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PubMed2003

Local and systemic chemotherapy with taurolidine and taurolidine/heparin in colon cancer-bearing rats undergoing laparotomy.

Experimental studies in the therapy of malignant abdominal tumors have shown that different cytotoxic agents suppress the intraperitoneal tumor growth. Nevertheless, a general accepted approach to prevent tumor recurrences does not exist. Following subcutaneous and intraperitoneal injection of 10(4) colon adenocarcinoma cells (DHD/K12/TRb), the influences of both taurolidine or taurolidine/heparin on intraperitoneal and subcutaneous tumor growth was investigated in 105 rats undergoing midline laparotomy. The animals were randomized into 7 groups and operated on during 30 min. To investigate the intraperitoneal (local) influence of either taurolidine or heparin on tumor growth, the substances were applied intraperitoneally. Systemic and intraperitoneal effects were evaluated after intravenous injection of the substances. Both application forms were also combined to analyze synergistic effects. Tumor weights, as well as the incidence of abdominal wound metastases, were determined four weeks after the intervention. In order to evaluate the effects of the agents, blood was taken to determine the peripheral leukocytes counts. Intraperitoneal tumor growth in rats receiving intraperitoneal application of taurolidine (median 7.0 mg, P = 0.05) and of taurolidine/heparin (median 0 mg, P = 0.02) was significantly reduced when compared to the control group (median 185 mg). The simultaneous instillation of both agents also reduced the intraperitoneal tumor growth (median 4 mg, P = 0.04), while the intravenous injection of the substances caused no local effect. In contrast, the subcutaneous tumor growth did not differ among all groups. In all groups, abdominal wound recurrences were rare and did not differ. Independent of the agents and the application form, the operation itself caused a slight leukopenia shortly after the operation and a leukocytosis in the following course. Intraperitoneal therapy of either taurolidine or in combination with heparin inhibits local tumor growth and abdominal wound recurrences in rats undergoing midline laparotomy. Neither the intraperitoneal nor the intravenous application or the combination of the two agents influenced the subcutaneous tumor growth. The substances did not alter the changes of peripheral leukocytes.

Animals↗
PubMed2001

Interpreting atmospheric pollen counts for use in clinical allergy: allergic symptomology.

BACKGROUND: Allergists generally consider atmospheric pollen counts to be an estimate of the antigenic challenge confronting allergic individuals. The nature of this challenge depends on the particular pollen types found in the atmosphere and also the airborne concentration of these pollen types. Both clinical experience and clinical investigations support these assumptions; however, a coherent system for relating pollen counts and allergic symptomology does not exist. OBJECTIVE: This review article will systematically review the medical and technical literature concerning the clinical significance of atmospheric pollen counts. DATA SOURCES: This review article will consider three independent bodies of literature: 1) data contrasting human exposure patterns with rooftop pollen counts; 2) data concerning dose-response relationships between atmospheric pollen counts and allergic symptomology; and 3) data concerning methods for indexing atmospheric pollen counts based on a pollen type's in vivo allergenicity and terminal velocity. RESULTS: Three principal results emerged. First, rooftop pollen counts imperfectly approximate human exposure to atmospheric pollen. Differences in both the concentration and type of pollen encountered by humans can be expected to differ from samples obtained on rooftops. Second, allergic symptomology is positively correlated with atmospheric pollen counts. Investigations involving Betula (birch) pollen offer quantitative dose-response models. Complex, nonlinear relationships that seem to reflect both the priming effect and late-phase reactions exist. Last, atmospheric pollen counts can be indexed based on a contemporary application of Thommen's postulates. This system provides allergists with a means to estimate the clinical significance of various pollen types by combining data concerning in vivo allergenicity and terminal velocity. CONCLUSIONS: These conclusions should allow allergists to judge the clinical significance of atmospheric pollen counts with greater sophistication than was previously possible.

Air Pollution↗
PubMed2001

Application of a spectrophotometric method for the determination of post-antibiotic effect and comparison with viable counts in agar.

The post-antibiotic effects of gentamicin and ciprofloxacin at 1x, 2x and 4x MIC on Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 29213 were studied using a spectrophotometric method and the classic method of viable counts on agar as a reference. Monitoring of the growth kinetics was carried out by viability counting on the plate every hour and by means of the optical density of the cultures measured by spectrophotometry at a wavelength of 450 nm. No statistically significant differences were found between the results obtained with the spectrophotometric method and the reference method. The former method was much quicker, much easier to use and to replicate.

Agar↗
PubMed1986

Effective use of dairy herd improvement somatic cell counts in mastitis control.

The single most important factor affecting somatic cell count in milk is mammary gland infection status. In comparison, all other factors are minor. Consideration needs to be given to diurnal effects on Dairy Herd Improvement a.m.-p.m. sampling schemes. Somatic cell count linear score of 5 (283,000) appears to be a good choice of threshold for mastitis control applications. A greater understanding of the nonbacteriological factors affecting somatic cell count is needed so that relative thresholds could be used to improve the clarity of somatic cell count interpretation. Linear score loss estimates are effective educational tools providing motivation for mastitis control implementation. Infection status or milk loss estimates based on single somatic cell count tests on individual cows are weak. A lactational average linear score on individual cows or linear score compilations across a herd provide credible estimates. Treatment of subclinical mastitis based on somatic cell count levels is not economically beneficial and is not recommended. Usefulness of Dairy Herd Improvement somatic cell count data as a mastitis management tool requires measures of mastitis level, new infection rate, and mastitis pattern within the herd over time.

Animals↗
PubMed2000

A method for the selection of the optimum counting conditions in a ZnS(Ag) scintillation detector.

The well-known criteria for the selection of the optimum counting conditions in a ZnS(Ag) scintillation detector seem to restrict its applicability. These do not consider simultaneously operating voltage and electronic threshold variation to reach the best counting conditions. Therefore, a more general method for the determination of the optimum counting conditions in ZnS(Ag) scintillation detectors is proposed. In this method, a relationship between voltage and electronic threshold is derived for counting efficiency. In order to test the method, quality control procedures have been carried out as well as the determination of gross alpha activity in environmental samples.

Americium↗
PubMed1983

Reproductive hazards in the workplace. Development of epidemiologic research.

Application of the techniques of epidemiology and clinical toxicology has accelerated study of the reproductive effects of toxic chemical and physical exposures in the workplace. Three examples of work in progress are included in the present communication. The first concerns 1,2-dibromo-3-chloropropane, a known cause of male sterility, which continues to be used as a nematocide in Hawaii. Occupational exposures of Hawaiian agricultural workers to airborne 1,2-dibromo-3-chloropropane are mainly in the range of parts per billion. A prospective study of pineapple field workers has been undertaken to evaluate sperm counts and morphology before, during, and after 1,2-dibromo-3-chloropropane application. To date, no sperm count depression is evident at this level of exposure. The second example involves a cluster of seven spontaneous abortions in female office workers exposed to video display terminals. The cluster has been analyzed with the use of fetal life tables. Excess incidence was confirmed (p = 0.0045), but no etiology was determined. The findings may have been due to chance. The third example pertains to male chemical workers manufacturing diaminostilbene, an optical brightener, and the workers' reported sexual impotence. Impotence was confirmed in 7 of 29 workers by questionnaire and suggested for another 7. Serum testosterone analyses found depressed values (less than 300 mg/ml) in 8 of 28 exposed workers. The luteinizing hormone and follicular stimulating hormone levels were generally normal.

Abortion, Spontaneous↗
PubMed1986

A field evaluation of Bacillus thuringiensis var. israelensis as a biological control agent for Simulium chutteri (Diptera:Nematocera) in the middle Orange River.

Bacillus thuringiensis Berliner var. israelensis de Barjac (Serotype H-14) (B.t.i.) at a concentration of 1.6 ppm/10 min and a toxicity of 1500 AAU/mg was tested against Simulium chutteri Lewis larvae in the Orange River near Prieska, South Africa. Samples of benthic fauna from the stones-in-current biotope were collected before application of the product and at various intervals up to 80 h afterwards at 4 stations from 200 m to 11 km downstream of the application site. Fauna drift increased slightly after the arrival of the Bacillus at 2 stations 1.4 and 6 km respectively downstream of the application site. Large numerical decreases in benthic simuliid larval numbers after the application of B.t.i. in the Orange River were not statistically different (P greater than 0.05). This indicated that the size of replicated samples that showed significant decreases (P less than 0.05) of simuliid numbers in the Vaal River was not adequate to show statistical differences in the Orange River. The quantity of dead larvae on stones collected from rapids after application of the B.t.i., and the numerical decreases found by comparing median values of larval counts on stones indicated that B.t.i. effectively killed simuliid larvae. Three days after application of the Bacillus, recruitment of small simuliid larvae on stones 1.4 km downstream of the application site was discernible again. Tanytarsini were also numerically reduced after B.t.i. application. At a flow rate of 38 m3/s B.t.i. was visibly effective in killing S. chutteri up to 6 km downstream of the application site and statistically significant decreases (P less than 0.05) in numbers of larvae were seen at a site 11 km downstream of the application site.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1996

How to count synapses unbiasedly and efficiently at the ultrastructural level: proposal for a standard sampling and counting protocol.

After almost 40 years, there is still no consensus on criteria for identifying different types of synapse seen in electron microscopical thin sections or on methods for counting them unbiasedly in 3D. This review proposes a procedure which meets these aims and could be adopted as a standard best-practice sampling and counting convention. It deals exclusively with unbiased stereological methods for counting particles in 3D space because these are efficient and applicable to arbitrary particles regardless of their size, shape and orientation. Methods based on individual sections are excluded because arbitrary particles cannot be counted unbiasedly with such sections. Model-based methods (e.g. treating synaptic membrane densities as circular disks) are excluded because they are not unbiased in general and now have limited (mainly historical) interest only. For unbiased counting, the absolute minimum requirement is a pair of parallel sections (dissector). The following protocol is recommended for future studies on synapse number: (1) use para(membrane) densities as synaptic counting units, (2) do not qualify definition of the counting unit by reference to a minimum number of synaptic vesicle profiles, (3) sample and count synapses unbiasedly using the dissector, and (4) in preference convert number per volume into absolute number or, in this is not possible, estimate a synapse-to-neuron ratio.

Animals↗
PubMed2002

Evaluation of a universal template for single-platform absolute T-lymphocyte subset enumeration.

The single-platform absolute T-lymphocyte subset analysis was evaluated utilizing a universal protocol in a Canadian multicenter study with the collaboration of the members of the Canadian HIV Trials Network (CTN). Participants used flow cytometers and reagents of their choice for labeling and lysing whole blood. Over a 2-year period, CTN laboratories performed single-platform absolute T-lymphocyte subset enumerations on fresh and commercial stabilized blood products using commercially available microfluorospheres TruCount and Flow-Count. This multicenter evaluation demonstrated that the application of a universal template for single-platform analysis provides a generic approach that embraces a wide array of immunophenotyping settings available in clinical laboratory.

CD3 Complex↗
PubMedDate not supplied

Effects of allopurinol on free-radical-induced reduction of the proliferation of retinal pigment epithelial cells.

PURPOSE: To investigate the effects of allopurinol on free-radical-induced reduction of growth of retinal pigment epithelial (RPE) cells. METHODS: Bovine RPE cells were seeded at a density of 1 x 10(5) cells/Petri dish (60 x 15 mm) containing 4 ml MEM-Earle plus 15% FCS plus antibiotics. Twenty-four hours after seeding, cultures were exposed to a free radical generating system hypoxanthine(HX)/xanthine oxidase (XO) (HX: 0.1 micromol/l; XO: 700 microU/ml) for 10 or 60 min. Thereafter, the cells were washed. After washing the cells, allopurinol was added at 500 or 1000 micromol. To evaluate the effect of the radical generating system one group was not washed after treatment ('no wash'). The cultures were divided into eight groups: (1) no treatment (control); (2) HX/XO, no wash; (3,4) HX/XO, washed after 10 or 60 min; (5,6) HX/XO, washed after 10 or 60 min, application of 500 micromol of allopurinol; (7,8) HX/XO, washed after 10 or 60 min, application of 1000 micromol of allopurinol. Cell counts were carried out 96 h post-seeding. The values are expressed as means +/- SE. RESULTS: After 72 h (HX/XO, no wash), the radical generating system resulted in a significant decrease in cell growth as compared to controls. When being eliminated after 10 or 60 min, the radical generating system also led to significant decrease in the values as compared to controls. Allopurinol treatment: All therapy (scavenger) groups (4,5) were significantly different from the respective control group; following exposition to the radical generating system for 60 min, allopurinol showed significantly higher values when given at 1000 micromol as compared to 500 micromol. CONCLUSIONS: The results demonstrate that allopurinol, when given at a scavenger dose (500-1000 micromol), can prevent free-radical-induced cell damage and stop chain reactions. Thus, the possible beneficial value of allopurinol on diseases with involvement of oxidative tissue damage, such as age-related macular degeneration, should be investigated further.

Allopurinol↗
PubMed1986

Plasma renin assay calculation using Lotus 1-2-3.

The calculation of results from a Plasma Renin Activity (PRA) assay requires many intermediate steps that are both tedious and prone to error. Using Lotus 1-2-3C and the IBM PCT, these assay calculations can be reduced to simply entering the raw counts obtained from the gamma counter. This calculation method is for use with Clinical Assay's Gamma-CoatT PRA kit, one of the most widely used commercial kits. A template that utilizes a logarithmic curve fit equation to calculate a point to point standard curve for the assay is set up on the Lotus spreadsheet. By using a point to point curve fit, a standard curve that is a very close approximation to a manually drawn plot is generated by the computer. Using Lotus's macro feature, a routine is built into the template to automatically move the cursor from cell to cell for the entry of the raw counts. All data can be entered using only the numeric key pad and RETURN key. When all data has been entered, the macro calculates the assay results and prints out a hardcopy report. In 52 samples, comparing the PRA results obtained from the manually plotted standard curve and those calculated by the template yielded a coefficient of correlation of 0.997, p less than 0.001. We conclude that the computer generated results are comparable to results obtained from a manually drawn curve. All calculations can be quickly obtained simply by entering the raw counts from the gamma counter using this application of Lotus 1-2-3C with the Clinical Assay's GammaCoatT PRA kit.

Humans↗
PubMed2004

A protocol for quantifying the birth, death and emigration rates of produce-associated bacteria, illustrated by its application to Salmonella enterica serovar Typhimurium on cultivated mushrooms.

Colony counts, counts of immunostained cells, fluorescent assays for cell viability and titration of a superinfecting bacteriophage were incorporated into a protocol for studying the growth kinetics of produce-associated bacteria in vivo. A set of equations was assembled for measuring the true rates of birth, death and emigration of the bacteria within the frame of a "transit growth" model, thus allowing the independent measurement of the carrying capacity of the substrate and of the overall productivity of the system. Implementation of the protocol on two species of cultivated mushrooms inoculated with Salmonella enterica serovar Typhimurium showed that large bacterial populations developed on Agaricus bisporus A15 but emigration was not detected, whereas resident populations on Agrocybe aegerita FAR142 amounted to 79.7%, 65.1% and 80.7% of the cultivable, dead and total bacterial cells produced, owing to emigration.

Agaricales↗
PubMed1993

Quality assurance for sperm concentration using latex beads.

OBJECTIVE: To provide a simple, universally applicable method of quality assurance for sperm counting, thereby reducing intercounting chamber variation. DESIGN: By using a known concentration of latex beads, the sperm:bead ratio can be used to calculate the actual sperm count. MAIN OUTCOME MEASURES: The mean sperm and bead counts were determined in both a Spot-lite hemocytometer (Baxter Diagnostics, McGaw Park, IL) and a Makler chamber (Polymedco Inc., Yorktown, NY) from 21 different ejaculates mixed with a known concentration of beads. The hemocytometer chamber was used as the standard counting chamber because it consistently yielded a low variation in sperm count. The adjusted sperm concentration of the Makler chamber was calculated using the following formula [hemocytometer beads]/[Makler beads] x [Makler sperm]. RESULTS: Observed mean +/- SD sperm counts were significantly different between the hemocytometer chamber (110.6 +/- 66.2 x 10(6)/mL) and Makler chamber (173.3 +/- 103.5 x 10(6)/mL). However, calculated Makler chamber sperm counts (118.1 +/- 76.1 x 10(6)/mL) was not statistically different from observed hemocytometer sperm counts. CONCLUSION: This novel approach to sperm counting using a known concentration of latex beads as a reference material can be used to reduce variation in sperm counting between observers, counting chambers, and possibly computerized sperm analyzers.

Equipment and Supplies↗
PubMed1999

GLLS for optimally sampled continuous dynamic system modeling: theory and algorithm.

The original generalized linear least squares (GLLS) algorithm was developed for non-uniformly sampled biomedical system parameter estimation using finely sampled instantaneous measurements (D. Feng, S.C. Huang, Z. Wang, D. Ho, An unbiased parametric imaging algorithm for non-uniformly sampled biomedical system parameter estimation, IEEE Trans. Med. Imag. 15 (1996) 512-518). This algorithm is particularly useful for image-wide generation of parametric images with positron emission tomography (PET), as it is computationally efficient and statistically reliable (D. Feng, D. Ho, Chen, K., L.C. Wu, J.K. Wang, R.S. Liu, S.H. Yeh, An evaluation of the algorithms for determining local cerebral metabolic rates of glucose using positron emission tomography dynamic data, IEEE Trans. Med. Imag. 14 (1995) 697-710). However, when dynamic PET image data are sampled according to the optimal image sampling schedule (OISS) to reduce memory and storage space (X. Li, D. Feng, K. Chen, Optimal image sampling schedule: A new effective way to reduce dynamic image storage space and functional image processing time, IEEE Trans. Med. Imag. 15 (1996) 710-718), only a few temporal image frames are recorded (e.g. only four images are recorded for the four parameter fluoro-deoxy-glucose (FDG) model). These image frames are recorded in terms of accumulated radio-activity counts and as a result, the direct application of GLLS is not reliable as instantaneous measurement samples can no longer be approximated by averaging of accumulated measurements over the sampling intervals. In this paper, we extend GLLS to OISS-GLLS which deals with the fewer accumulated measurement samples obtained from OISS dynamic systems. The theory and algorithm of this new technique are formulated and studied extensively. To investigate statistical reliability and computational efficiency of OISS-GLLS, a simulation study using dynamic PET data was performed. OISS-GLLS using 4-measurement samples was compared to the non-linear least squares (NLS) method using 22-measurement samples, GLLS using 22-measurement samples and OISS-NLS using 4-measurement samples. Results demonstrated that OISS-GLLS was able to achieve parameter estimates of equivalent accuracy and reliability in comparison to NLS or GLLS using finely sampled measurements (22-measurement samples), or OISS-NLS using optimally sampled measurements (4-measurement samples). Further more, as fewer measurement samples are used in OISS-GLLS, this algorithm is computationally faster than NLS or GLLS. Therefore, OISS-GLLS is well-suited for image-wide parameter estimation when PET image data are recorded according to the optimal image sampling schedule.

Algorithms↗
PubMed1999

In vitro selection of an allosteric ribozyme that transduces analytes to amplicons.

We have selected an allosteric ribozyme ligase from a random sequence population that is activated up to 10,000-fold by oligonucleotide effectors. The ribozyme conforms to a classic two-state model for allostery in which the equilibrium between inactive and active conformers is dramatically altered by the presence of effector ligands. In the presence of the effector the allosteric ribozyme ligase generates templates that can subsequently be amplified using conventional amplification technologies, such as RT-PCR. Thus, the allosteric ribozyme can transduce (or convert) analytes into amplicons. We demonstrate two potential diagnostic applications of the selected allosteric ribozyme ligase: 'counting' short oligonucleotide effectors by RT-PCR, and counting a non-nucleic acid effector, ATP, by ligation.

Allosteric Site↗
PubMed2004

Efficient exact p-value computation for small sample, sparse, and surprising categorical data.

A major obstacle in applying various hypothesis testing procedures to datasets in bioinformatics is the computation of ensuing p-values. In this paper, we define a generic branch-and-bound approach to efficient exact p-value computation and enumerate the required conditions for successful application. Explicit procedures are developed for the entire Cressie-Read family of statistics, which includes the widely used Pearson and likelihood ratio statistics in a one-way frequency table goodness-of-fit test. This new formulation constitutes a first practical exact improvement over the exhaustive enumeration performed by existing statistical software. The general techniques we develop to exploit the convexity of many statistics are also shown to carry over to contingency table tests, suggesting that they are readily extendible to other tests and test statistics of interest. Our empirical results demonstrate a speed-up of orders of magnitude over the exhaustive computation, significantly extending the practical range for performing exact tests. We also show that the relative speed-up gain increases as the null hypothesis becomes sparser, that computation precision increases with increase in speed-up, and that computation time is very moderately affected by the magnitude of the computed p-value. These qualities make our algorithm especially appealing in the regimes of small samples, sparse null distributions, and rare events, compared to the alternative asymptotic approximations and Monte Carlo samplers. We discuss several established bioinformatics applications, where small sample size, small expected counts in one or more categories (sparseness), and very small p-values do occur. Our computational framework could be applied in these, and similar cases, to improve performance.

Computational Biology↗
PubMed2001

The impact of maternal smoking during pregnancy on delivery outcome.

BACKGROUND: Maternal smoking during pregnancy is associated with pre-term birth, intrauterine growth retardation, a small head circumference, a low Apgar score at 5 min and stillbirths and neonatal deaths. This study was undertaken in order to investigate the impact of maternal smoking during pregnancy when all these outcomes were considered. METHODS: With the use of the Swedish Medical Birth Registry, infants in any one of the above mentioned outcome groups were selected from 1,413,811 infants born between 1983 and 1996 with known smoking exposure in early pregnancy. Confounders such as year of birth, maternal age, parity and educational level were controlled for. The attributable risk of maternal smoking on the various negative delivery outcomes was obtained by application of the risk estimates to population counts. RESULTS: The present study confirmed the associations between maternal smoking and the miscellaneous outcomes mentioned above with high significance. The odds ratios (with 95% confidence intervals) for maternal smoking (< 10 cigarettes/day and > or = 10 cigarettes/day) for any one of the outcomes were 1.39 (1.37-1.41) and 1.65 (1.62-1.68) respectively (dose-response p < 0.001). The number of attributable cases caused by maternal smoking was estimated at 15,000, which represents 9% of all cases and 1% of all infants born in Sweden during the study period. CONCLUSION: Maternal smoking during pregnancy accounts for a substantial part of various negative delivery outcomes.

Adult↗
PubMed1983

Precorneal drainage of polyvinyl alcohol solutions in the rabbit assessed by gamma scintigraphy.

A method for monitoring the ocular distribution of solutions for ophthalmic use was developed using the technique of gamma scintigraphy. This method was used to monitor the effects of polyvinyl alcohol on the precorneal drainage of [99mTc]pertechnetate in the rabbit. The rate of drainage of solutions decreased on addition of PVA and precorneal residence of the marker was significantly prolonged, compared with saline controls, at a PVA concentration of 5% W/V. Increases in the activity in the inner canthal region mirrored the decrease in corneal counts. The method has a more general application for the study of ophthalmic formulations and devices in larger mammals and in man.

Animals↗