it specifies luminance for a reproducible, standard daylight condition. V*(lambda) is defined as 1.55L(lambda) + M(lambda), where L(lambda) and M(lambda) are the Stockman & Sharpe L- & M-cone (quantal) fundamentals. It is extrapolated to wavelengths shorter than 425 nm and longer than 675 nm using the Stockman & Sharpe cone fundamentals.

Adaptation, Physiological↗
PubMedDate not supplied

A comparative evaluation of bedside capillary blood glucose monitoring devices designed for hospital use.

Capillary blood glucose monitoring devices (CBGMs) that incorporate "wipeless" technology recently have been designed and marketed for hospital use. Our objective was to evaluate three such devices for accuracy and precision, comparing them to a popular device that utilizes older technology and to a reference standard. Blood glucose level was simultaneously determined on the CBGMs and a reference standard. Results were analyzed for precision by performing repeated measurements of a single sample and for accuracy across the entire range of determinations. Clinically relevant subsets of the entire range also were determined and arbitrarily defined as low (< 60 mg/dL), normal (60 to 140 mg/dL), high (141 to 300 mg/dL), and very high (> 300 mg/dL). We found that accuracy and precision of these devices varied considerably. Lack of accuracy was particularly evident upon analysis of the clinically relevant subset ranges of blood glucose levels. Consequently, routine evaluation of CBGMs should include analysis of clinically relevant subset ranges of blood glucose levels. The marked differences in accuracy and precision between CBGMs that are currently.

Adult↗
PubMed1990

Using the revised APON standards of practice.

In 1988, the Association of Pediatric Oncology Nurses published its first Scope of Practice Statement. At that time the Standards of Practice were revised in the process outcome format. Six standards refer to direct care of the child and family and a final standard refers to the nurse's professional responsibility to maintain expertise as a specialist or competency as a generalist. The development of these two documents and how they are used by the practitioner and the educator is discussed.

Humans↗
PubMed2002

General practice and computing standards.

BACKGROUND: 'Standards' refer to common standards for communication and exchange of information about goods and services. Embedded within these common standards are gold standards for quality, privacy, safety and performance. Technical and semantic standards are essential building blocks for the required information and communication infrastructure to support the secure management and sharing of high quality information across general practice and the health care system. OBJECTIVE: To describe the current developments and implications of terminology, architecture and messaging standards in general practice. CONCLUSION: The current Health Online framework and National Health Information Standards Plan, with nationally coordinated implementation strategies like HealthConnect and the Better Medication Management System, are encouraging, However, there is little common understanding of technical and semantic standards among clinicians, administrators and researchers in general practice and health care system. The state-Commonwealth and private-public dichotomies are other barriers. As part of their roles as gate-openers in an integrated health care system, GPs must explicitly promote the implementation of national communication and information exchange standards.

Australia↗
PubMedDate not supplied

Flame atomic absorption spectrometric determination of trace amounts of nickel after extraction and preconcentration onto natural modified analcime zeolite loaded with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol.

Nickel is a moderately toxic element compared with other transition metals. However, inhalation of nickel and its compounds leads to serious problems, including cancer of the respiratory system and a skin disorder, nickel-eczema. Thus, attention has focused on the toxicity of nickel at low concentrations, and the development of reliable, analytical approaches for the determination of trace amounts of nickel is needed. This paper describes a simple, rapid, and sensitive flame atomic absorption spectrometric method for the determination of trace amounts of nickel in various samples after adsorption of its 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complex on a modified Analcime column in the pH range of 7.5-10.5. The retained analyte on the Analcime is recovered with 5.0 mL 2 M nitric acid and determined by flame atomic absorption spectrometry. The detection limit is 20 ng/mL, and the calibration curve is linear for analyte concentrations in the range of 0.1-8 microg/mL final solution, with a correlation coefficient of 0.9993. Eight replicate determinations of nickel at 2 microg/mL in the final solution gave an absorbance of 0.1222, with a relative standard deviation (RSD) of +/-1.2%. The interference of a large number of anions and cations was studied, and the proposed method was used for the determination of nickel in various standard reference samples. The accuracy of the proposed method was evaluated by analyzing standard reference samples, and the results were satisfactory (recoveries of >96%; RSD of <3.5%).

Absorption↗
PubMed1991

[Serum cholesterol levels in normal subjects taking into consideration the accuracy of the measuring system].

Serum cholesterol levels were determined in 5,843 normal subjects aged zero to seventy years. The accuracy of our assay method was checked by Standard Reference Material 909 and Certified Reference Serum, both of which were supplied by the National Bureau of Standards. Reference values of serum cholesterol were confirmed for each age group. That of male subjects in the 15-20 year age group was within a range of 109-203 mg/dl, and that of female subjects in the 20-25 year age group was within a range of 133-215 mg/dl. Therefore, among normal subjects, the above-mentioned age groups had the lowest serum cholesterol levels. Serum cholesterol levels increased with age in both male and female subjects. The upper limit of cholesterol levels was 248 mg/dl for males in the 50-60 year age group and 284 mg/dl for females in the same age group. We observed the necessity of paying consideration those changes which occur with aging, in the determination of reference values of serum cholesterol. Our findings also showed that serum cholesterol levels remained nearly constant in male subjects of all age groups over a period of 25 years. However, we found mean levels in female subjects in the 50-70 year age groups to be significantly elevated, when compared with those observed in persons in the same age group of 25 years previous. We also found that the mean cholesterol level in girls aged 12 years was higher than that of boys the same age.

Adolescent↗
PubMed1996

[Determination of crude drugs in the pharmacopoeia].

The determination of crude drugs by high performance liquid chromatograph (HPLC) method was introduced to the Japanese Pharmacopoeia (JP) 12 for the first time. At JP 13, another HPLC methods were established for eight kinds of crude drugs and relative medicines. Special conception is used in the determination of crude drugs, different from chemical medicines. Determinations were classified to two methods: "assay" and "component determination" according to standards. "The Japanese Reference Standard" or "Reagent for assay" is used in assay, and "Reagent for component determination". is used in component determination. In addition, the analysis and the dryness of crude drug were discussed because they were important to evaluate the result of analysis exactly.

Chromatography, High Pressure Liquid↗
PubMed2006

A multi-centre evaluation of nine rapid, point-of-care syphilis tests using archived sera.

OBJECTIVES: To evaluate nine rapid syphilis tests at eight geographically diverse laboratory sites for their performance and operational characteristics. METHODS: Tests were compared "head to head" using locally assembled panels of 100 archived (50 positive and 50 negative) sera at each site using as reference standards the Treponema pallidum haemagglutination or the T pallidum particle agglutination test. In addition inter-site variation, result stability, test reproducibility and test operational characteristics were assessed. RESULTS: All nine tests gave good performance relative to the reference standard with sensitivities ranging from 84.5-97.7% and specificities from 84.5-98%. Result stability was variable if result reading was delayed past the recommended period. All the tests were found to be easy to use, especially the lateral flow tests. CONCLUSIONS: All the tests evaluated have acceptable performance characteristics and could make an impact on the control of syphilis. Tests that can use whole blood and do not require refrigeration were selected for further evaluation in field settings.

Humans↗
PubMed2005

Comparison of quartz standards for X-ray diffraction analysis: HSE A9950 (Sikron F600) and NIST SRM 1878.

A further comparison of the Health and Safety Executive (HSE) standard quartz, A9950 (Sikron F600), and the National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 1878, standard respirable alpha-quartz, has been carried out for the four principal diffraction peaks. In the earlier comparison by Jeyaratnam and Nagar (1993, Ann Occup Hyg; 37: 167-79), the standards were both treated in ways which might change the particle size distribution and therefore the proportion of crystalline quartz. The two standards have now been compared in the most direct way possible with the minimum of sample treatment. There are no significant differences in the diffraction peak positions for the two standards. Nor do the peak area intensities differ significantly. The peak height intensities are consistently and significantly higher for Sikron F600 than for NIST SRM 1878. The particle size broadening of the diffraction peaks is evidently greater for NIST 1878, whose mass median diameter is quoted as 1.6 microm against 2.6 microm for Sikron F600. Taking the certified reference value for SRM 1878 as 95.5 +/- 1.1% crystalline quartz, the HSE standard A9950 (Sikron F600) contains 96.3 +/- 1.4% crystalline quartz based on a comparison of peak area intensities. On the same basis but using peak height intensities, the nominal crystalline quartz content of A9950 (Sikron F600) is 101.2 +/- 1.8%. Results obtained by comparison of quartz standards may not be generally applicable because of the effect of sample treatment on particle size and crystalline quartz content.

Air Pollutants, Occupational↗