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At least 1,711 records · Page 95Linked to original sources
PubMed1980

Fracture healing under factor XIII medication.

Following application of factor XIII for 3 weeks bone healing was studied in Sprague-Dawley rats on the 20th postoperatively day qualitatively (radiographs, scintigraphy) and quantitatively (determination of callus thickness, of bone mineral content, and scintillation counting). No significant difference could be detected between animals treated with factor XIII and animals which served as controls. Therefore, a stimulating effect of factor XIII upon bone healing can not be expected in case of a normal factor XIII serum-level. The application of factor XIII is indicated only in high risk patients with a low factor XIII serum-level.

Animals↗
PubMed2001

How to optimize the drop plate method for enumerating bacteria.

The drop plate (DP) method can be used to determine the number of viable suspended bacteria in a known beaker volume. The drop plate method has some advantages over the spread plate (SP) method. Less time and effort are required to dispense the drops onto an agar plate than to spread an equivalent total sample volume into the agar. By distributing the sample in drops, colony counting can be done faster and perhaps more accurately. Even though it has been present in the laboratory for many years, the drop plate method has not been standardized. Some technicians use 10-fold dilutions, others use twofold. Some technicians plate a total volume of 0.1 ml, others plate 0.2 ml. The optimal combination of such factors would be useful to know when performing the drop plate method. This investigation was conducted to determine (i) the standard deviation of the bacterial density estimate, (ii) the cost of performing the drop plate procedure, (iii) the optimal drop plate design, and (iv) the advantages of the drop plate method in comparison to the standard spread plate method. The optimal design is the combination of factor settings that achieves the smallest standard deviation for a fixed cost. Computer simulation techniques and regression analysis were used to express the standard deviation as a function of the beaker volume, dilution factor, and volume plated. The standard deviation expression is also applicable to the spread plate method.

Bacteriological Techniques↗
PubMed2006

Simple detection of small amounts of Pseudomonas cells in milk by using a microfluidic device.

AIMS: Flow cytometry offers rapid and reliable analyses of bacteria in milk. However, a flow cytometer is relatively expensive and operation is rather complicated for an unskilled operator. We applied flow cytometry using a microfluidic device (on-chip flow cytometry) in detection of small amounts of milk-spoiling bacteria. METHODS AND RESULTS: Pseudomonas cells in milk were in situ hybridized with Cy5-labelled probe specific for Pseudomonas spp. under optimized condition. Numbers of Pseudomonas cells in the stationary phase and in the starved state determined by on-chip flow cytometry were compared with those determined by conventional plate counting, and on-chip flow cytometry detected targeted cells in milk that were undetectable as colony forming units(CFU) on Standards Methods Agar. CONCLUSIONS: The contamination in milk with fewer than 10 CFU ml(-1) of targeted cells in starved state was detectable with simple procedure (0.5 h milk-clearing, 1 h fixation, 2 h hybridization and 0.5 h on-chip flow cytometry following 12 h enrichment of cells). SIGNIFICANCE AND IMPACT OF THE STUDY: On-chip flow cytometry following fluorescence in situ hybridization could be applicable to simple detection of milk-spoiling bacteria.

Animals↗
PubMed1976

Systemic Mycobacterium lepraemurium infection in mice: differences in doubling time in liver, spleen, and bone marrow, and a method for measuring the proportion of viable organisms in an inoculum.

Counts of acid-fast bacilli were made on homogenates of whole liver, whole spleen, and two femurs of CBA mice killed at various time intervals after intravenous infection with Mycobacterium lepraemurium. The growth curves so obtained showed that the bacillus multiplied faster in bone marrow than in liver or spleen. No evidence of redistribution during the early part of infection was obtained. The time of appearance of significant numbers of bacilli (10(7)) in the bone marrow was used to make estimates of viability of M. lepraemurium suspensions. Several applications of the techniques described are discussed.

Animals↗
PubMed1993

Intravenous interleukin-8 inhibits granulocyte emigration from rabbit mesenteric venules without altering L-selectin expression or leukocyte rolling.

Injection (i.v.) of the granulocyte chemoattractant/activator IL-8 has been shown to reduce neutrophil recruitment into dermal inflammatory sites in vivo. To further investigate the mechanism of this phenomenon, we examined the effect of i.v. [Ser-IL-8]72 (12-20 micrograms/kg) on leukocyte rolling and chemoattractant-induced emigration in mesenteric venules of New Zealand White rabbits and on expression of L-selectin (mAb LAM1-3) and CD18 (mAb 60.3) on circulating rabbit granulocytes. Within 1 min of IL-8 i.v., granulocytes virtually disappeared from carotid blood samples for approximately 5 min. Concomitantly, the flux of rolling leukocytes in mesenteric venules fell from 83 +/- 21 to 2 +/- 1 leukocytes/min. Both rolling leukocyte flux and systemic granulocyte count returned to or exceeded control values within less than 30 min. The chemoattractant/activator FMLP (0.15 microgram/kg i.v.) produced similar results. A second i.v. injection of IL-8 or FMLP, 90 min after the first challenge, had equipotent effects. Local extravascular application of IL-8 via micropipette close to a venule induced adhesion and emigration of 63 +/- 21 leukocytes per site before, but only 26 +/- 9 leukocytes per site 50 to 75 min after i.v. IL-8, when systemic granulocyte count and rolling leukocyte flux had reached or exceeded control values. This was not due to agonist-specific desensitization, because a similar reduction of leukocyte emigration was seen after FMLP i.v. Rabbit granulocytes circulating in vivo uniformly expressed near-control levels of L-selectin at all times between 3 and 360 min after IL-8 i.v. CD18 expression transiently increased after IL-8 i.v. and returned to base line by 90 min. These findings show that IL-8 i.v. reduces granulocyte recruitment to inflammatory sites by inhibiting function(s) necessary for transmigration that are independent of L-selectin and subsequent to rolling.

Animals↗
PubMed1980

Seasonal changes in prolactin and growth hormone cells in the hypophyses of white-tailed deer (Odocoileus virginianus borealis) studied by light microscopic immunocytochemistry and radioimmunoassay.

Numerous investigators have shown a relationship between basal serum prolactin (PRL) levels and photoperiod in domestic ungulates, and we have shown recently that a similar seasonal baseline serum PRL profile exists in both sexes of a captive but free-breeding population of white-tailed deer. In order to localize and describe the distribution and possible seasonal changes of PRL and growth hormone (GH) cells in the adenohypophyses of deer, we have used antisera raised against ovine PRL and bovine GH and the unlabeled antibody enzyme technique, in conjunction with point counting morphometry. In addition, we have measured seasonal changes in pituitary PRL concentrations in this same population, using a heterologous application of a recently developed homologous radioimmunoassay (RIA) for ovine PRL. Our results show that GH and PRL cells comprise two morphologically separate and immunologically distinct populations. Growth hormone cells were distributed evenly throughout the gland, except in the zona tuberalis, and males had a slightly greater volume density of immunoreactive GH than females; however, there were no differences between sexes in the average size of these cells, and little seasonal change was observed in these cell populations. In contrast to GH cells, the volume density of PRL cells, the size of PRL cells, and the pituitary concentration of RIA--measurable PRL all showed marked seasonal changes in deer of both sexes. These changes were well correlated with one another and with previously reported changes in basal serum levels (in these animals), in that they all reached zenith during midsummer, and nadir in midwinter. Our results demonstrate the necessity of reporting the time of year and latitude (to specify photoperiod) in studies concerning PRL cell physiology, particularly when dealing with any wild animal population.

Animals↗
PubMed1999

Quantitation of adenovirus DNA and virus particles with the PicoGreen fluorescent Dye.

A microplate assay for the rapid quantitation of adenovirus DNA has been developed using the fluorescent dye PicoGreen, which selectively binds double-stranded DNA. The method was first applied to extracted adenoviral DNA and then extended to samples of intact, purified adenovirus after lysis of the viral capsid with the ionic detergent SDS. Utilizing the stoichiometric relationship between adenovirus DNA and intact particles, a physical particle count of intact virus is then derived for the sample. This PicoGreen-based assay has excellent reproducibility, linearity, and sensitivity. In its present form, this assay has a limit of quantitation of 10.3 ng/ml viral DNA, predicted to correspond to 2.6 x 10(8) virus particles/ml. This procedure was compared to a widely utilized spectroscopic method, in which samples are lysed with SDS and absorbance is read at 260 nm, and found to be 10- to 20-fold more sensitive. The dye binding assay also uses considerably less sample volume (<20%) than that needed for the spectroscopic method. Particle count values generated by the PicoGreen procedure are consistently lower (typically 1.5- to 2-fold) than this spectroscopic method. The applications and limitations of this method in the analysis of adenovirus samples are discussed.

Adenoviridae↗
PubMed2003

Performance evaluation of a hand-held, semiconductor (CdZnTe)-based gamma camera.

We have designed and developed a small field of view gamma camera, the eZ SCOPE, based on use of a CdZnTe semiconductor. This device utilises proprietary signal processing technology and an interface to a computer-based imaging system. The purpose of this study was to evaluate the performance of the eZ scope in comparison with currently employed gamma camera technology. The detector is a single wafer of 5-mm-thick CdZnTe that is divided into a 16x16 array (256 pixels). The sensitive area of the detector is a square of dimension 3.2 cm. Two parallel-hole collimators are provided with the system and have a matching (256 hole) pattern to the CdZnTe detector array: a low-energy, high-resolution parallel-hole (LEHR) collimator fabricated of lead and a low-energy, high-sensitivity parallel-hole (LEHS) collimator fabricated of tungsten. Performance measurements and the data analysis were done according to the procedures of the NEMA standard. We also studied the long-term stability of the system with continuous use and variations in ambient temperature. Results were as follows. INTRINSIC ENERGY RESOLUTION: 8.6% FWHM at 141 keV.LINEARITY: There was excellent linearity between the observed photopeaks and the known gamma ray energies for the given isotopes. INTRINSIC SYSTEM UNIFORMITY: For the central field of view, the integral uniformity and the differential uniformity were, respectively, 1.6% and 1.3% with the LEHR collimator and 1.9% and 1.2% with the LEHS collimator. SYSTEM SPATIAL RESOLUTION: The FWHM measurements made at the surface of the collimator were 2.2 mm (LEHR) and 2.9 mm (LEHS).CONTRAST TEST: The average S/N ratios (i.e. counts in the irradiated pixel divided by counts in the surrounding pixels) for the inner ring pixels (8)/outer ring pixels (16) using the LEHS collimator and LEHR collimator were 3.2%/0.2% and 3.7%/0.3%, respectively. COUNT RATE CHARACTERISTICS: We could not determine the maximum count rate and the 20% loss count rate from these data because the plateau was not reached while using the solutions measured. SYSTEM SENSITIVITY: The average acquisitions were 11,052 cpm/MBq (LEHR) and 28,590 cpm/MBq (LEHS). TEMPERATURE DEPENDENCE: The system displayed minimum corresponding shift in cps with temperature changes in the measured temperature range. We designed and developed a semiconductor-based gamma camera using CdZnTe. The basic performance of this camera compares favourably with the existing gamma camera technology that is deployed in the medical field today. The most significant differences include the spatial resolution, sensitivity, high count rate characteristics and energy resolution. We believe that this device will be of value for a number of clinical applications including sentinel node detection and radiopharmaceutical-guided surgery.

Cadmium↗
PubMed1994

Reduction of dietary protein and phosphorus in the Modification of Diet in Renal Disease Feasibility Study. The MDRD Study Group.

OBJECTIVE AND DESIGN: The Modification of Diet in Renal Disease (MDRD) Feasibility Study was designed to test procedures and evaluate the feasibility of a full-scale clinical trial aimed at assessing the effects of reduction of dietary protein and phosphorus on progression of renal disease. SETTING AND SUBJECTS: Ninety-six patients with chronic renal insufficiency were randomly assigned to different diets in one of two studies depending on their glomerular filtration rate. INTERVENTION: The diets contained three different protein and phosphorus levels: moderate diet = 1.3 g protein per kilogram per day and 16 to 20 mg phosphorus per kilogram per day; low diet = 0.575 g protein per kilogram per day and 5 to 10 mg phosphorus per kilogram per day; and very low diet with keto or amino acids = 0.28 g protein per kilogram per day and 4 to 9 mg phosphorus per kilogram per day. Eight-five patients were monitored for at least 6 months; maximum follow-up was 22 months. MAIN OUTCOME MEASURES: Compliance with study diets was measured monthly using urea nitrogen appearance and 3-day diet diaries plus one 24-hour recall. The main outcome measure was change or maintenance of glomerular filtration rate. STATISTICAL ANALYSES PERFORMED: Data were analyzed by analysis of variance and paired t tests. RESULTS: Mean dietary protein intake, as determined by urea nitrogen appearance, decreased significantly in participants assigned to the diets low and very low in protein and phosphorus (P < .05). Overall, the follow-up protein intake (based on urea nitrogen appearance) as a percentage of baseline ranged from 45.8% to 83.1%. Analysis of diet diaries showed better dietary adherence than indicated by urea nitrogen appearance. Review of the exchange methodology used in dietary instruction suggests that imprecision of the exchange lists may have been a factor in the difficulty study participants had in achieving +/- 10% of the target protein goal. APPLICATIONS: Based on the MDRD Feasibility Study, the protocol for the full-scale study was modified to include protein counting instead of food exchange methodology to monitor protein intake.

Amino Acids↗
PubMed1989

A rapid and direct method for the detection and quantification of interleukin-1 receptors using 96 well filtration plates.

A rapid method for the detection and quantification of interleukin-1 receptors in cultured cells has been developed. The receptor binding assay is carried out in sealed 96 well filtration plates. At the end of the incubation period the seal is removed and the cells are filtered under vacuum to separate free ligand from bound. After washing several times, individual wells are removed using a well punch and counted in a gamma counter. The method is rapid, accurate and capable of high sample throughput and should find wide application as a screen to evaluate IL-1-like drugs.

Cell Line↗
PubMed1992

Reproducibility of mitosis counting in 2,469 breast cancer specimens: results from the Multicenter Morphometric Mammary Carcinoma Project.

The Multicenter Morphometric Mammary Carcinoma Project is a prospective study on the reproducibility and prognostic value of routine quantitative assessments, especially the mitotic activity index (MAI), the multivariate prognostic index (MPI; a combination of MAI, tumor size, and lymph node status), the mean nuclear area, and DNA ploidy assessments in patients with invasive breast cancer. Fourteen pathology laboratories providing routine services to 35 hospitals throughout The Netherlands are participating in this project. In this article, the reproducibility of MAI and MPI assessments is described. Assessment of the MAI was, according to a strict protocol, first performed in the participating laboratories; thereafter, slides were transferred to the coordination center in Amsterdam for quality control. Analysis of the reproducibility of the assessments in 2,469 patients showed correlation coefficients between 0.81 and 0.96 (mean, 0.91) for the MAI and between 0.91 and 0.97 (mean, 0.96) for the MPI. The reproducibility was fairly constant in time, although it showed a slight drop in the middle of the 2-year intake period. A prognostically relevant discrepancy in MPI (caused by differences in MAI) between the original and quality control assessments was found in only 7.2% of the cases. When analyzing the reasons for these discrepancies, a plausible explanation could be found in all cases: bad tissue processing and ignorance of or negligence in following the protocol guidelines for selection of the counting area or in the process of counting were the most important flaws. Since these errors are largely controllable, an even lower discrepancy rate is theoretically achievable. In conclusion, in a routine setting it can be learned, within a reasonable time, to perform mitosis counting in a highly reproducible way if a strict protocol is carefully followed. This opens the way for a wider application of the MAI and MPI in breast cancer patients. Motivation is, however, an important factor to obtain reproducible results, and ongoing quality control is essential to guarantee the reproducibility of the assessments.

Breast Neoplasms↗
PubMed1991

The red blood cell distribution width.

The availability of automated blood cell analyzers that provide an index of red blood cell distribution width (RDW) has lead to new approaches to patients with anemia. While the emergency physician is primarily responsible for the detection of patients with anemia, the inclusion of the RDW in the complete blood count has made diagnosing certain anemias easier, especially those that are microcytic. The derivation of the RDW and its clinical application to emergency physicians is discussed and a categorization of anemias based on the mean corpuscular volume (MCV) and RDW is included.

Adult↗
PubMed2004

Imaging molecular interactions by multiphoton FLIM.

The spatio-temporal localisation of molecular interactions within cells in situ and in particular in vivo is of great importance in elucidating the key mechanisms in regulation of fundamental process within the cell. Measurements of such near-field localisation of protein complexes may be achieved by the detection of fluorescence (or Förster) resonance energy transfer (FRET) between protein-conjugated fluorophores. The use of fluorescence lifetime imaging microscopy (FLIM) to determine both intra- and intermolecular FRET has become an important and powerful technique for investigating biological systems. In this review we focus on the time-domain-based fluorescence lifetime sensing, using time-correlated single photon counting multiphoton microscopy. We give a description of the technique, including data acquisition and analysis, and discuss the different biological applications of this technology.

Animals↗
PubMed2004

Coding with noisy neurons: stability of tuning curve estimation strongly depends on the analysis method.

An important issue in the neurosciences is a quantitative description of the relation between sensory stimuli presented to an animal and their representations in the nervous system. A standard technique is the construction of a neural tuning curve, that is, a neuron's average firing rate as a function of some parameter characterizing a family of stimuli. It is unavoidable that some of the response data are erroneously attributed to a cell, e.g., during spike sorting. However, the widely used method of statistical analysis based on the sample mean and least-squares approximation for the spike count can perform extremely badly if the noise distribution is not exactly normal, which is almost never the case in applications. Here, we present a method for constructing neural tuning curves that is especially suited for cases of high noise and the presence of outliers. Since it is usually not decidable if an outlier is faulty or not we limit the influence of far outlying points rather than try to identify and discard them. In contrast to traditional methods employing a point-by-point estimation of a tuning curve, we use all measured data from all different stimulus conditions at once in the construction. Given the measured data at only a finite number of stimulus conditions, a robust tuning curve is obtained that approximates the cell's ideal tuning curve optimally in all stimulus conditions with respect to a given distance measure. A measure that assesses the quality of this fitting method with respect to the traditional least-squares fitting method and to a median-based fitting method is introduced. The reliability of inference with respect to the encoding accuracy that can be achieved by a population of neurons is demonstrated in both artificially generated and experimentally recorded data from rat primary visual cortex. While the data shown in this paper are responses to orientation stimuli, the method of tuning curve construction is also viable and maintains its optimality properties for the case in which the stimulus is defined on a finite interval.

Action Potentials↗
PubMedDate not supplied

Application of simple mathematical expressions to relate the half-lives of xenobiotics in rats to values in humans.

INTRODUCTION: Previous publications from GlaxoSmithKline and University of Toledo laboratories convey our independent attempts to predict the half-lives of xenobiotics in humans using data obtained from rats. The present investigation was conducted to compare the performance of our published models against a common dataset obtained by merging the two sets of rat versus human half-life (hHL) data previously used by each laboratory. METHODS: After combining data, mathematical analyses were undertaken by deploying both of our previous models, namely the use of an empirical algorithm based on a best-fit model and the use of rat-to-human liver blood flow ratios as a half-life correction factor. Both qualitative and quantitative analyses were performed, as well as evaluation of the impact of molecular properties on predictability. RESULTS: The merged dataset was remarkably diverse with respect to physiochemical and pharmacokinetic (PK) properties. Application of both models revealed similar predictability, depending upon the measure of stipulated accuracy. Certain molecular features, particularly rotatable bond count and pK(a), appeared to influence the accuracy of prediction. DISCUSSION: This collaborative effort has resulted in an improved understanding and appreciation of the value of rats to serve as a surrogate for the prediction of xenobiotic half-lives in humans when clinical pharmacokinetic studies are not possible or practicable.

Algorithms↗
PubMed2005

Bacteriophage P100 for control of Listeria monocytogenes in foods: genome sequence, bioinformatic analyses, oral toxicity study, and application.

Listeria monocytogenes is an opportunistic foodborne pathogen responsible for Listeriosis, a frequently fatal infection. This investigation represents a comprehensive approach to characterize and evaluate the broad host range, strictly virulent phage P100, which can infect and kill a majority of Listeria monocytogenes strains. First, the complete nucleotide sequence (131,384 basepairs) of the genome of P100 was determined, predicted to encode 174 gene products and 18 tRNAs. Bioinformatic analyses revealed that none of the putative phage proteins has any homologies to genes or proteins of Listeria or any other bacteria which are known or suspected to be toxins, pathogenicity factors, antibiotic resistance determinants, or any known allergens. Next, a repeated dose oral toxicity study in rats was conducted, which did not produce any abnormal histological changes, morbidity or mortality. Therefore, no indications for any potential risk associated with using P100 as a food additive were found. As proof of concept, and to determine the parameters for application of P100 to foods sensitive to Listeria contamination, surface-ripened red-smear soft cheese was produced. Cheeses were contaminated with low concentrations of L. monocytogenes at the beginning of the ripening period, and P100 was applied to the surface during the rind washings. Depending on the time points, frequency and dose of phage applications, we were able to obtain a significant reduction (at least 3.5 logs) or a complete eradication of Listeria viable counts, respectively. We found no evidence for phage resistance in the Listeria isolates recovered from samples. Taken together, our results indicate that P100 can provide an effective and safe measure for the control of Listeria contamination in foods and production equipment.

Animals↗
PubMed1988

Influence of preoperative showers on staphylococcal skin colonization: a comparative trial of antiseptic skin cleansers.

We undertook a prospective randomized observer-blinded study comparing the ability of preoperative showers with chlorhexidine gluconate (Hibiclens), povidone-iodine (Betadine), and a lotion soap (Safe 'N Sure) to diminish the staphylococcal skin flora of patients. By block randomization, patients scheduled for an elective cardiac operation or coronary artery angioplasty were assigned to shower with one of the study skin cleansers either once (evening only) or twice (both evening and morning) before the procedure. Semiquantitative samples for culture were obtained from the subclavian and inguinal sites on the evening before the procedure (baseline culture) and again the next morning before the operation. The chlorhexidine skin cleanser consistently reduced staphylococcal colony counts at both the subclavian and inguinal sites before the procedure. This reduction was significant for patients showering both evening and morning (p less than 0.05). The use of the povidone-iodine skin cleanser inconsistently affected skin flora. Patients using lotion soap either experienced no change or had an increase in colony counts. Chlorhexidine is more effective than povidone-iodine in diminishing skin colonization with staphylococci in patients before operation. Repeated applications of chlorhexidine are superior to a single shower with this agent.

Anti-Infective Agents, Local↗
PubMed1997

Treatment of acne with a combination clindamycin/benzoyl peroxide gel compared with clindamycin gel, benzoyl peroxide gel and vehicle gel: combined results of two double-blind investigations.

BACKGROUND: It has previously been shown that a combination of erythromycin and benzoyl peroxide is superior to either ingredient when used alone in the treatment of acne. A clindamycin/benzoyl peroxide combination gel might have an advantage over erythromycin/benzoyl peroxide gel because the former does not require refrigeration after it is dispensed. OBJECTIVE: Our purpose was to determine the efficacy and safety of a combination clindamycin/benzoyl peroxide gel when compared with benzoyl peroxide, clindamycin, or vehicle gels. METHODS: In two double-blind, randomized, parallel, vehicle-controlled trials, patients were treated for 11 weeks with once-nightly application of one of the above preparations. Evaluations were performed at 2, 5, 8, and 11 weeks and included lesion counts and assessment of global responses and irritant effects. RESULTS: A total of 334 patients completed the study. All three active preparations were significantly superior to the vehicle in global improvement and in reducing inflammatory lesions and noninflammatory lesions. The combination gel was significantly superior to the two individual agents in global improvement and reduction of inflammatory lesions and also to the clindamycin gel in reducing noninflammatory lesions. There was no significant difference in tolerance to the active gels versus the vehicle gel. CONCLUSION: In the treatment of acne, topical clindamycin/benzoyl peroxide combination gel is well tolerated and superior to either individual ingredient.

Acne Vulgaris↗