Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “application count”

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 163 records · Page 9Linked to original sources
PubMed1989

The application of a photon-counting camera in sensitive, bioluminescence-enhanced detection systems for nucleic acid hybridization. Ultrasensitive detection systems for protein blotting and DNA hybridization, III.

A relatively simple, bioluminescence-enhanced detection system for nucleic acid hybridization, using alkaline phosphatase as a label, was described recently (Hauber, R. & Geiger, R. (1988) Nucl. Acid Res. 16, 1213). The principle of detection is as follows: Alkaline phosphatase releases D-luciferin (Photinus pyralis) from D-luciferin-O-phosphate. Liberated D-luciferin reacts with luciferase, ATP and oxygen with light emission. Light produced is measured with a very sensitive photon counting camera system (Argus-100), allowing the visualization and localization of the specifically bound alkaline phosphatase on nitrocellulose sheets. Under non-optimized conditions the limit of detection is at present about 30 pg of pBR322. A sulphonylated nucleotide probe was used for hybridization.

Alkaline Phosphatase↗
PubMed1988

The early effects of a single application of acetone and various doses of 7,12-dimethylbenz(alpha)anthracene on CD-1 and hairless mouse epidermis. A cell kinetic study of so-called initiation and complete carcinogenesis (initiation plus promotion) in chemical skin tumor induction.

To study the early kinetic effects of different single doses of 7,12-dimethylbenz(alpha)anthracene (DMBA) on hairless mouse epidermis, about 1,800 female CD-1 mice and 340 hairless mice of both sexes were treated with a topical skin application of acetone alone or with various doses of from 4.3 to 200 micrograms DMBA in 200 microliter reagent grade acetone for the CD-1 mice, and with 0.5, 5 and 50 micrograms DMBA for the hairless mice. Five cell kinetic variables were measured at different times, from 6 h up to 14 days, after the application: cell counts in 40 vision fields of basal and suprabasal cells, [3H]TdR-labeling indices, DNA-specific radioactivity, and mean grain count after flash labeling with [3H]TdR, fractions of cells in S and G2 by flow cytometry, and the mitotic rate with the Colcemid method. The idea was to see whether there are significant (qualitative, or clearly stepwise) differences between small (allegedly) only initiating single doses of DMBA and larger, completely carcinogenic (and hence allegedly also promoting) doses of the same carcinogen. Higher doses of DMBA (25.6-200 micrograms) led, as expected, to an initial reduction in both DNA synthesis and mitotic activity. The reduction in DNA synthesis seemed more to be due to a low rate of cellular DNA synthesis than to a block at the entrance of cells into the S phase. The decreases lasted for about 3-5 days, and was followed by a period of increased rate of cell proliferation. The number of suprabasal cells (after a very short initial peak after 51.2 micrograms DMBA) was then reduced, probably due to toxic cell death. Subsequently a pronounced hyperplasia developed, which was dose-dependent as regards both size and time pattern. At medium doses, 8.5-12.8 micrograms DMBA, the pattern of reaction changed gradually. The reduction in DNA synthesis and mitotic activity was less pronounced and lasted somewhat shorter, and the ensuing hyperplasia was more moderate. After the lowest doses, 4.3 and 6.4 micrograms DMBA, an initial, short-lasting decrease in the mitotic rate only was observed, but an initial inhibition of DNA synthesis could not be observed in the CD-1 mice. Instead, an early, moderate increase in overall cellular DNA synthesis and in the fraction of G2 cells was observed, concomitant with an almost immediate increase in the number of suprabasal cells. Hence, after these small doses a primary moderate increase in the number of suprabasal cells developed, remaining for at least 10 days. After a temporary reduction the MR increased to normal or slightly above.(ABSTRACT TRUNCATED AT 400 WORDS)

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1988

The application of a photon-counting camera in very sensitive, bioluminescence-enhanced detection systems for protein blotting. Ultrasensitive detection systems for protein blotting and DNA hybridization, II.

A relatively simple, very sensitive bioluminescence-enhanced detection system for protein blots was described recently. This method utilizes antibodies conjugated with alkaline phosphatase. Alkaline phosphatase releases D-luciferin (Photinus pyralis) from D-luciferin-O-phosphate. Liberated D-luciferin reacts with luciferase, ATP and oxygen with light emission. The light produced is measured with a very sensitive photon counting camera (Argus 100), permitting visualization and localization of the alkaline phosphatase-conjugated antibodies on nitrocellulose sheets. Under non-optimized conditions the limit of detection is at present 5 to 500 fg of protein (rabbit immunoglobulin G), corresponding to 30 to 3 amol. The method is therefore 10(5) times more sensitive than other used at present.

DNA↗
PubMed1987

[Application of the RI-counting method in CSF rhinorrhea].

Some diagnostic procedures for CSF rhinorrhea have been reported, but they can not always identify and localize CSF leakage. This method, using intranasal cotton pledgets after the intrathecal injection of radioisotope (111In-DTPA) is thought to be reliable, informative and innocuous for localizing the sites of CSF leakage. This technique was named RI-counting method, and applied in two cases that were difficult to diagnose especially with positional-loading. The patients were first in the supine position, then in the sitting position, after the intrathecal injection of radioisotope and the intranasal insertion of cotton pledgets. After exchanging these pledgets, the patients were set in the prone position. After measuring the radioactivity of these pledgets and of 1 ml of blood, the ratios of the radioactivity of the pledgets to that of the blood were calculated. In case 1 the ratios of the left sphenoethmoid recess and the left middle meatus were significantly higher when the patient took the prone position, but in the supine or sitting position the ratios were in the normal range. In case 2 the ratio of right olfactory cleft was significantly higher in the sitting position or neck flexion. Both cases were operated and demonstrated that the location of the CSF leakage was presumable by using RI-counting method, regarding the anatomical relationship between the intranasal sites of pledgets and the opening of the paranasal sinuses. Positional-loading seemed to be essential. We obtained 72 pledgets of patients without CSF rhinorrhea, and the ratios of radioactivity of these pledgets had a mean value (M) of 0.156 and a standard deviation (SD) of 0.107.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebrospinal Fluid Rhinorrhea↗
PubMed1993

A plant-capture method for estimating the size of a population from a single sample.

To estimate the size of a population a plant-capture method, an alternative to the classic capture-mark-recapture model, is presented. Known or marked individuals otherwise indistinguishable from the remainder of the population are planted followed by an effort to capture members from the augmented population. Maximum likelihood estimators and a confidence region together with the expected length of the confidence interval for the size of the population as a function of the number of plants are given. A methodology for comparing the cost efficiency of plant-capture to capture-recapture is developed. An application to counting the homeless is given.

Bias↗
PubMed2001

A unifying electron-counting rule for macropolyhedral boranes, metallaboranes, and metallocenes.

A generally applicable electron-counting rule-the mno rule-that integrates macropolyhedral boranes, metallaboranes, and metallocenes and any combination thereof is presented. According to this rule, m + n + o number of electron pairs are necessary for a macropolyhedral system to be stable. Here, m is the number of polyhedra, n is the number of vertices, and o is the number of single-vertex-sharing condensations. For nido and arachno arrangements, one and two additional pairs of electrons are required. Wade's n + 1 rule is a special case of the mno rule, where m = 1 and o = 0. B20H16, for example has m = 2 and n = 20, leading to 22 electron pairs. Ferrocene, with two nido polyhedral fragments, has m = 2, n = 11, and o = 1, making the total 2 + 11 + 1 + 2 = 16. The generality of the mno rule is demonstrated by applying it to a variety of known macropolyhedral boranes and heteroboranes. We also enumerate the various pathways for condensation by taking icosahedral B12 as the model. The origin of the mno rule is explored by using fragment molecular orbitals. This clearly shows that the number of skeletal bonding molecular orbitals of two polyhedral fragments remains unaltered during exohedral interactions. This is true even when a single vertex is shared, provided the common vertex is large enough to avoid nonbonding interactions of adjacent vertices on either side. But the presence of more than one common vertex results in the sharing of surface orbitals thereby, reducing the electronic requirements.

Journal Article↗
PubMed2003

Ion-counting nanodosimetry: current status and future applications.

There is a growing interest in the study of interactions of ionizing radiation with condensed matter at the nanometer level. The motivation for this research is the hypothesis that the number of ionizations occurring within short segments of DNA-size subvolumes is a major factor determining the biological effectiveness of ionizing radiation. A novel dosimetry technique, called nanodosimetry, measures the spatial distribution of individual ionizations in an irradiated low-pressure gas model of DNA. The measurement of nanodosimetric event size spectra may enable improved characterization of radiation quality, with applications in proton and charged-particle therapy, radiation protection, and space research. We describe an ion-counting nanodosimeter developed for measuring radiation-induced ionization clusters in small, wall-less low-pressure gas volumes, simulating short DNA segments. It measures individual radiation-induced ions, deposited in 1 Torr propane within a tissue-equivalent cylindrical volume of 2-4 nm diameter and up to 100 nm length. We present first ionization cluster size distributions obtained with 13.6 MeV protons, 4.25 MeV alpha particles and 24.8 MeV carbon nuclei in propane; they correspond to a wide LET range of 4-500 keV/microm. We are currently developing plasmid-based assays to characterize the local clustering of DNA damage with biological methods. First results demonstrate that there is increasing complexity of DNA damage with increasing LET. Systematic comparison of biological and nanodosimetric data will help us to validate biophysical models predicting radiation quality based on nanodosimetric spectra. Possible applications for charged particle radiation therapy planning are discussed.

DNA↗
PubMed1989

A rapid and convenient assay for counting cells cultured in microwell plates: application for assessment of growth factors.

There is currently much interest in the role of mediators that regulate cell proliferation. Methods to assay proliferative effects of such mediators usually involve cell counting techniques, which are tedious to perform, or methods based on uptake of radiolabelled thymidine, which may be prone to errors caused by precursor pool artefacts. We describe here an assay for estimating the number of adherent cells present in a microculture and its application to the study of growth factors. The assay depends on the binding of Methylene Blue to the fixed monolayer at pH 8.5 and, after washing the monolayer, release of dye by lowering pH. The use of an elution solvent containing acidified ethanol ensures a linear correlation between absorbance of the dye and cell number, and enables the assay to be carried out in 96-well plates measuring absorbance with an automated vertical light-path microplate photometer. The assay is rapid, highly reproducible and easy to perform, making it ideal for screening large numbers of samples. It was shown to be applicable to a number of foetal and adult cell lines derived from man and experimental animals. It was also demonstrated to be useful for assaying purified growth factors and detecting growth promoting activity in cell and tissue extracts.

Animals↗
PubMed1987

Particle counting immunoassay--an overview.

The principles and applications of the Particle Counting Immunoassay technique (PACIA) are summarized, and the limit of detection of the method is estimated. The various serum interferences are discussed and solutions to the problems proposed.

Journal Article↗
PubMed1982

The application of bulk tank somatic cell counts to monitoring mastitis levels in dairy herds.

The objective of this study was to investigate the feasibility of developing a system whereby measurements taken on bulk tank milk samples could be used to monitor the level of subclinical mastitis in dairy herds. The variables that were examined were the logarithmically transformed total somatic cell counts and percentages of cell volume in channel 8 (volumes from 89.2 to 178.3 microm(3)), the presence or absence of Streptococcus agalactiae and various husbandry/management factors including herdsize and the use of teat dips. Each of the use of actual monthly and rolling average bulk tank cell count determinations was investigated. It was found that the inclusion of all variables resulted in a correct classification of approximately 85% of herds and that no improvement was achieved by the use of rolling as opposed to actual monthly values. The inclusion of various husbandry/management practices improved the percentage correct classification to some extent over that achieved by the sole use of total somatic cell counts and percentages of cell volume in channel 8 when the herds were grouped on the basis of quarter infection rate (<10%, >10%) but not in the case of the cow infection rate categories (<20%, >20%). The use of both total cell counts and percentages of cell volume in channel 8 did not improve the overall predictive value over that achieved by the sole use of percentage of cell volume in channel 8 in the case of the quarter infection rate groupings but did to some extent in the case of the cow infection rate groupings. When the classification functions were applied prospectively and considering combinations of the two cell count determinations only, it was found that they were able to correctly classify, on the basis of the quarter infection rate groupings, approximately 75% of the study herds. It is concluded that the system described herein has limited application as a basis for selecting problem herds.

Animal Husbandry↗
PubMed1991

Evaluation of surgical scrub and antiseptic solutions for surgical preparation of canine paws.

The purpose of the prospective study reported here was to evaluate surgical preparation of canine paws. Three combinations of surgical scrub solutions and antiseptic solutions were used: (1) 7.5% povidone-iodine scrub/10% povidone-iodine solution; (2) 2% chlorhexidine acetate scrub/2% chlorhexidine diacetate solution; and (3) tincture of green soap/70% isopropyl alcohol. The control was warm (38 to 42 C) tap water. Four microbial colony counts were used to evaluate surgical preparation of 4 paws of 8 dogs. Specimens were obtained from the paws for a baseline microbial flora count. After surgical scrub was performed, additional specimens were obtained for bacteriologic culturing. Antiseptic was applied followed by collection of another specimen for bacteriologic culturing. A final specimen was obtained following a 24-hour period under a sterile occlusive bandage. The 3 scrub solutions and the tap water control resulted in lower colony counts following scrubbing of the paws; however, only the 3 antiseptic solutions resulted in further colony count reduction after their application. Evaluation of residual colony counts isolated from specimens taken after a 24-hour period under a sterile occlusive bandage revealed chlorhexidine and povidone-iodine scrub/antiseptic combinations to be similar in antibacterial activity, with significantly (P less than or equal to 0.05) lower colony counts than those from specimens of paws treated with either the tincture of green soap/isopropyl alcohol combination or the tap water control. The lack of a significant difference between the bacterial counts immediately after surgical preparation with povidone-iodine and chlorhexidine and their respective 24-hour residual counts, indicated no particular advantage to surgical preparation and occlusive bandaging 24 hours prior to surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2000

Evaluation of plate count methods for determination of maximum specific growth rate in mixed microbial communities, and its possible application for diversity assessment.

Two plate count methods are proposed for direct assessment of the maximum specific growth rate (microm) of bacteria in mixed communities. An estimate of microm of individual colonies is obtained by plating samples on an agar medium and determining either the time required to form macroscopically visible colonies, Tv (diameter < or =0.2 mm), or the linear radial growth rate, Kr, of single colonies. In accordance with theoretical models, a linear relationship was found between microm determined in liquid culture and 1/Tv, and between microm and Kr. Empirical relationships were established for these relationships. The time required to form a visible colony was 17 +/- 9 h longer for cells in the stationary growth phase, whereas the linear radial growth rate was not affected by the physiological state of the cells. The proposed plate count methods are simple and applicable for describing the community structure, and for estimating the frequency distribution of maximum specific growth rates in mixed communities. By using this frequency distribution it is possible to calculate diversity indexes and to assign a microbial community a position on an r/K-gradient.

Bacteria↗