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At least 469 records · Page 26Linked to original sources
PubMed1997

New technique using room temperature diodes for the direct assessment of internal contamination by low energy gamma-ray emitters.

Silicon PIN diodes were tested as direct detection elements for in vivo counting. They have a low sensitivity to background radiation in the energy range below 80 keV so that they can be used outside a shielding room for the measurement of weakly absorbing organs or tissues in cases of incorporation of fuel particles and medical radionuclides. Results are reported on the spectral characteristics of these detectors. Comparison with other techniques is examined. This paper describes a novel technique of in vivo counting which needs no shielded room and which is applicable to other types of room temperature detectors. The concept of wearable counting devices is presented with description of their design.

Americium↗
PubMed1977

Three utilization styles at an urban mental health center.

The authors report a study of utilization of services based on data obtained on two patient groups at an urban mental health center: a one-year applicant population, consisting of an unduplicated count of all adults applying for psychiatric care during a one-year period; and a one-day prevalence population, consisting of all persons on a psychiatric roster on a single selected day. Juxtaposing diagnosis, applicant-to-prevalence ratios, and treatment or services used, they found three styles of utilization of services--the intensive user, as exemplified by the neurotic in psychotherapy, the casual user (the schizophrenic attending medication clinic), and the pseudo user (the alcoholic using detoxification services). The intensive user represents a minority utilization style, while the last two styles are predominat at the center. Taken together they characterize the typical patient as a therapeutically passive user of services.

Alcoholism↗
PubMedDate not supplied

Mutans streptococci and lactobacilli in saliva after the application of fissure sealants.

Because dental fissures may serve as reservoirs for mutans streptococci, preventive measures should be taken to control microbial concentrations at these sites. This study estimated the influence that sealing permanent first molars would have on the levels of mutans streptococci and lactobacilli in saliva of healthy seven-year-old schoolchildren. Permanent first molars were sealed in 31 children without caries (NC group) and in 32 children with caries (C group). None of the children had caries in their permanent first molars. Conventional methods were used to count mutans streptococci and lactobacilli in saliva before applying the sealant and again at 4 and 12 weeks after application. Baseline counts of lactobacilli and mutans streptococci were significantly higher in the C group. A significant reduction in mutans streptococci was observed in the NC group at 4 and 12 weeks. It was concluded that fissure sealants in permanent first molars can help reduce salivary levels of mutans streptococci in children without caries.

Child↗
PubMed2006

Estimation of bias between 2 analytical methods at clinically important ranges.

An approach for estimating bias between 2 analytical methods at different clinical ranges is introduced in this article. The approach models replicated data obtained from the reference and the test method in terms of repeatability and trueness bias. The latter can be partitioned into constant and proportional bias. The approach is based on maximum likelihood estimation and can accommodate normal as well as Poisson and binomial distributions that apply to hematology applications and/or other laboratory methods that count particles per unit of volume and/or time. A full spectrum of statistical inference in the form of confidence intervals for each estimate as well as any statistical hypothesis testing is provided. At the same time these estimates can be practically interpreted and related to any clinical important range or decision point. We recommend this approach as an alternative to the National Committee for Clinical Laboratory Standards (NCCLS) EP9-A2 approach in cases where the application of the NCCLS standard is not appropriate.

Bias↗
PubMed1992

Exact likelihood evaluation in a Markov mixture model for time series of seizure counts.

This paper provides an alternative to Albert's (1991), Biometrics 47, 1371-1381) approximation to the E-step when using the EM algorithm for parameter estimation in Markov mixture models. Use of a recursive algorithm of Baum et al. (1970, Annals of Mathematical Statistics 41, 164-171) results in exact evaluation of the likelihood, optimal parameter estimates, and very efficient computation. Applications to time series of seizure counts and fetal movements clearly show the advantages of this exact approach.

Algorithms↗
PubMed2000

Evaluation of a surgical gamma probe for detection of 18F-FDG.

Because fluorine-18 fluorodeoxyglucose (18F-FDG) is an excellent tumor-localizing radio-pharmaceutical, a hand-held radiation detection probe capable of localizing an area with high 18F-FDG uptake would make radioguided surgery possible. In this laboratory study, we investigated the capability of a widely used intraoperative gamma probe with a cadmium zinc telluride (CdZnTe) detector for detection of 18F-FDG. For sensitivity tests, an 0.1- ml 18F-FDG preparation was made to act as a point source with radioactivities of 1.0, 2.0, and 3.0micro Ci (37 kBq, 74 kBq, 111 kBq). Relative transmission across the side wall of the probe and sensitivity at each source-to-probe distance were measured. For simulation studies, 2 l of 18F-FDG solution (0.02micro Ci, 0.74 kBq/ml) served as normal background. One ml of 18F-FDG was prepared to simulate tumors with radioactivities of 0.05, 0.1, 0.2, and 0.4micro Ci (1.85 kBq, 3.7 kBq, 17.4 kBq, and 14.8 kBq). The ratios of the radioactive concentration of tumor to that of the background were 2.5, 5, 10, and 20:1, respectively. The tested gamma probe was shown to be sensitive to 18F. The high-energy annihilation radiation was detected from the side wall of the probe despite application of a supplementary collimator. The count rate decreased markedly as the source-to-probe distance increased, owing to the effects of the inverse-square law. In the simulation studies, the probe detected a considerable amount of background activity. However, the measured count rate increased with the increasing source-to-background ratio. In our setting, the probe was capable of distinguishing the 18F-FDG source from the background when the source-to-background ratio was no less than 5:1. To make a surgical application feasible, however, collimation or shielding against high background radiation is necessary.

Fluorodeoxyglucose F18↗
PubMedDate not supplied

Modulation of the cell kinetics of pig skin by the topical application of evening primrose oil or Lioxasol.

The daily topical application of two compounds, a cream containing 10% evening primrose oil (EPO) and Lioxasol (a compound used clinically to treat radiation burns), resulted in increased cell proliferative activity in the skin of female Large White pigs. The effect was most pronounced in the case of the EPO based cream, and was comparable in magnitude with that observed in a previous study on pig skin using orally administered EPO. There was an increase in the size of the rete pegs in the epidermis by 6 weeks after the start of application of the EPO cream. However, this did not translate into an increase in the total thickness of the viable epidermis (excluding the stratum corneum) due to a reduction in the density of rete pegs, from 2 weeks after treatment. Lioxasol had no overall effect on the size of the rete pegs. The labelling index (LI) of cells in the basal layer of the epidermis of pigs receiving a daily topical application of EPO increased progressively with time from the start of application. The LI was maximal (17.9 +/- 2.4%) at the end of the observation period (8 weeks) at which time it was a factor of approximately 2 higher than in the basal layer prior to treatment. A considerably less marked increase in the LI of the basal layer was seen after the application of Lioxasol. The overall increase was approximately 20%, relative to the LI in the untreated epidermis. Labelled cell nuclei were also counted in the papillary dermis. After the application of the EPO cream, no significant increase in the number of labelled cells was observed until week 8, at which time values were approximately twice those in untreated skin. In Lioxasol treated skin the effect on the numbers of labelled cells in the papillary dermis was more immediate, with a approximately 60% increase at 2 weeks. This enhanced level of labelling was maintained until the end of the observation period of 10 weeks. Studies on the cell kinetics of the skin using the alcohol component of the Lioxasol preparation suggested that alcohol rather than Lioxasol was the most significant ingredient. It was concluded that the EPO cream merited further evaluation as a potential modulator of skin response to ionizing radiation.

Administration, Topical↗
PubMed2004

Frozen-section fluorescence microscopy and stereology in the quantification of neuronal death within dorsal root ganglia.

Histochemical and morphological research increasingly relies upon quantification of complex biological systems. For such investigations to be meaningful, quantification techniques must meet the seemingly conflicting requirements of being theoretically robust, yet sufficiently practical to facilitate widespread applicability. Validity ought to be enhanced by theoretical simplicity, use of measured rather than assumed variables, and minimising observer interpretation. Practicality is facilitated by simplifying and reducing measurements, broadening applicability, and reducing costs and analysis time. As a result, quantification systems that rely upon sampling and estimation have been favoured over serial reconstruction techniques. To provide reliable estimates, sampling must be valid at all levels from tissue harvest, to the selection of microscope fields in which quantification is performed by techniques that account for the anisotropic distribution, and variable size of many elements in biological systems. These principles are embodied in the development of a stereological approach to the quantification of neuronal death within dorsal root ganglia after peripheral nerve injury. This frozen section technique is efficient and flexible, since it permits simultaneous morphological examination, TUNEL, or standard fluorescence immunohistochemistry, broadening its applicability. Section shrinkage is minimal, and counting by optical disection has proved to be time-efficient and sufficiently reproducible to reliably detect losses in the order of 5, with minimal inter-observer variation. As is discussed, stereology has not yet met with universal acceptance, but by balancing theoretical validity with practical applicability, it has proved an excellent approach to the investigation of neuronal death within dorsal root ganglia. Frozen-section fluorescence microscopy and stereology in the quantification of neuronal death within dorsal root ganglia.

Animals↗
PubMed1997

Influence of oxygen ventilation on Doppler microemboli signals in patients with artificial heart valves.

BACKGROUND AND PURPOSE: The purpose of this study was to evaluate the influence of inhalation of 100% oxygen on microembolic signal (MES) counts in patients with artificial cardiac valves. METHODS: A total of 134 outpatients were examined. Transcranial Doppler baseline monitoring (45-minute duration) was performed in all patients under resting conditions. The first 30 patients subsequently underwent transcranial Doppler monitoring for at least 20 minutes under noninvasive positive pressure ventilation with 100% oxygen and for an additional 30 minutes under resting conditions. The same protocol was applied to all following patients with a baseline MES count > or = 10, while the examination was discontinued in the remaining patients. RESULTS: Baseline MES counts < 10, which remained unchanged during oxygen inhalation and the subsequent resting period, were observed in 26 of 30 initial patients. A total of 46 patients with MES counts > or = 10 were identified. Oxygen application was feasible in 43 patients. An exponential MES decrease was noted in 42 patients during oxygen inhalation (statistically significant in 38 patients), followed by a subsequent increase in 38 of 43 patients (statistically significant in 25 patients) under resting conditions. CONCLUSIONS: The exponential reduction of MES counts observed in this study corresponds to blood denitrogenation, thus strongly arguing for nitrogen bubbles as underlying embolic material in prosthetic valve carriers.

Adolescent↗
PubMed2005

Evaluation of nested PCR assays for the detection of Legionella pneumophila in a wide range of aquatic samples.

AIMS: To compare the sensitivities of two nested PCR assays for the detection of Legionella pneumophila to each other and to the plate counting technique (ISO 11731) in a wide range of aquatic samples. METHODS AND RESULTS: The nested PCR assay with the primer set LEG 225-LEG 858 revealed 56% of the 46 analysed aquatic samples as being positive for Legionella spp., while the primer set JFP-JRP yielded 98% positive samples. The detection was confirmed by sequencing the PCR products. These results are considerably higher than the result obtained with the plate counting technique (41%), indicating the higher sensitivity of PCR-based diagnostic methods. As the PCR assay with the LEG 225-LEG 858 primer set resulted in a lower number of positive samples, it is considered not sensitive enough for aquatic samples. Similar results for the respective primer sets were obtained for the detection of the species L. pneumophila, responsible for 90% of all human Legionella infections, in the aquatic samples analysed. Both microbial community analysis by PCR-denaturing gradient gel electrophoresis and the analysis of biotic and abiotic water quality parameters revealed no relation between L. pneumophila-positive and -negative samples and the physico-chemical and bacteriological characteristics of the aquatic samples. CONCLUSIONS: The results show the additional value of the PCR assay with the JFP-JRP primer set compared with the plate counting technique, as well as its applicability in a wide range of aquatic samples. SIGNIFICANCE AND IMPACT OF THE STUDY: This study shows the importance of comparing different primer sets for nested PCR assays for the detection of L. pneumophila in aquatic samples, as well as the lower sensitivity of the widely accepted plate counting technique (ISO 11731).

Base Sequence↗
PubMed1981

Persistence and distribution of pollution indicator bacteria on land used for disposal of piggery effluent.

Numbers of pollution indicator bacteria (fecal coliforms and fecal streptococci) were assessed on land to which effluent from intensively housed pigs had been applied. Topsoil (to a 30-mm depth) was found to provide a more favorable environment for fecal coliform persistence than was pasture or subsoil. Times required for a 90% reduction in number (T90) in topsoil (calculated by linear regression of log counts obtained in a 6-week period after effluent application) ranged from 7 to 20 days (mean T90, 11 days). T90 values for fecal coliforms fell within this range irrespective of the season of application and for a number of soil types and climatic conditions. The range in die-off times was encountered irrespective of the fecal coliform count in the applied effluent or the application regimen (125 to 1,000 kg of elemental nitrogen in the form of effluent per ha; return periods, 3 to 12 months). Autumn and winter conditions were conducive to the persistence of a survivor tail of these bacteria at 10(1) to 10(3) cells per g of topsoil. Fecal streptococci survived similarly on soil and pasture (T90, ca. 14 days) and appeared slightly more suited to survival in the environment than did fecal coliforms. Contamination of subsoils after effluent applications occurred at a rate well in excess of the infiltration capacity of the soil, presumably by percolation of the effluent through soil cracks. Contamination levels of subsoils in the experimental area generally remained low.

Animal Husbandry↗
PubMed1996

Lack of microbial proliferation and phototoxic potential of a new matrix patch for estradiol delivery.

OBJECTIVES: To examine the potential of a new matrix system developed for estradiol delivery to cause microbial proliferation under the occluded site or to cause acute phototoxicity reactions. METHODS: Twenty healthy post-menopausal women participated in a microbial proliferation study and 11 in a phototoxicity study. Both studies were single centre, single blind and placebo controlled. Microbial proliferation was assessed by quantitative counts of the total aerobic bacterial population and of eight individual species before patch application and after removal following a 4 day application period on the abdomen. Acute phototoxicity potential was assessed following an 8 h application period on the abdomen by irradiating the application site after patch removal with ultra violet A radiation and visible light and evaluating the sites for up to 48 h post irradiation. Non-irradiated active and placebo patches on the other side of the abdomen served as controls. RESULTS: Total aerobic bacterial populations both before and after the matrix patch application period were low as expected for dry skin. Separate counts of microbial species were also low and did not change in any meaningful or consistent manner after patch application. In the phototoxicity study, mild erythema was observed in some patients at 0, 0.5 and 24 h post patch removal with no differences between irradiated and non-irradiated sites. CONCLUSIONS: These two studies demonstrate that a new matrix patch developed for estradiol delivery does not promote microbial proliferation under the occluded patch site or cause acute phototoxicity following removal.

Adult↗
PubMed1977

The automation of cytochemical methods for automated cytophotometers.

The development of an automated differential white blood cell counter is reviewed. After the red cells have been lysed, the white cells are counted by staining and passing through an electro-optical chamber in liquid suspension, surrounded by a laminar, or sheath, stream. Staining procedures were made specific for each type of leukocyte, and separate channels were used for counting each type. Staining intensity and characteristics of the various types of blood cells are discussed. They relate to enzyme levels and the effect on differentiation and identification of the cells. Since reasons for some of the design features are not obvious, discussion of the relevant problems is included. Several applications that go beyond routine differential counting are described.

Basophils↗
PubMed1999

Modelling MRI enhancing lesion counts in multiple sclerosis using a negative binomial model: implications for clinical trials.

In multiple sclerosis (MS) the number of new enhancing lesions seen on monthly magnetic resonance imaging (MRI) scans is the most widely used response variable in MRI-monitored studies of experimental treatments. However, no statistical model has been proposed to describe the distribution of the number of such lesions across MS patients. This article briefly summarizes the statistical models for counted data. The negative binomial (NB) model is proposed to fit the number of new enhancing lesions counted in a set of 56 untreated MS patients followed for 9 months. It is shown that the large variability present in this data set is better addressed by the NB model (residual deviance=66.6, 54 degrees of freedom) than by the Poisson model (residual deviance=1830.1, 55 degrees of freedom). Applications of the parametrization of lesion counts are discussed, and an example related to computer simulations for the sample size estimation is presented.

Adolescent↗
PubMed1990

Flow cytometry: clinical applications in haematology.

The time interval between the development of a new technique or methodology and its acceptance, if successful, as a recognized clinical application can be many years. The application of flow cytometry to reticulocyte counting, for example, has taken 8 years from the appearance of the first publication, and in 1990 it is still in its infancy as a clinical method. It is therefore a challenging task to anticipate which of the methodologies currently under development will achieve acceptance. It would be impossible to deal with all the candidates in the space available, and so a review is provided to those methods that may have potential applications in clinical haematology, together with some of the more practical details of methods that have recently been demonstrated to be viable in the clinical laboratory. The first category consists of leukocyte enumeration and studies on bone marrow, neutrophils, platelets and cellular DNA content, whilst the second covers reticulocyte counting and total red cell volume measurement. The contribution of flow cytometry to the field of immunophenotyping haematological disorders is probably unique in already being clinically acceptable. Finally, the question of quality control is addressed, as this is an essential prerequisite to the adoption of any new method in the clinical laboratory.

Blood Cell Count↗
PubMed1983

[Clinical significance of bacterial contamination of enteral nutrition solutions].

Tube feeding with elemental and peptide diets is used as therapy for the acute phase of Crohn's disease. It should improve the nutritional status of the patients and reduce bacterial counts in the intestine. In this study we investigated the frequency of bacterial contamination of solutions of chemically defined diets and the clinical effects of the application of contaminated diets (stool frequency, body temperature, leucocyte counts). 15 patients with acute phase of Crohn's disease were treated with chemically defined diets over a total period of 323 days via a nasoduodenal tube. 7 patients received BSD, 8 patients Peptisorb. In all 36 BSD solutions examined in concentration procedures we found microbes, most frequently Streptococcus and Bacillus spp. Without concentration procedures it was possible to cultivate bacteria in 12% out of BSD solutions and in 81% out of Peptisorb solutions; in BSD mostly Streptococcus and in Peptisorb solution E. coli, Bacillus spp. and aerobic spore forming bacilli. Stool frequency, body temperature and leucocyte counts did not show significant differences after application of contaminated solutions in comparison to the others. Deterioration of the disease has not been observed in any case.

Adult↗
PubMed1995

A radionuclide study of regional gastric motility.

The aims of this research were to study some methodological aspects of radionuclide methods for assessing regional gastric motility and to determine the parameters that can be extracted along with their normal values or patterns. During the lag phase, the antral contraction curve showed three different patterns. At the beginning, the antral activity was too low to be analysed. Irregular variation of the count rate was then observed, followed by a more regular contraction. The application of Fourier transformation to the well-defined cyclical count rate variations revealed two areas with high amplitude values but with phase opposition. No peristaltic wave could be identified. After the lag phase, the antral curve showed cyclical variations of count rates with a frequency of about three cycles per minute. Slightly displaced curves but with a much lower amplitude were observed at different parts of the stomach. Several factors were found to influence the antral contraction curve, including the choice of region of interest and time since the last meal. Irregularities in the antral curve, both in terms of frequency and of amplitude, were not unusual in healthy subjects. These should be taken into account when interpreting antral contraction curves. The phase image showed a well-defined peristaltic contraction pattern. Three 360 degrees cycles were usually observed throughout the stomach, suggesting that the time necessary for a peristaltic wave to sweep through from the upper part of the stomach to the antrum is about 1 min. Similar phase images were obtained in all subjects regardless of the amount of time since the meal containing the radioactive tracer, suggesting that gastric peristalsis can easily be assessed and interpreted. The amplitude image showed high amplitude in the antral area and in the greater curvature of the stomach. In the lesser curvature, the amplitude was much lower. Unlike the phase image, however, there was marked variability in the regional amplitude distribution. The value of the regional amplitude distribution for evaluating regional gastric motility is therefore limited.

Adult↗