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PubMed2006

[Intravascular optical coherence tomography: differentiation of atherosclerotic plaques and quantification of vessel dimensions in crural arterial specimens].

PURPOSE: Intravascular optical coherence tomography (OCT) is a new technique based on infrared light that visualizes the arteries with a resolution of 10-20 microm. Intravascular ultrasound (IVUS) is the current in vivo reference standard and provides a resolution of 100-150 microm. This study compared OCT to IVUS and histopathology with respect to the ability to differentiate atherosclerotic plaques and quantify vascular dimensions in peripheral crural arteries ex vivo. MATERIALS AND METHODS: 50 segments of atherosclerotic arteries derived from five amputated human lower extremities were examined. The different plaque types (fibrous, high-lipid content, calcified) were assigned by two independent examiners, and the sensitivity and specificity of OCT in comparison with histopathology as well as intra- and interobserver consensus were calculated. A comparison of OCT with IVUS addressed the parameters: luminal area (LA), vascular wall area (VA) and plaque area (PA). RESULTS: When comparing OCT and histopathology with respect to the differentiation of various plaque types, sensitivities of 81 % and specificities of 89 % for fibrous plaques, of 100 % and 93 % for lipid-rich plaques and of 80 % and 89 % for calcified plaques were achieved (overall correlation 83 %). Intra- and interobserver consensus was very high (kappa = 0.86 and kappa = 0.89, p < 0.001, respectively). There was also a high correlation between quantitative measurements (Bland-Altman plot [LA]: mean bias, 0.1 mm(2) accuracy +/- 1.8 mm(2), r = 0.95 [p < 0.001] Bland-Altman plot [VA]: mean bias, 0.3 mm(2) accuracy +/- 2.3 mm(2), r = 0.94 [p < 0.001] Bland-Altman plot [PA]: mean bias, 0.4 mm(2) accuracy +/- 2.3 mm(2), r = 0.80 [p < 0.01]. CONCLUSION: OCT allows the differentiation of atherosclerotic plaque types in crural arteries with high accuracy compared to histopathology. Quantitative measurements show a high correlation with IVUS, the current reference standard.

Atherosclerosis↗
PubMed1976

Study of genetic relationships among marine species of the genera Beneckea and Photobacterium by means of in vitro DNA/DNA hybridization.

Strains representative of species of the marine genera Beneckea and Photobacterium were used as reference standards in in vitro DNA/DNA competition experiments. Within a given species, strains were found to be related by over 80% competition. (Competition was defined as the amount of radioactive DNA displaced by heterologous DNA relative to the amount displaced by homologous DNA.) On the basis of interspecies competition values (expressed as averages), the following groupings could be made: 1. "Photobacterium" fischeri was related to strain ATCC 15382 by a competition of 38% and was distinct from all the other strains tested (competition less than or equal to 11%). 2. The genus Photobacterium consisted of 3 species, P.phosphoreum, P.leiognathi, and a newly designated species, P.angustum (composed of non-luminous strains). The latter species was found to be related to P.leiognathi and P.phosphoreum by 56 and 28% competition, respectively, while P.phosphoreum was related to P.leiognathi by 29%. 3. In the genus Beneckea, 65% competition was detected between B.harveyi and B.campbellii as well as between B.parahaemolytica and B.alginolytica. These pairs of species were related to each other by 51-58% and to B.natriegens by 34-56% competition. A newly designated pathogenic species, B.vulnifica, appeared to have a low but significant relationship to all the above mentioned species of Beneckea. 4. Two biotypes, related by 68% competition, were recognized in the species B.splendida. Similarly, B.pelagia was found to consist of 2 biotypes related by a competition of 67%. The competition values between these species were 38-40%. 5. B.nereida, B.nigrapulchrituda, and "Vibrio" anguillarum had competition values less than or equal to 30% to each other as well as to other species of Beneckea. 6. With Vibrio cholerae as the reference standard, V.albensis was found to be related by a competition of 82%, while V.proteus and V.metschnikovii had competition values of 22 and 12%, respectively. These results suggested that V.albensis should be synonymized with V.cholerae, while the latter two organisms should remain distinct from this species. V.cholerae as well as the other terrestrial organisms tested did not appear to be significantly related to any of the marine strains (competition values less than or equal to 27%). The speciation derived from the results of the DNA/DNA competition experiments was compared to previous speciation based on phenotypic similarities.

DNA, Bacterial↗
PubMed2004

A responsive, sensitive, and reproducible dermal tumor promotion assay for the comparative evaluation of cigarette smoke condensates.

The mouse dermal initiation/promotion bioassay has been used for several decades to study cigarette smoke condensates (CSCs). However, these studies have used highly variable methodologies that differ in the manner of CSC collection, duration of treatment, mouse strain, number of mice and endpoints measured. In this report, a protocol that uses female SENCAR mice and standardizes many of the procedures is presented. A reference cigarette (University of Kentucky 1R4F), readily available to researchers, was used. This report presents the combined data from four independent studies. Female, SENCAR mice (40/group) were treated with a single dose (75microg) of dimethylbenz[a]anthracene (DMBA) as an initiator, followed 1 week later by treatment (three times/week) with 10, 20 or 40mg "tar"/application of 1R4F CSC for 29 weeks. There were no treatment-related effects on body weights. Histological diagnosis of all masses at study termination indicated a dose-dependent increase in the number of tumor-bearing mice and total tumor number. These studies support the conclusion that the 1R4F cigarette is suitable for use as a reference standard and the protocol presented is an appropriate and standardized model suitable for the comparative evaluation of CSC.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2004

Comparison of sample preparation procedures for the determination of trace heavy metals in house dust, tobacco and tea samples by atomic absorption spectrometry.

The effect of wet ashing, dry ashing and microwave procedure for the determination of trace metal levels was investigated in house dust, tobacco and tea samples by atomic absorption spectrometry. The study of sample preparation procedures showed that the microwave method was the best. The recovery of trace metals was very good and precision and accuracy were compatible with standard reference material. The relative standard deviations for all measured metal concentrations were lower than 10%. The digestions of HNO3/H2SO4/HClO4 (4: 1: 1) mixture for house dust, HNO3/H2SO4/H2O2 (2: 2: 2) mixture for tea and HNO3/H2O2 (4: 2) mixture for tobacco were very efficient.

Dust↗
PubMed2006

Comparison of serological methods for the diagnosis of Neospora caninum infection in cattle.

The aims of this study were to evaluate the performance and agreement of various commercial and in-house Neospora caninum antibody assays used in dairy cattle in North America, and to investigate reproducibility of two assays performed in different laboratories. From 1998 to 2005, three enzyme linked immunosorbent assays (ELISAs, a competitive ELISA-VMRD Inc., an indirect ELISA-Biovet Inc., and another indirect ELISA-Herdchek IDEXX Corp.), two indirect fluorescent antibody tests (IFATs, VMRD Inc., and in-house USDA) and one N. caninum agglutination test (NAT, in-house USDA) were utilized to test 397 randomly selected dairy cattle serum samples from 34 herds in eastern Canada for antibodies to N. caninum. The manufacturers' recommended cut-off values were used to evaluate test performance and agreement between tests. One IFAT (VMRD Inc.) performed well (sensitivity and specificity: 0.97 and 0.97, respectively) using reference sera (n = 452), therefore, results from this IFAT on the 397 samples could subsequently be used as the reference standard to calculate test characteristics for the other assays. Only 11% of the 397 sera were found to be N. caninum-positive with the IFAT. Prevalence-adjusted bias-adjusted kappa (PABAK) ranged from 0.06 to 0.99. Positive agreement was moderate to very good (P(pos) = 0.25-0.96). Negative agreement was very good for all assays (P(neg) > 0.94) except NAT (P(neg) = 0.66). Sensitivity was > or =0.89 for all assays except the NAT, which had a significantly lower sensitivity (0.66). Specificity was high (>0.94) for all assays except for one indirect ELISA (specificity = 0.52). This indirect ELISA did not perform satisfactorily when used in 1998, but an improved version of the ELISA performed as one of the best assays in 2004. Reproducibility of the competitive ELISA was excellent, but the reproducibility of the indirect ELISA that was improved was low (concordance correlation coefficient = 0.90 and 0.36, respectively). The performance characteristics observed for most assays in this study make them useful for screening antibodies to N. caninum in cattle.

Agglutination Tests↗
PubMed1994

Serum growth hormone-binding protein (GHBP) in domestic animals as measured by ELISA.

This research was conducted to develop and characterize a competitive ELISA for bovine serum growth hormone-binding protein (GHBP) using recombinant bovine GHBP and a polyclonal rabbit antiserum. In addition to bovine, however, the assay was found to measure some activity in equine, chicken, porcine, ovine, and human sera. The reference standard curve had an effective range of 3 to 200 ng/mL. Recovery of increasing amounts of GHBP added to ovine serum was 103% but seemed to overestimate the amount of GHBP at low concentrations (intercept = 2.5 ng/mL). Recovery from bovine and porcine serum was near ideal but seems to be overestimated at concentrations higher than 50 ng/microL. Within and between assay coefficients of variation were 12.1 and 18.9%, respectively, for a sheep serum pool. Neither exogenous GH (20 ng/mL) nor prolactin (100 ng/mL) interfered with the measurement of GHBP in serum. The GHBP activity measured in increasing doses of serum from ovine, porcine, and bovine inhibited the assay in a parallel manner. This observation suggests that the GHBP antiserum contains antibodies that are directed toward epitopes of GHBP, which are common among these species. Serum GHBP concentrations were similar among samples from a line of miniature Brahman and normal stature Brahman and Angus cattle. In mature ewes, there were no differences in serum GHBP among three different breed types. An increase (P < .0001) in serum GHBP was observed in pigs between 1 and 6 mo of age but no sex effect was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1990

Current analytical approaches to measuring blood analytes.

In recent years, laboratory testing in the critical-care setting has increased, a trend due, in part, to the evolution of electrochemical sensors. Various innovations have extended sensor lifetimes, reduced sensor maintenance, and led to the development of single-use and unit-use disposable sensors. These sensor technologies allow the accurate and precise determination, either at or near the bedside, of several analytes including pO2, pCO2, pH, Na, K, Cl, ionized calcium, hematocrit, total hemoglobin, and glucose. Use of these new systems, however, has raised new issues regarding sensor calibration and sample handling and collection. The number of direct-reading analyzers for electrolyte determinations has also increased dramatically. Issues regarding calibration of ion-selective electrodes (ISEs) for Na/K have also been raised after demonstrations of between-instrument variation. Recently, collaborative efforts between eight ISE instrument manufacturers and the National Institute of Standards and Technology resulted in the development of a Standard Reference Material, SRM 956, for the purpose of standardizing direct-reading Na/K ISEs to the flame photometer. Other widely used technologies that provide noninvasive, continuous monitoring include pulse oximetry and transcutaneous gas electrodes. These trends are expected to continue and to produce a new generation of electrochemical and optical sensors.

Autoanalysis↗
PubMed1990

A new approach to define the upper normal limits of ambulatory blood pressure.

One of the major problems with ambulatory blood pressure monitoring is the lack of clearly defined normal limits that can be used as reference standards. In the present work normal levels of ambulatory blood pressure were established on the basis of the average disparity between office and daytime blood pressure calculated in a population of 60 normotensives, 109 borderline hypertensives and 353 subjects with established hypertension. Non-invasive 24-h blood pressure monitoring was carried out during a non-working day in freely moving subjects. The office-ambulatory daytime blood pressure difference averaged 14.2/6.7 mmHg and the office-24-h blood pressure difference averaged 18.4/9.6 mmHg in these subjects. The pressure difference was unrelated to the level of ambulatory blood pressure. In fact, when the subjects were subdivided into five classes of increasing ambulatory blood pressure levels the office-ambulatory mean blood pressure disparity was constant throughout the five classes, even though in each class a wide intersubject variability was present. We established the upper normal levels of ambulatory blood pressure by subtracting the average office-ambulatory blood pressure difference from the World Health Organization (WHO) normal limits for office blood pressure. For ambulatory daytime blood pressure the upper normal limits were calculated as 125.8/83.3 mmHg and for 24-h blood pressure as 121.6/80.4 mmHg. In contrast with previous studies, which were conducted exclusively on normotensive subjects, this approach avoids selecting patients on casual blood pressure readings and has the advantage of including the WHO blood pressure limits.

Adult↗
PubMed1998

Transcutaneous renal function monitor: precision during unsteady hemodynamics.

OBJECTIVE: Hospital acquired renal dysfunction, most commonly caused by renal hypoperfusion, dramatically increases mortality in intensive care patients. Glomerular filtration rate (GFR) is rapidly altered during renal hypoperfusion, and a more rapid means of GFR measurement may prompt institution of renal-specific therapy. We hypothesized that a transcutaneous renal function monitor can rapidly and accurately assess acute changes in GFR within a time frame much shorter than the 2-4 hours currently available. METHODS: The study design was a prospective determination of the capability to measure GFR transcutaneously. In three different studies, concurrent transcutaneous measurement of GFR, using the rate of disappearance of 99mTc-diethylenetriaminepentaacetic acid (DTPA), was compared by correlation and standard deviation (SD) to reference standards of DTPA plasma clearance, serum inulin clearance, or serum creatinine. RESULTS: Continuous transcutaneous clearance (TC) measurement correlated with standard DTPA plasma clearance techniques (r = 0.93). Acute pharmacologically induced changes in GFR are detectable by TC measurement within 12-20 min, a time interval significantly affected by the data acquisition interval. Excess patient movement in the ICU patients created clearance artifacts in 50% of clearance traces. Retrospective analysis of ICU patient data reveal TC measurements are 93% specific and 92% sensitive for serum creatinine levels in critically ill patients. CONCLUSIONS: TC monitoring provides prompt indication of directional changes in GFR and may provide the clinician warning of inadequate resuscitation. Prospective analysis of the specificity, sensitivity, and TC guided renal-specific resuscitation is needed.

Critical Illness↗
PubMed1993

Determination of serum creatinine by isotope dilution method using discharge-assisted thermospray liquid chromatography/mass spectrometry.

A discharge-assisted thermospray (plasmaspray) liquid chromatography/mass spectrometric method for the determination of serum creatinine is described. The method incorporates stable isotope dilution using (D3)creatinine as an internal standard. Separation is performed in reversed-phase high-performance liquid chromatography using 0.01 M aqueous ammonium acetate as a flow solvent. Effluents are directly introduced to the mass spectrometer and [MH]+ ions are monitored during LC/MS using the selected ion monitoring method. Satisfactory agreement between the analytical result and the certified value of the serum sample of standard reference material and relative standard deviation ranging from 0.6% to 1.2% was obtained.

Chromatography, Liquid↗
PubMed1994

The predictive value of a single beta human chorionic gonadotropin in pregnancies achieved by assisted reproductive technology.

OBJECTIVE: To investigate whether a single serum beta-hCG in pregnancies achieved by assisted reproductive technologies (ART) can accurately predict pregnancy viability and, in viable pregnancies, multiple gestation. DESIGN: Four hundred sixty-one consecutive successful ART pregnancies were studied retrospectively. Seventy-one of the 461 patients were excluded because their beta-hCG was either drawn on the incorrect day or outside our facility. Three hundred ninety subjects had a serum beta-hCG drawn 14 days after ET or 16 days after gamete transfer. The beta-hCG samples were analyzed by immunoradiometric assay based on the Third International Reference Standard (IRS) (First International Reference Preparation (IRP)). Pregnancy status was followed, at minimum, through the first trimester. RESULTS: One hundred fifty (38%) of the 390 were found to be nonviable, resulting in spontaneous abortion (n = 38, 10%), ectopic pregnancy (n = 27, 6%), or biochemical pregnancies (n = 85, 22%). A statistically significant difference by the Scheffe F-test was found between the mean beta-hCG value of the nonviable (115 mIU/mL) (conversion factor to SI unit, 1.00) and viable (428 mIU/mL) pregnancies. The positive predictive value of a single beta-hCG > 100 mIU/mL in distinguishing viable from nonviable pregnancies was 0.83 (sensitivity 91%, specificity 71%). Of the 240 viable pregnancies, 74 (32%) were multiple gestations (57 twins, 14 triplets, and 3 quadruplets). The mean beta-hCG of the singleton pregnancies (266 mIU/mL) was significantly different from that of the multiple gestations (792 mIU/mL). The positive predictive value of a single serum beta-hCG < or = 400 mIU/mL in distinguishing singleton from multiple gestations was 0.92 (sensitivity 86%, specificity 82%). CONCLUSION: A single early serum beta-hCG may be used in ART pregnancies to predict which pregnancies will continue beyond the first trimester and to identify multiple gestations. Early reassuring tests may reduce anxiety.

Adult↗
PubMed2001

A microbiological six-plate method for the identification of certain antibiotic groups in incurred kidney and muscle samples.

A microbiological method was developed for group level identification of antibiotics in incurred kidney and muscle samples from cattle and pigs. The method was composed of six test bacterium-plate growth medium combinations and the result was recorded as a profile of growth inhibition zones. The sample profiles were compared to two sets of references: one constructed with standard antibiotic solution profiles, and the other with these combined with profiles of microbiologically and chemically identified residues from incurred samples. The algorithm employed in profile comparison located the minimal sum of absolute pairwise differences over the tests, with the addition of a number of experimentally observed intra-test criteria. Chemical identification and quantitation of incurred residues was based on liquid chromatography. The method identified penicillin G as a penicillinase sensitive penicillin, enrofloxacin and ciprofloxacin belonging to fluoroquinolone group, and oxytetracycline belonging to tetracycline group. Each of these residues was microbiologically identified below the Maximum Residue Limit (MRL) for kidney tissue. Combining sample profiles with the standard reference data set did not enhance the resolution. Microbiological and chemical identification test results were in good agreement. The results of this study show that a microbiological identification method is a useful tool in preliminary characterisation of antibiotic residues in animal tissues.

Animals↗