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PubMed1996

Further observations on comparison of immunization coverage by lot quality assurance sampling and 30 cluster sampling.

Lot Quality Assurance Sampling (LQAS) and standard EPI methodology (30 cluster sampling) were used to evaluate immunization coverage in a Primary Health Center (PHC) where coverage levels were reported to be more than 85%. Of 27 sub-centers (lots) evaluated by LQAS, only 2 were accepted for child coverage, whereas none was accepted for tetanus toxoid (TT) coverage in mothers. LQAS data were combined to obtain an estimate of coverage in the entire population; 41% (95% CI 36-46) infants were immunized appropriately for their ages, while 42% (95% CI 37-47) of their mothers had received a second/ booster dose of TT. TT coverage in 149 contemporary mothers sampled in EPI survey was also 42% (95% CI 31-52). Although results by the two sampling methods were consistent with each other, a big gap was evident between reported coverage (in children as well as mothers) and survey results. LQAS was found to be operationally feasible, but it cost 40% more and required 2.5 times more time than the EPI survey. LQAS therefore, is not a good substitute for current EPI methodology to evaluate immunization coverage in a large administrative area. However, LQAS has potential as method to monitor health programs on a routine basis in small population sub-units, especially in areas with high and heterogeneously distributed immunization coverage.

Cluster Analysis↗
PubMed1996

Cross-sectional sample preparation by focused ion beam: a review of ion-sample interaction.

A focused ion beam (FIB) was applied for cross-sectional sample preparation with both transmission electron microscopes (TEM) and scanning electron microscopes (SEM). The FIB sample preparation has the advantage of high positioning accuracy for cross sections. On the other hand, a broad ion beam (BIB) has been conventionally used for thinning TEM samples. Although both FIB and BIB use energetic ion beams, they are essentially different from each other in many aspects such as beam size, beam current density, incident angle of the beam with respect to cross sections, and beam scanning (i.e., dynamic or static beam). In this study, FIB cross-sectioning is compared with BIB thinning. We review inherent characteristics such as positioning accuracy and uniformity of cross section, radiation damage, and beam heating. Discussion is held from a view-point of ion beam and sample interaction.

Ions↗
PubMed1996

On planning of samples for linkage analysis: two ways of a sample size reduction.

The sample size required for a given type I and type II errors of linkage decision is determined by using the earlier proposed method of the linkage test power estimation [Ginsburg et al., 1996]. Dependence of the sample size on the heterozygotic genotype penetrance is investigated. Two approaches to sample size reduction are considered: the choice of marker gene and the special extension of analyzed pedigree structures. Their effects are quantitatively evaluated in some illustrative situations. It is shown that a practical reduction in sample size can be achieved only when the added part of a pedigree has a special set of phenotypic characteristics in its members.

Genetic Linkage↗
PubMed2000

Collection devices for obtaining cervical cytology samples.

OBJECTIVES: The false-negative rate of cervical smears varies between 1.5% and 55%. This variation may be partly due to differences in sampling device and technique. The objective of this review was to assess different cervical sampling devices for collecting endocervical cells, which are thought to be a surrogate for detection of abnormal cells and adequate smear rates. SEARCH STRATEGY: We searched the Cochrane Gynaecological Cancer Group trials register and MEDLINE up to July 1997. We also handsearched 16 journals. SELECTION CRITERIA: Randomised and quasi-randomised trials and non-randomised comparative studies comparing cervical smear collection devices in women attending for primary screening, colposcopy following an abnormal smear or colposcopy after treatment. DATA COLLECTION AND ANALYSIS: Two reviewers independently abstracted data. Study quality was assessed. MAIN RESULTS: Thirty-four trials and six observational comparative studies were included. The Ayre spatula was shown to be less effective compared with extended tip spatulas for collecting endocervical cells in eight trials (odds ratio 2.25, 95% confidence interval 2.06 to 2.44). Use of a spatula with the cytobrush was more effective than spatula alone at collecting endocervical cells (odds ratio 3.33, 95% 3.05 to 3.63) and the same effect was present for adequate smear rates (odds ratio 1.51 95% 1.19-1.92). Extended tip spatulas were also superior for the detection of dyskaryosis in seven trials (odds ratio 1.21, 95% confidence interval 1.10 to 1.33). Based on data from two trials and three observational studies, smears that contained endocervical cells were more likely to detect dyskaryosis, particularly in severe disease. The proportion of smears with endocervical cells present increased with increasing severity of the disease. REVIEWER'S CONCLUSIONS: Extended tip spatulas of various designs appear to be better for collecting endocervical cells than the commonly used Ayre spatula. The most effective combination appears to be the cytobrush with an extended tip spatula. The rate of detection of endocervical cells appears to be a valid and convenient surrogate for the ability to detect dyskaryosis and for adequate smear rates. The ability of the extended tip spatula with the cytobrush compared with the extended tip spatula alone to detect disease, needs to be evaluated in a trial.

Female↗
PubMed2003

Improving sensitivity by large-volume sample stacking using the electroosmotic flow pump to analyze some nonsteroidal anti-inflammatory drugs by capillary electrophoresis in water samples.

Large-volume sample stacking using the electroosmotic flow (EOF) pump (LVSEP) has been used to analyze some nonsteroidal anti-inflammatory drugs (NSAIDs) in water samples. With methanol as the run buffer solvent to suppress the EOF, sensitivity was enhanced by 80-100-fold. The sample for the analysis of real water sample was pretreated by solid-phase extraction (SPE). When the method was based on off-line SPE-LVSEP-CE, sensitivity improved by as much as 1000 times.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2005

On-line sample preconcentration with chemical derivatization of bacterial biomarkers by capillary electrophoresis: a dual strategy for integrating sample pretreatment with chemical analysis.

Simple, selective yet sensitive methods to quantify low-abundance bacterial biomarkers derived from complex samples are required in clinical, biological, and environmental applications. In this report, a new strategy to integrate sample pretreatment with chemical analysis is investigated using on-line preconcentration with chemical derivatization by CE and UV detection. Single-step enantioselective analysis of muramic acid (MA) and diaminopimelic acid (DAP) was achieved by CE via sample enrichment by dynamic pH junction with ortho-phthalaldehyde/N-acetyl-L-cysteine labeling directly in-capillary. The optimized method resulted in up to a 100-fold enhancement in concentration sensitivity compared to conventional off-line derivatization procedures. The method was also applied toward the detection of micromolar levels of MA and DAP excreted in the extracellular medium of Escherichia coli bacterial cell cultures. On-line preconcentration with chemical derivatization by CE represents a unique approach for conducting rapid, sensitive, and high-throughput analyses of other classes of amino acid and amino sugar metabolites with reduced sample handling, where the capillary functions simultaneously as a concentrator, microreactor, and chiral selector.

Acetylcysteine↗
PubMed2003

Feasibility of a liquid-phase microextraction sample clean-up and liquid chromatographic/mass spectrometric screening method for selected anabolic steroid glucuronides in biological samples.

Anabolic androgenic steroids (AAS) are metabolized extensively in the human body, resulting mainly in the formation of glucuronide conjugates. Current detection methods for AAS are based on gas chromatographic/mass spectrometric (GC/MS) analysis of the hydrolyzed steroid aglycones. These analyses require laborious sample preparation steps and are therefore time consuming. Our interest was to develop a rapid and straightforward method for intact steroid glucuronides in biological samples, using liquid-phase microextraction (LPME) sample clean-up and concentration method combined with liquid chromatographic/tandem mass spectrometric (LC/MS/MS) analysis. The applicability of LPME was optimized for 13 steroid glucuronides, and compared with conventional liquid-liquid extraction (LLE) and solid-phase extraction (SPE) procedures. An LC/MS/MS method was developed for the quantitative detection of AAS glucuronides, using a deuterium-labeled steroid glucuronide as the internal standard. LPME, owing to its high specificity, was shown to be better suited than conventional LLE and SPE for the clean-up of urinary AAS glucuronides. The LPME/LC/MS/MS method was fast and reliable, offering acceptable reproducibility and linearity with detection limits in the range 2-20 ng ml(-1) for most of the selected AAS glucuronides. The method was successfully applied to in vitro metabolic studies, and also tested with an authentic forensic urine sample. For a urine matrix the method still has some unsolved problems with specificity, which should be overcome before the method can be reliably used for doping analysis, but still offering additional and complementary data for current GC/MS analyses.

Anabolic Agents↗
PubMed2005

Simple strategies for reducing sample loads in in vitro metabolic stability high-throughput screening experiments: a comparison between traditional, two-time-point and pooled sample analyses.

Higher-throughput ADME programs in early drug discovery are becoming common throughout the pharmaceutical industry as companies strive to reduce their compound attrition in later-stage development. Many of the ADME assays developed into higher-throughput formats rely on LC/MS analyses. Since the biological aspects of the assay are amenable to parallel processes using dense plate formats, the number of samples generated from these assays produce a large analysis load for serial LC/MS. Presented in this report are two novel strategies, including a sample pooling method and a two time-point method, that could be used in drug discovery to reduce the number of samples generated during multiple time-point in-vitro ADME assays. One hundred and sixty-three compounds were subjected to human microsomal incubations with full time-point method samples taken at t = 0, 5, 15, 30, and 45 min. The ER data correlation (R(2)) between the full time-point method and the pooling method and two time-point methods were 0.98 and 0.97, respectively. Both methods have the potential to: 1. produce data of similar quality to traditional high throughput ADME assays, 2. be easily implemented, 3. shorten analytical run times, and 4. be reproducible and robust.

Algorithms↗
PubMed1982

Automated sampling of in vitro dissolution medium: effect of sampling probes on dissolution rate of prednisone tablets.

The effect of sampling probe size and location on the in vitro dissolution rate of prednisone tablets was examined. Using USP XX Apparatus 2 with an automated sampling system, dissolution rates were determined using two types of large filter-tipped probes and a small capillary probe. Each probe was tested at three locations within the kettle. The large probes caused hydrodynamic changes which, when compared with results obtained through manual sampling, resulted in significant changes in dissolution rates at each location. These changes were less evident when the capillary probe was used, with an insignificant difference between results of automated and manual sampling when the capillary probe was placed midway between the paddle shaft and the kettle wall.

Autoanalysis↗
PubMed2005

On-line multi-bed sorption trap for VOC analysis of large-volume vapor samples: injection plug width, effects of water vapor and sample decomposition.

A multibed on-line sorption trap is used to preconcentrate organic vapors from air samples and inject the analytes into a GC separation column. Injection plug widths depend on the boiling point for the lipophilic compounds and on the polarity and boiling point for the polar compounds. Injection plug widths are sufficiently small (0.7-0.8 s) as to allow the direct injection of the most volatile compounds into the GC column without the need for a second focusing device. The presence of water in the samples has an effect on the retention of polar compounds by the trap. However, this effect is reproducible for a fixed water content and so can be overcome by using calibration standards under the same conditions of humidity as the samples. The thermal decomposition of many volatile organic compounds in an on-line sorption trap during the GC analysis of air samples is examined. The results show that degradation of unstable compounds is governed by the amount of heat transferred to the compounds during desorption (i.e., applied temperature and pulse duration). The use of an on-line trap results in the immediate transfer of desorbed compounds to the analytical column, which can reduce the formation of artifacts.

Journal Article↗
PubMed2004

On sampling and sampling errors in histomorphometry of peripheral nerve fibers.

Histomorphometrical assessment of regenerated peripheral nerves is a very common goal of many studies in experimental microsurgery. In this paper, the main critical issues in nerve fiber sampling for quantitative morphological assessment are addressed. The equal opportunity rule, i.e., the basic paradigm of random sampling, is described, together with an explanation of how sampling errors, in the selection of histologic fields and of the nerve fibers inside them, can produce a bias in quantitative estimates. Finally, some practical suggestions on how to cope with the most common sampling errors are provided, in order to help researchers obtain reliable histomorphometrical data on peripheral nerve fibers.

Humans↗
PubMed1993

A liquid chromatographic method for the simultaneous determination of alpha-tocopherol and tocopherolquinone in human red blood cells and other biological samples where tocopherol is easily oxidized during sample treatment.

A liquid chromatographic method for the simultaneous determination of alpha-tocopherol and tocopherolquinone in human red blood cells is described. Tocopherols in the red cell membrane are very susceptible to oxidation during sample processing. Red cell samples are saponified in the presence of a mixture of butylated hydroxytoluene, ascorbic acid, and pyrogallol and then extracted with hexane. The tocopherol compounds are separated on a C-18 column using a mobile phase containing 12% acetonitrile, 83% methanol, and 5% buffer (NaH2PO4.H2O, 7.5 mM final concentration) and are detected electrochemically. The mixture of antioxidants is essential to avoid loss of the tocopherol compounds during processing of samples. The use of acetonitrile in the mobile phase results in the separation of tocopherolquinone from delta-tocopherol. The proposed method may be generally suitable for the analysis of biological samples where tocopherols are especially vulnerable to oxidation. The levels of tocopherolquinone and delta-tocopherol in normal red cells are quite small (less than 1% of alpha-tocopherol). The ratio of tocopherol and tocopherolquinone concentrations might serve as a useful index of the redox status of red cell membranes, particularly under in vitro conditions.

Biological Assay↗
PubMed2000

Techniques for sample preparation including methods for concentrating peptide samples.

In the current era of proteomics two main analytical techniques are employed for protein identification. By far the fastest and most sensitive procedure for protein identification employs biological mass spectrometry, while de novo sequence analysis by classical Edman degradation is currently diminishing. In order to achieve the highest sensitivity for both techniques, great demands need to be put on sample preparation. In this paper we review three different aspects of protein sample preparation. Firstly, we discuss the use of polyacrylamide or agarose gel systems in which, during electrophoresis, proteins present in multiple primary gel pieces are eluted and simultaneously concentrated in a small secondary gel volume, whereby the overall sensitivity of Edman sequencing can be greatly increased. In a second chapter we review automation strategies occurring in the protein field which allow the automatic handling of multiple protein spots at the same time. In this context, we describe the use of auto-sampling techniques for further mass spectrometric studies and protein digestion robots allowing the simultaneous preparation of tens of gel-separated proteins. Finally we discuss various strategies for the preparation of biological peptide samples such as protein digests for both matrix-assisted laser desorption ionisation and electrospray ionisation mass spectrometry.

Automation↗
PubMed2005

[Molds in air-sampling and detection. Validation of sampling methods to verify molds in air].

The assessment of mold concentrations in air samples requires generally accepted evaluation criteria. It is not possible to derive guideline values based on risk assessment. Background concentrations are therefore used as the basis for the assessment of measured concentrations. The assessment criteria established by the Federal Environmental Agency in Berlin and by the State Health Agency of Baden-Wurttemberg are founded on the experience of some laboratories. The general application of these criteria is only meaningful if validated and generally applied methods of analysis are used. Until now, laboratories have been using many different methods for sampling and detection of culturable molds and total spore counts in air. In this study, different steps for sampling by impaction or filtration are validated. The results presented will contribute to standardization of sampling and detection of molds in air.

Air Pollutants↗
PubMed2002

Determination of manganese in herbal medicine samples by slurry-sampling electrothermal atomic absorption spectrometry with a metal tube atomizer.

An ultrasonic slurry-sampling electrothermal atomic absorption spectrometry with a molybdenum tube atomizer has been developed for the determination of manganese in herbal medicine samples. Ten percent glycerol solution was used as the slurry medium. The optimum pyrolysis temperature was 400 degrees C. The detection limit was 69 fg (3xS/N). Matrix element interference was checked and it was found that glycerol as a chemical modifier eliminated the interference. The amounts of manganese in herbal medicines determined by the proposed method are in good accordance with those measured in dissolved acid-digested samples. The method enables rapid calibration, and simple and rapid analysis of manganese in herbal medicine samples at low cost.

Herbal Medicine↗
PubMed2004

Accurate determination of sulfur in gasoline and related fuel samples using isotope dilution ICP-MS with direct sample injection and microwave-assisted digestion.

Inductively coupled plasma isotope-dilution mass spectrometry (ICP-IDMS) with direct injection of isotope-diluted samples into the plasma, using a direct injection high-efficiency nebulizer (DIHEN), was applied for accurate sulfur determinations in sulfur-free premium gasoline, gas oil, diesel fuel, and heating oil. For direct injection a micro-emulsion consisting of the corresponding organic sample and an aqueous 34S-enriched spike solution with additions of tetrahydronaphthalene and Triton X-100, was prepared. The ICP-MS parameters were optimized with respect to high sulfur ion intensities, low mass-bias values, and high precision of 32S/34S ratio measurements. For validation of the DIHEN-ICP-IDMS method two certified gas oil reference materials (BCR 107 and BCR 672) were analyzed. For comparison a wet-chemical ICP-IDMS method was applied with microwave-assisted digestion using decomposition of samples in a closed quartz vessel inserted into a normal microwave system. The results from both ICP-IDMS methods agree well with the certified values of the reference materials and also with each other for analyses of other samples. However, the standard deviation of DIHEN-ICP-IDMS was about a factor of two higher (5-6% RSD at concentration levels above 100 mircog g(-1)) compared with those of wet-chemical ICP-IDMS, mainly due to inhomogeneities of the micro-emulsion, which causes additional plasma instabilities. Detection limits of 4 and 18 microg g(-1) were obtained for ICP-IDMS in connection with microwave-assisted digestion and DIHEN-ICP-IDMS, respectively, with a sulfur background of the used Milli-Q water as the main limiting factor for both methods.

Fuel Oils↗
PubMed2004

Enzymatic probe sonication extraction of Se in animal-based food samples: a new perspective on sample preparation for total and Se speciation analysis.

This paper describes a fast, simple and novel extraction method for total selenium and selenium species determination in food samples. Parameters influencing extraction, such as sonication time, extracting media, temperature, sample mass, ultrasound amplitude and sample/enzyme mass ratio were investigated. The enzymatic hydrolysis proposed, enhanced by probe sonication, allowed the quantitative extraction of selenium in chicken muscle, liver, kidney and feed (97, 93, 95 and 102%, respectively) in 2 min, maintaining the original Se-species integrity. Total Se content of the samples was determined using inductively coupled plasma mass spectrometry. Se-species were identified and quantified using high-performance liquid chromatography in conjunction with inductively coupled plasma mass spectrometry. Chromatographic analyses were carried out under two chromatographic conditions and led to the identification of SeMet in all samples. The accuracy of the proposed method was assessed using certified reference materials as well as microwave digestion. Potential advantages of the proposed method over traditional hydrolysis are speed, simplicity and safety of the procedure.

Animal Feed↗
PubMed2006

Evaluation of sampling technique and transport media for the diagnostics of adenoviral eye infections. Adenovirus sampling and transport.

BACKGROUND: Human adenoviruses (HAdV) may cause pharyngoconjunctival fever, follicular conjunctivitis or epidemic keratoconjunctivitis (EKC). Especially, outbreaks of the latter may lead to severe economic losses when preventive measures are implemented too late. Thus, a safe sampling method, proper specimen transport conditions and a fast and sensitive diagnostic technique is mandatory. METHODS: Two commercially available virus transport systems (VTS) were compared with two NaCl-moisturised sampling devices, one of which comprises Dacron-tipped plastic-shafted swabs and the other a cotton-tipped wood-shafted swab, available in most ophthalmologists' offices. Downstream methods for specific detection of HAdV included direct immunofluorescence assay (IFA) of conjunctival swabs, virus isolation by cell culture and quantitative real-time polymerase chain reaction (qPCR). Furthermore, the influence of application of local anaesthetics prior to swabbing on subsequent detection of HAdV was investigated. RESULTS: Application of local anaesthetics had a positive influence on the amount of swabbed cells, thus increasing the chance of obtaining positive results by IFA. Neither isolation of HAdV by cell culture nor by qPCR was negatively influenced by this pretreatment. Surprisingly, both commercially available VTS performed significantly worse than the NaCl-moisturised swabs. This was shown with regard to virus recovery rates in cell culture as well as viral genome copy numbers in the qPCR. CONCLUSIONS: Based on our results, the following recommendations are provided to improve sampling, transport and diagnostic techniques regarding conjunctival swabs for diagnosis of human adenovirus infection: (1) application of local anaesthetics, (2) NaCl-moisturised VTS for shipment of specimens, and (3) detection of HAdV by qPCR. The latter method proved to be superior to virus isolation by cell culture, including subsequent identification by IFA, because it is faster, more sensitive and allows simultaneous handling of a number of samples. Hence, countermeasures to prevent further virus spread in an outbreak situation can be implemented earlier, thus reducing the number of subsequent adenoviral infections.

Adenovirus Infections, Human↗